>> i think we've covered a lot

of important ground probably no area that is of greatest significance and the effects of global warming . not only to our water supply but the system as a whole. it's appropriate that we have commissioner harrington for this discussion as well willing to do that and take away. >> thank you so much president moran. the people and government we often see usually what's happening yesterday, maybe next week, ultimately next year but one of the things about the public utilities commission is weare looking way out, 20, 50 years .we know there's going to be things that affect this organization for years to come and that it takes a long time

to get ready for thesethings and make the changes we need to make but as we look at climate change is one of thethings that has been one of the larger unknowns . we get severe weather events . we understand thatwe get that there's sealevel rise but things like precipitation, is going to come as rain or snow ? will there be more or less of it and what is the watershed? these are things that make us thinking more conservatively so the more we know and learn about these items the better decisions we can make. that's the reason for having these conversations and this workshop today. the purpose is to have the commission and public have a common understanding of what we know about climate change and in its effects on the regional water system and realize that climate change also means wastewater focusing on the

regional water systems. we've been planning for climate change for more than 15 years. you'll hear about the history of that including our involvement with the water utility and climate alliance which house started when she was general manager of the transects and also presentation from staff and doctor casey from the university of massachusetts amherst which will cover information on the climate analysis on the regional water system. whether we are seeing precedents ofclimate change in our watershed and how we are staying engaged in the climate approaches . the stretch that is going to be hearing from staff and expert presentationsfollowed by commission discussion and there should be plenty of time for that. then we schedule some time to hear from a variety of ngos , not to ask for their agreement, disagreement butfor all that are chairing us todaybut we want to make sure they had time to give us their thoughts, comments, and questions as we go forward .

and then we will and with public comment . before we start like to thank alan levine for putting this presentation together and so with that i asked the commission secretary to call the next item and then we will turn it over to ellen for the presentation . >> your first order of business is item 3, climate change and regional water testing. >>. >> good afternoon commissioners, i'm ellen levin, deputy manager of the water enterprise and i'm real happy to be here to talk about climate change and the regional water system. next slide please. i'll start with a brief introduction of the topics we will cover in our presentation and introduce you to our panel members. will start off with a history of climate change analysis that have been conducted by the puc. and then i'll turn it over to alexi for a water resource

engineer of our hydrology and water systems growth. alexi will share observations of climate change in our watershed and talk about relatively new tools that we're using to better forecast runoff to our reservoirs. the climate program director will talk about our engagement in collaboration about climate science and then finally doctor casey brown from the university of massachusetts stanford systems research group is the principal investigator in the long-term vulnerabilities that will providean overview of that agency. next slide please . so this is a timeline that provides a bit of a snapshot of work that the sfpuc has been involved in evaluating climate change over the last nearly 15 years . i'm going to spend a few minutes on the analysis that we relied upon in pei are for the water system treatment program

and the sensitivity analysis that we completed in 2012 and then doctor brown will be covering the long-term vulnerability assessment . i'll just say that this was a research collaboration that was conducted through the water research foundation with ds after puc, university of massachusetts, national center for atmospheric research and the study that's expected to be published in mid-november water research foundation to say you're getting a preview, i'm sorry that we did not have to study available for review prior to this but i think it's will be very appropriate to hear about what the study found and the methods that were applied. the next slide please. our climate analysis on the regional water system really started with just looking at the effects ofincreased in temperature . this image shows the ground

surface and the watershed and staff, puc staff focused on changes due to a 1 and a half degree and three degreeincrease in temperature . these temperature rises were based on a consensus among many climatologists that global climate modeling at that time suggested as a three degree rise in to 2020 60 and a six degree rise would occur by at 2100. the evaluation predicted the snow line would rise by 500 feet for every increasein one and a half degree in temperature . the old yellow outline on the image shows the snow line moving up in elevation as a result of temperature increase. where snowpack coverage in the watershed decreases from 87 percent to 83 percent, 76 percent from 2000 to 2025 to 2050 and really the conclusions

that the water system improvement program was that the shift from 87 percent to 83 percent in snowpack wasn't going to be a significant effecton our water supply . this is a verylimited analysis next slide please .the next more seminal climate analysis would be performed on the regional water system as well and this was a joint study with the irrigation district. evaluated the sensitivity of free flow and potential changes in temperature and precipitation resulting from climate change. in this study we studied five degrees celsius increase and a 15 percent decrease in precipitation. through 18 different climate scenarios. the findings were that climate changeaffects would be most severe in dry years .

that's no population isreduced and snow melts earlier in the spring . the distribution of runoff will shift with winter and early spring runoff increasing and late spring and summer runoff decreasing. and while temperature increases alone after affect the most significant effects are seen when temperatureincreases and precipitation decreases . i just want to note that neither this analysis nor the pir analysis reallylooked at the effects on water supply. they were focused on the effects of changes in inflow to our reservoir . and this is where the long-ter vulnerability sets in . that elevates our analysis of climate change because it looks atand will look at the water supply effects of climate change as well as other changes that could occur . i am now going to turn it over to alexi to start talking about

an observation of climate change in our watershed. next slide please. >> thank you helen.thank you commissioners. for tackling this important topic. i'll begin by showing you observations of signal most likely caused by climate change in the puc watersheds. as you probably know it contains a system of monitoring stations and although also fun state and federal monitoring efforts and it's because of these collections we can analyze the trends that i will resent.so first, this further metric here in temperature. we do observe the water main in all regions as far as systems. so this figure shows a historic average dailyminimum temperature .

it's since the mid-1950s, for first be country and in the middle of the peninsula in the east bay onthe right. on the vertical access we have the temperature and on the horizontal axis we have the time . we can see a clear warning trend in all watersheds and the largest increase that we can observe in any given temperature is the east bay where it reaches about two degrees c since the 1950s. next slide please. so another important variable is precipitation and here i'm presenting to you an annual portfolio so we donot observe a significant trend in annual precipitation . this figure shows the historic ... >> make sureto speak into your

microphone, you're coming up a little bit blurred . >> i would say that this figure shows the historic annual precipitation since the mid-1950s again or again the upcountry lancelot and the deep bay. and on the vertical axis we show the annual total precipitation and of the year. we do not observe a significant trend in annual precipitation. you will see a slight angle in the blue line. but that trend is not specifically evident. next slide. >> another important hydrology variable is the snowpack. and it's on our records since 1988. we observed that the snowpack disappears earlierin the year .

we observed a trend in earlier snow disappearing by about 15 to 20 days over the last 30 years. we also observed that a greater portion of our annual water available to the city on the river appears prior to june 15 and we presumably think that it's dueto earlier snowmelt . we have not observed a trend in annual volume of water available to the city. but we have observed a trend in distribution. next slide. this slideillustrates my previous point . on snow disappearance but first the top plot shows the statistics on date of the snowpack. and i'm presenting this data

for debbie. data snowpack per decade doesn't is a moving decade.it doesn't seem to have a clear trend. it drops, it goes back up, it drops, it goes backup . it's not clear trend. however the lowerlot , the bomb plot shows the date of snow disappearance.again for these moving decades. and here you see that we have a steady decline in that date. meaning that earlier and earlier in the year the snow disappears at our snow monitoring stations . and this could be caused by observed warming. next slide. so another important aspect of climate change that we hear a lot about is precipitation. intense precipitation events

and we experienced anintense precipitation last weekend . but we observed it even more important event in 2018 moccasin reservoir. when we had a real extreme event. we received three inches in fourhours which is unusual . we moccasin diverging dad which is just upstream of moccasin reservoir overtop which does happen, the inflows into the moccasin reservoir were about 16,000 cfs whichfor us is unheard of . and these inflows exceeded the probable maximum flood which is really hard to imagine because the probable maximum flood is designed for them. it is the event that we don't even try to put a probabilityto it . it's completely a detail of the

distribution. so this was a real shocker for us. next slide. so of course, with all these changes, we're also trying to develop new tools for forecasting and monitoring. and i will present three ongoing projects. next slide. the first one is the advanced precipitation information system or hup i-4 short which improves the resolution of rainfall forecasting in the bay area. it improves both spatial and temporal resolution. it is designed to better capture the atmosphericrivers which are currently not really well captured by the current

radars . mister rivers tend to be lower in elevation than the current observation radar beams. part of this project is to add er into the area variable and the rainfall forecast will be used by both water and wastewater enterprise for better forecasting of runoff and then improvingoperation at facilities . this is a project that nola, national oceanic and atmospheric agency is the lead contractor and they're working with academics and local partners including sfpuc, valley water and flood control and sanitary districts from the day. the project is funded and i want to say sfpuc also spearheaded this project initially before it was picked up again by seminal water.

next slide. another effort is the forecast informed reservoir operations. the idea combine weather forecasts and inflow forecasting tools so that we have over a 14 day lookahead period forecast of inflows into the reservoirs and we then combined with operation restrictions that we have on our reservoirs in the system so we better guide the operations of these reservoirs. it is currently implemented at cherry and calaveras reservoirs. this allows for a more flexible operation so that we can maximize our over storage. it's an ongoing effort at multiple events in california. many other agencies are doing

the same work. next slide. so lastly the third example is the airbornesnow observatory for aso . and sfpuc has been participating since its inception in 2013. so the idea is to fly a plane over to watershed to measure the depth of this snowpack and therefore have a continuous estimation of the snowpack volume over the entire watershed. instead of relying only on dozens of snow monitoring stations and monthly snow surveys. so we fly watershed twice a month and get as much more accurate picture of the snowpack volume so that we can better forecast the runoff into

our reservoirs. we believe that this is a more reliable method and tool to forecast water supply in these changing climates. actually all three approaches aretaking advantage of new forecasting methods . for a more flexible operation to which we believe is needed in a changing climate. so thank you. and let me know if you have any questions.otherwise i will pass to david. >> can we ask questions now and or do you want all the questions at the end of the presentation. >> there's something burning but other than that it wouldbe nice to see ifwe can have later presentations . it would be great to see if we have a chance there . >> i can wait, that's fine. iq.

david. >> david br, climate program director. great to be with you. i want to say quickly i am havingmovement issues. it's about 22nd delay . you guys are seeing slides right away. so it won't bother me at all. i've got them in front of me. so climate change is not new. obviously we've been working with it and understanding it for decades but what is new is that we're all having to evaluate ourvulnerability and then start to planadaptation measures. for all new at this . we're sort of making it up as

we go along . water utilities, local state national government, the private sector exploring the implications of the unprecedentedevents and long-term changes , many of which have not been experienced in this district. there's greatuncertainty about the science of climate . not about climate change and what about the when and how. there is uncertainty about density of climate and concentrations in the atmosphere. two future commissions where are we going in a planetary scale on emissions. and of course then the tools and balls are still evolving that telus what we can expect in the future. so where acting in an environment of uncertainty and we don't have a clear roadmap about what to do about where were going . but we do know we need to take action. next slide please . so again in that context what were doing is enhancing our

collaboration across institutional and in some ways organizational borders. this has been part of the sfpuc's approach since 2007 when we contain the climate change summit according to observers at the time to talk about what our vulnerabilities look like and what we were going to do . i'm focusing today on that collaboration and how it's contributed to our activities on climate. and those collaborations have a national regional and departmental level. next slide please. so the first example is the water utility climate alliance which commissionerharrington mentioned in his opening remarks . there are 12 utilities as we call it for short. we have over 15 million drinking water customers

overall. we have a number of wastewater and storm water including combined system water utilities in the gulf as well. and it is now rotating between the utility members. it's beenin his 14th year of work overall . next slide please. hold on. i can't see the slide and ican see my page . so we have a number of programs and that we've been working on. a lotof it is about learning. learning from each other, learning from folks in the science community and elsewhere . we're in a tremendous amount science and models we've learned about uncertainties in

which to deal with that uncertainty while still making plans . we learned about the implications of one or another variable on operations. on our land, on our ecosystems and water supplies. on our management of our wastewaterstorm water systems as well . i want to just highlight one briefly the leading actresses of adaptation. next slide, this is a report that came out just this year and it really draws on the utility experience individually and there are 16 case studies in there are examples of how we rattle with the challenges of climate change at the utility level with different principles that are represented in those projects. for san francisco the sea level rise which i'll come back to in the second was an example that was brought into that paper. we learned a lot from this work in terms of for example the

impacts of heat on workers. the as i mentioned but cautioned that one has to bring to the exercise was part of the modeling application spearheaded in the late teens. mainstreaming of climate information. not just the usual suspects like water supply or wastewater or storm water management but at different places we've looked at and seen in the last year likehealth and safety services, watershed management . so this is an example of how we think expand the understanding that we all have collectively and individually and the threats that we face. next slide please. at the regional level the bay area climate adaptation network is about four years old. it's a place where local governments and utilities can increasingly assign community-basedorganizations .

once put together to understand public utilitylevel what we're all doing and what we're all understanding about climate change . it's 43 number organizations, local governments and a growing list of ceos as i mentioned . part of a larger network of collaboration that they call this statewide and the alliance of regional collaboratives and the agents of the local government commission . and it's a real going concern that we have. it's excellent engagement on the part of our local governments community. next slide. one of the key roles that we had within daytime has been to surface equity. hopefully you have the equity slide up there now . the global adaptation is increasingly an agenda item that we are thinking about. and it's extremely important.

historically disadvantaged communities will be more disadvantaged as the adaptation measures that we need to take have an impact on everyone and disproportionate impact on historically disadvantaged communities in that they their mission statement is our goals is to help equitably climate change pictured here, are resources that they developed meeting practices in local adaptation and again a new but totally important field that we need to stay focused on. the next slide please. i think what's next is climate change coordination collaborationcommittee . thank you commissioner . >> sea level rise okay. so this is at a city level. this came out of an effort but in 2013 directed which is to

understand the effects of sealevel rise on our 10 year capital. making capital improvements of the city and we want to know how these investments are resilient . so we can be a multi agency multi departments committee within city and county government. everybody who had capital programs with the planning department and others to develop from a blank page this diagnosis that was adopted after almost exactly one year of development and implemented in 2014, revised in 2015 based on what we learned and revised again in 2020 based on the new science. one of the challenges of the first exercise was to understand the science and what we were faced with was a bit of a conundrum was that we had

three sources that all said something different particularly about high-end sealevel rise. this is acommon phenomenon in our world . the science is confusing, it's constantly changing, as reported in the media different ways so have to take that on. long story short we did and that resulted in the first i think official climate change connections adopted on a citywide basisfor sealevel rise in 2030, 2050 and 2100 . what was important a number of things were important but one of them was i think in an innovative way we develop an understanding of likelihood that wasn't quantitatively expressed which can be a little bit messy but really expressed by an understanding of what's likely based on what we know.

and was unlikely but possible. this is the uncertainty that grows in nature the loner out in time you go. the longer out you go the less predictive. and this is likely and unlikely but possible framing is still in place as the city and county's work on sealevel rise that i think is an important clue on how to take on this work in general. not to eliminate the high end of what's possible or worst-case scenarios that might have one present or 1/10 percent chance of what's occurring but to remember to keep it in the center of your mind, the center of the institution curve which is the most likely based on what we know. next slide. which hopefully will be puc. i don't have my plans in order. in addition master is an important part of this process

and what they did was tell us what different scenarios on sealevel rise were will inundate to what extent they will inundate the shoreline of sanfrancisco . since its increasingly common approach and unnecessary approach to understanding locations of sealevel rise i think what we have is 77 inches of sealevel rise which includes 36 inches of actual sealevel rise and then one percent storm on top of that which you evaluated as part of this where we suggested that itbe evaluated as part of the guidance . these were produced by the puc and used by the city produce for that stupid system improvement program and were really the first hydraulically sophisticated inundation maps that we saw in the bay area. where the first maps in 2007 conference had maps these models were less hydraulic than what these had so these were quite impactful .

and important. next slide. the last item in the guidance was a checklist which actually got a lot of attention. we had a lot of people telling us how did you do this checklist. it's very concrete and it was intended for project managers to look at their projects, evaluate them in detail. therefore abilities to authorize in a 100 year storm. as a tool that we expose 87 project managers to in the training in 2014 the first year we implemented and had two main purposes. one facilitated the implementation of project level which is important but not necessarily sufficient and the other is socialized staff to the reality of informed people what this is all about and the training that we did on

sealevel rise explain the upsurge, inundationmaps and vulnerabilities . they brought that understanding to their program. so it's kind of a powerful tool that we use in city government. next slide. finally is c-5 which is the collaboration that we have within the department. c-5 is the climate change coordinationcollaboration committee . it was formed in 2018 i believe with the charter that was approved and executive theme and is responding to the strategic plan at the time which said that we should develop coordination and can indicate in a comprehensive and consistent approach to mitigate and adapt to climate change so their mitigation which is the reduction of transmissions and adaptation which is responding to the realities of howclimate is changing . last slide please. and c-5 has been meeting since

thenit's been a little bit slower . and we did a number of important things and continue to do them. we did when we were still in the same building, lunch and learn sessions that will expose that we were interested in learning more about climate change . about issues like the california court and the prudential marketapproach to understanding vulnerability . the inventory climate change project is underway to ensure the basis of and contributed to the sb five multi-enterprise climate change that we presented two weeks ago tothe commission and we do on annual annual basis . we present one other what we're working on and finally we're working onclimate change policies i mentioned in our last meeting . that went along with an importation plan that we think can be alongside many other policies that we seem to govern how were doing climate change were developing the

implementation now after already having gotten the policy itself. to be considered by the executive team to have a lot more work to do on the importation and the things that we hope to raise the commission after it's been through multiple levels of staffing. that concludes, thank you. sorry for thequestions . >> over to doctorbrown . taken away. >> thanks ellen. if you can't hearthe okay , i'm going to go to the next slide. it should just be the title. so hello everyone. hello president moran, thank you for the opportunity to you today and present this study which has been a long time in

the making and really educational to me for sure. the name of the study is identified long-term vulnerabilities for our systems and it's done by the water researchfoundation. a tiny bit about me because i know we haven't met . i ama professor of engineering at the university of houston . i've been working on water and climate for about 20 years. i've been studying climatology at columbia university as a scientist. and i'd be curious why someone from massachusetts works on california water issues, i'll get into that later. but today i want to first talk about the objective of our study which is in the next slide. and i think you know the first overarching objective is our goal of creating a comprehensive understanding of the water system performance

under a wide range of uncertainties. and he, really the key aspect of this that i want to emphasize over and over again is our goal is to explore a range of plausible pictures rather than trying to make a guess of the most likely features. it would be wonderful if we could do that . i can tell you are climate goals for the systems. that would be awfully valuable. unfortunately we can't do that so we tried to focus on understanding what's plausible and what they mean for the census. that allows us to identify which of those features is vulnerable which then allows us to think abouthow we can build robustly . and i think what's nice about this approach is that not only is it useful for understanding

lines but understanding how to address the full abilities in the future. and so i have been working on a particular issue for quite a while and that is how do we use this time to inform our decisions because it's a key gap and the challenge that i find a lot of spacing. i think this field began with what i call and others call top-down impactstudies . first we come up with climate change projections. we run them through our model and say okay, here's what these projections mean for our system. those are useful but they don't give you a comprehensive understanding of how the system responds to the wide range of plausible issues that we face . so if you click one more time will show a cartoon of the

approach that we use which is targeted forinforming adaptations . it begins with framing the decision, defining what our system is, what the objectives for the system are, how we're going to measure success for example and in this case building models . this piece is something we call climate stress and this is a carefully designed algorithm that samples a widerange , thousands of plausible features so that we really leave no stone unturned and understand what future features are problematic for the system. once we do that we can use various sources of information including climateprojections and if you click one more time you'll see that appear . to essentially evaluate the vulnerabilities. how worried shouldwe be ? what's the level of concern with those vulnerabilities? but that's the approach we use

with the study. specifically we use it if you click one more time to the next slide which the questions that were motivating us as we applied this and the first was under what conditions and when will the regional water system no longer meet specific performance criteria over the horizon. the secondary question is climate change the most important driver of mobility for the system and here you have the key framing for this question is we realize we're pretty confident that economy is going to change in the future but it's not the only thing that's going to change in the future so it'simportant to thinkabout these other sorts of changes that could compound and maybe mitigate the climate change effects . next slide please . this is just a schematic of the various modeling systems that have been built. the kinds of inputs or

scenarios we investigated two stress test the system and the outputs . how do we interpret, what results do we get and how do w interpret the performance ? it's quite a framework. it's yours and unhappy to present it now and now i'll just go through some of the slides that wefound . and next slide please. what i'd like to do is talk a little bit more about this idea of stress tests and the stress testsagain the goal is future climate is uncertain , climate scientists are doing their best . often as they improve our understanding of the climate systems the range of possible climateoutcomes gets broader because we realize how complex it is . so our goal is to understand what the uncertainties of the future climate are such that we make sure we design our stress tests for thoseuncertainties so

the question is why is future climate uncertain ? the first is that there are unknown greenhouse gas emissions and were not sure what they are in terms of our various mitigation efforts so it's uncertain and this has an influence on climate. this was something that we didn't extensively explore in the studies along the deep body of literature including some literature that we published shows the greenhouse gas emissions are less consequential at the local scale of our adaptation. if you click one more time that is the unknown response of greenhouse gas emissions. so greenhouse gas emissions are increasing and what does that mean for the climate variables? if you click one more time

these scenarios of warming of and precipitation change. we need scenarios to investigate thatso they are part of the stress test . the last part of uncertainty is sometimes overlooked in the water community is what we focus on the most and that's natural climate variability. even if i knew the exact temperature in 2050 i still couldn't tell you what would happen in 2050 because it's highly variable so we have to make sure we also test if we're going to have a comprehensive analysis test variability because we know the historical record will not repeat itself so we have to be ready for the different types of droughts in the future so the stress test consists of mean change and

temperature and variability from the client perspective. then the question is how do these climate changes affect our system, how will weanswer those questions and if you click through these bullets , the first part is changing runoff so we investigate changes in runoffused in multiple hydrologic models in this case . the next question is how do those changes in runoff affect the water supply system itself. what's the ability to manage those so we don't infrastructure model. and then there are other factors that constrain those operations or drive them and those are things like water rights, water demand and water supply augmentation so those are aspects we built into the water system. that's really the essence of the stress test and modeling approach that we use. this shows you a graph of

climate change projections and i should note we work with the center for atmospheric research to derive climate change projections for this reason, for this region and these inform our study. this gave us a sense of the range of possible climate changes or at least the projections so these are shown as gold and you can see blue and yellow circles and plotted in terms of changes in mean precipitation, that's the x axis. and something fun that we did in the study as well is we realized the projections only tell you so much and that when you think of climate scientists they'll say yes but. we convened a group of local

climate scientists that have a good understanding of the caliber of the climate and had a session that was facilitated by grants to get their estimates of the range of possibilities as well so that thatinformation we designed our stress test . over what range of temperature andprecipitation should we test the system ? if you click one more time you'll see the details of this stress test. this is the range you'll cover and how do we cover it -mark we used 10 realizations of what we call natural climate variability so new traces of wet and dry period synthetically created. we've looked at changes in precipitation from a reduction of 40 percent to an increase of 40 percent in mean precipitation and looked at changes in temperature from an increase no change to an increase of seven degrees and this created over 1000 climate

is that we use to test the system to create a very comprehensive understanding of how to respond to climate change. next slide please. okay, so now i'm going to talk about first hydrologicresults . this is the influence of climate change on inflows to the system and did a pretty comprehensive studyhere. this shows the upcountry watersheds . and this is just theimpact of , this is a warming area so this is five degrees warmer in upcountry watersheds and what this shows is the effective warming on the shift in the hydrograph so the red, the solid red line is the means and the paint area around that red line is the range of our ability 45 degrees warmer relative to the great shaded area which is thehistorical hydrograph . so you see along the lines

there's a shift in the hydrograph to earlier runoff and lower screenflows . if you go to the next slide. you'll see i think sort of the most interesting result related to water available to the city. this is the effect on warming that results in more variability for the city. so warming did not have much impact on the total volume of the water available to the city but on average what it did do is increase the variability so essentially this line is zero which sort of demarcates the blue from the red here on this graph.if there's no change in variability than the scenario would just have astraight line . the farther you spread out the more variable whack so the lines go from lighter color to

darker colors in terms of warming so the darkest line is 10 degrees warmer and if you viewthat second-degree warm light is spread out . and that means more variability. and for us that's a big funding, sort of the headline is that leads to more variability. >> if we now look at the other watersheds, that's the next slide. this iseast bay watershed . these are figures that try to show you the hydrologic response in terms of precipitation change and temperature change at the same time and there are essentially maps. where you are right now is where let mesay there's precipitation change , temperature change. where you are right now is tha zero. right at the bottom and middle of the graph . that's the present.we read this matthew had north on the. that means warmer conditions. and if you notice had north on

those maps and it becomes red. everywhere red means less flow. so what you see here is in these watersheds as it warms you get less flow on average. if you had east you get more precipitation, your glue that means less. if you had west it's red, less precipitation, lessflow. that's pretty straightforward. the here is if you click one more time . the headlinehere is more warming reducesmore inflows. if you then go to the next slide . you see the same thing . really this is just showing we stress test every one of these watersheds . here are the peninsula watersheds, same exact story similar . you click on that one more time, warming reduces green inflow. now if you go to the next slide another big question was what about the effects on specific droughtevents . in particular in the water

business we talk about current interval for droughts. just the probabilities of occurrence in any given year on an annual basis.it's not the most intuitive way to talk about an event happening but it's the way we use. so i have twoplots here. precipitation changes, three scenarios of precipitation . no change, 10 percent reduction in the red line and 20 percent reduction in the blue line and what you see is 20 percent reduction the blue line is much lower than the black line is where the arm which means that droughts have lesser occurrence intervals which means they become more likely. that'skind of a no-brainer headline there . you have less precipitation you come must less likely. on the right it shows the effect of temperature on droughts and two degrees

warmer, four degrees warmer, not much effect. if you click one more time it's you see the table. it shows you drought recurrence intervalin years work for the same scenario .but looking at historical drought so look at the historical droughts and how their friends interval has changed under these different precipitation scenarios. so you see 7677 drought the estimated current interval of 100 years or term. of 100 years for that. under a 20 percent dryer scenario the occurrence interval is 25years . so to put that into more intuitive terms, if you have a drought event within 100 year return period means that over the next 30 years you have a 26 percent chance of that drought occurring or something worse than that occurring. over the next 30 years at 26

percent chance. when he goes to a 25 year return. that same draft now has a 70 percent chance of occurring or something worse than that over the next 30 years so that's from a planning interval timeframe perspective that's a significant increase. okay next slide please .so that was before we got to the fifth. those are hydrological and those are results that take into account the storage and operation of the systems and i'm going to present those using an indicator that is commonly used in our resources engineering. we call it liability of the water delivery. it's the frequency of years that the system delivers the whole demand and so there's no rationing that's been applied. weuse a target , typical planning target of 90 percent as what our threshold is for accessibility. so we're measuring

vulnerability when the reliability falls below 90 percent which again is typical for planning and water resources. if you go to the next slide i'll show you this is the figure that i sort of described as the most rewarding and most disappointing figure of maybe not my whole career but this study so it took us two years of modeling and floodplains to create this figure that shows the response to systems to change in temperatures. here's just an view of changes increases in temperature on the x axis of the slide. zero on the left all the way up to eight on the right. and they have reliability and the blue line shows the reliability for all these different temperatures. and what you see is look closely. at the slightest decline so not

much going on in terms of the system response . you might ask what might we see in terms of increases in temperature and this does cover the range that we might see. here we got histograms of the number of gcm projections. and the green shows you 2040, average of 2040 ratio. so these are histograms which means that the size of the bar just indicates the number of projections that temperature. so you see here for 2040 most of the projections are for one, two or threedegrees warmer . so at most is for you see. so for the range of those projections we don't see much concern where they did those temperature increases. although i show the

solicitations these are a number of climate experts that say these particular changes may be plausible so over the range of climate experts say it's possible, the system doesn't seem to be vulnerable to temperature changes. next slide please. this one is more interesting. these are now precipitation changes inprecipitation along the x axis , zero is in the middle decreases to the left. this line shows the decline in particular crossing of our reliability pressures. at about 20 percent reduction. so according to the metrics were using in the study we would call that the vulnerability . the systems vulnerable to 20 percent reduction. the next question you might ask is should i be concerned? is this going to happen or not?

let's look to what the climate experts show. these are again the first row is the tcmprojections , counts of each, which of these precipitation changes they project and the low debt are the experts range. you can see and if you click one more time it will spell it out. that 20 percent reduction of precipitation is not simulated in many of the projections. there's one projection that projects that level of decline in precipitation. the experts, there's a few experts are saying this is a range ofpossibilities . [please stand by]

>> according to this analysis, the system for 265 million-gallons per day, the process is vulnerable unless the precipitation increases by about 5%. those lines get lower and we're

never above that threshold. if the demand goes up the system is very vulnerable for climate change. we look at other factors that could change. i don't have any good visualization, if you look at the reports there's plenty that do try to visualize. the headlines is that the state amendments for rationing. the equivalent to about a 15 percent increase to a mean precipitation. you saw that does have an effect on the system specifically on demand scenarios.

maybe i should have set at the start, we talked with the team and what are their concerns for the future. what might make the system vulnerable. what if we had a treatment plant break or line break due to an earthquake. we looked at a variety of scenarios for this and came away with a few conclusions. failures are very important and we quantify those effects in the study. decreases in precipitation exacerbate the vulnerability of the system generally to various other kinds of changes.

an unplanned outage of the treatment plant cause less vulnerability to water supply. we also looked at water quality. this is described in the next slide. water based quality face challenges because although there's a lot of data, there's not a lot of data of high levels of the variables that we looked at. water carbon, although it's good, it gives little data as to why it goes bad. we did model it, take these results with a grain of salt. increases of mean resip taitionn

was found. overall water quality deterioration in terms of mosh i morbidity. we have temperature effects, not much effect of temperature and on the right we have effects of changes of precipitation. we primarily focus on mean of resip taition an don't look at the changes of extreme precipitation events. if you look one more time, that should come up. ch i think an interesting study for us. this is the first time we did this, it's something that came up with our meeting with the executive team was looking at

trying to delve into the idea of climate change on finance. there's a variety of ways this can play out. what's interesting in what we modeled is how to keep a fund balance for different scenarios of climate change. it became what we realized is what really drives us is response it climate change f. have you to invest, making new capital investments to climate change, what does that mean for prices in order to keep the fund balance where you want it to be. if major capital investments is needed, this has substantial increases in the prices of

water. you're balancing up against what you saw previously which causes decline in the reliability of the system. there's an interesting interplay between climate demand and finance that you just need to be aware of and certainly could warrant additional study. if you bring up a chart. this is a figure that shows that, click one more time. this is a plat and demand and capital expenditures. where we are, current conditions is the lower left. if you go up in the map, north, that's increasing scenarios of demand. to the right is increasing capital expenditure which is what you might have to do in regard to loss nz demand in

climate change. as you move right, the prices increase substantially. if you click one more time, this is a summary of this. in these scenario where's demand doesn't increase and you need high capital expenditures, you face substantial increases in the price of water in order to keep that balanced. i invite you to dig deeper into it in the report. it's the first time that i know of that a study has looked at this and it could be interesting. next slide. thank you. these are the headline conclusions from the study. the regional resilient to changes in mean climate and other drivers for a mean demand to 27 million-gallons per day f. the precipitation.

climate change exacerbates the impact from other internal drivers of change. there's a lot of interplay between climate airchgs and how other factors change. for my last slide, the way i think about this is continued preapedness. what are the next steps. you have a great modeling platform now to evaluate how to address the study. alternative water supplies. the big question is when should

we act. in other words at some future point, you might have mean production of 20 percent. you want to have active before we got there. these are the things we should monitor so we know, we need to act. as part of that is the continue to monitor climate change nz the water shed and other kinds of changes as well and keep a breast of the climate projections as they continue to improve and become available. it was difficult for us to calibrate the hydro logic model. it was a ties ass that we could not get ready. we underestimate the depth of

low flows. during low periods we have too much water. wet periods we have too much water. there's a bias there that require further work. i'll stop right there. thank you very much for your attention. it's been a pleasure to work with the team. thank you. >> i just had some concluding remarks to tighten this up and open it up for discussion. clearly we've been studying climate change and the effects op the steads for a long time. this allowed us to look at a wide range of climate futures with other vulnerabilities effecting our systems. we are resilient in many climate futures. when combined that resiliency

faced. new alternative watt every supplies and this is really important for us. when it come it the commission, we'll be able to use the information from the tool that's were developed in the assessment to inform policy decisions for the commission. as casey talked about, we need to continue to improve some of our tools and monitoring change nz our water sheds is going to be critical as we move into our futures. it's really important to continue engagement in the climate science and collaboration to keep us up to date and responsive. continue to develop our forecasting tooling. that is all we have. thank you so much for your

attention. i know was a lot of material. the floor is now yours. you have lots of people available to answer questions. gentleman thanks so much. a lot of information, you're right. chunks of it went over my head. let's open it up for questions. >> if you don't mind p i'll go. this was a lot of these things have been done doing for a long time. i really did enjoy the presentation. i would say i really appreciate some of the work that he has done. early in 2006 and seven. the reliability and resiliency

it's easier to say okay, the mean of the precipitation and temperatures is changing. it's difficult to know the variability every year. this is where the rubber hits the road. one of the things we have seen in the recent years is we get snow and then it gets hot. it was cold last week and this week it's hot. a bunch of things melt. this inconsistency that we have right now. we're going to the cold season

and staying there for a few months. therefore the capacity of our snow pack level has changed. i'm not sure if this was considered as part of the study besides looking at the average changes over the years. if you get tons of snow, imagine we got tons of snow during the weekend, the noise you hear in the background, my house had a leak, we had a bunch of people fixing things. the rain storm was quite intense. we got a lot of snow which is exciting. we could have totally hit a hot period. it was not cold at all. some of that snow can melt. let's say in some indications in

the past few years we have had a lot of know melt. how is that go to go impact us as a utility, our water bank, vurs us the reservoir system that we have. how do we deal with these variabilities in a more strategic way? that's one question. i would love to hear different perspectives on that. the second question that is sort of related to this is as we are looking at these reservoir systems and the change supply and demand which i think is quite important. i would like to see a little bit, it was good to see in case

this presentation, there were a few slides in cases of demand in different ways. we don't want

>> i have a small but mighty team that spends all their time on these kinds of models. all of the tools that he's been

building we're training staff to be able to use. this is a platform for us. it's a platform for us to continue using. i'm not going to say we have a full team that has enough people in it to do all the things that you're sugging. suggesting. >> what you heard there was an invitation. >> i did. thank you. i do think i want to turn it over to casey to talk about the other comments that you made and particularly around variability. i think that's one that we also agree we need to do more work on. we didn't do very much work in this study at all on those

extreme events. the heavy rainfall one day and extreme events the next. i'll let casey talk about his perspective on that. >> thanks. thanks for the excellent question. let me just reiterate that work withing the team and matt and chris was essential to what we did. they were involved every step of the way. that's really great. our goal is essentially to put ourselves out of business and really hand off, the term we use is codevelop. this was absolutely codeveloped. in terms of availablity is a great point. we create results that's a summary of many many different scenarios. that include scenarios of

variability. we have those changes and monthly time series of temperature. we have big slides that breakdown the big picture. the most important picture is how the variability plays out. we have and the team now has all of these scenarios of variability that they can explore and understand more comprehensively and what is problematic for the system an what operating rules can be used to manage that variability such as you're describing. i'll reinforce what you said about demand.

it's a super interesting question. forecasting demand is a real challenge. there's a lot of uncertain associated with that. not knowing anything about future demand. yes, the system is sensitive to demand. demand. same with the finance, we weren't considering any type of specific investments. we just said what if you have to spend more. without thinking about whether it was any kind of specific option. >> let me ask you a follow-up question. we've been doing these kind of climate modeling for a long long time. potentially you could have ran this from 2000 on.

did you do anything with the sea life with those analysis to hold what you're experiencing today. can you sample and see what were the projections right before. do they hold? how does the system operate? i'm just wondering you have done any validation of some of these things that you have done? >> we did a system model that monitors the validity of the

system as well as hydrology. we did validate and that's how we discover the bias. same with the system model. we have a fair bit of confidence that the system model is pretty true to the way operations work at present. of course, they could be altered in the the future. we tried and alexi spent a week here standing side by side. that was a big big part of the work that we did. and as always it's a super important question. >> this is steve, i would like

to throw in one more point here. we have the folks in san francisco and the folks up country looking at the models up there. for control of snow melt and the power generation. that was one aspect that the study didn't get into. once we take care of water first, how do we optimize the system. one point that may not have been clear. forecast and foreign reservoir operations. you look closely at forecast coming up and operate your reservoir consistent with that. that sounds on the face of it a very common sense thing and something that is not widespread across the united states.

the army corp. of engineers of reserves. y volume. don't look at the forecast or anything else, it has to be this on that date. break away from the old mod parking lot and move to something that is much more realtime oriented. a lot of these thicks may seem obvious. it hasn't been obvious for generations. >> i want to quickly say -- sorry i did not highlight that. i'm so glad are you doing them. it's moving our system operation to the twenty first century rather than being stuck in the 20th century. that caused what happened and

trying to step away from some of the conventional ways that we operate the system. >> thank you. commissioner moran. >> thank you. a couple related questions. when i was listening to the discussion of the different types of precipitation patterns. what i think i heard was an analysis that looked at single year. multiple year droughts are important to us. the effect and viablity of storage is important to us.

did i hear that right and the use of storage over time or the length of drought sequences that you can expect over global warming as opposed to the warming of dry years. >> thank you for that question. excellent question. i'm sorry it wasn't clearer. we did certainly look at multi year drought and new multi year droughts. i report -- we report that metric on a year by year basis whether you met the demand or not. in a is in a single year. the drought scenarios that we ran it through and many new droughts that the system has never seen before are all multi year, they all account for the

storage. the water system mod parking lot model.it is all of that is incorporated there. >> did the results of the analysis that did include the multiary droughts, was that part of the information that you juf prepped to us. >> yeah. exactly. when he showed you the eliability of the system for 10% precipitation. all of those estimates are new drought.

the average reliability through different droughts. >> did you reach any conclusion as to whether long droughts were going to be more or less likely? >> we did. we looked at that quite a bit as a function of possible changes in climate. for example, we did find, if you look at historical droughts such as '77 and '78 droughts we estimate a return period of 100 years. under different precipitation scenarios. 20 percent reduction, that return period is reduced to 25 years. in this case this is the inflows system that reduced precipitation leads to an

increase of droughts like that [indiscernible].

>> we tried to avoid the prediction business of what was going to happen. what we were trying to figure out is given what could happen, what are the implications for the system. the question and it's obviously an important one, what's going to happen regarding drought in the future. that's not a question that we explored in the city. >> one of the questions we're being asked and we're asking of ourselves is we have a planning process that is largely informed by history. it's been suggested that that planning process is unnecessarily conservative. there are also people that given

the prospect of climate change it may be woefully unconservative. trying not to say recless. that's the thing that we're going to be wrestling with and discussing. the question will be once a -->> we started to talk about that. i think you were the one that identified it, that that scenario is a stress test. we look at this whole effort as a whole series of stress tests that we have applied and can continue to apply in different way as we move these tools forward. that will be valuable for us in

a suppress test model as opposed to a prediction test model. >> a couple things we're showing is that snow melt was happening earlier. run off was happening earlier. whether or not we get to keep water or not. the city is part of that. i didn't hear any kind of conclusion from that. do we think we're getting more water available to us now and have that exacerbate. or is that not important enough. >> good question. what we found in terms of water available to the city, in terms of precipitation changes, it

works the way you expect. we get more precipitation in the future availability increases. if you get less it decreases. it's pretty clear in terms of projections which way we think it's going to go. we think it's going to get warmer. if you look at the projection trend it shows almost no change. the point i tried to highlight, maybe i didn't do a good job. the mean on average, it becomes more available. variable. you'll have years where have you more and years where have you less. the way i think about it is that snow pack is storage. it's storage.

storage smooths things. it a accumulates and slowly releases. without that smoothing effect things become more variable especially with a threshold of what's available to the city. i don't see a lot of changes that we can hang our hat on. we see it's going to get warmer and that results in more available results to the city. >> my bigger question for lack of knowledge. warmer will not effect our reliability. it's almost like those are two different variables that aren't dependent on each other. i would think that's quite

dependent on temperature. >> those are definitely tied together. there are many more in.report te report that show that connection. in some of the plots i showed if you show more at once, they become a little more difficult to interpret. changes in temperature and changes in precipitation together and how they interact with each other. for the most part, temperature has a relatively limited effect and the presip station changes are dominant. >> can you make any assumption that as it gets warmer you'll have more or less precipitation

or is that not connected. >> there's not a clear signal there. for many of the projections it gets dryer and for many of the projections it gets wetter. >> i think that to answer your question is with warmer air, you will have more intense precipitation. there will be heavier down pour or more total accumulation on a specific event. changes on an annual time scale of precipitation on an entire year. trz no changes of preaccept taition among a higher here. >> the intervariable is going to

be key. i did have a slide which i thought that was very very useful in showing the snow level and the elevation and the snow pack. i think that is quite important. that another relationship between temperature and precipitation because we're go to go get a higher elevation we're go to go get less snow - sorry. different way. the elevation that we're going to go get snow is going to go up. we're not going to get snow going up. to be honest with you, our water

bank. i didn't know until a couple months ago that it doesn't function with the other things like, put a straw and pull it out. that's a huge limitation when dealing with something like this. it's just meaningless. when you need it rntion you , you can'treally use it as muc. when you're thinking about which relationship, that's going to be important forp us. for us. >> i think it goes back to think tg how you operate this whole system. that's the bottom line.

we can't operate it the way we did over the years. we have to rethink it. >> i would comment and i was glad steve jumped in, i would feel remiss not to mention our operators. the forecasting tools, that's becoming more and more important to be on the forefront and see relationships and help actually formulate some of those tools that they are usable for us in an operating setting. i think casey would probably want to say it as well. bringing that thinking down to operations level and getting the format of a new date awz and

data and beingable toll think or operations. we have to think of their job rz only going to get harder. >> any other questions or thoughts. we'll move onto some of the other stake holders. >> just a little more basic information that this material is going to be published hopefully next month by the water research foundation. it's about a 600 page report total. it will be a daunting document by itself. we produced the fact sheet before this which is basically a fron and back sheet. we'll be producing a slightly

longer brochure. overtime as we start to use the tools that come out of the long term vulnerability assessment we'll have further opportunity it describe exactly what we're doing and how we're doing it in as common temples as possible so everybody ask see trans paryntly. that's a nays thing to see but disn get the communications kick. >> we don't have the answer, we have the tool. >> maybe a quick comment before we move on. i just want to say, i really appreciate this partnership.

this is a great model, you know, i'm so excited that we're going to have a tool that we can work with. it's ours to play with it and modify it and obviously i think it's very valuable for whatever students that worked on this project. we have a different generation of people that are thinking about reality on the ground. i'm so glad we did this an just want to commend you for that. >> thank you. with that in mind, we have some stake holders that came prepared for give their initial thoughts. madam secretary, could you read the next item. >> item 3b.

>> this was been a really interesting workship. thank you for having me to participate. as you know we have consistently supported these efforts for water change. the long term vulnerability system. i'm excited to see the final analysis. it's a risk to the water supply that we all reply upon. i think it's vitally important moving forward that we use this information now to ensure our

planning. this will be able to be used for alternative studies. i'll be really interested in tool it's and potentially update it. we've had a lot of conversations about this in the last year. i appreciate president moran's question and the topic earlier. i look further to looking at the information further myself. as we all look into it and struggle with that question. it's certainly going to be a critical one. these models are going to be used as a part of the water supply being investigated. i want to get deeper into the models and this important task as we figure out how we're going to make our next investment and do that appropriately. we had a lot of conversations

here about water demand and impact on water shed reliability. we're comparing analysis and what it means for demand. there's always these ranges for what we plan for in that possible scenario in that possible window. these tools rz going to help with yous that. you guys answered most of my questions as we went through this. this analysis looks at these vulnerability factors, do you sense that these are highly connected and does the report talk about that. as warmer temperatures increase wild fire risk, we have seen

this in the state especially this summer. the shed is something historically we didn't think was possible. does that effect the water quality. as water temperatures ip crease in the streams and in the delta. this connection between these vulnerability factors is something i'm interested in. i would like some thoughts on. thank you for allowing me this opportunity to express my thoughts and ask my questions. >> i'll take this question. thank you for your question about these interdependencies of these factors of vulnerability.

i think here what we tried to do as we follow your example of wild fires and temperature increase the wild fires. we tried to simulate a proxy. through a smart thinking exercise of experts. what would happen? what would lakely happen is we would not be able to use sheds as a extended period of time. it takes two months for the water to clear up. is that an issue for our system or not. if that's an issue for our

system. we can then determine the level of concern. what is really the likelihood or risk of these things happening? similarly for demand, we explored a wide range of demand. we presented a few on the slide by dr. brown. we explored a wide range of demand without try to go say which one is going to be the right one. we try today say what if this demand happened. are we going to be if trouble or no. kl we tray to track and better model. that was the approach that was presented in this study. >> thanks. that's very helpful.

joofl thank you. helpful.gentleman thank you. >> thank you for your thoughts.. >> it's a pleasure to be part of this workshop. i'm going to go start with a few questions and comments and hand it over to my colleague. i wanted to start just by confirming a few numbers and assumptions. my first question is the model rules we saw, is that based on the design drought.

>> no. we have not provided the results of design drought. we're providing the results of plausible droughts if we simulate the weather in our region. we looked at 500 years of plausible hydrology. we have not simulated the design drought. >> that's interesting to hear. thank you. second question, is the base line demand is around 226, 227 that you used. where did that figure come from? >> very good question. this figure came from a base line of -- to be honest with you. i think i have to go back to the

study. at the time it was in 2018. we looked at 2013 and we based on the urban water manage. mentplan. we based it it on the study. we're not try to go pinpoint the right value. what is the vulnerability of the system at certain levels of demand. we said that 227 is an acceptable level of demand to use. >> what is the current level of demand? >> we were at about -- fy1920 is sticking in my head.

i can't remember what 21, 22 was. we're somewhere around 200, peter. requests for reduction brings our water uses down. >> 227 is about 12 percent higher than actual consumption. anytime we talk about a 10% increase in demand we're talking about a 20% increase over current demand? >> i suppose you could say that. the point of the study was not to point at a demand. we have tools to look at lots of different demands in there. perhaps that will be something we will decide to do.

>> we're going to have earlier run off, correct? >> i believe so. we're not saying in this study, we're not making conclusions of what will happen to mean

precipitation. it could increase or decrease the mean is pretty broad in terms of what it could mean in the future. >> could someone bring up slide 39, please. while that's coming up, i didn't feel a lot of confidence in the answer to chair harrington's question in how water run off will impact water rights. you may not be familiar with the raker act and the way it works. the first 2200 cubic feet per distance, there's a two no

period between april and mid june that jumps up to 4,000. that's going to be a huge benefit to san francisco. if you look at the upper left one here and look to between april and may. lack for april 15th and look to the left. look at how much more water is in that period where san francisco gets anything above 2400. agricultural water management plan, it concluded that by 2100 april through july run off which in 2010 accounted for 60% tote run off will drop to twenty to

40%. that's a huge amount of water. greg from the bay institute did a quick look at what would happen if the 87 to 92 drought would pick up earlier. demand is about 225. i'm wondering if anyone has any comments on that when it was claimed that the water rights -- the shift in run off maight not be that beneficial to san francisco. was there an understanding of the raker act?

>> i'm going to ask casey again to go over the study. yes, we did have an understanding of the raker act. >> i'll confirm that coming to the site we probably didn't have a good understanding. she did make sure we were representing it accurately. we look at the city in depth in the report. you can totally dig into that. there's certainlily what this figure shows here is the average shift in the hydro graph. everything looks nice and smooth. in the report you have a time

series and storms come through at all sorts of times. sometimes they go over the threshold. the example that you had of a specific event. if we looked at all sorts of time series, we could find for the same amount of average flow for the year, we could find years where it was very high and very low. what happens is it becomes very variable what the water available toll the city is when you warm things up and have reduced snow pack. we dig into it and better than i can do here with the report.

there's a lot of variability not being expressed here and you having the benefit of seeing that work and dig into that work may get us to some other questions. >> is the report going to be a draft report or a final report? >> a final report. >> actually, so peter, let me try to explain this a little bit here because i think it's worth paying attention to. what you see here within those black areas, they're thousands and thousands of them can be between those two bounds, right. not every sippingel one of them falls on the right side, some of them are actually below on the

left and so many different variabilities and that's what they were trying to say. depending on which year we fall under, not every one of those realizations you have the red on the left of the black? there are cases that you actually don't even have that, right? so imagine instead of being those shaded areas, instead of that you would see thousands of lines lining up on top of each other that create that, right. and if you pick one of the bottom lines, you actually might not see what you are saying. when you pick unon the top, that's what you are saying. >> this is the average. the example i brought up was '8s and moving the run off three

weeks earlier 217,000-acre feet. so i think it's something we can revisit. we don't need to hash it outright now but something that could strengthen this report quite a bit. could we move on to slide 47, please? first of all, the blue-line here blue-line hereis 226. 12% higher than current demand. the green line, i'm not sure if it was intentional but that's the contractual obligation of the sales cap 265 and red and black are numbers demand numbers that we have not seen or talked about in decades. so i'm wondering if they really

apply. i'm wondering if this -- a lot of these models could be rerun looking at other factors like what if water demand stayed current or even reduced by 10%? what if we included additional water supplies if it turns out that san francisco's water rights are improved? what if we mention that it's not really based on the design drought but if it did, what if we took a year off of the design drought. i'm curious how -- it sounds like san francisco will get this model and we could run all sorts of model runs based on whatever commissioners or the public would like to see. increases on drought planning and demand and alternative water supplies we can see the outcome of this.

will the model be be available in san francisco and will we do quick runs that different scenarios? >> we will have the tools. we will have the tools. >> and they're very sophisticated models. >> and one of my concerns is this report will be published and people will refer it as the bible and it will have a baseline demand higher than today and it probably won't adequately look at san francisco's water rights so i want to encourage the commissioners if you are interested to suggest model runs that can be klein you haded in this report so people can say oh, it's not going to play out a certain way every time.

>> thank you, it's such a pleasure to be with you guys. i'll just comment, i'm really looking forward to reading the report and for me it doesn't might make sense on earlier flows of the year but i'm excited to read the report. i only have one area i want to explore and is there any chance if you go to page 43 or slide 43, and the drought recurrence intervals. and i'll just ask, what was the source? how do you come up with these numbers? what was the data used to develop these intervals and i'm asking in part because when i did such an analysis my numbers

came out shorter than these but it's understanding the basis of calculating them would be great. >> if you are still with us? >> yes. i'm sorry. yes, that's right. so, i mean, these sorts of calculations can be dependent on the data that you use to do them so we used the historical record we got from our sfpuc partners and lexie right remember, i can't remember the specific years we used but we used an extensive record that we had for what the observed inflows were. >> the key question is the last 100 years or the data lexie, any chance you know? >> so, you will be able to dig

in the report a lot into this. we actually used historical observed. we also used the data and we also used five -- 25,000 years of simulated hydrology. >> would you have any sense for what is the confidence in those figures is that -- and i reel liked dr. brown's comment about if it's 100 years to 1976-1977 draw that means in 30 years there's a 36% probability and he mentioned another one just outstanding. i think that the question that comes to mind are, one is, it seems like there was a big rangd here. you used the for what the

precipitation could be and it was a plus 25% to a -30% or something like that and i wonder if we should add a column that showed like a plus -- what happens if there's 10% more precipitation and what might it look like? and then two other we can comments. one is i'd also say i think this gets to the design drought and i would love to preface any discussion about the to my knowledge, any chance we get out of this table a line that would show, and here is what the joint recurrence interval for the design drought and maybe a year off of that that might be useful for a future discussion. >> anyone want to tackle that? >> yeah, sure.

well, so dave, increasing precipitation we found in the hydrology response to the watershed makes everything better and so for us increasing participation to look at drought and it's not of the most trying to identify our vulnerability and it's not by increasing this that we'll find our drought so that's not the direction we went on that specific aspect drought and how -- the recurrence of drought is very tricky because they're rare. if you took our 100 year record, we don't have that many droughts. if you take the tree ring, we have some more but we still don't have that many to come up

with probabilities, we attempted to increase the plausible years so we could try to come up with a probability of (inaudible). can we theoretically add the design drought? we can think about doing that i assume. >> well, maybe to your point, and i'm taking too much time. the confidence -- i think the other thing i tend to say is it's important to assess what's the confidence in these figures? is there a high amount of figure. it's only a 80% confidence figure then we need to be more cautious about using it and if it's 95% confidence then it's a more reliable figure and we're trying to plan for what our

water might look like 50 years from now. maybe that's the answer if you can't add the design drought great but maybe more important if there's anyway trying to assess a number to these to how much confidence should the commission have in relying on these drought recurrence intervals. >> it's a very good question. sitting probability distributes you find that there's a huge uncertainty so there's an error to these values here. there's a range. when we say 100 year recurrence interval there's a range. it could be 400 or it could be 50 and that is actually produced in the report. you will see the error bounds on these estimates. i think the message here, the message here is relatively to

each other. it's extremely sensitive. a small change, a 10% change in per precipitation which is very plausible for the comment projection. more than double the frequency of your likelihood of a 76, '77 drought. it nearly triples the likelihood of a '87 to '92 drought. >> excellent. if i could just make my only closing remarks would be if you could quickly jump to slide -- i think it's 46. just the expert elisetation. it looks like the range is -30% to plus 30%.

with we need to be prepared for all of that. thank you so much for letting me comment. >> thank you dave and peter. can we do something that would change the report? my understanding is it's pretty much done. ellen, do you want to comment on that? >> so the water research foundation, the way they conduct their studies, they don't provide for public input we had the ability inform review the draft and ask questions of the principle investigator which was dr. brown. these are tools. just because this report has been produced or will be published it doesn't mean that we can't do additional work on our own using these tools and

and we're bound to that. >> i guess, when you have it in and you are using it, a couple of things we'll be interested in seeing is 200 versus 227 make a big difference? and what about that time shift? any other thoughts before public comment. >> would you read the next item. >> the next item is item number 4. public comment. members of the public who wish to make two minutes of public comment specifically on item

number 3, dial 1-415-655-0001 and meeting id249 3119-6853-pound pound. to raise your hand to speak, press star 3. >> i'm amazed how anyone can remember those numbers if they're trying to dial in. people work it out. >> it's also on the screen. >> are there any callers? >> there are two callers wishing to be recognized. >> hello, caller, i've opened your line. you have two minutes. >> caller: commissioners, i just want to focus on one point. you commissioners should be

ashamed of yourselves because missing in this situation the most important don't smile, get yourselves, think that this discussion is -- why don't you start with 300 years? so we have the record act. why is the record act not followed to the stricter standards? it wasn't followed to the stricter standards because you are all greedy and you wanted more money. so, who is suffering? you stole the water from the first people and the less can you do is have the salmon. next year we won't get any salmon. and in five years, the salmon so what we've done and say

something because 500 years ago there was no climate change and (inaudible) and the greedy people said we can accommodate everybody. this is all about greed. you must acknowledge greed and you stole the water from the first people. and stop laughing when i give my comments because i can write someone pretty nice stuff about y'all. i'm not like one of those other commenters that doesn't have empirical data. i have empirical data. >> thank you for your comments.

next caller, i've opened your line, you have two minutes. >> caller: hi, this is is iris stewart. professor of hydro gee and focused on climate change on stream flow and the especially also run off timing in california and throughout western u.s. i'd like to say that i much appreciate the complex and thorough model and explanation of results on the reliability of water delivery that dr. brown is presented. this looks like an amazing tool but as mr. jack mire has pointed out, the number of scenario that's could be explored in addition and i would like to pose a question regarding dr. brown's statement on instream flow requirements that the water quality controls plans increases frequency on the need for rationing and i would like to know if the model what is the difference and how demand and increases and higher instream flow requirements were

represented. where they represented the same? so if we're looking at alternative water supply projects to streams and the stressors on the water system and could also be other things like is increase and demands of weaknesses and infrastructure were also increasing frequencies and rationing. and that in stream flow requirements is just one of the knobs in the model to turn to ensure water reliability and of course also going to the' logical need for requirements that the water systems are tapping for the highly vulnerable salmon population which we cannot bring back once they are extinct. thank you so much. bye-bye. we want to finish public comment and if we have a chance, we

would love to answer your question. are there any other people waiting? >> there are no more callers wishing to be recognized. >> then with the commission's approval, because we don't typically do this, could we ask our group to have a comment on that question. >> thank you. >> hi. i'm sorry, i can't catch the name of the caller and thank you so much for your comments and it's described explicitly in the report and so i'm sorry you can't get it yet but it will be out soon and you can dig into and using his understanding of how we implemented those

instream flow requirements and i just want to agree with your -- or affirm your second question regarding the fact that in stream requirements reduces the frequency of rationing and demand changes do as well and as we saw, it also does that. >> again, a useful along the way as opposed to an answer? we appreciate all the work. and it's going to be fun to say can you run this and as ellen says, nothing will be easy it will be nice to figure out how people can ask questions though and get responses and some kind of reasonable time. do any commissioners have any closing thoughts or comments before we end the session? >> i would just say alexei will have a few other colleagues and they can all keep running this

model for all the different scenarios that we lost. and we'll have a running board that keeps saying ok for this scenario, this is what is going to happen. people. >> some employment contract, yes. >> yes, exactly. i just joking aside, this is really a great tool to have and i think one hope that i have and i think lining to what alexei was saying and some of the comments that ellen also made, it would be valuable if we can ourselves also make changes to this as sort of some of our assumptions and parameters changes over time and so having that capacity is extremely important and i'm so glad that alexei was so much involved in this that he is you know, he knows the model inside and out and outside in and all this interaction so that is really reassuring and i'm so glad we have it and i look forward to kind of using it and improve

particular over the years to help us better understand how our water system is working or vulnerable and i also want to say that i know there was a comment about i did smile when mr., one of the speakers making a comment but my daughter was in front of me and she just arrived so that was not meant to be a disrespect to the speaker, it was actually my reaction to my daughter so i hope you don't take it personally but i absolutely appreciate all the comments and i think it's important to acknowledge and we mess up the system and we're fix particular and we're working towards it which is very important and there's no easy fix on the table. at least we're trying and that's important. >> the only closing comment i

have is i think there's a rich body of information to work with and i look forward and how we take the insights or the information that is in that report and use it to make the decision that's have necessary we have to make every year anyway. and while the research will go on and the knowledge base will increase, life is what happens while you are busy making plans and we need to figure that out and how to accommodate one into another and that's a very important task as well. >> thank you, commissioner. commissioner maxwell. >> i just want to thank the team. it's not often we get an opportunity to see behind the scenes and know how all the information comes to us. i want to really thank you for that. this was really a wonderful in

sight and the people thaw brought in were very helpful and very good to know that there are a lot of them are in-house so again, thank you and i want to thank commissioner for her last comments. i really feel the same way. and so again, thank you and thank you, peter and thank everybody for continuing to hang in there. we're so really fortunate to have so many people that care about this. thank you. >> commissioners, you've done a great job of recapping and i love it. i enjoy being on this commission so much. we have great staff, we have commissioners engage in knowledgeable which is kind of fun and different than how it has been in the past. so, and i'm glad everybody is patient with each other as we work through this p our stakeholders are to much with us trying to make these decisions. i appreciate all of that and i

also appreciate this friday afternoon and so unless there's further business, i think this meeting is adjourned. thank you. >> thank you. have a nice day, everyone. >> you too. >> thank you, again.

>> hello. secretary silva, can you please call the roll? >> thank you. [roll call] madame chair, you have a quorum. >> go on to our next item. >> item number 3, announcement of prohibition of sound producing devices during the meeting. we are in a virtual meeting. approval of minutes for the october 19 regular meeting. for members of the public, the phone number is