ben tracy shows us around lake mead in nevada. >> reporter: when you head out in nevada on lake mead,thing you notice is this white line. that's where the water used to be. what did this look like a decade ago? >> this was all under water. boats were everywhere. there was a whole marina here. she said the drought began 14 years ago. satellite photos show the colorado river which feeds lake mead is drying up, so the lake is rapidly sinking. islands are growing and boats are floating far from where they once were. how critical a point are we at? >> it's a pretty critical point. theweight at which our weather patterns are changing is so dramatic that our ability to adapt to it is really crippled. >> reporter: lake mead was created by the hover dam in 1935. it provides water for 20 million people in southern nevada, southern california, and arizona. since 2000, the lake has lost 4 trillion gallons of water. this bathtub ring is going to get bigger. lake mead is expected to drop at least another 20 feet this year. if it does, that could trigger automatic cuts to the water supply for nevada

been tracy had a look at lake meade in nevada. >> reporter: when you head out on nevada's lake meade, first thing you notice is this white line. that's where the water used to be. what did this look like a decade ago? >> well, this was all underwater. i mean, boats were everywhere. there was a whole marina here. >> reporter: pull is the general manager of the southern nevada water authority. she says the drought began 14 years ago. satellite photos show the colorado river, which feeds lake meade, is drying up, so the lake is rapidly shrinking. islands are growing. and boats are floating far from where they once were. how critical a point are we at? >> it's a pretty critical point. the rate at which our weather patterns are changing is so dramatic that our ability to adapt to it is really crippled. >> reporter: lake meade was created by the hoover dam in 1935. it provides water for 20 million people in southern nevada, southern california, and arizona. since 2000, the lake has lost 4 trillion gallons of water. this bath tub ring is going to get bigger. lake meade is expected to drop at

. >> reporter: that white line is where the water used to be in nevada's lake mead. [ male announcer ] so when he catches a cold, he's got to power through it. ♪ ♪ vicks dayquil. powerful non-drowsy 6 symptom cold and flu relief. winter olympian ted ligety can't take a sick day tomorrow. [ coughs ] [ male announcer ] so he can't let a cold keep him up tonight. vicks nyquil. powerful nighttime 6 symptom cold and flu relief. ♪ ♪ at panera bread, we've crafted our power bowls to help you power your day. start with protein-packed egg whites and savory roasted turkey for breakfast. or power up your lunch with antibiotic-free chicken and our flavorful cilantro jalapeno hummus. power bowls from panera bread - power up today. [ male announcer ] want healthy joints?° ♪ the joint is jumpin' ♪ osteo bi-flex® helps strengthen your joints.° like calcium supplements can help your bones, osteo bi-flex can help your joints.° osteo bi-flex... also in joint & muscle and joint & bone. [announcer] a healthy dog is a playful dog. give him the calorie-smart nutrition of beneful healthy we

very strong this morning hannah and had family come to the hospital for routine case to the queen lake mead he's wanted to thank treats. he encourages him to plain rude. now bush is in the wrong hole. it's like doing. we're doing well a lot of different he was in it. it has a twin but she has to hold onto wishes. the kids it has for grasping things down low bringing them up i am left to right. it has all the scum of the movie characteristics between a couple of foreigners the idea was to be sitting properly isn't interfering with her elbows. she's getting to the price initiatives the ultimate goal is that they may someday this piece of equipment will make her strong enough in the arms that she won't have to rely on it. i wanted to be all the time stop and watch her hair brush your teeth wash face off on that. it'll get her to suspect that she can do it on her own. the grease three gp to call devices that use daily. green team in the nepali congress people read the one exception it really means much. iam going to disney in an agency application to stay in the baby's life. i was going to be a

lake mead is where most of the people from las vegas get their water.at's part of a plan drawn up by the feds attempting to figure out a solution to the record low colorado river. major metropolitan centers like los angeles, phoenix and denver are facing the very real possibility of demand outstripping supply unless the rocky mountains get a lot more snow for a very long time. and if need gets too low, water managers say rationing is next. >> the future of the west is a realization that we don't have as much water as we thought we had in the 20th century and everybody from municipalities to industrial users to agricultural users are going to have to use water more efficiently and we're all going to have to learn to get by with less. >> a 2012 federal report warns the colorado may not be able to keep up or meet the demands of the states depending on it by 2060 but that hasn't stopped proposals for new reservoirs and fights to block them. >> there are certain places where new reservoirs probably make sense. but in general, you know, if you're running out