things. nelsen: they include gastroenteritis, which is an upset stomach, and sinus infections, ear infections, eye infections, and there's also virulent versions of streptococcus that can actually cause severe illness and even death. moriarty: our goal with surfrider foundation is essentially to have the city understand that the water is, in fact, dirty, and then work with the infrastructure and the various issues to change that. narrator: but building more systems and more plants can't work alone as a sustainable solution. and, as in pittsburgh, as in new york, part of the answer lies in protecting the watershed. nelsen: we need to reduce the amount of impervious surfaces in our watershed, which are surfaces that don't let the water soak in and then create more pervious surface, whether it's by having driveways that allow water to soak in or different landscaping to try to eliminate the amount of runoff that comes off our land so that the system, even with the development it has,