Think globally and s**t locally. Do a Blue Water Task Force program by Surfrider Foundation if you want data. It takes a few committed volunteers - 4 to 6 to collect and run samples. The government (local, state and feds) can be shamed and are scared of real data. It can be used to clean up specific areas affected by septic fields, poor flush, excessive point source violators etc. I have done this and it does work on a limited basis, but it takes an awful lot of work. Good luck. Remember, everyone has to eat, therefore..
...Also storm runoff is another issue, and golf courses can be shamed into using more organic fertilizers. But the sugar farmers here in Florida send crap water all over the state with impunity. Another issue for another time. Only fight the battles you can win.