Pollution levels off the California coast have dropped significantly since the passage of the Clean Water Act (i.e., contra Repulicans, government is not always the problem):
First evaluation of the Clean Water Act's effects on coastal waters reveals major successes, EurekAlert: Landmark legislation helped clean up LA's coastal waters over the past 40 years, study indicates
Levels of copper, cadmium, lead and other metals in Southern California's coastal waters have plummeted over the past four decades, according to new research from USC.
Samples taken off the coast reveal that the waters have seen a 100-fold decrease in lead and a 400-fold decrease in copper and cadmium. Concentrations of metals in the surface waters off Los Angeles are now comparable to levels found in surface waters along a remote stretch of Mexico's Baja Peninsula.
Sergio Sañudo-Wilhelmy, who led the research team, attributed the cleaner water to sewage treatment regulations that were part of the Clean Water Act of 1972 and to the phase-out of leaded gasoline in the 1970s and 1980s. ...