I thought that this PBS News Hour piece about water in Puget Sound was something useful to consider. The part about the impact of run off (heavy metals, oil, etc) and the use of rain gardens and other natural filters (green storm water infrastructure) to improve water quality. This seems to have implications for our local groundwater systems.
Scientists Search for Solution to ‘Toxic Cocktail’ in Washington’s Puget Sound
Summary: In Washington state’s Puget Sound, scientists have made discovery of a “toxic cocktail,” made up of excess rainfall that flows into the nearest body of water, carrying pollutants along with it. Kate Campbell from KCTS-9 in Seattle reports on efforts to prevent that runoff from making it into the sound.
Watch Seattleites Make Rain Gardens to Curb Stormwater Pollution on PBS. See more from PBS NewsHour.