“Water is the most critical resource issue of our lifetime and our children's lifetime. The health of our waters is the principal measure of how we live on the land."
- Luna Leopold
Humans and every other species depend upon water for survival. Fresh, clean water is a very limited resource–less than 1% of the water on the planet is available for human consumption, and that number steadily decreases as we pollute our waters and use up prehistoric groundwater supplies.
In Marin County all the fresh water supply comes as rainfall, mostly from November through April. Native plants and animals are adapted to the seasonal extremes of wet winters and warm, dry summers, but human communities and their public agencies need to manage carefully to provide reliable, high quality water while maintaining good habitat conditions in streams and wetlands.
Water that infiltrates the ground during the rainy season is stored as shallow groundwater in the uplands and alluvial fill of the valley floor, and is slowly released into streams and springs throughout the summer. Some rural residents get their fresh water directly from wells and springs, but most Marin County residents use streamflow that has been collected behind dams in reservoirs in the Lagunitas Creek, Novato Creek, and Russian River watersheds. A small but growing number are replacing a portion of their household water with rain collected from roofs and stored in barrels or tanks.
Wastewater either enters a septic system and is leached slowly back into the soil, or is transported to a sanitary sewage system where it is treated and eventually released into wetlands or directly into the Bay. Some treated wastewater is used to irrigate landscaping and pastures through recycled water projects, reducing the demand on drinking water supplies and decreasing the amount of water sent to the Bay.
Water conservation saves not only water, it saves energy needed to transport and treat water, and it helps maintain sufficient summer flows for fish and other aquatic wildlife.