Marin’s watersheds include more than 3,000 miles of creeks. Some of these water ways flow into our lakes for storage, while others feed into San Francisco Bay and on to the ocean. The Mt. Tamalpais Watershed is one of county’s most valuable natural resources and the source of domestic water for the majority of residents. Try out this interactive tool to locate your watershed.
The water out of your faucet gets captured in one part of the watershed, then is passed through a drinking water treatment plant for physical and chemical processing. Once used in the home, drains carry wastewater from toilets, sinks, and showers to wastewater treatment plants. These facilities treat and disinfectant wastewater before releasing it into the bay. The process doesn’t detoxify pesticides – their residue ends up in our waterways.
Ideally all the water you use for irrigation lands on soil where it soaks in carrying valuable nutrients with it. Water that hits hard, impervious surfaces will likely end up in street gutters and then into storm drains that are designed to prevent flooding. Unfortunately, the storm drain system provides a direct route right to the bay for the fertilizers, pesticides, and other chemicals commonly used around our homes and gardens.
Fertilizers are a particular problem. When nitrogen and phosphorus are not fully utilized by growing plants, the excess nutrients are washed into our waterways during rain events. Known as nutrient pollution, too much nitrogen and phosphorus in water causes algae to grow faster than ecosystems can handle. Significant increases in algae harm water quality, food resources and habitats, and decrease the oxygen that fish and other aquatic life need to survive.
We can all play a part in maintaining the water quality in our watershed and protecting the plants, fish, birds, and other wildlife that depend on it. Here are some specific things that we can all do to help keep Marin’s watershed healthy:
- Plant a variety of types and species of plants from grasses for erosion control and wildflowers for bees and butterflies, to shrubs and trees for birds and healthy streams.
- Encourage rainwater to slow, sink, and spread into soil. Use porous alternatives such as gravel or permeable pavement for driveways and paths.
- Reduce the use of chemical fertilizers and pesticides that can lead to excess plant and algae growth in waterways.
- Test your soil before applying fertilizers and add only the nutrients your soil needs.
- Use natural fertilizers; compost or slow-release fertilizer release nutrients slowly.
- Time fertilizer application right – avoid fertilizing before a heavy rain to prevent runoff, or late in the season when plants head into dormancy.
- Pick up pet waste – left out in the yard, on sidewalks or on roadsides it washes away when you irrigate, or it rains. Put it in a sealed bag in the trash.
Learn more about the Marin Watersheds Program.