What Green Infrastructure Does For Water Quality in Marin

The terms Green Infrastructure and Low Impact Development (LID) are approaches to water management that protect, restore, or mimic the natural water cycle in the urban environment. Simply put, the goal is to divert stormwater into natural areas where the water can be filtered and infiltrate rather than run directly into storm drains and carrying pollutants into our creeks. These approaches can be as small as catching roof runoff from a downspout and diverting to rain barrels or a rain garden in your yard or as large as green streets projects and whole parking lots draining to an underground cistern or bioretention areas in the parking islands.

The projects shown below are a portfolio highlighting various types of Green Infrastructure implemented throughout Marin County. Additional potential future projects are listed in Appendix E of the Marin County Stormwater Resource Plan.

How Urban Areas Affect Our Waterways
Urban areas cover much of the land with impervious surfaces including streets, sidewalks, and roofs. Rather than allowing the rain to slow down and infiltrate into natural environments, it runs off instantly to gutters, storm drains, and straight into the nearest creek. The runoff from these surfaces often carries pollutants such as heavy metals, petroleum products, pet wastes, pesticides, and trash washed from streets, parking lots, and yards.

The result is flooding, creek bank erosion, water pollution, and decreased summer flows in our creeks. Studies show that these effects begin when as little as 10% of an area is developed.

Making Urban Areas More Creek Friendly
Urban development can do a lot to filter out pollutants, slow down storm flows, let water soak into soil, and recharge the groundwater table to improve summer creek flows. These features can also can also increase neighborhood beautification, add greenspace, provide native habitats for bees, butterflies, and birds, and even increase pedestrian safety.
Marin County Stormwater Resource Plan
The Marin County Stormwater Resource Plan was completed in September 2017 with the objective of identifying and prioritizing potential projects within the MCSTOPPP agency’s jurisdictions that are designed to capture, treat and increase infiltration capacity, and/or use stormwater in ways that provide multiple benefits. The list of projects (Appendix E) is reviewed and updated on an annual basis. The most current final documents are listed below.

Marin Countywide Green Infrastructure Projects

All
Bioretention Areas
Cisterns and Rain Barrels
Green Parking
Green Roofs
Green Streets
Permeable Paving
Rain Gardens
Swales and Bioswales
Tree Boxes
Agate Beach Park
Leo T Cronin Fish Viewing Area
Hamilton Marketplace
Whole Foods - The Millworks