Location Ocean Pkwy, Bolinas, CA 94924 (see map)
In the summer of 2013, using Proposition 84 grant funds, the County implemented improvements to the Agate Beach County Park parking lot to address potential stormwater pollution to the Duxbury Reef Area of Special Biological Significance. ASBS. The parking lot was retrofitted with pervious pavement and integrated storm water retention and infiltration structures. Improvements were also made to the adjacent drainage swale to create a series of rock check dams to slow and filter storm water during periods of heavy runoff when the parking lot BMPs may not be able to absorb the full volume of runoff.
The paved trailhead of the path from the parking lot to the beach was also replaced with decomposed granite to allow runoff to sink in, and the portable toilets were relocated away from the top of the stream bank and placed in a covered enclosure to prevent spills.
Water quality monitoring of the parking lot project demonstrated a nearly 60% reduction in runoff volume as well as reductions in the concentrations of sediment, oil and grease and some trace metals resulting from the parking lot improvements.