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A Sustainable Approach to Stormwater Management

In most places, stormwater has been traditionally treated as a waste rather than a resource. For the past hundred years or so, urban areas attempted to prevent flooding and debris related to storms. This was done by designing streets, roads, buildings, plazas, parks, and schools to move rainwater as quickly and efficiently as possible from where the rain falls to a downstream receiving water like a creek, the bay, or the ocean via mostly underground networks for pipes, channels, and other conveyances. In many developing cities, the problem of managing stormwater volumes and associated pollutants was dealt with by combining stormwater with sewer infrastructure, so that polluted runoff would be managed by wastewater treatment plants. Lessons learned from the emerging and arguably worse problem of frequent “combined sewer overflows” during large storm events that have resulted in long-term and often tremendously harmful sewage spills into receiving waters, newer cities opted to keep stormwater and wastewater sewers separate, which is the case in San Mateo County. 

In the past several decades, there’s been a shift in perspective. As more and more communities face periodic or even chronic drought interspersed with intense and long-duration storms, causing a confusing mixture of unusually warm and dry bouts, followed by periods of heavy rain, it is increasingly obvious that a new approach to stormwater management should be embraced, one that features green stormwater infrastructure—designed to capture, store, and filter polluted runoff where it falls through vegetation and special infiltrating soils—and opportunities to harvest and reuse stormwater for other purposes like irrigation and even toilet-flushing. These practices not only manage stormwater more effectively and are great at removing many kinds of pollutants, they also generate calmer, safer, and more appealing environments. 

San Mateo County municipalities are making significant headway with climate adaptation planning and sustainable stormwater management strategies led by the San Mateo Countywide Water Pollution Prevention Program. The program works collectively with all of its member agencies to advance planning, building, and maintaining green infrastructure facilities as they progress towards a “greener” community, emphasizing the importance of working collaboratively and across jurisdictional boundaries, because water flows according to the shape of a watershed, not the shape of a city. Whether it’s planning a regional stormwater capture project, developing standardized design guidance for new infrastructure, or planning to meet regional goals for pollutant reductions to comply with the Municipal Regional Permit (MRP), the municipalities in San Mateo benefit from working together. Below are a few examples of regional collaboration that the program has taken on to promote widespread and sustainable stormwater management in our county.

Stormwater Resource Plan

Sustainable Streets Master Plan

Safe Routes To School

San Mateo County Flood and Sea Level Rise Resiliency District