A watershed is a basin-like landform that captures falling precipitation (rain, sleet and snow) which is divided by peaks and ridges that collect into streams, rivers and lakes eventually leading to the ocean.
In San Francisco all watersheds terminally lead to the SF Bay or to the Pacific Ocean. California Climate Action Now! has removed pavement in almost every watershed in the City, from Islais Creek (SF’s largest watershed) to the Sunset NAME OF BASIN.
When large portions of urban areas are heavily paved-over San Francisco’s combined sewer system can become stressed, especially during large storms. And as we continue to increase carbon dioxide and other greenhouse gases into the atmosphere, storms and most weather systems are becoming more and more extreme.
In California’s Mediterranean climate, precipitation is heaviest in the winter months. When these winter storms become extreme, this can create a huge flow of water that the City’s combined sewer system cannot effectively clean. It is then, during heavy storms, that the stressed sewer system releases untreated (contaminated) water into local waterways. Atmospheric river description?
These large winter storms in San Francisco sometimes force the SF wastewater treatment plant staff to discharge untreated water into the SF Bay or the Pacific Ocean. By removing pavement we capture stormwater in the ground, reducing pressure on San Francisco’s combined sewer system.
There are two wastewater treatment plants in San Francisco. 80% of all the waste from all of San Francisco’s nearly 1 million residents heads to the SFPUC’s Southeast Treatment Plant located in the Bayview neighborhood. The other 20% flows to the Oceanside Treatment plant adjacent to the SF Zoo.
As the City’s population grows, important green infrastructure improvements will need to increase exponentially to ensure that all California’s have access to clean air, fresh drinking water and access to nature.
