Cleaning Urban Stormwater On Its Way To The Ocean: Ecosystem Services From Natural Treatment Systems

Project Overview:

Sustaining adequate water resources is a priority given the ongoing water crisis in Southern California. Vast quantities of water are wasted in urban areas via runoff from storms and daily local usage that flows directly into the ocean.  The journey through impervious urban surfaces such as streets and parking lots accumulates nutrients, metals, fire retardants, pharmaceuticals, and organic contaminants, such as hydrocarbons, into the water. Contamination from runoff is a well-documented problem for both marine life and humans.

One underutilized tool to retain potable water and remove contaminants from runoff are biofilters. Biofilters are constructed to use natural processes, e.g. plant uptake, and living materials, e.g. microorganisms in the soil, to treat urban runoff before it reaches the ocean.  Small biofilter systems have been built in Los Angeles, Orange and San Diego Counties by individual developers, universities, municipalities, transportation authorities and water districts, but there is no comprehensive listing of their location, design, and size. This project will study both the ecology of biofilters and how to optimize the design and locations of biofilters to maximize their benefits.

This project will:

• Map the locations of existing biofilters in Los Angeles and create an inventory of their size and configuration, design, age, and proximity to drainage pipes, streams and other outlets to the ocean.  This inventory will be cross referenced with the city’s drainage patterns and used to help determine each biofilter’s ability to intercept and treat stormwater flow. 

• Compile and/or generate information about the ecological attributes of urban biofilters, such as vegetation, soil invertebrates, and sediment that determine their impacts on the environment.

• Describe and quantify the ecosystem services, e.g. benefits such as water detoxification, from these biofilters in order to help managers assign economic values to them for use in cost-benefit analysis during planning.

Biofilters require low-energy input yet provide multiple benefits including flood and erosion control, biodiversity conservation, and detoxification that can improve the water quality of our coastal ocean. Lisa Levin, the principal investigator of the Sea Grant project, is Director of the Center for Marine Biodiversity and Conservation at Scripps Institution of Oceanography in La Jolla and Distinguished Professor at Scripps. 

Read the summary project proposal.