Research Areas > Stormwater > Runoff Characterization > Pollutants in Dry-Weather Runoff

Project Area: Dry-Weather Runoff Pollutant Loading

SCCWRP Research

Dry-weather urban runoff can be a source of bacteria, nutrients, and metals to receiving waters. These constituents may be of particular concern in arid, urban watersheds where dry weather flow entirely consists of wastewater effluent and/or urban non-point source runoff. Furthermore, during dry weather, constituents may occur predominantly in the dissolved phase (vs. the particulate phase typically associated with stormwater) and thus may be more bioavailable. Most studies of urban runoff focus on stormwater, but few have evaluated the relative contribution and sources of dry-weather pollutant loading for a range of constituents across multiple watersheds. This is problematic because management of dry-weather water quality and loading to coastal receiving waters may require different strategies than those used for wet weather stormwater runoff.

This project area aims to assess dry-weather pollutant loading and the associated toxic effects in urban watersheds across southern California. The overall goal is to characterize the relative contribution of dry-weather runoff to total annual loading of nutrients, metals, and organics, and to evaluate the toxicity associated with this runoff. This information can also be used to support regional models of pollutant loading to the Southern California Bight.

Projects investigating dry-weather pollutant loading include:

• Dry-Weather Water Quality in the San Gabriel River
• Characterization of Dry-Weather Metals and Bacteria in Ballona Creek
• Pesticides from Residential Land Uses