Cooperative Partnership Between California Regional Water Quality Control Board and Imperial County Farm Bureau Creates Positive Results in TMDL Implementation

Irrigation surface runoff (a.k.a. “tailwater”) from agriculture in Imperial Valley, located in Southeast California, has contributed high levels of sediments and other pollutants to the New River, Alamo River, and Imperial Valley Drains. The New and Alamo Rivers are the main tributaries of the Salton Sea—California's largest inland waterbody. The Salton Sea is located in a closed desert basin in Riverside and Imperial Counties, and it is the most prominent feature of the Salton Sea Transboundary Watershed. The Sea has been home to a historically high productive fishery and more than 400 species of resident and migratory birds.The Salton Sea Transboundary Watershed is the priority watershed for the Colorado River Basin Regional Water Quality Control Board (Regional Board) and contains five of the six impaired surface water bodies in the Region's Clean Water Act Section 303(d) list: Salton Sea, New River, Alamo River, Imperial Valley Agricultural Drains, and the Coachella Valley Stormwater Channel. Most pollutants scheduled for total daily maximum loads (TMDL) development and implementation are nonpoint source pollutants from irrigated agriculture in the Imperial Valley. The Regional Board is using a watershed management approach with “geographically nested” TMDLs to address the impairments in these waters. Stakeholder participation is key in this approach, particularly the involvement of the Imperial County Farm Bureau.