Pyrethroids Management Program

On June 8, 2017, the Central Valley Regional Water Quality Control Board (Regional Water Board) adopted Resolution R5-2017-0057, the Basin Plan Amendment (BPA) for the Control of Pyrethroid Pesticide Discharges. The BPA was subsequently approved by the State Water Resources Control Board on July 10, 2018 and the Office of Administrative Law (OAL) on February 19, 2019. The United States Environmental Protection Agency (USEPA) approved the Pyrethroid Total Maximum Daily Loads (TMDLs) for the nine urban creeks in Sacramento and Roseville on April 22, 2019. With these approvals, the TMDLs and BPA became fully approved and effective. 

The BPA established a Pyrethroids Control Program that includes a variety of actions including, but not limited to:

Monitoring requirements to assess baseline conditions, as well as continued trend monitoring.

A conditional prohibition for pyrethroid discharges in exceedance of numeric triggers for Sacramento and San Joaquin River Basin water bodies with the aquatic life beneficial uses. 

If the numeric triggers are exceeded, the conditional prohibition requires the development and submittal of a Pyrethroid Management Plan (Management Plan) to reduce pyrethroid levels in discharges to the maximum extent practicable. 

All municipal stormwater cities (Phase I and Phase II) are subject to the conditional prohibition, and all municipal stormwater cities not subject to the TMDL are required to provide baseline monitoring to the Regional Water Board. However, municipalities regulated pursuant to the Phase II Municipal Separate Storm Sewer System (MS4) permit Phase II Permit may, as an alternative, acknowledge that the existing data are representative of their discharge and forego baseline monitoring and develop a Management Plan. 

As such, this Management Plan is being developed on behalf of the City of Patterson, as required by the State Water Resources Control Board.  The City's Pyrethroid Management Plan was developed in collaboration with 21 other agencies. To obtain a copy of the City's Pyrethroids Management Plan click here.