2019 Basin Plan Amendment and TMDLs for (Region 5) TMDL


The Central Valley Regional Board’s Basin Plan Amendment (BPA) for the Control of Pyrethroid Pesticide Discharges was finalized in April 2019 and is in effect for nine urban creeks in the Sacramento and Roseville areas. The goal of the amendment was to develop clear requirements for the control of pyrethroid pesticide discharges in order to provide reasonable protection of beneficial uses in the Sacramento and San Joaquin River Watersheds, including the Delta. It establishes Total Maximum Daily Loads (TMDL) for Clean Water Act Section 303(d) impaired waterbodies and sets measurable pyrethroid concentration goals.

Six pyrethroid compounds — bifenthrin, cyfluthrin, cypermethrin, esfenvalerate, lambda cyhalothrin, and permethrin — were identified as priority constituents due to the prevalence of their use and documented impairment impacts. Water quality impairments can occur in urban water bodies from municipal separate stormwater systems (MS4s), municipal and domestic wastewater and agricultural dischargers

The BPA requires the development of a Pyrethroid monitoring plan followed by the baseline and trend monitoring of stormwater, wastewater and irrigated lands. Dischargers will provide monitoring information to the Board in order to determine compliance with TMDL numeric limits.

Pyrethroid Analytical Methods

In March of 2019 the Central Valley Water Board requested Method Validation packages from Environmental Laboratory Accreditation Program (ELAP) accredited laboratories. The laboratories were required to provide performance-based analytical methods that were able to achieve the low limits required for the Pyrethroid BPA and TMDL. While Caltest has been able to achieve these low limits for over a decade, few commercial labs could. After Board review and approval, Caltest’s EPA 625.1 method was approved and is now included in our Fields of Testing (FOT) on our current ELAP certificate. Current reporting limits and compound list are noted below and align with the requirements of the BPA.

CAS# Compound Name Units MDL RL
82657-04-3 Bifenthrin ng/L 0.3 0.5
68359-37-5 Cyfluthrin ng/L 0.4 0.5
91465-08-6 Lambda-Cyhalothrin ng/L 0.3 0.5
52315-07-8 Cypermethrin ng/L 0.3 0.5
51630-58-1 Esfenvalerate:Fenvalerate ng/L 0.4 1
52645-53-1 Permethrin ng/L 2 5

For more information about Caltest’s Pyrethroid analysis or to get a quote, email