Get Full Government Meeting Transcripts, Videos, & Alerts Forever!
Get email alerts on the Water Quality Tmdl topic
No spam. Unsubscribe anytime.
State board adopts TMDLs for pyrethroid pesticides in Alamo and New Rivers
Summary
The State Water Resources Control Board unanimously approved a basin plan amendment to establish total maximum daily loads for six pyrethroid pesticides in Imperial County's Alamo and New Rivers, directing implementation through regional agricultural orders and NPDES permits and coordinating with federal partners on transboundary pollution from Mexico.
The State Water Resources Control Board on May 19 unanimously adopted a resolution establishing total maximum daily loads (TMDLs) for six pyrethroid pesticides in the Alamo and New Rivers in Imperial County.
Emma McCorkel, senior environmental scientist with the Colorado River Basin Regional Water Quality Control Board, told the board the rivers have been listed for pyrethroid impairments after detections between 2003 and 2020. "The Alamo River and New River are surface water bodies in the Imperial Valley that are impaired by pyrethroid pesticides that are toxic to humans and aquatic life," McCorkel said, describing staff's recommendation to set numeric targets based on updated UC Davis criteria and implement allocations through waste load and load allocations in NPDES permits and regional irrigated-lands orders.
The staff report and presentation outlined that water-column pyrethroid concentrations frequently exceeded numeric targets, that sediment concentrations did not exceed the criteria, and that the TMDL will be implemented through the regional board's Imperial Valley Agricultural General Order for irrigated lands and through NPDES permits for point sources. McCorkel said monitoring gaps among some municipal permittees made them "uncertain sources" that will be required to monitor for pyrethroids through permit conditions.
Board members thanked the regional staff and emphasized the watershed perspective. Chair Walkin Esel said the work complements forthcoming Salt and Sea planning and encouraged a basinwide approach, noting in remarks to staff: "This work to really take a watershed look and ensure that the source water that feeds the sea is as appropriate and clean as it can be."
Presentation slides and staff responses explained how the TMDL will address both California-based agricultural sources and transboundary contributions from Mexico. Staff said the Colorado River Basin Water Board will coordinate with federal partners including the International Boundary and Water Commission and U.S. EPA to address discharges at the international boundary, while proceeding with phased, adaptive implementation that does not defer regulation of California sources.
A motion to adopt the resolution passed by roll-call vote; the board recorded affirmative votes from Board Member Laurel Firestone, Board Member Shawn Magcguire, Board Member Nicole Morgan, Vice Chair Darin Diodamo, and Chair Walkin Esel. The record notes the resolution as "R7202424" in the staff packet and supporting materials.
Votes at a glance - Adoption of May 5 meeting minutes: motion made and seconded; minutes adopted (roll-call majority). - Resolution R7202424 (pyrethroid TMDLs for Alamo and New Rivers): motion made and seconded; resolution adopted unanimously.
What happens next Regional staff will implement numeric targets through waste discharge requirements and NPDES permits, begin permit- and monitoring-based tracking of pyrethroids for point sources, and coordinate with federal partners on transboundary pollution while pursuing a phased implementation schedule. The staff report and related documents are posted with the board's hearing materials.
