Ulatis Sediment Toxicity

Our Current Management Plan: Ulatis Creek Sediment Toxicity Management Plan*

Map of California counties with rivers, creeks, drainage areas, monitoring site, and the UCBRD area marked. — Map of the Management Plan Boundaries for the Cache Slough Represented Drainages

History of Ulatis Creek/Brown Road Monitoring Site:

Sediment toxicity exceedances

April 17, 2018 - Lambda-Cyhalothrin
April 18, 2019 - Lambda-Cyhalothrin, Bifenthrin
April 21, 2022 - DNQ (Detected, not quantified
*April 16, 2025 - DNQ (Detected, unknown pyrethroid)

Water column detections

August 21, 2018 - Lambda-Cyhalothrin
March 19, 2019 - Lambda-Cyhalothrin

Water column exceedances

June 23, 2021 - Lambda-Cyhalothrin
December 17, 2024 - Bifenthrin, Lambda-Cyhalothrin, Cyfluthrin, Esfenvalerate
May 20, 2025 - Bifenthrin

*Sediment Toxicity Management Plan (MP) with Water Column addendum, extended 3 years until 2028

We had zero sediment toxicity exceedances (or detections) in 2023 and 2024 thanks to collective efforts to use BMP (best management practices) when applying pyrethroids. Growers are also using alternative pest control products or techniques such as biological control, habitat manipulation, and cultural practice changes to reduce the need to apply pyrethroids.

Note: The exceedances in December 2024 and May 2025 have triggered an additional management plan. The Regional Board approved an addendum to be included in the current sediment toxicity management plan. This was approved on January 9, 2026.

Management Plan Focus:

Sediment Toxicity

Monitoring Site: Ulatis Creek at Brown Road
Crops: Alfalfa, processing tomato, barley and pear
Pesticides: Pyrethroids: Lambda-Cyhalothrin, Bifenthrin
Our Goal: Zero exceedances

Water Colunm Addendum

Monitoring Site: Ulatis Creek at Brown Road
Crops: Alfalfa, almond, corn (grain), dried bean, melon, processing tomato, sorghum milo, sunflower, uncultivated agriculture and walnut
Pesticides: Pyrethroids: Bifenthrin, Lambda-Cyhalothrin,
Our Goal: Zero exceedances