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Delta Watch

Stormwater and Agricultural Runoff

Via both discharges from storm drains and natural run-off to rivers and streams, a number of cities within and up stream of the Delta release hundreds of thousands of gallons of water containing contaminants and toxic chemicals each day. According to the Center for Biological Diversity, both delta smelt and the plankton on which it feeds are suffering direct mortality or impairment from the presence of toxic substances in the water.

Pyrethroids, among the most widely used home pesticides, are winding up in the Delta at toxic levels, and endangering the food supply of fish and other aquatic animals, according to a new study by researchers at the University of California, Berkeley. Pyrethroid insecticides, commonly used in California to kill ants and other pests around the home have been widely found in street run-off and in the outflow from sewage treatment plants in the Sacramento area. The insecticide is being increasingly found in two urban water ways, the San Joaquin River and a 20-mile stretch of the American River, traditionally considered to be one of the most pristine rivers in the region. Pyrethroids have been around for decades, but their use skyrocketed after 2004, when other home-use pesticides were banned. The main sources appear to be readily available insecticides applied around the home by homeowners and professional pest control operators to control pesky ants.

Additionally, salinity, herbicides, pesticides, and other toxic chemicals and pollutants from agricultural sources directly impact delta smelt, salmon and other endangered fish and their ecosystem. According to the Center for Biological Diversity (CBD), "...all life stages of delta smelt are at least periodically exposed to lethal or sub-lethal concentrations of herbicides and pesticides discharged and transported from upstream into their habitat." According to CBD, both the smelt and the plankton on which it feeds are suffering direct mortality or impairment from the presence of toxic substances in the water.

Additional Information

Violating the Delta

Sacramento Valley Pesticide Application - Agriculture vs. Urban

Pyrethroid Pesticides in the Sacramento-San Joaquin Delta: Sources and impacts on Delta waters

Delta Coalition Initiates Legal Action on Illegal Pollution Discharges (July 1, 2008) 
Notice of Intent to Sue for Violations of the Clean Water Act and Endangered Species Act 
- Pollutant Discharges

News Articles

First flush fish kill
Post from Alex Breitler's Blog (Oct. 7, 2011)

Groups plan suit against Stockton 
Article from the Stockton Record (July 2, 2008)

Delta group to file suit 
Article from the Tracy Press (July 2, 2008)

Delta group threatens suit over runoff
Article from ABC News 10 (July 1, 2008)

Storm Runoff and Sewage Treatment Outflow Contaminated With Household Pesticides 
Article in Science Daily (Feb. 3, 2010)

Pollution’s high price tag...Stockton settles pollution lawsuit for $4 million 
Article in the Chico News & Review (Aug. 6, 2009)

Urban pesticides found to be major Delta stressor...Sacramento again major polluter 
Editorial in Stockton Record (July 16, 2009)

Sacramento area is Delta's top pesticide source, study finds
Article in Sacramento Bee (July 14, 2009)

2010 Pulse of the Estuary Report

Center for Biological Diversity Poisoning Our Imperiled Wildlife