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Sonny Bono Salton Sea Refuge Endocrine Disruptor Study

Date Posted: February 10, 2003

The Sonny Bono Salton Sea NWR has a variety of freshwater ponds managed for wildlife that are supplied with Colorado River water that carries municipal and industrial discharges and agricultural return flows from upstream sources. Earlier studies indicate that p,p’DDE, a metabolite (breakdown product) of DDT, is widespread in the plants and animals of the Imperial Valley probably from historic applications of DDT to the Imperial Valley agricultural fields. DDT and its metabolites and sewage effluent have been associated with endocrine effects in aquatic species including intersexuality in fish (abnormal steroid hormone levels, vitellogenin [a protein precursor to egg yolk] induction in male fish and high incidences of ethynil estradiol [a synthetic estrogen component found in oral contraceptives]). No studies have measured the endocrine effects of these constituents on aquatic species in the Imperial Valley. CFWO is implementing a study on fish inhabiting these agricultural drainage ponds. The objective of this study is to determine if aquatic species are exhibiting some form of endocrine disruption by evaluating: (1) exposure to synthetic organic compounds; (2) sperm viability in male fish; and (3)egg development in female fish. The constituents potentially responsible for any observed endocrine impacts will be identified by sediment sampling and analyses. Initial results from analysis of fish and sediment have been received and need further evaluation to determine the focus of the remaining field sampling activities. Initial evaluation of these results indicate that endocrine disruption in fish may be a concern in the Imperial Valley.


Scott Sobiech or Carol Roberts, 760/431-9440.


U.S. Fish and Wildlife Service, Division of Environmental Quality. DDT and Wildlife

U.S. Fish and Wildlife Service, Division of Environmental Quality. Endocrine (Hormone) Disruptors

Last updated: June 12, 2015