PROGRAM INTRODUCTION

Wastes from oil refineries contribute selenium, petroleum compounds, and other chemical pollutants to surface waters. This refinery is located along San Francisco Bay.

Freshwater, anadromous, and marine fishes and other aquatic organisms in the Western U.S. are potentially threatened by a wide variety of environmental contaminants. These contaminant threats originate from a variety of sources, including active and abandoned mining operations, irrigated and non-irrigated agricultural activities, silviculture and timber harvest operations, urban runoff and sewage wastewater disposal, air pollution from combustion products, aquaculture, and many other natural and anthropogenic activities. The contaminants include heavy metals and metalloids,

Lumber mills and paper manufacturing plants have been implicated as sources of dioxins and other chemical contaminants. This now-closed paper mill is located adjacent to the Sacramento River.

synthetic pesticides, organic and inorganic fertilizers, pharmaceuticals, detergents and fragrances, and even altered physical and chemical water quality characteristics such as high temperatures, high salinities (including atypical ionic ratios), high turbidity, gas supersaturation, and anoxia.

Although various federal and state regulations are helping to ameliorate or curtail fish kills and other catastrophic toxic events, the disposal of many potentially hazardous chemicals are unregulated due to insufficient knowledge. In some instances, chemicals accumulate in aquatic organisms although their ecological effects are unknown. In addition, new chemicals are continuously being synthesized, many of which could eventually pollute surface waters and adversely affect fishery resources.

Aerial application of pesticides and fertilizers can drift into adjacent waterways, leading to toxicity problems. This aircraft is spraying parathion on a tomato field in the Sacramento-San Joaquin Delta.

Detecting, quantifying, understanding, and ameliorating the ecological effects of environmental contaminants are high priority concerns of the Department of Interior and the U.S. Geological Survey. Contaminant research at WFRC is focused on addressing the information needs of the U.S. Fish and Wildlife Service, U.S. Bureau of Reclamation, National Park Service, and many other federal, state, and local agencies and tribes. Objectives of the WFRC contaminants program include the following:

Agricultural return flows contaminate surface water with pesticides and fertilizer compounds, and oftern contribute turbidity and oxygen-demanding waste products that adversely affect fish and their forage base.

•  Survey and monitor water quality and contaminants: provide USGS partners with information from properly designed surveys of water quality and environmental contaminants that identify the sources and extent of contamination, ascertain severity of contamination (risk analysis or hazard assessment) and routes of uptake, and determine if cleanup efforts are achieving desired goals.

•  Detect, quantify, and understand toxic or stress responses in important fishery resources: develop new techniques and protocols or use existing technologies to identify, measure, and assess toxic or stress (biomarker) responses such as increased mortality, reduced growth or body condition, impaired physiological processes, reduced reproductive success, behavioral alterations, histopathological anomalies, and biochemical changes in fishes and other aquatic organisms inhabiting contaminated environments.

•  Relate toxic or stress responses in individual fish to impacts on populations and communities: relate results from contaminant surveys and detection of toxic or stress responses in individual fish to health of fish populations and communities.

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Fish kills are a typical consequence of polluted waterways. This fish die-off in a canal in the San Joaquin Valley resulted from improper disposal of agricultural drainwater tainted with an ammonia-based fertilizer.	In the mid-1980's pollution from selenium-laden subsurface agricultural drainwater prompted a warning to anglers about eating contaminated fish. This warning sign was posted on Salt Slough at the San Luis National Wildlife Refuge near Los Banos, California.