OCR Text |
Show freshening of the bay might allow aerobic bacteriological decomposition of organic materials previously " fixed" by the lake water's high salinity. In 1965, the Utah Department of Health reported "... positive evidence of sewage pollution in the [ Farmington Bay] lake water to such an extent that bathing should not be approved of in any of these areas for this reason." A study completed in 1971 confirmed organics comprised up to 37 percent of some bottom sediment samples in the south end of the bay, and found unacceptably high counts of E. Coli and other coliforms at salinities up to 5.5 percent ( Carter, 1971). It was subsequently suggested that an accumulated sludge layer in the bottom of Farmington Bay could be a major water quality concern if sediments were disturbed or if the water continued to freshen ( DWRe, 1974). In 1985, Utah State University ( USU) conducted an investigation to determine the potential for contamination of Farmington Bay water from bay sediments in different water freshening scenarios. The study suggested the potential for contamination exists in two sediment core samples contained freshwater soluble heavy metal accumulations. The study also concluded that more information on the potential for release of toxic metals and organic materials should be gathered before any bay freshening proposals should be considered. It was suggested that if the salinity of Farmington Bay were lowered, the " consequences might be dramatic," and result in large algal blooms and resulting odors due to high nutrient levels. Past sediment surface core sample analyses in Farmington Bay have indicated metal accumulations in bottom sediments. ( USU Water Lab, 1988) Initial results for Farmington Bay show generally low concentrations of contaminants. Lead concentrations peaked at 130 ppm about 1978 and have declined to near 70 ppm in recent years. This is likely due to declining use of leaded gasoline and lead shot for hunting. South Arm In 1994, USFWS conducted a limited evaluation of trace elements in brine shrimp and brine flies from the south arm of GSL. The report concluded that some trace elements are elevated to levels of concern and further study was recommended. Currently USFWS is evaluating contaminants including trace elements, polycyclic aromatic hydrocarbons ( PAH), polychlorinated biphenyls ( PCB), and pesticides in wetlands associated with the lake as well as its tributaries. Although sampling has focused on biota from these areas, some sediment samples have also been collected. This current study is also expanding on the study completed in 1994 to include sediment samples as well as brine shrimp to further characterize contaminants in the food chains of the south arm of the lake. Bear River Bay An investigation by USFWS near the BRMBR between 1989- 90 discovered no indications of the presence of hazardous materials ( DNR, 1995 and Waddell et al., 1990). There is currently underway a National Water Quality Assessment ( NAWQA) study to determine trends in water quality using a variety of methods including sediment coring to determine magnitude and trends in contamination. 58 |