9696 - Laserfiche WebLink

Home Browse Search

1.5 Framing the Controversies The controversies can be illustrated in a number of ways, but a specific example is the issue of whether Kesterson-like avian deformities have been found in the Grand Valley. Lemly (1999) states that such deformities have been found and quotes Seiler (1998). Seiler indicates that the information came from biologists working in the Grand Valley (Seiler 1999). The individuals named by Seiler; however, state that only one such nest has been found (Krueger 1999; Osmundson 1999). These researchers emphasize their belief that the reason there are not more incidents is the overall lack of reproduction in the area, not that selenium levels are insufficient to cause toxicity. Nevertheless, this finding that reported avian deformities represent a small number of incidents, is supported by another researcher who interviewed persons knowledgeable about other locations where selenium problems are suspected (Raisbeck, M.F., University of Wyoming, personal communication, July 2, 1999). As would be expected, the low number of incidents causes doubt regarding the severity of selenium toxicity. Similar circumstances exist with respect to the endangered fish. Deformed fish were found at Belew's Lake, but there is apparently no evidence of deformed fish in the Upper Colorado Basin. Selenium is considered by some to be a major factor in the population declines of the Colorado pikeminnow and razorback sucker because of high concentrations found in adult fish and in water and sediments in rearing areas. Laboratory research has demonstrated that selenium affects these endangered species, but as will be discussed in subsequent sections, much of this research is controversial. 1.5.1 Historical Accounts of Decline of the Endangered Species An important aspect of determining the reasons for the decline of the endemic fish in the Upper Colorado Basin is an evaluation of their historical distribution. Because of the nature of the regional geologic environment (see Sect. 2) and the habits of the endangered species (see Sect. 4), it is likely that in presettlement times, native fish were occasionally exposed to concentrations of selenium that are considered elevated based on present-day standards for the protection of aquatic life. It is also apparent that fish populations were exposed to waters with higher than present-day concentrations of selenium for most of the twentieth century. For these reasons, relating the decline of the fish to historical exposure may provide important insight. Of particular interest is whether the decline occurred substantially before or after about 1950. Although water development began in the early 1900s, the most extensive alterations of the Colorado River through the Grand Valley occurred after 1950. In other words, the predominant effect on the endangered species prior to 1950 was human harvest and selenium exposure, whereas habitat loss and changes in the timing and. magnitude of peak flows became most severe after 1950. 1.5.1.1 Selenium Exposure It is known that water quality has always been a problem in the Upper Colorado Basin. Grand Junction newspaper reports from the late 1890s stated that there would never be settlement and growth unless better sources of water were located. Such statements suggest that the river water was often saline. Present-day research demonstrates a general correlation of dissolved solids with selenium. Nonetheless, without chemical analyses, these reports also may be referring to the high level of other dissolved salts and suspended sediment.