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2b. Wastewater Contaminant and Pharmaceutical Compounds <br />A study conducted by the USGS, "Comprehensive water quality of the Boulder Creels <br />Watershed, Colorado, during high-flow and low-flow conditions, 2000" (Murphy, Verplanck and <br />Barber, 2000), showed nearly 50 wastewater contaminant and pharmaceutical compounds at <br />concentrations ranging over five orders of magnitude. Studies of Boulder Creels downstream <br />from the Boulder WWTP have detected trace organic wastewater compounds such as steroids, <br />hormones, prescription and nonprescription drugs, surfactants, and pesticides (Murphy et al <br />2003, and Barber et al, 2006). The effects of many of these compounds are ui~lalown, and there <br />are no water quality standards for most of them. h7 fish, potential concerns include abnormal <br />physiological processes and reproductive impairment (Daughton and Ternes, 1999). Studies of <br />fish in Boulder Creels and the South Platte River downstream from WWTP's detected a high <br />female to male ratio and reproductive abnormalities (Vajda et al, 2004). <br />2c. South Boulder Creek In-stream flows <br />A 1994 draft report by the Colorado Division of Wildlife defined preliminary in-stream flow <br />goals for two separate reaches of South Boulder Creels: the upper reach between Eldorado <br />Springs and South Boulder Road and the lower reach between South Boulder Road and Boulder <br />Creels. h1-stream flow needs are important during winter because of the chronic and nearly <br />complete dewatering of South Boulder Creels and the critical limiting effect on the survival of <br />adult fish populations. The study emphasized the critical need to sustain winter stream flows at <br />or near 7cfs to ensure biotic integrity. <br />2d. Invasive Suedes <br />Loss of native species and biodiversity can lead to a decline in population and diversity of fish, <br />because their food supply has been affected. The New Zealand Mud Snail (Potunzopyrgrrs~ <br />ar~tipoda~um) and the aquatic plant Eurasion watermilfoil (Myrio~hy111rn~ s~icatum) are two <br />invasive non-native species that have been found in the Boulder Creek watershed. These species <br />were accidentally introduced, have no natural predators in the watershed, and spread rapidly. <br />They negatively affect aquatic ecosystems by outcompeting native species and reducing <br />biodiversity. Also, a native species of algae, the diatom Didymosphenia geminata, is affecting <br />Boulder Creek. This diatom was once rare and restricted to pristine lakes and streams. In recent <br />years, however, it has formed excessive growths in Boulder Creek. <br />_ ~ ~ <br />Eurasian ~~ atei7iulfoil(photos courtesy of Cit<r of Boulder Mountain Parks and Open Space) <br />4 <br />