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Settling Pond Sediment Analysis for the Pueblo Fish Hatchery <br />Jim Carsella, Colorado State University — Pueblo Testing Center. <br />Sediment samples from the Rifle Falls Fish Hatchery (RFH) settling ponds were submitted by Dave Harris <br />to the CSU -P Testing Center for elemental and nutrient analysis in June of 2016. <br />Methods <br />The elemental analysis of sediment samples was completed using a total digest procedure following EPA <br />method 3052 (United States Environmental Protection Agency 1996) and alkaline extraction using EPA <br />method 3060a (United States Environmental Protection Agency 1996). The digests and extracts were <br />analyzed by ICPMS using EPA Method 6020a (United States Environmental Protection Agency 2007). The <br />leachates were obtained from the samples by following the USGS leaching protocol (Hageman 2007). <br />Leachable nutrient determinations were obtained by analyzing the leachates by ion chromatography. <br />The Colorado Department of Health guidelines for allowable limits in sludges were used to define limits in <br />this report. <br />Results <br />The results are presented in the attached Tables 1-3. The samples are below allowable limits in all <br />categories except total arsenic. The elevated levels of arsenic in the total digests relative to the <br />allowable limits required further study in order to determine the leachability and toxicity of these <br />elements from the substrate. The results of this additional analysis are also reported in Table 1. In <br />summation it was determined that the arsenic is mostly bound to the substrate and is not highly <br />leachable. <br />Results of leachable nutrient analyses are shown in Table 3. Nitrate is present in significant amounts in <br />the Old Pile sediment sample. Nitrite is present in the significant amounts in the Pond sediment sample. <br />