This water quality investigation describes sampling to determine if one or more trace elements are present at concentrations high enough to limit productivity in some springs on the Double O unit. This document describes sample methods and results. It includes a discussion of the water quality sampling results and compares the results to the Canadian Water Quality Guidelines for Protection of Aquatic Life and to USEPA water quality criteria. Malheur NWR has identified poor aquatic health as the biggest issue the refuge is facing and has identified common carp as the largest contributor to degrading aquatic habitat. The Double O unit is a management unit of the refuge that has a low carp population compared to other areas of the refuge and it may be feasible to exclude or control carp on the unit. However, Barnyard Spring on the Double O unit had almost no response in submergent vegetation or aquatic invertebrate production following carp removal. In contrast, Sodhouse Spring, near the refuge headquarters, responded almost immediately with luxuriant growth of submergent vegetation and abundant aquatic invertebrates and bird use has been very high since carp removal. The objective of this investigation was to determine if one or more trace elements are present at concentrations high enough to limit productivity in some springs on the Double O unit. Water quality samples were collected at a number of sites on the Double O and analyzed for 22 constituents, including arsenic, which is common in springs and groundwater in the Great Basin. The results showed that concentrations of arsenic were highest in the Barnyard Springs area and were above the Canadian Water Quality Guidelines but below the USEPA Water Quality Criteria. Aluminum and boron concentrations were also high in these springs. The water quality sampling results provide evidence that arsenic could be limiting productivity in this area, although the evidence is not conclusive. The study indicates that refuge springs with higher arsenic levels (geothermal sources) should receive lower priority to conduct carp control for habitat restoration given the expense of rotenone treatments.
