Clean Water Program

The purpose of the in situ toxicity testing program is to determine whether direct exposure of test organisms to SLD water at selected locations results in toxicity to a sensitive species. Details of the program may be changed based on test results.

Data will be evaluated using the TOXIS statistical package, which includes USEPA flow through chart. Statistics may include Fisher's exact test, Probit, Spearman-Karber, Dunnett's Procedure, Steel's Many-one Rank and the t-test. Depending on data input, TOXIS selects the most appropriate statistics.

Laboratory QA/QC measures will consist of following a written SOP for each type of test, including general laboratory procedures. Reference toxicant tests will be run with each test.

After each algal bioassay, test and control replicates will be composited. Samples will be transported to USFWS for analysis of selenium. A determination will be made as to whether selenium uptake is greater at any site as compared to the control. Data will also be compared to selenium concentrations in the water.

Water quality and chemical analysis will be performed on each grab water sample collected. Analyses will include pH, conductivity, dissolved oxygen, alkalinity, hardness (as calcium carbonate) sulfate and selenium. Alkalinity, pH, conductivity, and dissolved oxygen will be measured in the field. Sulfate and selenium will be analyzed by USBR.

Laboratory techniques selected for toxicity testing include USEPA methods using the short term chronic bioassay protocol. These methods are generally used to evaluate the toxicity of an effluent to receiving water. Specific methods for culturing and conducting toxicity tests using fathead minnows and Selenastrum may be found in (EPA 600/4-91-022). All tests have chronic end points, either growth or reproduction. In addition, fatheads and Daphnia are scored for survival (acute end point).

Test species include the larval fathead minnow, Pimephales promelas (less than 24 hours old), the cladoceran, Daphnia magna (10-d old) and the alga Selenastrum capricornutum (4-7 d old). The test species were selected for their sensitivity to selenium, diazinon and chlorpyrifos and tolerance of usual water quality of the study area. Fathead minnows are sensitive to selenium; Daphnia magna is sensitive to pesticides; the algal study will include a bioaccumulation component.

Field sampling techniques will follow the protocol described in "Short-Term Methods for Estimating the Chronic Toxicity for Effluents and Receiving Water to Fresh Water Organisms" 3rd Ed (EPA-600-4-91-022) for fatheads and algae. The Daphnia magna 7-D test protocol is found in EPA-600-D87-080. The protocol is included in the QAPP. Grab samples will be collected as they are easier to collect and may capture potential peaks in toxicity.