Grassland Bypass Project (GBP) Toxicity Program

Phase l

Phase l of the Grassland Bypass Project (GBP) Toxicity Program stretched over the period of October 1, 1996 to September 30, 2001.  The program was initially composed of two parts: Laboratory Toxicity Testing, and in situ Toxicity Testing. However, in 1997, in situ toxicity testing was discontinued.  For 1998, sediment bioassays were conducted in lieu of in situ toxicity testing.  Selenium and sulfate concentrations were measured every other day during seven day tests.

Phase ll

Phase ll of the Grassland Bypass Project Toxicity Program started on October 1, 2001 and will stretch over a period of 8 years.  Tests, sampling procedures and protocols used in Phase l will stay the same for Phase ll with the following changes:  Testing will be done quarterly, however, sampling frequency can be changed depending on the quarterly results; and sulfate concentrations will no longer be measured during the seven day tests.


A complete description of these tests, the sampling procedures, and protocols can be found in the Grassland Bypass Project Compliance Monitoring Work Plan.

Toxicity Testing Reports

Beginning in 2006, electronic copies of all data reports can be found here.  All reports are subject to approval prior to being posted


2006 2007 2008 2009


Laboratory Toxicity Testing Program

Samples are collected  from the five sites listed below for the Laboratory Toxicity Testing Program. Results are provided in the links below.

Total Suspended Solids (TSS)

TSS measurements in mg/L taken for each sample at BES laboratory.

TSS Concentrations (Phase l  //   Phase ll)

Selenium and Sulfate Concentrations

Selenium and sulfate collected at the same time and location as samples described above. For seven day Laboratory Toxicity Testing Program, selenium concentrations were determined from each of the three renewal samples collected on test days 0, 2, and 4. For the in situ Toxicity Program, these data correspond to the first, third, and fifth test day.

Selenium Concentrations (Phase l   //  Phase ll)
Sulfate Concentrations (Phase l)

In Situ Toxicity Program

In situ studies were conducted on a quarterly basis in 1997. These studies consisted of placing four-day old fathead minnow larvae in plexiglass containers directly into the water at stations described below. A detailed description of the protocol used can be found in the GBP Compliance Monitoring Work Plan.

In situ Toxicity Program Results


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