Research Areas > Contaminants > Stormwater Toxicity Laboratory Intercalibration Study

Project: Laboratory Intercalibration for Stormwater Toxicity Testing 

Background

The Stormwater Monitoring Coalition (SMC) has commissioned an intercalibration study to quantify stormwater-sample testing comparability among laboratories for toxicity methods. This study aims to assess variability among laboratories, identify potential quality improvements, and improve comparability and consistency in toxicity measurements. We are conducting a round robin exercise to characterize and ultimately minimize inter-laboratory variability for testing marine and freshwater species, and to develop a manual to provide guidelines for testing precision and sensitivity. The SMC has conducted similar studies with its chemical testing program to address comparability issues. These studies have provided a platform to quantify the range of variability and a vehicle to improve the variability among testing laboratories.

Agencies and laboratories currently participating in the study

• Marine Pollution Studies Laboratory at Granite Canyon (UCD)
• Aquatic Toxicity Laboratory (UCD)
• City of Los Angeles
• Los Angeles County Sanitation Districts
• Orange County Water Quality Compliance Division
• Aquatic Bioassay and Consulting
• Aquatic Testing Laboratories
• MBC Applied Environmental Sciences
• Pacific EcoRisk
• Nautilus Environmental

Study participants are receptive to inviting additional, interested participants to join this study. To inquire about becoming a study participant and for more information about the study, contact Doris Vidal-Dorsch at 714-755-3216 or dorisv@sccwrp.org. 

Approach

A Laboratory Working Group composed of expert laboratory managers from the participating institutions has selected the toxicity methods, species, and endpoints for the round robin exercise. In addition, the group is developing pass/fail comparability evaluation criteria for data generated by participating laboratories.

Iterative sample testing with freshwater and marine species is being conducted. The species and endpoints selected for testing freshwater samples are the 7-day chronic survival and reproduction test for Ceriodaphnia and the 96-h acute survival test for Hyalella. For marine or estuarine receiving environments, the species and endpoints selected are the larval development test with purple sea urchin (72 h) and larval mussel survival and development (48 h). These species have been selected by the group because they are the most commonly tested permit organisms; they also are sensitive, easy to conduct the test with, readily available, representative of local species, and have relatively high variability of test method.

Two rounds of testing are being conducted in this study. During each round, one or more matrices is being tested. The first round of testing includes:

• a toxicant-spiked solution
• an artificial rainfall runoff
• a blind duplicate 
• a non-toxic sample

Samples for testing during the second exposure are to be determined based on the results of the first round and on discussions of the Laboratory Working Group.

The information generated from this assessment will be used to generate performance-based guidelines for precision and sensitivity to conduct standardized toxicity test with stormwater samples. The SMC member agencies will be able to use the information as pass/fail criteria to select contract laboratories.

Additional Resources

Southern California Stormwater Monitoring Coalition

Stormwater Monitoring Coalition Laboratory Guidance Document: Second Edition