AQUATIC BIOLOGICAL LABORATORY SERVICES

Home | WET Testing | Benthic Invertebrates | Nutrient Chemistry | Helpful Sites | About Us | Publications | 

Whole Effluent Toxicity Testing

What is whole effluent toxicity (WET) testing? Basically, it’s testing of the potential toxicity of effluents to biological organisms – often municipal wastewater effluent, but also from industrial processes, mining, coal-bed methane extraction, and simply any activity that requires an NPDES discharge permit.  Using U.S. EPA methods, the short-term “acute” tests (48-96 hr) are conducted using the water fleas (Ceriodaphnia dubia or Daphnia magna) and fish, such as the fathead minnow (Pimephales promelas) or perhaps the rainbow trout (Oncorhynchus mykiss).  Longer-term “chronic” tests (usually 7-day tests) are conducted as well.  The only two U.S. EPA approved test organisms for chronic freshwater WET testing are Ceriodaphnia, the algae Selenastrum, and the fathead minnow. 

Chadwick Division of GEI Consultants has been providing WET testing services for over 15 years.  Our acute and chronic WET testing services are provided primarily for NPDES discharge permit compliance testing using the standard test organisms Ceriodaphnia dubia and the fathead minnow (Pimephales promelas).  We also conduct a wide variety of special acute and chronic toxicity tests, specifically using WET tests as a research tool in water quality investigations and bioassessments.  These research-based tests often use these same test organisms under different test conditions (extended life-cycle, early life stage, sediment testing) – perhaps even using field collected aquatic insects.

Chadwick Division provides WET testing services from a unique perspective – specifically our extensive biological experience with the aquatic organisms commonly used with standard U.S. EPA methods.  This isn’t just another service from a contract chemistry lab.  Rather, we can provide the necessary biological expertise to meaningfully interpret WET test results that can often vary as a direct result of the fact that these tests use living organisms. 

Our laboratory strictly follows U.S. EPA WET test protocols and has been certified for WET testing by the States of California and Washington.  We strive to ensure data quality.  Nonetheless, some knowledge of the behavior of the test organisms is necessary to place WET test results in the context of potential impacts to receiving streams, the history of past WET testing of the effluent, and the current research into the reliability and variability of WET test methods.

 

Toxicity Laboratory           Testing Services
Acute Toxicity Testing Chronic Toxicity Testing
Invertebrates:
Ceriodaphnia dubia (zooplankter)
Daphnia magna, Daphnia pulex (zooplankter)
Hyalella azteca (amphipod)
Fish:
Fathead minnows (Pimephales promelas)
juvenile rainbow trout (Oncorhynchus mykiss)
Algae:
Selenastrum capricornutum
Invertebrates:
Ceriodaphnia dubia (zooplankter)
Hyalella azteca (amphipod)
Fish:
Fathead minnows (Pimephales promelas)
juvenile rainbow trout (Oncorhynchus mykiss)
           
Sediment Toxicity Tests Toxicity Tests for Criteria Development
Invertebrates:
Hyalella azteca (amphipod)
Chironomus tentans (midge)
 

 

 Acute:
Daphnia magna, Daphnia pulex (zooplankter),
Ceriodaphnia dubia (zooplankter),
Fathead minnow (Pimephales promelas),
Chironomus tentans (midge),
Girardia dorotocephala (flatworm)
Drunella grandis (mayfly)
Isoperla (stonefly)
Lepidostoma (caddisfly)
Chronic:
Daphnia magna, Ceriodaphnia dubia (zooplankter)
Early Life Stage:
Fathead minnow (Pimephales promelas)
juvenile rainbow trout (Orcorhynchus mykiss)

Toxicity Identification Evaluations (TIE's)

If an effluent appears to cause consistent toxic responses in the test organisms, it may be necessary to conduct further testing to attempt to narrow down exactly what compound in the effluent is causing this response. These are toxicity identification evaluations, where the effluent is "fractionated" through various manipulations (like adjusting the pH, subjecting the effects to filtration, adding EDTA to complex metals, etc.) and these fractions are tested using the same WET test methods as a normal test. Any changes in toxicity due to these manipulations can help determine what compound, or class of compounds, may be causing the problems in the WET testing.

Chadwick Division can help you conduct a TIE through a detailed test design, thorough review of historic WET and water quality data, effluent manipulations and WET tests, and interpretation of test results.  Contact us if you need help and we will assist with the design of your study.