Aquatic Health Program

Aquatic Toxicity Testing Capabilities

Standard EPA Toxicity Testing:

The Aquatic Health Program (AHP) is certified by the California Department of Health Services to conduct standard EPA freshwater toxicity testing methods. These test methods are a cost effective mean to evaluate the extent, frequency, duration and magnitude of toxicity in inland surface waters. In these tests, surrogatespecies are used to represent various levels in the food chain. The protocols for these species (with the exception of H. azteca) are described in US EPA’s Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms, Fourth Edition (2002) and Methods for Measuring the Acute Toxicity ofEffluents and Receiving Waters to Freshwater and Marine Organisms, Fifth Edition(2002). The AHP conducts the following tests:

  • 96-hour Selenastrum capricornutum (green algae) growth test
  • 96-hour Ceriodaphnia dubia (waterflea) survival test
  • 96-hour Pimephales promelas (fathead minnow) survival test
  • 96-hour Oncorhynchus mykiss (rainbow trout) survival test
  • 7-day Ceriodaphnia dubia reproduction and survival test
  • 7-day Pimephales promelas larval biomass and survival test

Resident Species Toxicity Tests:

Resident species often have different sensitivities to toxic chemicals relative to the standard freshwater species. The AHP has expertise and experience in developing toxicity tests with non-standard aquatic species of interest in the Sacramento-San Joaquin watersheds and estuary, for example, delta smelt, striped bass, resident chironomids and resident water flea species:

  • 96-hour Hyalella azteca (amphipod) survival test
  • 10-day Hyalella azteca growth and survival test
  • 96-hour Hypomesus transpacificus (delta smelt) survival test
  • 7-day Hypomesus transpacificus (delta smelt) survival and growth test
  • 96-hour Morone saxatilis (striped bass) survival test
  • 7-day Morone saxatilis (striped bass) survival and growth test
  • 96-hour Daphnia magna survival test

Toxicity Identification Evaluations (TIEs):

Used in conjunction with chemical analyses, TIEs are a series of procedures designed toidentify the chemical cause of toxicity. TIEs are typically used with one of the following test species: Ceriodaphnia dubia, Pimephales promelas, and Hyalella azteca. The AHP has developed and continues to develop TIE methods for additional species to broadenthe application of this tool.


Bioassessment procedures utilize biological community information, such as macro-invertebrate species diversity and abundance, along with habitat quality assessments toevaluate the integrity and ecological health of a particular water body. These proceduresassess the effects habitat degradation, including chemical pollution, temperature andsuspended solids enrichment.

Benthic macro-invertebrates, organisms that spend at least part of their life cycleon or in the bottom substrates of freshwater habitats, are most commonly used for stream bioassessment procedures. Due to the invertebrate’s stationary nature, these in-stream indicators integrate the effects of environmental stress over time. The AHP performs sample collection, taxonomic identification and data analysis according to the Environmental Protection Agency’s Multi-Habitat Approach (EPA 841-B-99-002).