Bioassessment and Biocriteria Program Status for Delaware: Streams and Wadeable Rivers
State Program Contact
Delaware Department of Natural Resources and Environmental Control Exit
Water Quality Standards
The link to Delaware's WQS that are in effect for Clean Water Act purposes is provided. These are the WQS approved by EPA.
You may need a PDF reader to view some of the files on this page. Refer to EPA’s about PDF page to learn more.
Designated Aquatic Life Uses
All waters have a single aquatic life use. A (very) small subset also has “Cold Water Fish (put and take)” use to support annual stocked fish program.
__X__ No criteria
Section 5.0 of our WQS has narrative regarding Antidegradation (PDF) (35 pp, 420 K, About PDF). No specific biological criteria are in our WQS.
What biological assemblages are used in the bioassessment program?
Benthic macroinvertebrates only.
Are bioassessments used to support 303(d) listings?
Yes and No. Listing methodology: In the past, the Department made listing decisions to list for “Biology”, “Habitat” or “Biology and Habitat” based on comparisons of stream conditions to reference streams. We are working our way through the resultant 303(d) listings at this time.
How are assemblages used to make impairment decisions?
Not actively making impairment decisions at this time as we work through the past listing decisions.
Other uses of biocriteria or bioassessment within the water quality program:
TMDL development and assessment
Technical Support Information and Documents:
DE has no ‘reference’ sites. IBIs are based on the 5th/95th percentile of all sites sampled at time of creation. We use ‘control’ sites that represent the best known sites in the state, based on previous sampling, to evaluate changes over the years.
Stressor identification/causal analysis approach: