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Delaware River Biomonitoring Program

The DRBC's Delaware River Biomonitoring Program samples sediment, rocks, algae, aquatic insects, and water chemistry to provide a complete overview of the diversity and health of the aquatic life community and overall water quality of the 200-mile non-tidal river from Hancock, N.Y. to just above the head of tide at Trenton, N.J.

Every two or three years, samples are collected at 25 river sites, targeting the richest habitat areas of riffles, runs, or island margins. The bulk of the biomonitoring program occurs during the months of August and September.

At each site, the diversity and health of the benthic - i.e. bottom-dwelling - aquatic life community: macroinvertebrates (for example, aquatic insects) and periphyton (for example, algae) are sampled and examined. Habitat characteristics and water chemistry (for example, dissolved oxygen, temperature, and pH) are also monitored.

The biomonitoring program also gathers information on other significant natural resources of the Delaware River Basin, such as fisheries, aquatic plants, mussels, and invasive species (both aquatic and riparian plants and animals).

DRBC utilizes this information to implement biocriteria as part of its Special Protection Waters regulations for the non-tidal portion of the Delaware River. Data assessed are also included in the Delaware River Water Quality Assessment Report that DRBC develops every other year for the U.S. EPA.

Samples collected are analyzed by the Academy of Natural Sciences of Drexel University in Philadelphia, Pa.

In September 2017, WFMZ-TV 69 News joined the DRBC biomonitoring crew on one of their sampling events near Easton, Pa.

Learn specifics about the biomonitoring program by reviewing the DRBC Delaware River Biomonitoring Program 2014 Quality Assurance Project Plan (QAPP) (pdf 359 KB).

Benthic Macroinvertebrates

Benthic macroinvertebrates, for example, aquatic insects, worms, clams, and snails, are the main biological annual indicator assemblage monitored by DRBC and most other regulatory agencies. Analysis of macroinvertebrate communities is a reliable and cost-effective approach to water quality monitoring for many reasons that include the following:

  • They are abundant in most streams and are relatively easy and inexpensive to sample;
  • They are sensitive to environmental impacts;
  • They are less mobile than fish, and thus cannot avoid discharges, spills, etc.;
  • They are also able to detect non-chemical impacts to the habitat, such as siltation or thermal changes; and
  • They bioaccumulate many contaminants, so that analysis of their tissues is a good monitor of toxic substances in the aquatic food chain.

Because of these reasons, studying macroinvertebrates helps provide an overall picture of water quality at a particular site; finding species that are sensitive to pollution is an indicator of good water quality. Surveys cover the upper 200 miles of the Delaware River from Hancock, N.Y. to Trenton, N.J.; samples are collected at 25 different riffle habitat sites. 

Benthic Macroinvertebrate Use for Interim Biocriteria - 2009 Report (pdf 345 KB)

Benthic Periphyton

Benthic periphyton, for example diatoms and soft algae growing on rocks, were chosen as an additional monitoring assemblage because they are very specific indicators of short-term water quality changes, capable of providing biological signals for numerous pollution and habitat modification impacts such as eutrophication, salinity, ions, pH, and sedimentation. Since the Delaware River is generally wide, shallow, clear and exposed to full sunlight, periphyton are the dominant source of primary production in the river. Planktonic algae found in the non-tidal part of the river are entirely benthic in origin.

DRBC began surveying Delaware River benthic periphyton in a 2005 pilot study, launching full-scale periphyton monitoring in 2006. Samples are co-located with the benthic macroinvertebrate sites at 25 primary river sites and numerous special study sites on larger tributaries to the Delaware River. Methods can be found in the 2014 QAPP, linked above. These data will help assess general short-term Delaware River water quality and nutrient pollution impacts upon aquatic life.

Pilot Study: Implementation of a Periphyton Monitoring Network for the Non-Tidal Delaware River (pdf 1.7 MB; 2007)

Nutrient Enrichment Study Data from the Upper, Middle, and Lower Sections of the Non-Tidal Delaware River – 2009