Biomonitoring Program
DRBC staff perform biological monitoring of the Delaware River. Photo by DRBC. 
DRBC staff perform biological monitoring of the
Delaware River. 
Photo by DRBC. 

The DRBC's non-tidal Delaware River Biomonitoring Program samples sediment, rocks, algae, aquatic insects and water chemistry.

Every three or so years, typically during August and September, samples are collected at 25 river sites, targeting the richest habitat areas of riffles, runs or island margins. Samples are analyzed by the Academy of Natural Sciences of Drexel University in Philadelphia, Pa.

At each site, a variety of biological parameters are assessed:

--Diversity and health of the benthic (bottom-dwelling) aquatic life community, including macroinvertebrates (aquatic insects) and periphyton (algae);

--Habitat characteristics;

--Water chemistry (e.g., dissolved oxygen, temperature and pH);

--Diversity and health of fisheries, aquatic plants and freshwater mussels; and

--Occurrence of invasive species, both aquatic and riparian plants and animals.

Data from this program 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.

DRBC utilizes this information to implement biocriteria as part of its Special Protection Waters regulations.

Data assessed are also included in the Delaware River Water Quality Assessment Report that DRBC develops every other year for the U.S. EPA.

DRBC plans to collect data as part of this monitoring program in 2021.

Related Information

State of the Basin 2019:

DRBC State of the Basin 2019 Report (see Pt. 4 - Living Resources)

Biomonitoring Program Specifics:

DRBC Delaware River Biomonitoring Program 2014 Quality Assurance Project Plan (2014 QAPP) (pdf 359 KB)

See the DRBC Biomonitoring Team in Action:

DRBC Joined by WFMZ-TV 69 News on a Biomonitoring Sampling Event (2017)

Other DRBC Biological Studies:

Didymo, aka "Rock Snot," Discovered in the Non-Tidal Delaware River (2012)

Lower Delaware River Mussel Survey (completed in 2013)

Invasive Species:

U.S. Department of Agriculture: Aquatic Invasives

New York Invasive Species Clearinghouse

DRBC staff collect and examine a macroinvertebrate sample from the Delaware River. Photo by DRBC. 
DRBC staff examine a macroinvertebrate sample collected
the Delaware River. Photo by DRBC. 

Good Bugs Mean Healthy Rivers

Benthic macroinvertebrates are the main biological annual indicator assemblage monitored by DRBC and most other regulatory agencies. 

As stated above, benthic means bottom-dwelling. Macro means you can see with the naked eye (no microscope needed). Invertbrates are creatures without backbones.

Examples of benthic macroinvertebrates include aquatic insects, worms, crayfish, clams and snails. 

Analysis of macroinvertebrate communities to determine water quality is reliable and commonly used because:

--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.

As part of its biomonitoring program, DRBC surveys 25 riffle sites throughout the non-tidal 200 miles of the Delaware River from Hancock, N.Y. to Trenton, N.J. 

DRBC plans to develop and initiate a long term, basin-wide tributary macroinvertebrate monitoring program in order to monitor trends in macroinvertebrate community composition on a basin-wide scale. Currently, DRBC monitors the mainstem Delaware River and uses data collected by the basin states for the tributaries. These data are analyzed using varying methodologies, which can be difficult to compare.

Learn More

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

Common Stream Invertebrates Sampled in the Non-Tidal Delaware River (pdf 156 KB)

Atlas of Common Freshwater Macroinvertebrates of Eastern North America

DRBC staff collect periphyton data. Photo by DRBC. 
DRBC staff collect a periphyton sample. Photo by DRBC. 

Algae that Tells a Story

Because the Delaware River is generally wide, shallow, clear and exposed to full sunlight, benthic periphyton are the river's dominant source of primary production.

Periphyton are sampled and monitored as an additional biological monitoring assemblage.

Examples of periphyton include diatoms and soft algae growing on rocks.

Periphyton are excellent indicators of short-term water quality changes, capable of providing biological signals for numerous pollution and habitat impacts; for example, eutrophication, salinity, ions, pH and sedimentation. 

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 25 benthic macroinvertebrate river survey 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.

Learn More

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 (link to USGS site for report)