Biomonitoring team on the Upper Delaware River
On a glorious day on the Upper Delaware, members of the Delaware River Basin Commission's biomonitoring team investigate the river to check on its health. PHOTO BY MEG MCGUIRE

Looking for healthy bugs
DRBC’s biomonitoring team investigates the Upper Delaware

| September 15, 2022

The Upper Delaware was looking every inch “special” recently when a team from the Delaware River Basin Commission investigated its waters not far from the Roebling Bridge.

Biological monitoring is conducted every two years — when possible — to determine if anything has changed. All 197 miles of the Delaware River from Hancock, N.Y., to Trenton, N.J., has been designated Special Protection Waters to recognize that the existing water quality is better than established water-quality standards. Nice to know if you want to take a swim!

As one way to make sure that the water quality stays top notch, a team performs multiple tests and takes multiple samples from nearly 25 different sites throughout the SPW.


The monitoring team this year was led by Elaine Panuccio, a water resource scientist.

With her are interns: Colman Closser, from Penn State; Bailey Adams, from Rider University; and Kyle McAllister, who has an associate’s degree from Bucks County Community College and is between schools.

They have carried lots of equipment over an impressive array of river rocks and away from the bustle of the Ascalona Campground, upstream of the Roebling Bridge and near where the Lackawaxen enters the Delaware River in Barryville, N.Y.

(I want to thank the new owner of the campground, Kevin Ariyanonthaka, who shepherded me to the sampling site and Elaine, who brought me safely back to solid ground. Those river rocks are challenging!)

Not surprisingly, the site looked fabulous. The sun was shining, there was a slight breeze and the river flowed quietly by.

But there was work to be done. Sometimes working in teams and sometimes working singly, the sampling begins. It takes about two hours to get one site done.

One of the key components investigated are the macroinvertebrates, which they looked for on the river bottom. Macroinvertebrates are animals that lack a backbone and are large enough to see without a microscope. These critters are the canaries in the coal mine here.

There’s an expression “Good bugs mean a healthy river” because bugs are sensitive to environmental impacts and they are less mobile than fish and cannot move to avoid pollution.

They also are able to detect non-chemical impacts like siltation and temperature changes and they bioaccumulate many contaminants so an analysis of their tissues helps provide an overall picture of water quality at any site. More here.

‘Bug soup’

First the monitoring team found three sites it would sample at this location. The team usually targets the richest habitats: riffles, runs or island margins as well as mid-stream.

They used a metal frame, about two feet square, placing it in the river. McAllister donned a snorkel and bent down to see what he could in the square. Notes were taken at that stage — maybe there’s a mussel, a fish or a crayfish. They also take note of submerged aquatic vegetation within the frame. And also keep an eye out in the general area of the site for Podostemum — a sign of good water quality.

Panuccio holds the net as McAlister snorkels.
Panuccio holds the net while McAllister snorkels to see what is on the surface before they start to work. PHOTO BY MEG MCGUIRE

Then with special boots for this purpose, Panuccio scraped at the surface within the square to loosen the tiny critters they wanted to capture. A net was held immediately downstream of the frame to capture whatever floated up.

The “stuff” in the net was added to twice more, from the other samplings at this site, and then the haul was brought back to land to be emptied into jars of ethanol to preserve what they had gathered to be analyzed in the near future. Panuccio called the brown debris “bug soup.”

jar of bug soup
Debris collected from the sampling includes tiny critters — macroinvertebrates — that tell today’s river story. PHOTO BY MEG MCGUIRE

It would be almost impossible to analyze this flotsam and jetsam as it’s collected — it just looks like river mishmash, but hiding in it are the tiny critters that will tell a lot about how the river is doing.

Being careful to get all those critters requires some close examination of that net. The team examined it and used soft forceps to pry them off. Panuccio explained that — as tiny as they are — they are very strong in order to hold onto rocks, branches or whatever they can as the water rushes by.

I think of them as tiny Arnold Schwarzeneggers.

Panuccio and Colman gather small bugs with soft forceps
Once the net is brought to shore, Panuccio and Closser tug the tiny but very strong bugs from the net with soft forceps. PHOTO BY MEG MCGUIRE

Reading the algae

Algae in the river has its own story to tell, and Closser is set to read it.

He gathered six river rocks from alongside the sampling area and placed them in a box of river water with the same side facing up as they were in the river.

He has what looks like a circular cookie cutter to measure out about a 2-inch circle at the top of each rock and then uses a stiff brush to rub that circle, loosening the algae. Then he places the rock back in the box to allow that algae to float free.

Colman prepares an algae sample
Closser prepares an algae sample. PHOTO BY MEG MCGUIRE

The algae and other materials scraped from the rocks will be poured into a sample bottle to be preserved with formalin.

This from Panuccio: “So the sample is preserved and doesn’t rot, and also so that we are able to hold onto the samples until we send them to the analysts all at once (and/or get funding for the analyses.)”

Interested readers will know that funding for the DRBC is not all it has been promised. More here. This is an example of how that lack of funding constrains the science it performs.

The analysis checks:

● Diversity and health of the bottom-dwelling aquatic life community, including macroinvertebrates and algae

● Habitat characteristics

● Nutrient and water chemistry (dissolved oxygen, temperature, pH, chlorophyll-a, conductivity and turbidity.)

Adams works on water chemisty
Adams works on water chemistry. PHOTO BY MEG MCGUIRE

● Diversity and health of fish, aquatic plants and freshwater mussels

● The presence of any invasive species, both aquatic and riparian plants and animals.

The data is included in the Delaware River and Bay Water Quality Assessment Report that the DRBC develops every other year for the U.S. Environmental Protection Agency.

Jars of bug soup
With yet another site to go, this is today’s haul of “bug soup” to be taken back and analyzed to see how healthy the river is. PHOTO BY MEG MCGUIRE

Just because the water is clear and high quality doesn’t mean it isn’t complicated!

Meg McGuire

Meg McGuire

Meg McGuire has been a journalist for 30 years in New York and Connecticut. She started in weekly newspapers and moved to full-time work in dailies 25 years ago. She knows about the tectonic changes in journalism firsthand, having been part of what was euphemistically called a "reduction in force" six years ago. Now she's working to find new ways to "do" the news as an independent online publisher of news about the Delaware River, its watershed and its people.


  1. Glenn Uller on October 14, 2022 at 5:35 pm

    The Delaware and it’s tributaries are in a class by themselves! They are beautiful in their own way! Especially considering how close they are to metropolitan areas!
    It has been a pleasure to fish the river for the last 50 plus years and it’s tributaries! The thrill of seeing so many different species of fish or catching a trout or shad is priceless! Thanks for monitoring the river and keeping it healthy

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