What’s in the Delaware River?

The answers hold its long-term protection

By SANDY LONG

UPPER DELAWARE REGION — When it comes to managing water quality in the Delaware River, monitoring matters. Since 2001, the Delaware River Basin Commission (DRBC), in conjunction with the National Park Service (NPS), has conducted annual studies to assess the variables that reveal the river’s ongoing state of health. By conducting such inspections, the agencies hope to ensure the magnificent river’s long-term protection.

The Delaware River Biomonitoring Program

Recently, and continuing for the next several weeks, members of the DRBC and NPS are taking to the river, collecting samples of the aquatic insects and plant life at 25 sites ranging from Hancock, NY to Trenton, NJ. Such biomonitoring is one of the most important tools available to measure water quality trends over time. Should data begin to fluctuate, possible sources of impacts and potential corrective measures can then be evaluated.

The process partly involves positioning a specially designed net with a fine screen across a riffle as the riverbed is stirred, to capture and count the insects released by the disturbance. The same locations are sampled each year to establish consistency.

“The Upper Delaware is a special case because it represents some of the most pristine waters we have,” said Robert Limbeck, watershed scientist with the DRBC. “We invented our own net to catch enough bugs to represent the system. We take a three-kick sample to create a composite at each site, along a line that’s 40 to 50 meters long.”

The researchers also measure flow, substrate analysis (rock types, size, etc.), depth and light to characterize the site. “We seek out the ‘best of the best’ habitats to measure, to establish the ideal standard,” said Limbeck. “How can we regulate it if we don’t understand it?”

The DRBC/NPS Scenic Rivers Monitoring Program

According to NPS natural resource specialist Don Hamilton, the Delaware River Biomonitoring Program (DRBP) is an adjunct to the DRBC/NPS Scenic Rivers Monitoring Program (SRMP). “The SRMP focuses on standard physical and chemical water quality parameters such as dissolved oxygen, temperature, pH, specific conductance, nutrients and more, to give us a good snapshot assessment of water quality at a given time,” said Hamilton. Additional parameters are collected under related studies conducted by the United States Geological Survey and Environmental Protection Agency.

The objectives of the SRMP program are to establish existing water quality for future comparison, assess the attainment of water quality standards, set priorities to maintain or improve existing water quality and conduct long-term monitoring so that the DRBC can evaluate trends, prioritize management activities and assess the effectiveness of strategy implementation.

As cooperators in the SRMP, the two agencies meet to plan, coordinate and implement the program, sampling according to a planned schedule at designated sites, following agreed-upon protocols and according to an established quality control plan. Data is provided to the DRBC for incorporation into a database for periodic analysis and evaluation.

For the biomonitoring program, the goals are to assess existing conditions, develop biocriteria for the sites and biomonitor as a means of protecting biodiversity, according to Hamilton. The NPS assists the DRBC with biomonitoring efforts and performs additional nutrient sampling in addition to bi-weekly water quality monitoring at selected sites.

In 2005, the DRBC also began monitoring algae and diatoms (periphyton). Results of the pilot study conducted for the DRBC by Limbeck and Geoffrey Smith, watershed resources coordinator of ClearWater Conservancy, monitoring periphyton at five sites in the non-tidal Delaware River, were released earlier this year with recommendations that more extensive monitoring be implemented. Such programs are increasingly used for regulatory purposes since periphyton are indicator organisms of specific environmental conditions that reflect the physical, chemical and biological events that can occur at a site over a short period of time.

So why does it matter which bugs are being found in the river and which algae and diatoms decorate the substrate? “Biomonitoring helps us better understand our resources and the biological integrity of the Delaware River system,” said Hamilton. “It provides us with a broader view, and definition, of water quality, than just physical and chemical water quality parameters, and will help inform management decisions aimed at sustaining the water quality and natural resources of the Delaware River for future generations.”

Limbeck couldn’t agree more. “The richness, diversity and abundance of the Upper Delaware River are well worth protecting.”

Visit www.drbc.net and click on the Wild and Scenic Rivers section to view the poster “Common Stream Invertebrates.”