Science builds a bridge between politics and fish

Mapping Upper Delaware tailwaters with sonar technology

By CHARLIE BUTERBAUGH

Not more than a mile from the Pepacton Reservoir, grassy banks less than 30 feet apart hug the East Branch River. Cars parked in roadside lots along Route 30 set the stage for another fishing season to gradually build—in early May, anglers enjoy high waters on the East Branch, casting for brown and rainbow trout and other fish that dwell in the riffles, deep pools and side channels of the river that runs into the Upper Delaware.

But each year, the season ends earlier than it should, frustrated by low river flows regulated by an outdated management system. Since 1954, when the U.S. Supreme Court enjoined New York City with the right to divert water from the Delaware for consumption, ecological study of aquatic health in all of the Upper Delaware tailwaters has remained in its infancy, according to Colin Apse of The Nature Conservancy.

But time for a serious study has come.

Early this week, U.S. Representative Maurice Hinchey (NY-22) announced that he secured $250,000 in federal funds for the development of river flow recommendations that will be based in part on data presently being collected on the East Branch.

Adding a curious facet to the 2004 peak fishing season, two biologists from the U.S. Geological Survey (USGS) Fort Collins Science Center will be mapping the river with sonar technology never set afloat anywhere in the Delaware Basin—new technology for any river east of the Mississippi.

They might send an unwelcome wave as they speed through shallow sections in their Jon boat, but what might look like poor etiquette is actually courtesy to the fish—Ken Bovee and Terry Waddle are collecting data to understand the precise conditions needed for a thriving habitat and trout fishery.

After describing a real-time kinetic Global Positioning System (GPS), bathometric (water depth) data input and flow simulation on Monday morning, Bovee walked towards the Jon boat tied on the riverbank.

“It’s a classic example of a $1,000 saddle on a $100 horse,” he said.

Colin Apse, chair of the Delaware River Basin Commission’s (DRBC) subcommittee on ecological flows, is assisting the biologists as they collect data on the East Branch in May, the West Branch River in June and the Neversink River in July. Next summer, they will work on the Upper Delaware’s main stem.

The DRBC subcommittee will then make sure all parties involved in proposing revisions of flows management have accurate information regarding how much water is needed to sustain good habitat conditions for fish, mussels and other aquatic species.

The data will be used as a “decision support tool,” Apse said, influencing political management of water releases from the Pepacton, Canonsville and Neversink Reservoirs, which feed Upper Delaware tailwaters.

Since the reservoirs supply 50 percent of New York City’s water supply, convincing the city’s Department of Environmental Protection (DEP) to release reservoir water into the Upper Delaware River has, historically speaking, been anything but easy.

But by May of 2007, a major revision in flows management is expected to come before the city’s Department of Environmental Protection, the DRBC, the Delaware River Master and other voting parties designated by the 1954 decree.

The science — and spending six weeks on the river

Bovee and Waddle will map three- to five-kilometer sections, or “sites,” of the East Branch River each day. With real-time kinetic GPS equipment they can pinpoint their location via satellite with accuracy to one centimeter. Popular hand-held GPS units are precise only to about 100 feet, but a base station set up by Bovee and Waddle corrects a satellite’s margin for error.

As they track their movement on the river, they collect measurements of water depth to put together a contour map of the river bottom, or substrate, with accuracy to two inches. With the map, they will create a flow simulation model.

“We can tell how much water is flowing without measuring. It’s an efficient way to get data without putting your nose into the water,” Bovee quipped.

The simulation model enables them to understand the impacts any potential water level will create for river habitats. With it, they can predict habitat activity during the lowest recorded flow levels since the reservoirs were dammed as well as during a flood. Twelve to 15 different flow increments take depth, velocity and temperature into consideration.

All of the information is incorporated into a habitat map that can be used, for example, to identify temperatures needed to attract trout. They can predict daily mean temperatures within one-half of a degree Fahrenheit.

“And with a map of habitat patches, we can determine the range of depth and velocity trout like,” Bovee said.

“We get to know a lot about the river.”