A Fly Fisherman Diagnoses Maladies on a Beloved River

Wading into a parched stretch of the Pequannock River, Taylor VanGrouw got a jarring reminder of the fragility of New Jersey’s smaller waterways: a brown trout stranded in a shallow pool, too lethargic to swim away as he approached.

“As temperatures rise, dissolved oxygen levels decline, in the way a bottle of soda, when hot, can’t hold its fizz. Starved of oxygen, trout can’t feed or reproduce. As temperatures rise, they become more stressed and need more oxygen,” notes VanGrouw, an Albert Dorman Honors student majoring in mechanical engineering.

An avid angler, he’d been casting his flies up and down the river since he was 15 and had seen their numbers dwindle, even in its deeper sections. He was not prepared to attribute the entire problem to global warming, however, and write it off. “I’ve seen what conservation efforts can do and did not view this as a lost cause. There are factors that can be fixed.”

He decided to investigate the trout’s decline by testing a suite of water conditions at 16 places in the river and its tributaries, gathering a broad range of data, while pinpointing major points of stress. Depending on his findings, he planned to present his results to state environmental officials and propose possible interventions.

On a weekly basis in June and July, he checked pH, temperature, dissolved oxygen, nitrates, phosphates, macroinvertebrate populations and water clarity, according to “Trout Unlimited” guidelines on habitat sustainability. NJIT’s Albert Dorman Honors College provided research funds — and encouragement. He won a Moonshot Prize of $3,500, made possible by Vatsal A. Shah, Ph.D, P.E. ’08H ’09 ‘15, a principal engineer at ANS Geo, Inc. and member of the College's Board of Visitors, to support him over the summer and an additional $2,000 to buy professional equipment, including electronic testing probes, chemical kits, a water clarity device and a fine aquatic net to catch and identify bugs.

He found every factor in an acceptable range, except for water temperature. But in a key finding, this was only the case on a stretch of the river in the Macopin Reservoir, a decommissioned dam, and in the water below it, where temperatures spiked above the 68 degrees essential for trout survival. Temperatures upstream of the reservoir were 10 degrees cooler than 1.5 miles downstream.

Compared to other parts of the river, the old reservoir “has a huge increase in surface area exposed to the sun, with no overhanging tree canopy to shade it. The water is more stagnant, sitting longer to warm up.” A shallow reservoir, it lacks the deeper, colder water that can be released to lower temperatures.

VanGrouw met with a wildlife official from the New Jersey Department of Environmental Protection who was interested in his results, telling him there were no temperature probes on the river at that time, but that the state would consider installing them in the spring.

As possible remedies, he recommended removing the old dam, while also releasing colder water from larger, deeper reservoirs up the river as needed. Going forward, VanGrouw hopes to work with local governments to create a plan to mitigate the heating effects of the Macopin Reservoir on the river’s ecosystem.

“I saw the Pequannock as a forgotten river that no one was monitoring. Its problems were falling under the radar,” he says, noting that a coalition that had once advocated for cold water releases had fallen silent in recent years.

“The wild trout’s decline is a crucial indicator of water quality degradation in the Pequannock, which supplies water to 500,000 New Jersey residents, including the city of Newark,” he says, adding that hot spots in the river hurt the entire river ecosystem. “Bugs can’t survive, fish and birds can’t eat, and algae blooms increase.”

As a tributary to one of New Jersey’s largest rivers, the Passaic River, the Pequannock sends its problems downstream. “There has been a lot of effort to restore the Passaic and we don’t want to put that in jeopardy by bad water coming in from above.”