Black River in Kenvil Looks Good Despite the Odds Against It - Preliminary Stream Monitor Results

 by Brian T. Lynch, MSW

Here is my initial report on the Raritan Headwaters Association (RHA) monitoring of the Black River this year. The monitoring site is about 100 meters downstream from where it flows out of the Hercules Property in Kenvil (Roxbury Twp.), NJ.

Aerial view of the Black River monitoring site (white line) in Kenvil, NJ just after it emerges from the former Hercules Powder property. 

Unlike most headwaters, the Black River, a.k.a. the Lamington, originates under very threatening circumstances. It vents from the earth on a polluted tract of land where chemical explosives were manufactured for over one hundred and fifty years. Four hundred years ago this water source was a pristine wetland known as Great Spring. Early settlers two-hundred years later knew this stream and its cool, abundant water as the Black River. More recently it was relabeled as a drainage ditch for industrial chemical waste. Its name was removed from many modern maps. It was off limits to environmental scientists who studied this region, and it remains underappreciated for its contribution to the waters of the North Branch of the Raritan River.  

And there are other challenges. Unlike most streams in the Highland, this one flows over a stream bed of glacial sand without the benefit of the many rocks and riffles that add life-sustaining oxygen. Riffles also provide habitat for the bugs that live in the stream.

 Before this spring water travels 100 meters to the first RHA monitoring site, it crosses two busy roadways and receives the liquid burden of four major stormwater culverts. These storm drains contribute road salt in winter, tire dust, plastic trash, leaked motor oil, heavy metals, and who knows what else from Route 46, Hillside Avenue, and several large commercial parking lots. These challenges, threats, and a generally sub-optimal habitat always evoke a feeling of dread when I first enter the stream at the monitoring site. The question arises, "Will this be the year I discover the macroinvertebrates have disappeared?." 

Three other Raritan Headwaters Association stream monitors joined me this year. We spent half a day carefully assessing the status of the Black River site (known as BR07) off Hillside Avenue behind Krauser's. I was happy to have so many fresh eyes on the stream and their help collecting macroinvertebrates (small aquatic bugs living in the streambed) needed to test the water quality. 

The morning was clear and bright. The air was a comfortable 65°, and the recent air quality crisis from burning forests in Canida had cleared. The stream was a cool 58°, but the volume was less than usual.  The water height at the monitoring site was lower than normal but only about three inches lower than usual. It dropped an inch since it was last measured eight days earlier.  Less than an inch of rain fell in over a month. The last significant rain, about a half-inch, fell 21 days prior. This is a dry spell. 

Sampling for macroinvertebrates went better than expected. There was no difficulty obtaining the minimum sample size needed for the laboratory analysis. The variety of bugs was broader than in years past. The bugs' pollution tolerance ranged the full spectrum from pollution-intolerant to pollution-tolerant. We also caught a crayfish, three freshwater mussels, and three small fish (catch and release only) in the sample. I haven't identified the type of fish we caught yet, but we'll send the pictures to the experts. We also spotted three larger fish in the stream but couldn't get pictures or identify details. This was the biggest number of fish observed during stream monitoring at this site.

We were visited by two ducks, a squirrel, many species of birds. Deer tracks and other animal tracks were seen along the stream bank. A neighbor living by the stream told us she hears lots of frogs in the evening. She pointed to the spot where she saw six American Brook Lamprey this past April. These 380 million-year-old species of fish are considered a "species of concern" by the NJDEP. They are on the endangered list in several other states.  Freshwater brook lampreys' cannot survive in turbid, polluted, or overly warm water. The EPA lists them as a good bio-indicator species.  Their presence in the stream, and the good macroinvertebrate samples we gathered, indicate that this stretch of the Black River has miraculously overcome environmental adversity once again. We will await the laboratory results and subsequent chemical monitoring by RHA for confirmation. 

The other piece of good news is that despite the dry spell, the volume of water in the stream is good. Last year was a wet Spring carrying lots of stormwater into the Black River. This year there is no stormwater or even surface water runoff at all, yet the annualized volume of water is still over a billion gallons per year. 

Below are some of the raw monitoring data from the past three years.