Streams of the Great Swamp Watershed:
The Black Brook sub-watershed covers 9,089 acres, or 14 square miles.
Running northeast to southwest, the Black Brook sub-watershed’s most definitive hydrologic borders include both the ridge known as the Third Watchung in Long Hill Township and the terminal moraine of the Wisconsin glacier that makes up the southwest portion of Madison Borough. Its northwestern and southwestern borders are located in the very low-lying, level areas of the Great Swamp National Wildlife Refuge and are hardly noticeable. Nearly 90% of Black Brook is located within the Refuge, and it joins the Passaic River just beyond the Raptor Trust on White Bridge Road.
Black Brook has numerous tributaries, thus making it difficult to pinpoint its actual “beginning,” but it does have five identifiable tributaries outside the Refuge (see map). The first two of these arise near the heavily developed Hickory Tree shopping center area in Chatham Township, near the intersection of Green Village Road and Southern Boulevard. The tributary at the most western edge of the sub-watershed begins in a wet, wooded area to the west of Green Village Road, an area currently being developed into ball fields. The other begins in the Hickory Tree area proper, and is channeled through storm drains behind the Chatham Apartments on Green Village Road. The third tributary arises on Chatham Township municipal property just to the south of the intersection of Candlewood Drive in Madison and Shunpike. It flows south in a wooded area between the municipal playground (aka “the Castle”) and ball fields and the Long Hill Chapel, traverses the western-most section of the Fairmount Country Club, crosses Southern Boulevard (and the Black Brook Water Quality Monitoring Station), and flows into the Great Swamp National Wildlife Refuge. The fourth tributary arises within the Fairmount Country Club, where it crosses Southern Boulevard to the east of the Noe Pond Club and then flows southward into the Refuge. The fifth tributary runs parallel to the west of Fairmount Avenue on the eastern edge of the Great Swamp watershed. It is into this tributary that the Tanglewood Lane Wastewater Treatment Plant flushes treated effluent.
Black Brook is second only to Loantaka in terms of poor water quality. Under baseflow conditions, it fails the Ten Towns Committee’s 2002 water quality standards for Total Phosphorus, Dissolved Reactive Phosphorus, and Total Kjeldahl Nitrogen. Under storm conditions, Black Brook fails those standards and additionally cannot meet standards for Total Nitrogen and Total Suspended Solids. This is in part because its headwaters are impacted by the use of chemical fertilizers on lawns and on the Fairmount Country Club golf course in the relatively intensive land uses above the Water Quality Monitoring Station.
Additionally, Dr. Pollock’s macroinvertebrate (MIV) studies show that Black Brook has one of the lowest macroinvertebrate species counts of the watershed’s five feeder streams. This is crucial information, because macroinvertebrates are valuable indicators of overall stream health. As Dr. Pollock writes in the introduction to The Macroinvertebrate Communities of the Great Swamp Watershed, May 2012, “(p)hysical/chemical conditions within a stream can be monitored directly, although this tells you only about conditions ‘at the moment’ (standards). As long-term inhabitants of streams, the presence of macroinvertebrates reflects stream conditions over the preceding days, weeks, or months. The presence of the biological community or of particular ‘indicator’ species found at a given location depends on the availability of a range of required conditions during the past several weeks or months of that individual’s lifespan. Therefore, studies of macroinvertebrate communities provide [a] valuable historical perspective missing in direct physical/chemical studies.”