Sunset Lake – To Be or Not to Be, that is the Question

by Brian T. Lynch, MSW

The County Concrete Corporation in Roxbury has submitted an application to the NJ DEP to create new river bed channels that would reconnect the Black River's upper and lower reaches and the Lamington tributary that flows from the Canfield Avenue spring. These streams would no longer flow directly into Sunset Lake as they have for over half a century. This configuration did exist before sand mining operations in the early 20th Century. Like most water bodies in Roxbury, Sunset Lake is the remnant of an abandoned sand pit. Today, however, it is an ecologically productive and recreationally active lake. The idea of “restoring” the uninterrupted flow of the Black River may sound like a good idea if properly done, but the plans don’t address the environmental impact this would have on Sunset Lake.

To put the proposed Black River Restoration application into perspective, we first need to understand the role Sunset Lake plays in the production of concrete. Making cement and concrete (which is cement mixed with stones) requires a lot of water. Sunset Lake supplies that water to County Concrete. This has been true for decades, and there is plenty of water for this purpose. Some of that water, mixed with the concrete, is carted away to construction sites.

The operations also require water to clean the plant and equipment. Some of this wastewater can be reused, but some must be discarded. This wastewater is full of suspended solids, as you can imagine. It is first discharged into settling ponds where larger suspended particles fall out of solution and settle at the bottom. Not all the suspended solids, mostly comprised of silicates and other native materials, settle out of the water. The smallest particles (or fines) can remain in solution indefinitely. Wastewater from the settling ponds is then discharged back into the lake. County Concrete is licensed to do this by the NJ DEP, which regulates how much effluent or total suspended solids (TSS) can be discharged.

Suspended solids (evident in color differences seen in this satellite image) are present throughout Sunset Lake from County Concrete’s wastewater discharge. This has always been true. Even if the discharge volume, or TSS, is below DEP guidelines, there is always more turbidity than there is in Randolph Pond, which gets its water by infiltration from Sunset Lake. The sandbar between these two waterbodies filters out most of the suspended solids. However, the southern spillway flowing from Sunset Lake to Black River Pond introduces some suspended solids and turbidity into the pond and the Black River beyond.

This is the crux of the problem that County Concrete is trying to solve. I suspect the settlement ponds are less efficient over time while the need for more concrete production grows. There is a build-up of unusable dry material on their property, which must be disposed of, and there are constraints on the production of concrete due to DEP wastewater discharge limitations. Reconnecting the upper and lower reaches of the Black River, and rejoining the Lamington tributary with the Black River, such that neither flows into Sunset Lake, may lift their regulatory burden. 

So, the question is, what is County Concrete’s plan for Sunset Lake? Are they planning, for example, to subdivide the lake to preserve an environmentally healthy open water area for Mine Hill residents suitable for fishing, boating, and swimming? Mine Hill apparently owns part of the land under the lake, so this is a legitimate question.

Concrete is as vital to our modern society as fresh water is vital to our terrestrial environment. It is in everyone’s best interest to find a reasonable balance between the need for concrete and the need for freshwater habitat. As positive as the Black River Restoration project may sound, these plans are incomplete without an environmental impact study of the lake and a discussion on what is fair for the residents of Mine Hill.