If you’ve traversed Morris County often, it’s possible you’ve passed Black River County Park dozens of times and never fully realized the recreational opportunities within. The well-maintained Cooper Gristmill, at the park’s trailhead, is interesting enough to occupy 30 minutes, and a walk through a tunnel underpass leads to a gorgeous pond and spillway. The point is, you can get a daily dose of history and nature without hardly leaving the parking lot.
But if you have explored the rest of the park, you know it’s a gem. A long trail takes you to the stone remains of Kay’s Cottage, a summer home for area conservationists Elizabeth and Alfred Kay, for whom an environmental center accessible from the trail is named. Along the way, you’ll see water and forest environs and creatures, varying grades of hiking and opportunities to fish.

Start at the Cooper Gristmill (which is closed for the time being, but to which you can get up close). The site was first used for milling flour in the 1760s; retired General Nathan Cooper bought the existing infrastructure, and in the 1820s, built a four-story mill, which you can see today. The mill was restored in the early 2000s.
Walk under the road through a tunnel and you’ll be able to take in a spillway and a large pod fed by the Black River. There’s a trail on which you can continue from this point, but we turned back for the main trail.
Walk down the steps toward the back of the mill and cross the first of many tiny wooden bridges to take you toward the Black River. This time of year, the river is frothing and fast, but not very deep. Along this initial part of the trail, there are plenty of places to pull off and sit on a rock or fallen log and let the sound of the river’s churn pull you away.

The trail loops away from the river, and you’ll walk along a packed-dirt pathway, with abundant tree roots (indeed, be careful if you’re thinking of this as a running spot). Caretakers have placed sturdy wooden planks on particularly wet ground. About a quarter-mile in, you’ll reach Kay’s Pond, a still-water, sizable pond teeming with wildlife. You’ll get in sight of plenty of waterfowl, and within earshot of abundant frogs.
The trail carries on on flat ground to the end of Kay’s Pond, where there’s another spillway. On the way, the land side of the trail gradually becomes rockier, with sizable boulders that are very tempting if you’re into climbing such things.

Pass the spillway and the trail eventually joins the Black River again, and the walking moves from easy to easy-moderate. About a mile from the spillway, you’ll reach the Kay’s Cottage ruins, and the trail provides an opportunity to see it up close and from afar (if you’re looking for photos).
Continue on and you’ll be able to access the Kay Environmental Center, which provides hundreds of acres of meadow habitat, filled with dozens of bird varieties. Or turn back, as we did, and you’ll traverse the same trail but end up having hiked a peaceful, yet stimulating four-mile route.

The site is another example of the unique intersection between history and nature in New Jersey. And taking in the mill and the ruins reminds one that industry doesn’t have to come at the expense of nature; technological limitations meant early builders were reliant on the health of the river, and today, the man-made structures integrate seamlessly with the nature on which they relied to operate.
As the weather gets hot too, it’s worth noting that the rich canopy throughout the trail, and the cool air from the river kept the entire walk about 15 degrees cooler than the air in the parking lot and by the mill. As the flora comes to fruition in the late spring, it’s a wonderful time to take note of the natural beauty in every living thing in this park.
Cooper Gristmill and Black River County Park. 66 Route 24, Chester.