Patrick Pascuzzi of Zelienople spent the afternoon fishing with his father, Regis Pascuzzi and mother Joyce Pascuzzi at a small pond on Fyock Farm in Forward Twp. Monday afternoon. Harold Aughton/Butler Eagle

What goes in must come out. Below dams you’ll find outflows or tailrace sections. In many cases these areas tend to collect fish, and as such have the potential to be fishing hotspots throughout the year.

Outflows come in many configurations, based on the purpose of the impoundment and the size of the waterway being dammed. A basic understanding is beneficial in determining the fishing opportunity a place might provide.

Concrete dams, common in flood control and navigation dams, typically release water through a series of sluice gates. These are commonly located near the bottom of the dam. If the upriver impoundment is deep – meaning it stratifies during the summer – the water coming off the bottom will be cold and can fuel trout fisheries for miles below. Such is the case with the upper Delaware River, where bottom discharges from water supply reservoirs on both the East Branch and the West Branch (in New York State) furnish cool water suitable for trout for many miles below the outflows.

Navigation dams on major rivers like the ones within the Ohio River drainage in the western part of the state are either fixed-crest or gated. As the name implies, fixed-crest dams are concrete barriers, with the river water flowing over the top. Gated dams, which elevate the river pool to a higher elevation, discharge through a series of gates. All the dams on the Allegheny are fixed-crest. Both fixed-crest and gated dams are found on the Monongahela and Ohio. Hydroelectric power facilities are present at many of these dams as well and share the discharge water while generating electricity.

Earthen dams are also common throughout the state. Many of our state park lakes such as Glendale, Arthur, Pymatuning and Yellow Creek are formed by earthen dams. Typically, excess water discharges over a spillway back into the original streambed, though a bottom gate is present to draw down lake levels if necessary. Some flood control earthen dams release through an underground tunnel. Crooked Creek Lake, Tionesta Lake and Youghiogheny River Lake all feature tunnel discharges.

Within these basic types are variations. For instance, Mahoning Creek Lake, a concrete impoundment with bottom sluices, discharges into a stilling basin about 250 yards long. The water then flows over a fixed-crest dam back into the streambed.

The level of fishing opportunity and nature of the fisheries present provided by tailrace areas varies, depending on the type of impoundment and size of the waterway.

As mentioned earlier, when cold water is discharged from the bottom of the reservoir a trout fishery can result. Besides the wild browns and rainbows of the upper Delaware (including Pennsylvania’s share of the West Branch), good trout fishing exists below the Kinzua Dam (Allegheny Reservoir). Special regulations are in effect from the Kinzua outflow down to the mouth of Conewango Creek in Warren, a distance of 8.75 miles. From the opening day of trout season to Labor Day, two trout, 14-inch minimum length, can be creeled. It’s catch and release the remainder of the year.

Kinzua Dam features multi-level discharges, so water temperatures can be evenly controlled. The trout fishery is maintained by fingerling stocking.

Tulpehocken Creek, below Blue Marsh Lake, is a popular and high-quality trout destination. Outsized trout also show up in the Juniata River below Raystown Lake. The tailwaters of Youghiogheny River Lake provide good fishing in the immediate outflow, where adult trout are stocked, and within a nine-plus mile section managed as All Tackle, Trophy Trout, fueled by fingerling stocking. The outflow area of Shenango River Lake gets adult trout both spring and fall and is open to fishing year-round.

The three rivers of western Pennsylvania, as well as the lower Susquehanna River, provide good walleye action late fall through early spring, weather permitting. Fishing isn’t confined to the immediate tailrace, as fish concentrations can be high within the first mile or so below the dam, in areas with habitat to hold fish. These areas tend to stay ice-free in all but the coldest of winters.

In the case of the Allegheny, fishing piers are present at L&D 5, 6, 8 and 9 next to the hydroelectric facilities. These platforms provide shore anglers with good access to the river and can be productive throughout the year.

Smaller venues also provide potential sport. Crooked Creek Lake tailrace can be especially productive following a high-water event, one where crappies and other fish are flushed through from the lake above. Mahoning Creek Lake, in the scour hole below the spillway, holds walleyes, northern pike, muskies and smallmouth bass.

Jeff Knapp is an outdoors columnist for the Butler Eagle.