BOYDS -- As you look north from atop the railroad right of way over Little Seneca Creek, a large basin spreads toward the dam that holds back Little Seneca Lake at Black Hill Regional Park in Montgomery County.
The northeastern edge of the basin is cut by Little Seneca Creek, which curves back toward the south, runs through a large culvert under the B&O right of way and meanders past Clopper, Hoyles Mill and Schaeffer roads to its juncture with Bucklodge Branch and beyond.
Little Seneca Creek is a watershed in transition. For many years, the creek was a put-and-take trout fishing area. This year, from the B&O right of way to Bucklodge Branch, it has been reclassified as a catch-and-release trout area.
The key to its reclassification by the Department of Natural Resources is the dam at Little Seneca Lake -- behind which lies a decent impoundment for bass fishing, and below which lies a modest tailwater fishery, a mini-Gunpowder, perhaps, less than five miles off Interstate-270.
"Unfortunately, Little Seneca Creek does not have the flows that the Gunpowder or the Savage rivers have," Robert Bachman, chief of freshwater fisheries for DNR, said recently. "It does have cold water coming from the bottom of Little Seneca Creek Dam, and we have been stocking fingerling trout there the last couple of years."
Because of the cold water flow, these trout have survived over the summers and there is limited natural reproduction in the creek. But without catch-and-release regulations, Bachman said, high fishing pressure was removing the trout almost as soon as they got to catchable size, and natural reproduction was stifled.
"We went to catch and release with artificial lures and flies only and stopped stocking the creek to protect the fish and allow them to reproduce," Bachman said. "But guess what? The beavers have moved in to build dams there because they don't think the [engineers] have done a big enough job and now they want to help.
"The problem is that beavers don't put bottom release structures on their dams and these dams slow down the water, impound it, and it gets hot. That basically is what the problem is."
The Little Seneca apparently is in no immediate danger, but it is a good example of the effect that beavers can have on some areas.
An area such as the basin upstream of the railroad right of way may be the focal point for the beaver. The basin is designed to handle overflows and disperse them across the flat bottom, rather than to channel them directly toward the high bank of the right of way.
The beaver, having an intuitive sense of engineering, may have seen the basin as being well suited to their needs: The flow of the stream was fairly constant, the hillsides are thick with trees, and bottom of the basin is relatively flat.
A beaver dam built across the stream would quickly back water and spread it into a beaver pond, a large, slow area of warm water, rather than a fairly narrow stream of cold trout water.
"Beavers are doing that in a lot of places in warm water areas," Bachman said. "And if what you are looking for is wood duck habitat, they are great."
Beaver dams that interfere with man-made structures, said Peter Jayne of DNR's Wildlife Division, can be removed if it is determined they pose a problem.
Once a beaver dam has been in place through a full season, however, a wetlands permit may be required.
Beaver, Jayne said, are trapped and transplanted if necessary. But quite often beaver will move along on their own.
Trout fishing in Maryland has benefited from tailwater fisheries, and one has to suspect that Little Seneca Creek will prove to be successful as well.
"What we would like to do, and what the area was before the beavers moved, is have a developing trout fishery," Bachman said.
Judging from a few hours on the creek at midweek, the potential is there. The stream banks from Clopper Road up to the railroad right of way are cut by trails left from years of put-and-take fishing. The banks are level and fairly clear in many areas and the water is well suited to wading in hip boots.
Below Clopper Road and down to the ford on Hoyles Mill Road, still a mile or more above the juncture with Bucklodge Branch, the stream remains fairly fast and cold.