On a bright, breezy day in early June we paddled a canoe around Lake Pleasant, one of eight glacial lakes in northwestern Pennsylvania. Despite its prosaic name, the 64-acre lake in eastern Erie County has more natural diversity along its shoreline, in its surrounding wetlands, and in the lake itself than any other lake in the region.
A spring-fed lake no more than 45 feet deep, it was formed approximately 16,000 years ago by the same receding Wisconsin glacier that gouged out lakes in the Pocono Mountains of northeastern Pennsylvania. Instead of being acidic like the Pocono lakes, Lake Pleasant is alkaline and thus is buffered from the effects of acid rain. Because alkaline conditions are rare in Pennsylvania lakes and wetlands, Lake Pleasant supports an unusual number of Pennsylvania threatened, rare, and endangered plants.
The Western Pennsylvania Conservancy (WPC) owns 350 acres around the lake, which it calls the Lake Pleasant Conservation Area. This area includes most of the lake’s shoreline, numerous wetlands, two large reclaimed sand and gravel mines, and their Northwest Field Station. Biologist Todd Sampsell, who runs the station and is Director of WPC’s Northwest Conservation Programs, was leading eight of us on a tour of this pristine lake.
We learned that back in 1993, after its initial purchase of 206 acres, the WPC began its long-term goal of creating educational and recreational opportunities for neighboring communities and visitors while preserving and even improving the natural qualities of the property. Eventually, through purchases, easements, and cooperative landowners, they want to provide “bridges” or “wildlife corridors” to State Game Lands #161 west of the property and SGL#155 east of Lake Pleasant, Sampsell told us as he unveiled the WPC’s Master Site Plan. Drawn up with input from local citizens, conservation groups, state agencies, and educators, it is an innovative plan that includes an elaborate trail system, boardwalks, and study areas.
Shayne Hoachlander, Land Management Group Supervisor for Erie and Crawford counties, is as enthusiastic about this plan as Sampsell. “The key is that 155 and 161 can help buffer a unique watershed,” Hoachlander says, “and connecting them into a large unit helps move us toward a landscape level approach to management.”
Recreational opportunities, in the form of fishing and boating, have always existed at Lake Pleasant, but no gas or electric motorboats have ever been permitted. Because motorboat propellers churn the water, cutting the leaves and stems of aquatic plants, produce waves that stir up shallow lake bottoms and dislodge plant roots, and leak oil and gas into the water, the absence of motorboats is one reason why aquatic plant diversity has persisted. Another is because the lake’s unusually clear water allows the sun to penetrate at least 20 feet, which encourages the growth of healthy native aquatic plants.
The marshes surrounding Lake Pleasant include rare fens at its southwestern end that were created by alkaline groundwater seeps. Fens too have unique plant communities. During our June boat trip, Sampsell talked about the plants and wildlife living in and around the lake and about the threats to the lake’s purity. Lake Pleasant Road runs right beside the eastern edge of the lake and “delivers heavy metals, road salts and other contaminants to the lake, resulting in reduced plant growth and increased pollution loads,” Sampsell said. He also worries that “additional nutrients from human sources such as septic systems, agriculture or lawn fertilizers may cause water quality to deteriorate.”Only one boat of anglers was on the lake during our visit so it was hard to envision the throngs of trout fishers who arrive in April after Lake Pleasant is stocked by the Pennsylvania Fish and Boat Commission. The commission has been stocking the lake with trout since 1952 and holds a lease from the previous owner of WPC property for public access on the lake’s eastern shore. Parking and pull-off areas have almost destroyed riparian habitat there and the contrast between the road side of the lake and the remaining shoreline is stark, so the WPC hopes to design more lake-friendly access areas.
Largemouth bass, yellow perch, northern pike, and blue gill also draw fishers to Lake Pleasant, but two fish species of interest to biologists–the blackchin shiner and Iowa darter–are Pennsylvania endangered. A third endangered fish, the warmouth, used to be in the lake but hasn’t been seen lately.
Lake Pleasant also attracts a wide variety of bird species. Students of Penn State’s Behrend College recently documented 56 including the wetland-dependent American bittern, American coot, bald eagle, common snipe, green and great blue herons, common loon, common moorhen, canvasback, bufflehead, blue and green-winged teals, double-crested cormorant, osprey, pied-billed grebe, ring-necked duck, sora, ring-billed gull and wood duck. During our visit tree swallows swooped over the water and red-winged blackbirds “okaleed” in the marshes. As we canoed up the outlet stream we had a good view of a yellow warbler, purple martins, and cedar waxwings.
Other lake-dependent wildlife are beavers and snapping turtles. But the most famous animal at Lake Pleasant is extinct. In 1991 George Moon, a local scuba diver, surfaced with a woolly mammoth shoulder blade. Subsequent dives recovered the nearly complete skeleton of a 15-year-old male woolly mammoth sporting nine-and-half-foot-long tusks. Researchers found scratch marks on the bones which had been weighted down with rocks. They hypothesized that the woolly mammoth, subsequently named “Moon Mammoth,” had been killed by prehistoric humans 12,000 or more years ago and stored in the water over winter.
After telling us the mammoth tale, Sampsell brought us back to the present by having us peer into the water and observe the natural layers of plant vegetation. He also spoke about Lake Pleasant’s rostrum of 23 plant species of special concern including Beck’s water-marigold which blooms in August. That’s why my husband Bruce and I returned one hot, sunny day in late August to canoe the lake with WPC botanist Steve Grund and his assistant Sara Ernst. Grund and James K. Bissell of the Cleveland Museum of Natural History have been compiling a complete flora of the eight glacial lakes and their surrounding wetlands in northwestern Pennsylvania that is financed by a grant from the Wild Resource Conservation Fund.As we canoed around the lake, Grund pointed out a bewildering array of both common and uncommon aquatic plants. He was particularly pleased with the presence of northern water-milfoil (Myriophyllum sibiricum), a Pennsylvania endangered species that has been extirpated from all the other northwestern lakes because of the invasive exotic Eurasian milfoil which “grows very fast, branches near the surface of the water, and can produce a canopy at the top of the lake that shades out the native species below,” Grund said. It also breeds with northern water-milfoil. Since Eurasian milfoil hitchhikes on motorboat propellers, the ban at Lake Pleasant has probably kept it out of the lake.
Northern water-milfoil is just one of a host of endangered, threatened, and rare submerged plants living in Lake Pleasant. These plants may send up flowers to be wind-pollinated, such as the five species of rare, threatened, and endangered pondweeds–Fries, grassy, Illinois, red-head and flat-stem–but their leaves are usually underwater. Grund showed us one common pondweed, the big leaf (Potamogeton amplifolius) as well as the flat-stem (P. zosteriformis) and red-head (P. richardsonii), and then confessed that identifying pondweeds “drive botanists nuts, especially if they’re not blooming,” since they all have similar, long, slender leaves.
Another submerged plant, the Pennsylvania rare white water crowfoot (Ranunculus aquatilis var. diffusus), is heterophyllous, meaning that it produces two kinds of leaves on the same plant. In the case of white water crowfoot, it has simple floating leaf blades and dissected submerged ones. Its fragrant flowers open at, barely above, or beneath the water.
Beck’s water-marigold (Megalodonta beckii) is also heterophyllous, producing large whorls of threadlike leaves on stems underwater and simple, oval leaves above water. Its yellow, sunflower-like blossoms barely break the surface even though they are pollinated by flying insects. I spotted the first flower. Then suddenly we were in the Beck’s water-marigold zone and saw several dozen in bloom.
Coontail (Ceratophyllum demersum), which is not a rare plant, was not particularly impressive and looked to me like a bunch of small, ratty tails floating beneath the water. But among aquatic botanists it is famous because of its unique method of pollination. Its inconspicuous flowers grow underwater. The male flowers release their stamens when they are mature and they rise to the surface of the water. There they release their pollen, which sifts down through the water and may land on a female flower. Luckily for waterfowl, which relish coontail fruits and shoot fragments, this “hit-or-miss” method of reproduction is less common than its simpler reproductive strategy, that of breaking off its brittle stems to produce new plants.Most obvious to us were the many showy plants that float on the surface of the lake such as fragrant white water lily (Nymphaea odorata), yellow cow-lily or spatterdock (Nuphar lutea), and water-shield (Brasenia schreberi), the latter of which has “the best slime on the undersides of its leaves,” Grund commented. It also produces maroon or dull purple flowers that are wind-pollinated.
The emergent plants, which grow half in and out of water include the common pickerel weed (Pontedaria cordata), arrowhead (Sagittaria ringida), arrow arum (Peltandra virginica), bulrushes of various species and the water-willow, also known as whorled or swamp loosestrife. Water-willow (Decodon verticillatus) grows along the edges of wetlands in shallow water and produces clusters of attractive purple flowers at the bases of whorled, thin leaves. But it is best known for its arching stems with enlarged floating tips that often root in the water.
The mixed emergent marginal plant zone includes most of the swampy area surrounding the lake as well as the fens. The fens, Grund told us, are “the center of biodiversity.” Three of the threatened sedges–the lesser panicled (Carex diandra), broad-winged (C. alata) and prairie (C. prairea)–live only in the fens. So too do the endangered rush aster (Aster borealis), marsh bedstraw (Galium labradoricum), and endangered cuckoo-flower (Cardamine pratensis var. palustris), as well as the threatened swamp red currant (Ribes triste). Two other Pennsylvania endangered species, the downy willow-herb (Epilobium strictum) and the swamp smartweed (Polygonum setaceum var. interjectum) live both in the fens and the swamp.
The swamp also shelters the endangered Bebb’s sedge (C. bebbii), cyperus-like sedge (C. pseudocyperus), and highbush-cranberry (Viburnum trilobum). The threatened matted spike-rush (Eleocharis intermedia)lives along the lakeshore.
Two species of special concern, the endangered showy mountain-ash (Sorbus decora), which is found in a nearby upland habitat, and the rare bog goldenrod (Solidago uliginosa), which grows nearly a mile below the lake in the outlet swamp, are not strictly connected to Lake Pleasant and its wetlands. But, as Grund told us, both are protected in the process of protecting the lake and its surrounding habitat.
The list of Pennsylvania endangered, rare, and threatened plants at Lake Pleasant is a work-in-progress and Grund expects the list to expand. Last summer they added both the Bebb’s sedge and the highbush-cranberry. They also subtracted a few species that turned out to be more common than botanists previously thought.
“The closer we look, the more it becomes clear that Lake Pleasant is a very special place,” says Grund. A place that is in good hands and should become even more special as the Western Pennsylvania Conservancy’s Master Site Plan is implemented over the years to come.