Marsh Creek Lake, located in northern Chester County, is one of Pennsylvania's most underrated yet highly productive bass fisheries. According to Dave Miko, a state fisheries biologist, Marsh Creek ranks as one of the region's more prolific spots for older age-class largemouths. "The last electroshock study at Marsh Creek showed that of all southeastern lakes, it has some of the highest concentrations of largemouth bass over 12 inches," he says. Helping to ensure the quality of fishing at this 535-acre impoundment are special "big bass" regulations that place restrictive size and creel limits on largemouths. Work your lures along the edges of submerged weed beds that skirt the banks and concentrate on the underwater drop-offs at the mouths of various inlets extending off the main lake. Tube baits, plastic worms and spinner baits have been a hot number. Marsh Creek Lake also holds healthy numbers of tiger muskies up to 40 inches. Contact: Pennsylvania Fish and Boat Commission, Southeast Region (Box 8, Elm, PA 17521; 717-626-0228); Marsh Creek State Park (675 Park Rd., Downingtown, PA 19335; 610-458-5119).