Edward MacDowell Lake is a flood-control reservoir on Nubanusit Brook in the west part of Peterborough, in New Hampshire's Monadnock Region. The U.S. Army Corps of Engineers built the dam and still runs the recreation area around it, which the Town of Peterborough lists as MacDowell Dam. Some swimming guides call the water MacDowell Reservoir, and that is also the name on the federal water-body records. The lake covers about 165 acres inside a project of roughly 1,200 acres of forest, lawn and wetland, and it is named for the composer Edward MacDowell, whose wife Marian founded the MacDowell artists' colony in town in 1907.

To get there, leave Route 101 in Peterborough at Union Street, drive about half a mile, then turn left on Wilder Street and follow it to the end at 75 Wilder Street. The road climbs past the project office and splits. One branch crosses the top of the earthen dam to a parking circle and group shelter on the west side. The other heads north along the east shore to the day-use parking lots, which sit just above the beach.

The swim beach is a small sand beach on the east shore, a short walk north of the dam, with a picnic shelter, restrooms and a playground on the lawn behind it. There are no lifeguards, and the Corps posts it as a swim-at-your-own-risk beach. Pets are allowed in the park on a leash but not on the beach, and glass is not allowed on the sand. The lake is a reservoir, so the level and the size of the beach can change after heavy rain, and the Corps warns that the whole park can flood in big storms. Water-quality advisories can be posted at the beach at any time, so check for signs before you go in.

Admission is free. The Town of Peterborough describes the park as day use only with free admission, and the Corps does not list any day-use fee for the beach. The only reservable items are the two group picnic shelters, booked through Recreation.gov. Summer hours are 8am to 8pm, and the rest of the year the park is open sunrise to sunset. Camping and any occupancy between 8pm and 8am are prohibited. For current conditions, call the project office at 603-924-3431.

Grills are for charcoal only (bring your own) or self-contained gas grills, and ground fires are banned. A car-top launch just north of the beach suits canoes and kayaks, and the lake holds largemouth bass, pickerel, perch and horned pout. Several trails loop through the woods and wetlands, including the West Ridge Trail along the far shore, the Wetland Wonder Trail and the Sand Pit Trail. You can also walk across the top of the dam for a view up the lake toward the intake tower. Park rangers run interpretive programs and a Junior Ranger program for kids 6 to 12.