Boundary Dam Reservoir is a man-made lake situated in the southeast corner of Saskatchewan, approximately 8–10 kilometres south of Estevan along Highway 47. It sits within the RM of Estevan and was created in 1957 when a dam was built on Long Creek to supply water to the Boundary Dam Power Station and the city of Estevan. The reservoir covers roughly 688 hectares (1,698 acres) at full supply level, with a shoreline of approximately 22.65 miles. Its primary inflow and outflow is Long Creek, and a 10-kilometre diversion channel connects it to McDonald Lake, capable of moving excess water in either direction.

One of the reservoir's most distinctive characteristics is its consistently warmer water temperature. The Boundary Dam Power Station returns warm water to the reservoir, which keeps a large portion of the water open even during winter months. This thermal influence is what allows Largemouth Bass — introduced in the early 1980s — to survive here, making it the only water body in Saskatchewan where they can be found. Other fish species present include Walleye, Northern Pike, Yellow Perch, and White Sucker. Anglers should note that the limit for Largemouth Bass is zero in Saskatchewan.

Woodlawn Regional Park manages the recreation facilities at the reservoir, which opened as a paddling and recreation destination in 2009. Paddlers can access the water via a boat launch, for which a fee is required. Canoe and kayak rentals are available through the park, making it accessible to those without their own equipment. A sandy beach is also present on site. The park offers full-service campsites, a concession/convenience store, beach volleyball courts, and a basketball pad, providing a well-developed base for multi-day visits.

One safety consideration worth noting is the presence of a pump-house structure on the reservoir where water is drawn in to cool the power station's generators. The waters immediately surrounding this concrete structure can reach depths of 25 feet or more, and caution is advised near any active pump infrastructure. The park also operates a lifejacket loaner station for those who need one while on the water, and there is no lifeguard on duty at the beach. Two residential subdivisions — Sunset Bay and Lakewood — are located along the shore, meaning the reservoir sees a mix of recreational boat traffic alongside paddlers.