McLellan Reservoir, located in Littleton, Colorado, is a mile-wide body of water that is entirely off-limits to public access for paddling or any water activities. The reservoir is owned by the City of Englewood and is surrounded by a tall security fence that prevents water access. While historically the reservoir was open for fishing in the 1970s, it was subsequently closed to public use.

The reservoir holds 1,500 acre-feet of water and receives its water from the McLellan Pump Station, which transfers water from Chatfield Reservoir. Construction of the reservoir was completed in 1965.

While paddling is not permitted, the reservoir can be viewed from several surrounding areas. Writers Vista Park on the northern side provides viewing access with restrooms and other facilities. Walking trails circle portions of the reservoir, offering elevated views of the water. During spring, summer, and fall, waterfowl can frequently be observed on the lake. In winter, the reservoir's surface often freezes over.

The High Line Canal Trail intersects with paths near the reservoir, and a bridge on West County Line Road crosses a section of the water. The surrounding area features deciduous trees that provide fall color, and the location is known for particularly dramatic sunsets over the water.

Given the complete restriction on water access, paddlers should instead consider nearby alternatives like Chatfield Reservoir and South Platte Reservoir, which do permit water activities.