Clopper Lake Trail is a hiking and biking trail in Gaithersburg, Maryland. It is within Seneca Creek State Park. It is 3.4 miles long and begins at 361 feet altitude. Traveling the entire trail is 2.9 miles with a total elevation gain of 379 feet. The Clopper Lake reservoir can be seen along the trail. There are also parkings, piers, and a wood along the trail.