I visited this park to go for a run while I was visiting DC. The trail around the lake is a bit under 5 miles, but it's all trail. There is almost no elevation gain, and it is not very technically rigorous. The park is definitely more geared toward day use than overnight camping, though there is a small camping area that has pretty good facilities. Watch out for XC runners in the fall though-- they have a course at the park that gets used for races on Saturdays in the fall.