A second outdoor center, Cassidy Lake Group Camp on Cassidy Road, was developed by the NPS and the National Youth Administration as a year-round vocational school to teach inner-city boys skilled trades. Started in September 1936, it was hurried to completion in 1937 to accommodate its first scheduled group. Students were selected on the basis of economic need and were required to work seventy hours each month in return for a monthly wage of $29.96 and training in their selected vocations, which included electronics, smelting metals, and engine repair.
A third camp, Cedar Lake Outdoor Center on Pierce Road, was constructed by the CCC in 1940. Three camping units gathered around a central administration building had similar amenities to those at the outdoor center at Mill Lake. Slightly smaller, it had capacity for 124 campers.
Waterloo was administered by the NPS until 1943, when the 12,000-acre park was leased indefinitely to the state of Michigan. It was renamed the Waterloo Recreation Area at that time.