Canyon Lake is managed by the U.S. Corps of Engineers and access to the lake is limited to boat launches, a few beach areas, and a few marinas. The lake itself is quite clear. If you squint at the map above you can see the Guadalupe River Dam on the right side of the lake.
Found a nice topo map of the area under the Guadalupe River Dam. It shows the River Trail, Canyon Lake Power Station, Tye Preston Memorial Library, the Canyon Lake Gorge, and more …