This is a good map because it shows boat ramps, beach, parks, Guadalupe, and other features of the Canyon Lake area. You can get more detailed Canyon Lake literature at the the Canyon Lake Visitors bldg. at Trail Pass and FM2673.
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 …