From Tom Kelley's Colorado Fishing Guide
I found a Bighorn Lake in North Park but no Lake Bighorn...there is only one...here is the verbiage...look for trail 1126 in the Mount Zirkel Wilderness...Lakes in the Mount Zirkel Wilderness include Lake Katherine (9860 ft; 22 acres) Bighorn Lake (10,000 ft; 17 acres) at the headwaters of Lone Pine Creek, Ute Lake (9750 ft, 6 acres), Twin Lake (9800 ft; 37 acres) on Lake Creek and Peggy Lake and Blue Lake (11,165 ft; 10 acres and 10,000 ft; 6 acres, respectively). These lakes are in high, rugged country, often at or above timberline and are tough to reach. They offer brook and cutthroat, and some mackinaw in the larger, deeper waters.
Sound like the right spot?
Yes Zman I think thats the one. After reaching the summit you come to a fork a sign points to the right stating you have about 1.5 miles to go lake Katherine and another sign points to the left stating you have 2.0 miles to go to Bighorn....For us it was great fishing catching tons of brookies...Some cutts...and no lakers. However I heard they where in there from friends who went with us and had went several time before. We camped up there for a couple of nights...I am not sure if there still is camping...Great place...lots of choices...It was a deep lake from what I could remember. Also if you have a 4 wheel drive somewhere close to denver is Fall River Reservoir (exit just west of Idaho Springs) We had great sucess on big Cutthroats last time we went up there....in the feeder stream inlets. Only about 30 minutes to Idaho Springs from Denver and another 12 miles up to the reservoir on the 4 wheel drive road. There is also another lake above Fall River Reservoir dont know the name never fished it. Good Fishing to ya if you go up...Great Scenary as well.