The Little Grizzly and Big Grizzly creeks came together on our property and formed the North Platte. I spent a ton of time hiking up to Kathleen, Bighorn, Blue, and Peggy Lakes in what is now Zerkel Wilderness. Kathleen is one of the prettiest places to camp in Colorado. You should do a search on the unexplained lake monster sightings over the last 80 years. It is several hundred feet deep. It is a short 3 mile hike from the trailhead. You access it through the Noffsinger Ranch access. The fishing was great in the beaver ponds as well. Peggy lake had a bunch of hungry trout that were probably 22" inches long but extremely skinny.