Rainbow Lake (East Rosebud)

Drainage: East Rosebud
Approaches: Approximately 14 miles round trip to the lake, closer to 16 if you camp, because the good sites sit at the inlet past the far end. Roughly 1,600 feet of climbing.
Elevation: 7,797 feet
Fish: Rainbow and golden trout hybrids, common and self-sustaining. Pure rainbows rare. Yellowstone cutthroat present, abundance unknown. Montana FWP.
Coordinates: 45.13612, -109.6909
Bugs: Not a problem in August.

Getting there

The number you plan around depends on where you stop. The sign calls it 7 miles. FWP calls it 8. Our track read 6.7 to the shore and 7.2 to where we actually pitched a tent, because most of the camping is up at the inlet on the far side.

That gap is the whole planning lesson on this lake. However far you think Rainbow is, add most of a mile before you are done walking for the day.

It took us about eight hours with overnight packs. We have done it in four, but that is pushing the whole way and there is no reason to. The trail is maintained the entire distance, past Elk and then Rimrock, climbing about 1,600 feet total with no route-finding and nothing technical.

The hike

Rainbow is where the East Rosebud finally opens up, and it is not close. FWP measures it at 58 acres, 76 feet deep on average and 180 feet at the deepest point. For perspective on what the trail has been building toward, Elk is 5 feet at its deepest and Rimrock is 25. Rainbow is seven times deeper than Rimrock.

The camping is at the inlet end and there is a lot of it, which is both the good news and the bad news. This is a popular trail and Rainbow is where most people stop, so expect company. FWP's assessment is that the many campsites are overused and the firewood is picked over, and that is exactly what we found. You can gather wood, but it is mostly small branches. Anything of size has been taken.

The fishery has a good story behind it. Golden trout planted upstream at Lake at Falls in 1955 drifted down into Rainbow, and FWP reports the result is a self-sustaining population of colorful golden, cutthroat and rainbow hybrids. Their 2012 sampling pulled 21 fish averaging 11.8 inches with the largest at 15.9. Nothing has been stocked here since 1949.

Tips & safety

• Navigation: No route-finding. Trail #15 the whole way. Fourth lake in the drainage, third one you walk to.

• Camping: Plenty of it, concentrated at the inlet side past the lake. Sites are established and heavily used. Firewood can be found but is picked through, mostly small stuff with slim pickings on anything bigger. Expect neighbors.

• Fishing: Self-sustaining golden hybrids averaging around 12 inches, with fish approaching 16 in FWP's nets. No stocking since 1949.

• Bugs: Some mosquitoes close to the lake but nothing to pesky at camp.

• Depth: At 180 feet this is deep, cold water. Worth knowing before anyone swims out or trusts a shoreline shelf.