Painted Rocks Reservoir / Bitterroot Info
Painted Rocks reservoir is located in southwest Montana, near the Montana / Idaho border.
Originally created to store irrigation water, this popular reservoir hosts a State Park with camping, swimming and boating opportunities.
This article shares information about the history of Painted Rocks Reservoir, its location, recreation, and water management.
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Where is Painted Rocks Reservoir?
Painted Rocks Reservoir is 28 miles southwest of Darby, MT. It’s a beautiful drive and day trip.
Here’s a link to see the lake on a Google map.
Painted Rocks Reservoir Location / Bitterroot Info
Take the 40 minute scenic drive along the West Fork Road (MT 473) where you’ll follow the West Fork of the Bitterroot River to Painted Rocks Reservoir.
It’s 28 miles of some of the most beautiful country we have to offer in the Bitterroot Valley.
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Activities at Painted Rocks Reservoir
Popular activities include camping, boating, swimming, fishing and wildlife viewing.
Most people enjoy the area during the summer months, but some take advantage of the solitude of winter for cross country skiing, hiking and snowshoeing.
It’s important to know a few things about the recreation area before you head that way.
No commercial services are available. There’s no marina, rentals, restaurants, gas stations or cell service at the reservoir.
Swimming at Painted Rocks State Park / Bitterroot Info
Make sure you have what you need before you head up the canyon.
Access to the shoreline is fairly limited other than at the Painted Rocks State Park, as much of the shoreline meets up with steep canyon walls.
Water levels drop as the summer season progresses, with much of the water released from the reservoir by fall.
It’s a dramatically different reservoir in October than in June.
June, July and August tend to be the most popular times to visit Painted Rocks Reservoir.
Painted Rocks State Park
Painted Rocks State Park was established at Painted Rocks Reservoir in 1963, and ever since residents and visitors have had great recreational access to the reservoir.
You’ll find the 23 acre Pained Rocks State Park on the south end of Painted Rocks Reservoir.
The State Park offers 25 overnight campsites on a first come, first served basis.
Painted Rocks State Park / Bitterroot Info
A boat launch is located at the Park and provides easy access for watercraft of all types.
Swimming is popular at the Park, and visitors enjoy the picnic areas for day use.
Painted Rocks State Park is a fee area with resident and non-resident fees.
For up to date fee information, visit this page.
Dam and Reservoir Details
Painted Rocks Reservoir was built in 1939 when the West Fork of the Bitterroot River was dammed to provide irrigation water to farmers late in the summer growing season.
The Painted Rocks Dam is an earthen dam that is 800 feet long and 143 feet tall.
View from Painted Rocks Reservoir Dam / Bitterroot Info
The reservoir holds a maximum of 45,100 acre feet of water, with normal levels of 31,706 acre feet of water.
The reservoir covers 655 acres, or 1.02 square miles.
More than 80 years later the Reservoir still provides important irrigation water for Bitterroot Valley communities, but now also plays an important role in maintaining healthy fish populations in the West Fork of the Bitterroot River.
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Where are the Painted Rocks?
We found two main stories of where the Painted Rocks name originated.
According to Montana Fish, Wildlife and Parks, the name comes from “the green, yellow and orange lichens which cover the grey and black rock walls of the granite and rhyolite cliffs along the West Fork Road.”
Having seen these colors on the rock walls, this certainly seems plausible.
Painted Rocks near Painted Rocks Reservoir / Bitterroot Info
But, according to this article published by the University of Montana, the name comes from “the Native American pictographs on the rocks along the west side”.
A cursory search of information about Native pictographs in the West Fork doesn’t turn up much info besides the referenced UM article, so we’re not too sure about this claim.
We’re not taking sides on this issue since neither story changes what a great resource Painted Rocks Reservoir is for the community and our visitors.
Who Gets the Water?
The west fork of the Bitterroot River flows from Painted Rocks Reservoir
Water releases from Painted Rocks Reservoir is tightly managed and governed by 3 groups.
Montana DNRC, Montana FWP, and the Painted Rocks Water Users Association (PRWUA) work together to determine who gets water released and when.
DNRC owns the dam and reservoir, and is responsible for filling the reservoir and ensuring that water is released per contractual agreements.
West Fork of the Bitterroot River below Painted Rocks Reservoir / Bitterroot Info
25,000 acre feet of water is committed for release to FWP and PRWUA annually.
Currently, FWP gets 3/5’s of the ration, or 15,000 acre feet, and PRWUA gets 2/5’s, or 10,000 acre feet of the ration.
FWP and PRWUA both call for the release of water apportioned to them as needed for agricultural use and to manage stream flows for a healthy fish habitat.
That’s a Good Question
Where is Painted Rocks Reservoir?
The reservoir is located about an hour southwest of Hamilton, MT, and 40 minutes southwest of Darby, MT.
Yes, but water levels are much lower and boating is not available during winter months.