Introduction to the Bitterroot River Watershed
The Bitterroot River Basin is located in southwestern Montana. The watershed was formed by the upheaval of the North American Plate as it slid into and compressed the Pacific Plate in pre-Cambrian times. The rugged and tall (up to 10,000 feet) Bitterroot Mountain peaks that line the west side of the valley are the jagged edge of the Bitterroot Lobe of the Idaho Batholith, a huge slab of granite formed by tectonic and geothermal forces. Forming the east side of the valley is the softer and rounder Sapphire Mountain Range, possibly a broken off edge of the Idaho Batholith. The entire Bitterroot River Watershed is contained between these two mountain ranges. They hold the watershed between them like two cupped hands, spilling over into the Missoula Valley where it flows into the Clark Fork River, which flows into the Pend Oreille, which flows into the Columbia, which flows into the Pacific.
The valley was flooded and drained, flooded and drained again, over a period of centuries as an ice dam formed and collapsed repeatedly on the Pend Oreille River near present day Coeur dʼAlene, Idaho. During these submerged periods the Bitterroot Valley was simply an arm of Glacial Lake Missoula. As a result, the Bitterroot River Basin was a major contributor to the catastrophic floods that shaped the present day Columbia River Gorge and large portions of Washington, Idaho and Oregon. Today the Bitterroot River watershed is one of the easternmost headwaters of the Columbia River Basin. The Bitterroot River now runs for about 85 miles south-to-north through the Bitterroot Valley, from the confluence of its West and East Forks near Conner to where it flows into the Clark Fork River near Missoula.
The watershed drains a 2,814 square mile area. It receives an average of about 12 to 15 inches of precipitation annually. The Bitterroot peaks, which range from 7,000 to 10,000 feet, get an average of 100 inches of snowfall annually, while the smaller Sapphire Range averages about 50 inches. Four times as many streams enter the valley from the Bitterroot Mountain Range to the west than from the Sapphire Mountain Range to the east.
The Bitterroot River is a Class I river from the confluence of the East and West Forks to its confluence with the Clark Fork River for public access and for recreational purposes. Rainbow trout are fairly prevalent in the river with smaller populations of brown trout and Westslope cutthroat trout. It also contains some Bull Trout in its lower reaches. It is one of the most fished rivers in Montana. Anglers log over 100,000 fishing days annually on the river.
Although the Bitterroot River passes close by to many residential areas, it is an excellent place for wildlife viewing. Many species of ducks and waterfowl are common along with osprey, bald eagles, heron, and sandhill cranes. Both white-tailed deer and mule deer frequent the river as a source of water and to graze near its banks. The most notable wildlife viewing locale along the river is the Lee Metcalf National Wildlife Refuge. This refuge harbors a greater variety of wildfowl than almost any other in the national refuge system.
The fact that you can drive out of the valley and over the pass into the Big Hole, where the waters flow to the Missouri and on to the Mississippi, is another sign that the Bitterroot drainage sits at the easternmost extreme of the headwaters of the Columbia Basin. This fact is also reflected in the language of the aboriginal inhabitants of the basin, the Salish and Kootenai. Their language links them to the language groups spoken along the Pacific Coast and they represent the easternmost penetration into the Rocky Mountains of that people and language. It was they who named the river Spitlem Seukn, or “waters of the bitter root,” named after the Bitterroot flower whose roots the Salish harvested. The roots were a mainstay, along with fish, in the Salish diet. It is now the Montana State Flower.
The Salish were eventually evicted from the Bitterroot Valley and marched to a Reservation in the Flathead Valley north of Missoula. But the Salish Kootenai Confederated Tribes still hold aboriginal hunting and fishing rights in the Bitterroot and both the Tribes and the Federal Government claim significant water rights from the Bitterroot River and its tributaries on the national forest land surrounding the valley and on the valley floor. About three quarters of the land in the basin is Bitterroot National Forest land.
The Bitterroot Valley contains Montanaʼs oldest white settlement, Stevensville, where the Bitterroot River Protection Association (BRPA)is located. It is here the first water was diverted for irrigation of fields and the first grist mill was built. The valley became the site of the first court declared water rights in Montana following the killing of Charles Linscott by Rees Powell in a fight over water out of Three Mile Creek northeast of Stevensville. The Bitterroot River Basin was closed to any future surface water right appropriations in 1999.
As the numbers of farmers and ranchers irrigating out of the tributaries along the river grew, dams were created near the source of these tributaries high in the mountains to retain water for late summer when flows would run low. Today there are 28 dams on tributaries to the Bitterroot River that are located on Forest Service land, mostly in designated wilderness areas.
A few very large dams were created at Como Lake and Painted Rocks Reservoir. Over 31,700 acre feet of water is stored in the Painted Rocks Reservoir and over 35,100 acre feet is stored behind the dam at Como Lake. Approximately 110,000 acres of land is irrigated and some water is reserved by FWP for late summer flows in the river to preserve the fisheries.
Copper King Marcus Daly took up residence in the valley, helped bring in the railroad, and helped build the Big Ditch, turning the Bitterroot Valley into the breadbasket for the miners in Butte and Anaconda and the site of a land rush during the Apple Boom days.
The river also served as a giant conveyor for the logging of old growth Ponderosa forests located on the valley floor and up the mountain slopes.
Mining took place at many spots in the valley but notable operations were conducted up Eight Mile Creek and at Big Creek and Hughes Creek. The Curlew mine at Big Creek developed several miles of underground tunnels and became a major producer of copper, gold, nickel and other metals for decades. Eventually open pit mining methods were employed. Slag from that mine ended up being used as recently as a decade ago for road surfacing throughout the north valley.
The 2014 Bitterroot watershed TMDL report states potential sources of the Bitterroot River’s lead impairment investigated for this TMDL source assessment include a municipal separate storm sewer system (MS4), a wastewater treatment plant, and abandoned mines. Other sources may also include car bodies (briefly discussed above), the atmosphere, timber harvest, landfills, leaded gasoline, and outdoor recreation wastes. Lastly, a portion of lead is also attributable to natural sources. In 1993, DEQ developed a prioritized list of abandoned mine locations to facilitate reclamation efforts of the worst sites first. Four priority abandoned mines sites were initially identified in the Bitterroot River watershed.
The valley now contains five incorporated municipalities, Darby, Hamilton, Pinesdale, Stevensville and Florence and a total population of 40,000+ people. Although the towns and one city are relatively small and retain a lot of their history and small town charm, things are changing all around those towns as the greatest destroyer of wildlife habitat in the nation, subdivision development, has made major in-roads into the valley. In the late 1970ʼs the City of Missoula to the north began to spill over into the Bitterroot Valley and urban sprawl began to creep across the rural landscape as a commuter workforce moved in.
During the 1980s, 1,500 more people moved into the Bitterroot Valley than moved away. Then, from 1990 to 2000, that ʻin-migrationʼ figure jumped to 10,500. It meant new roads, more traffic, more garbage, more pollution, more septics, and the loss and fragmentation of wildlife habitat and wildlife corridors. While the municipalities contribute major amounts of pollution to the river, septic systems in the rural areas do as well. Now the size of the subdivisions being proposed and approved are larger than some of our current incorporated towns often based completely on independent septic systems.