The Boise River is a U.S. Geological Survey. National Hydrography Dataset high-resolution flowline data. , accessed May 3, 2011

tributary A tributary, or an ''affluent'', is a stream or river that flows into a larger stream (''main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which they ...

of the

Snake River The Snake River is a major river in the interior Pacific Northwest region of the United States. About long, it is the largest tributary of the Columbia River, which is the largest North American river that empties into the Pacific Ocean. Begin ...

in the Northwestern United States. It drains a rugged portion of the Sawtooth Range in southwestern

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

northeast of Boise, as well as part of the western Snake River Plain. The watershed encompasses approximately of highly diverse habitats, including alpine canyons, forest, rangeland,

agricultural Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created f ...

lands, and urban areas.

Description

The Boise River rises in three separate forks in the Sawtooth Range at

elevation The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...

s exceeding , and is formed by the confluence of its North and Middle forks. The North Fork, long, rises in the Sawtooth Wilderness Area, along the Boise– Elmore county line, northeast of Boise. It flows generally southwest through the remote mountains in the

Boise National Forest Boise National Forest is a United States National Forest, National Forest covering of the U.S. state of Idaho. Created on July 1, 1908, from part of Sawtooth National Forest, it is managed by the United States Forest Service, U.S. Forest Se ...

. The Middle Fork, approximately in length, rises within of the North Fork in the southern Sawtooth Wilderness Area in northeastern Elmore County. It flows west-southwest near the town of

Atlanta Atlanta ( ) is the List of capitals in the United States, capital and List of municipalities in Georgia (U.S. state), most populous city in the U.S. state of Georgia (U.S. state), Georgia. It is the county seat, seat of Fulton County, Georg ...

, joining the North Fork to form the Boise River, approximately southeast of Idaho City. The main stream flows southwest into Arrowrock Reservoir, joining the South Fork from the Anderson Ranch Dam. The South Fork rises in northern Camas County in the Smoky Mountains and Soldier Mountains of the Sawtooth National Forest north of Fairfield, east of Boise. It flows generally southwest, descending through a

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

canyon to fill the Anderson Ranch Reservoir, then turns northwest in central Elmore County. It joins the main stream as the southern arm of Arrowrock Reservoir, east of Boise. Boise River

Downstream from its confluence with the South Fork, the river flows generally west, adds the major tributary of Mores Creek along Highway 21, and passes through Lucky Peak Dam to emerge from the foothills southeast of Boise. It passes over several irrigation diversion dams above the city, the first and largest is the century-old Boise River Diversion Dam for the concrete New York Canal, which terminates at Lake Lowell (a.k.a. Deer Flat Reservoir) southwest of Nampa in Canyon County. The next diversion is for the Ridenbaugh Canal (1878) at Eckert Diversion Dam, immediately above Barber Park, five miles (8 km) from downtown Boise. Wooded through the city, the river is lined by an extensive recreational greenbelt. It flows west across the western end of the Snake River Plain in the Treasure Valley and becomes a braided stream with a wide

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...

as it crosses northern Canyon County to the

. At an approximate elevation of , it enters the Snake River, the Idaho-

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

border, west of

Parma Parma (; ) is a city in the northern Italian region of Emilia-Romagna known for its architecture, Giuseppe Verdi, music, art, prosciutto (ham), Parmesan, cheese and surrounding countryside. With a population of 198,986 inhabitants as of 2025, ...

and three miles (5 km) south of Nyssa,

History

The river was called "Reed's River" in the early 19th century, named after Pacific Fur Company employee John Reed, who explored parts of the river throughout 1813 and 1814. The river is diverted to canals for

irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...

on the plain west of what is now Boise. The dams that form the mountain reservoirs were constructed as part of the Bureau of Reclamation's "Boise Project" to provide agricultural irrigation,

hydroelectricity Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

, drinking water, and

flood A flood is an overflow of water (list of non-water floods, or rarely other fluids) that submerges land that is usually dry. In the sense of "flowing water", the word may also be applied to the inflow of the tide. Floods are of significant con ...

control to Boise and the Treasure Valley. The major projects' initial completion dates were: * 1909 – Boise River Diversion Dam & New York Canal * 1915 – Arrowrock Dam * 1950 – Anderson Ranch Dam - (S. Fork) * 1955 – Lucky Peak Dam - ( U.S. Army Corps of Engineers) The Boise River was proposed for 50 years for a dam at Twin Springs, culminating in a 1966 Project Travois proposal, which would have used nuclear explosives to either create large amounts of rockfill aggregate for dam construction, or to induce a landslide that would have much the same effect. Project Travois was a component of Project Plowshare. The project was abandoned in 1968 after concerns were raised about radiological contamination, and the seismic safety of downstream dams.

Recreation

The river is a popular destination for floating, specifically on the Boise greenbelt.

Tubers Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reprod ...

and floaters launch at Barber Park and land at Ann Morrison Park, between major irrigation diversion dams. Several minor diversion weirs are passed as well as several bridges on the trip.

Water skiing Water skiing (also waterskiing or water-skiing) is a surface water sport in which an individual is pulled behind a boat or a cable ski installation over a body of water, skimming the surface on one or two skis. The sport requires sufficien ...

is popular above the dam at the Lucky Peak Reservoir. On the lower (warmwater) course of the river, low summer flows and poorer water quality from agricultural runoff limit

fishery Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...

production. This section of river supports a fair fishery for largemouth bass, smallmouth bass, and channel

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

. Upstream from

Star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

, the river is a coldwater stream and supports a greater variety of fish. The most prevalent species on this section is mountain whitefish, as well as hatchery-reared

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

, wild rainbow trout, and fingerling brown trout. Upstream from Lucky Peak and Arrowrock reservoirs, the river and its tributaries contain excellent populations of wild rainbow trout, mountain whitefish, and bull trout. This is especially true immediately downstream from the outflow of Anderson Ranch reservoir, where the South Fork takes on the characteristics of a classic "tailwater" for over from the put-in below the dam to Cow Creek Bridge.

Fishing

The Boise River is also popular for

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment (Freshwater ecosystem, freshwater or Marine ecosystem, marine), but may also be caught from Fish stocking, stocked Body of water, ...

, mostly for

and, in the winter, steelhead. Spin-fishermen use roostertail spinners and bait such as

worm Worms are many different distantly related bilateria, bilateral animals that typically have a long cylindrical tube-like body, no limb (anatomy), limbs, and usually no eyes. Worms vary in size from microscopic to over in length for marine ...

s and Powerbait, while fly fishermen use a variety of flies mimicking the abundant aquatic and terrestrial insects present in the watershed, as well as streamers.

References

External links