Lakes, Rivers & Reservoirs
Idaho has areas of both substantial and negligible topographic relief due to geographic and geologic features creating rivers, creeks, and lakes. Several major river systems cross Idaho and two large rivers are contained completely within the state. The single most unifying geographical feature is the Snake River which has its source in the mountains of Yellowstone National Park and meanders west to the Oregon border and then north to Hells Canyon, where it joins the Salmon, continuing north to Lewiston, where the Clearwater enters, and heads west to join the Columbia River. The river is more than 1,000 miles long and drains more than 100,000 square miles of country. The Snake River carries 40 million acre-feet of water and drops more than 7,000 feet in elevation by the time it empties into the Columbia River.

The Snake River system contains many canyons along its expanses across Idaho. The Snake runs through a canyon fifty miles long as it enters Idaho from Wyoming. Several rivers, tributaries, flow into the Snake and enter through their own canyons. Blue Lakes Canyon is on the Snake River five miles below Shoshone Falls near the city of Twin Falls. Blue Lakes Canyon contains farmland and a country club along the Snake River almost 500 feet straight down from the desert floor. The Hagerman Valley is another interesting segment of the winding Snake River containing a grand Canyon. This valley is a wide canyon having a high, steep north wall that issues beautiful flowing springs, Thousand Springs. Here, millions of gallons of water gush from the rocky canyon wall cascading into the Snake River. Hydrologists infer that the water source is the Big Lost Sinks where the Big and Little Lost River’s disappear into the lava beds near Arco about 150 miles northeast of Hagerman Valley.

The most well known part of the Snake River Canyon, however, is between Idaho and Oregon. It is Hells Canyon, the Grand Canyon of the Snake, or Seven Devils Canyon. It is 7,900 feet from the bottom of the canyon to the top of Devil Peak. This makes it the deepest gorge in North America. It is about 2,250 feet deeper than the Grand Canyon of the Colorado River in Arizona.

In addition to deep canyon gorges the Snake also has several important waterfalls as a result of sudden regional changes in elevation. These include the spectacular Shoshone Falls which boasts, 212 feet of relief, 52 feet more than Niagara. Other waterfalls in the state include Big Fiddler Creek which has one of the highest falls in Idaho - 600 feet high. It is on the South Fork of the Boise River above Arrow Rock Dam. Moyie Falls is noted for its stone formations which make the water seem to be full of colored glass crystals. It is on the Moyie River near Bonners Ferry. Several towns in Idaho are named after waterfalls: American Falls, Idaho Falls, Post Falls, and Twin Falls.

The untamed and imposing Salmon River - "River of No Return" - winds 425 miles through the mountains of central Idaho, its canyon gorge deeper than the Grand Canyon of the Colorado. It flows through the Sawtooth Wilderness Area and finally joins the Snake about fifty miles south of Lewiston. A spawning stream for pacific salmon, it is one of the longest and most rugged rivers lying wholly within one state.

The Clearwater River, of northern Idaho, is another major river system lying entirely within Idaho’s boundaries. Bitterroot mountain streams feed the Clearwater. The Clearwater was used as a passageway by explorers and trappers, and later by miners and loggers because it was much more tame than its counterpart the Salmon River.

Far to the south is the Bear River, 300 miles long, which originates in Utah's Uinta Mountains, winds back and forth north to Wyoming, back to Utah, back to Wyoming, and then enters Idaho. It moves north (staying south of the tributaries of the Snake) and then back southwest, to where it enters Utah and deposits its water in the Great Salt Lake. Early trappers found beaver along the Bear. The Oregon and California trails entered Idaho with the Bear River and followed it for a considerable distance.

Major rivers in northern Idaho include the Kootenai and Pend Oreille, which flow into the Columbia; the Clark Fork, which flows into Lake Pend Oreille; the Saint Maries, the Saint Joe (St. Joe), and the Coeur d'Alene, which flow into Lake Coeur d'Alene; and the Spokane River which carries the waters of Coeur d'Alene Lake to the Columbia.

The Boise, Payette and Weiser flow into the Snake in southwestern Idaho as it forms the Oregon border, and there are many shorter tributaries of the Snake in southern Idaho.

Idaho has more than 2,000 lakes with names, and thousands of others without names. Some Idaho lakes can't be found on any map! Two of Idaho's northern lakes are said to be among the most beautiful in the world. Lake Coeur d'Alene and Lake Pend Oreille (the largest in the state with a surface area of 180 square miles). Both are large beautiful lakes in Bonner, Kootenai, and Benewah counties. Lake Coeur d'Alene is a popular resort area.

Farther north of Lake Pend Oreille is Priest Lake, early a heavily used trapper area. A few miles south of Pend Oreille is Hayden Lake. Surrounded by forested mountains, all of these lakes are in spectacular settings.

Payette Lake in central Idaho north of Boise is also a significant summer recreation destination. Farther east, in the Sawtooth National Recreation Area, Redfish, Stanley, and Alturas lakes fulfill the same role.

In eastern Idaho, only fifteen miles from Yellowstone, is Henry's Lake, a favorite trapper hangout and trout fishing lake. Farther south is turquoise Bear Lake, half in Idaho and half in Utah.

Many of Idaho's lakes are actually reservoirs, formed behind the numerous dams on the state's waterways. Dams are constructed to store water for irrigation, to generate hydroelectric power, and to keep flood water from destroying farms and cities. Idaho's rivers have such dams as the Anderson Ranch, Arrow Rock, Lucky Peak, Black Canyon, Dworshak, and many others.

Idaho’s five major cities are located on the Snake or its tributaries. A dozen or more dams were constructed along its course alone to provide affordable irrigation water and hydroelectric power for thousands of farms, homes, and most of Idaho's industries (two-thirds of the population of Idaho live in the fertile Snake River Valley). The Snake River has dams and reservoirs at Palisades, near the Wyoming line, American Falls, Minidoka, Salmon Falls, Brownlee, Oxbow, and Hells Canyon.I

Snake River water that is captured in reservoirs or flows on to the ocean comes, not from rainfall, but from the snow that accumulates on the vast peaks of Idaho's mountains. Shifting sand dunes near St. Anthony, Bruneau, and Weiser reveals the fragile environment of the semiarid Snake River Plain. Additional information on water sources can be obtained from our web links page, Hydrology Web Sites.