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Lewis and Clark
Survey of
Historic Sites and Buildings

historic site Gates of the Rocky Mountains

Location; Lewis and Clark County. A stretch of the Missouri River about 5-3/4 miles long in Holter Lake, roughly equidistant between Holter and Hauser Dams, along the northwestern tip of the Helena National Forest. Accessible only by boat. A secondary road, however, runs a little more than 3 miles to the northeast from I-15 (U.S. 91-287), at a point about 15 miles north of Helena, to Lewis and Clark Landing. The landing is on the western bank of Holter Lake not far above the upstream, or southern, end of the gates area. All other parts of the area are inaccessible by road.

Although the expedition had actually entered the Rocky Mountains at the Great Falls of the Missouri, Lewis named this stretch of river the "Gates of the Rocky Mountains," today usually called "Gates of the Mountains."

On July 19, 1805, not long after leaving the Great Falls of the Missouri and shortly before arriving at the Three Forks of the Missouri, the main body of the expedition, in eight canoes under the command of Lewis, passed through the gates—a cliff-walled, claustrophobic, gloomy expanse of river. The day before, Clark, Joseph Field, Potts, and York had set out overland to seek the Shoshonis, so they did not see it. Returning from the Pacific, on July 16, 1806, Ordway and nine men passed through the gates. They were en route from the Three Forks, where they had left the Clark group, to the Great Falls to join the Sergeant Gass detachment of the Lewis party.

Gates of the Mountains
Photograph of unknown date showing the Gates of the Mountains before downstream Holter Dam was built, which raised the water level about 100 feet. This view looks toward the south, or upstream. (Montana Historical Society.)

Today, Holter Dam, two more dams above it, and their reservoirs create an almost continuous 70-mile-long lake that has drastically changed the Missouri in a region originally comprising some of its most spectacular scenery. No one will ever again see this sight as the Lewis and Ordway parties saw it. The Montana Power Company's Holter Dam, a few miles below the northern exit of the gates, backs up 26-1/2 miles of water in Holter Lake reservoir to the same company's Hauser Dam. The latter creates 16-1/2-mile-long Hauser Lake and Lake Helena in the Helena Valley. Finally, the Canyon Ferry Dam, erected by the U.S. Bureau of Reclamation, makes 25-mile-long Canyon Ferry Reservoir, which extends to Townsend, Mont.

Yet, despite the greatly elevated water level in the gates area, the spectacular cliffs and sheer rock walls are still so high that the effect of the change is diminished. The only really perceptible difference is the stream's current, which is now placid instead of swift. During the summer months, a cruise boat named Sacajawea II takes visitors on daily trips through the gates from Lewis and Clark Landing.

Gates of the Mountains
Missouri River gorge and canyon within the Gates of the Mountains, near Helena, at an unknown date. (Montana Historical Society.)

To the north of the gates, from their downriver, or northern, end to a point about 30 road miles southwest of Great Falls where I-15 leaves the Missouri, the river passes through beautiful mountain scenery and threads its way through several closely confined canyons. The highway parallels the stream on its west side, avoiding many of its widest loops, but running alongside it at many places and affording a fine opportunity to see the Missouri in intermountain plain and mountain canyon. This area, as well as that north of it to the city of Great Falls, is much like it was in the time of Lewis and Clark. At the southern, or upstream, end of the gates is located a ranch, at which point the surrounding land bellies out into a pleasant wide mountain cove. This stretch of river is not visible from I-15 nor accessible by road.

Last Updated: 22-Feb-2004