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Glaciers in the Crown of the Continent Ecosystem

Natural Area, Geologic Feature
Scientists in Glacier National Park document the rapid decline of the park's iconic glaciers – Courtesy USGS

Approximately 50 glaciers can be found in high mountain cirques of the Crown of the Continent region. The status of many of these glaciers is in flux due to global warming, as several every decade are relegated to non-glacial status, either as puddling snowfields or as glacierets, small, permanent ice masses that show no signs of movement. The greatest concentration of glaciers in the region, about half of the total, are found in Montana's Glacier National Park. "Once we had 150 glaciers in this park. Now, there are only 25 left, and we expect them all to be gone by 2030," says Dan Fagre, an ecologist and climate watcher at the U.S. Geological Survey in West Glacier.

Highlights of this Geologic Feature

Glaciers are huge masses of ice that move over the land at a very slow pace. They exist in areas of high elevation where snow builds up over the years and remains at the end of each summer. The weight of new snowfall compresses the snow lying beneath, which undergoes physical changes, and after a few years time becomes new glacial ice.

Far from the mountains, glaciers are especially important for western Canada and the United States because they are huge frozen reserves of fresh water. For aquatic ecosystems as well as for farmers, anglers and other downstream water users, the greatest release of cold, clean waters is well timed during the hottest and driest days of late summer. But in the latter-day West, as they say, whiskey is for drinking but water is for fighting. More than 100 years ago, an international tussle over glacial-melt water erupted in the Crown of the Continent, a struggle that became a leading impetus behind the Boundary Waters Treaty of 1909. That treaty guides the resolution of water quantity and quality issues in watersheds shared by Canada and the United States. Among the most immediate conflicts resolved by the Treaty was the St. Mary/Milk apportionment issue.

The St. Mary River originates in Glacier National Park, high above the windswept plains of northern Montana, where mountain glaciers and snowfields send cascades of fresh, cold water into the St. Mary and Many Glacier valleys. The waters coalesce in the St. Mary River and move due north to Canada, the Saskatchewan River and, ultimately, Hudson’s Bay. Nature’s export of Montana’s fresh mountain water to Canada became a source of frustration to a growing number of small farmers that began settling north-central Montana along the Milk River in the latter half of the 19th Century. Farmers began building small irrigation projects and diversion dams in the 1880s to water their crops. These projects had a limited financial return. Unlike the St. Mary River with its steady, year-long flows, the Milk River was fed by ephemeral foothill streams that were swollen with spring runoff, but mostly dry during the hottest days of August. By 1900, Montana farmers set their gaze on the St. Mary River less than 50 kilometers across a low divide from the North Fork of the Milk River.

When the U.S. Bureau of Reclamation was created in 1902, one of its first projects was to construct a siphon-and-canal system that would divert the St. Mary River into the Milk River. Canadians had a decidedly negative view of the project, which they viewed as a water grab, and Canada held a trump card. In a twist of geopolitical fate, the Milk River flows north into Alberta before swinging back south into Montana and eventually the Missouri River. Canada warned that if Montana robbed the St. Mary, then Canada would permit Alberta irrigators to divert the Milk River back into the St. Mary River. The Canadian diversion would be downstream of the U.S. diversion, clearly nullifying any advantage for Montana.

The only solution to this dispute was compromise. Water issues were a big deal across the entire northern frontier of the United States, but it was the St. Mary and Milk Rivers dispute that instigated treaty discussions. Today, the state, provincial and federal governments continue to coordinate - and sometimes argue - about the management, maintenance and apportionment of the St. Mary and Milk waters.

But the strategic importance of the St. Mary River for downstream irrigators may be in decline, reflecting the steady melt rate of Glacier's glaciers. Since the end of the Little Ice Age in the late 1800s, most glaciers across the globe have been shrinking in size. Scientists now agree that human-caused emissions of carbon dioxide and other greenhouse gases are greatly accelerating this trend. Researchers at the U.S. Geological Survey are closely measuring changes in the size of mountain glaciers to monitor the effects of climate change. The USGS Glaciers Study Project uses satellite imaging and maps to monitor changes in the volume of glacier ice and sea levels across the globe.

Here is a detailed inventory of the remaining glacier in the Crown of the Continent ecosystem, compiled by University of Calgary student Elyse Barchard.

Glaciers in the Canadian Crown of the Continent

The Canadian side of the Crown of the Continent area includes sections of four major mountain ranges: the Border, Front, Park, and Kootenay Ranges. This area is home to many glacierets (small, permanent ice masses that show no signs of movement) and rock glaciers (large, moving ice masses that are hidden from view under build up of rocks) but very few actual glaciers. The glacierets and ice aprons in this area are remnants of larger glaciers that once occurred here but have now shrunken or are gone entirely.

The Joffre Mountain Group, located at the very northern tip of the Crown of the Continent Ecosystem, part of the southern Front Ranges, boasts the only glaciers of a substantial size in the area. The Mangin and Petain Glaciers are about 5km2 in area. The Foch, Elk, Castelnau, Lyautey, and Neville Glaciers are 1.5 to 2 km in length, and there are a few other unnamed glaciers of comparable size in the area.

Glaciers in the US Crown of the Continent

Glacier National Park, Montana, was established in 1910 because of its many glaciers and its unique glacially carved landscape. The glaciers of this area have been extensively mapped and studied since the 1850s. It is estimated that the area of coverage of ice-and-snow bodies in Glacier National Park totals approx. 36km2; glaciers are estimated to occupy 17km2 of this area. In the 1990s, 30 named glaciers existed in Glacier National Park, all but one contained in the northern two-thirds of the park. This is by far the largest grouping of glaciers in Montana. In the 160km of mountain ranges surrounding the park to the south and west, only six other glaciers exist. Three are in the Mission Range, two in the Flathead Range, and one in the Swan Range.

In Glacier National Park, almost all the permanent ice and snow bodies are located in the northwestern (including Kintla, Agassiz, and Rainbow Glaciers) and south-central (including Sperry, Jackson, Blackfoot, Harrison, and Pumpelly Glaciers) regions of the park. Only five glaciers (Blackfoot, Jackson, Harrison, Agassiz, and Rainbow Glaciers) have areas larger than 1.0 km2. Sperry and Grinnell Glaciers have areas of about 0.9 km2. Five glaciers (Kintla, Weasel Collar, Chaney, Ahern, and Pumpelly Glaciers) have areas between 0.5 and 0.8 km2. All of the glaciers of Glacier National Park have shown considerable loss in mass in the time that they have been studied. At least two glaciers, Logan and Red Eagle Glaciers, have become stagnant ice masses since the late 1800s.

More information:

1. U.S. Geological Survey. Description: Glaciers and Glacier Hazards. 2006 [cited November 2007]; Available from:\_glaciers\_hazards.html 2. U.S. Geological Survey. Satellite Image Atlas of Glaciers of the World. 2007 [cited November 2007]; Available from: 3. U.S. Geological Survey. Sea Level and Climate. 2000 [cited November 2007]; Available from: 4. U.S. Geological Survey. Glaciers of Canada: U.S. Geological Survey Professional Paper 1386-J-1. 2002 [cited; Available from: 5. U.S. Geological Survey. Glaciers of North America - Glaciers of the Conterminous United States. 2002 [cited November 2007]; Available from: 6. "Resolving transboundary conflicts: The role of community-based advocacy," by D. Thomas and S. Thompson, in Sustaining Rocky Mountain Landscapes, T. Prato and D. Fagre, editors, Resources for the Future, 2007.