The Upper Yellowstone Watershed

The Upper Yellowstone Watershed Group

Mission: To understand and conserve the Upper Yellowstone watershed, including its agriculture, open space, rural character, wildlife, fisheries, natural resources, and recreational use while protecting private property rights.

The Upper Yellowstone Watershed Group works through consensus-based collaboration among the stakeholders of the region to enhance watershed health and the economy. The goals of the organization are as follows:

1. To preserve production agriculture by promoting a stewardship approach to watershed management.
2. To protect and respect private property rights.
3. To provide information through collection and dissemination of scientifically sound monitoring and assessment data.
4. To maintain and preserve the overall health of the watershed by developing best practices, seeking innovative solutions, and working to improve drought response and preparedness.
5. To lead community education and outreach efforts pertaining to the watershed.
6. To provide a collective “voice of the watershed” through the exchange of ideas and response to issues.

The Upper Yellowstone Watershed Group operates within, but is not limited to, a specific sub-region of the Greater Yellowstone Watershed consisting of the sub-basins and the watersheds along the Upper Yellowstone River. The sub-region can be roughly defined as the area between the unincorporated community of Gardiner in the South, near the Northern entrance of Yellowstone National Park, to the city of Livingston, Montana, to the North. The heart of this region is known as Paradise Valley and has a rich history of agriculture, preservation, exploration and recreation.

The Yellowstone River has headwaters in the Southern reach of the Absaroka Range, flowing into Yellowstone Lake, down through, and out of Yellowstone National Park before ultimately winding through Paradise Valley. The city of Livingston marks where the river transitions from being confined within large mountain valleys to flowing into the Great Plains. There, the flowpath abruptly shifts directions and heads due East, along the foothills of the Northern Absaroka and Beartooth Ranges, passing through agricultural and mining communities. The river eventually intersects Billings, Montana's most populated city, and later merges downstream with the Missouri River near the states Eastern boundary.

Though hardly exhaustive, there are some noteworthy geologic events that have played a major part in shaping the landscape we observe today in the Upper Yellowstone Watershed.

The Laramide Orogeny was a mountain building event that began 80mya and ended 40mya during the Eocene Epoch. This orogeny is responsible for creating the modern Rock Mountains and was quite anomalous when compared to orogenies that preceded it. The reason that the Laramide Orogeny was an anomaly is because it was caused by the Farallon Plate transitioning from normal subduction to a flat-slab subduction. In other words, the Farallon Plate transitioned from subducting at a steep angle to one that was at a much shallower angle. This transition caused compressional stress on the overlying North American plate, which created a series of thrust faults that helped form the Rocky Mountains.

The Hyalite Volcanics were a series of volcanic eruptions that took place during the Eocene Epoch and were part of the Absaroka-Gallatin Volcanic Province. Some of the volcanic deposits found in the Upper Yellowstone Watershed Group are from the Hyalite Peak Volcanics and are primarily composed of andesite lava flows and breccias. These deposits were sourced stratovolcanoes, which was the dominant volcano type in the Absaroka-Gallatin Volcanic Province.

There has been a total of 3 caldera forming super eruptions that took place in the current Yellowstone National Park region. The oldest and largest of these 3 super eruptions is Huckleberry Ridge, which occurred around 2.1mya. This eruption released around 2,45 cubic kilometers of volcanic material that covered a total area of around 15,500 square kilometers. After Huckleberry Ridge, around 1.3mya, the Mesa Falls super eruption occurred. Mesa Falls is the smallest of the 3 eruptions, which released around 280 cubic kilometers of volcanic material that covered an area of 2,000 square kilometers. The last of these super eruptions is Lava Creek, which occurred around 640,000 years ago and is responsible for creating the present-day Yellowstone caldera.  Lava Creek erupted around 1,000 cubic kilometers of volcanic material which covered an area of around 7,500 square kilometers.

This is a geologic cross section drawn across Paradise valley, with A being located on the Gallatin range and A' being located on the Absoraka range. We can see that on the Gallatin side of this cross section that erosion has exposed a series of volcanic rocks that belong to the Hyalite Peak eruptions (labeled as Tv on the crossection). As we cross the valley, this rock unit is then hidden under two different sedimentary rock units that that range from Miocene Epoch (23mya-2.5mya, labeled as Ts) to the Quaternary Period (2.5mya-present, labeled as QT) in age. But once we reach the Absoraka range, we can see that all of these rock units are displaced, with the older rock units being brought closer to the surface. This displacement was caused by faults uplifting older rock units to the surface.

An important contributor to the geologic history and landscape of the region is the impact of glaciers. The Upper Yellowstone Watershed's was transformed during multiple glacial events, from valley glaciers to the large ice cap that advanced and retreated from Yellowstone National Park in the last glacial maximum. Cooler global temperatures and the topographic effect of the Beartooth and Absaroka mountain ranges funneled weather up the Snake Valley to the West, depositing vast amount of precipitation within Montana and Wyoming's high elevation mountain ranges. Glaciers grew as ice and snow accumulated in these regions, eventually flowing out of the park through key corridors. One of these main corridors was present day Paradise Valley.

The Upper Yellowstone Watershed sub-region has many glacial land forms that can be seen today. Large terminal moraines are responsible for the hummocky terrain near Emigrant, while other areas of the valley have topography have narrow canyons carved into sediment from ice marginal channels where water flowed adjacent to the glacier that had once filled the valley. Below are selected geologic units gathered from a 2003 Preliminary Geologic Map of the Paradise Valley produced by the Montana Bureau of Mines and Geology, that have been selected out and highlight glacial sediments that are present in the valley today.

Study of migratory patterns of the nine major elk populations of the Greater Yellowstone Ecosystem, using GPS tracking data of more than 400 elk provided by a variety of state, federal, and non-profit organizations.

The seasonal distribution of Yellowstone bison is shown here in comparison with the Inter-agency Bison Management Plan management areas.

There is still a lot ot learn about how groundwater is stored in the Upper Yellowstone watershed, and whether there is enough water to support growing development and agricultural practices. An example of the complex interaction between geology and ground water might include the cluster of wells in the Hyalite Peak Volcanics deposits of the Gallatin Range. These deposits are poreous (water will flow through them) and if we look at the geologic cross section above, we can see that below the Hyalite Peak deposits lies a layer of Palezoic and Archean rocks. These much older rock units are not poreous, which creates an impermable layer that causes water to be stored/trapped in the overlying permable layer (which is the Hyalite Volcanics deposits in this case).

Potential Future Studies and Story Maps

• Using satellite data to predict runoff and flow
• Complete Human history of the area
• Water Quality Assessments
• Drainage ditches and beaver mimicry
• Recreational Use
• Irrigation History
• Invasive Weed Management
• Wildlife-Vehicle Collison Hot Zones