Climate Change Science: Water

Climate change creates ripple effects throughout the environment of Mount Rainier and the Pacific Northwest. Park scientists are studying the effects of climate change in a variety of areas in the park.

A thermal imagery map of the Puyallup Watershed showing how cold (purple colored) waters that start from the north and west sides of Mount Rainier heat up (orange-yellow colors) as the distance from the mountain increases.
A thermal imagery map of the Puyallup Watershed showing how cold (purple colored) waters from Mount Rainier heat up (orange-yellow colors) as the distance from the mountain increases as the rivers enter Puget Sound.

Excerpt from Puyallup Watershed Thermal Imagery Web Map, created by Brian Zierdt, South Puget Sound Salmon Enhancement Group.

Water Temperatures & Fish

Mount Rainier National Park is home to a variety of native and non-native fish. But the fish that makes Mount Rainier special, and that gets most of the attention, is the bull trout (Salvelinus confluentus). Bull trout are a federally listed threatened species that require cold, complex, and connected habitats. There are over 30 miles of designated critical habitat for bull trout within the park. The reason for this is that Mount Rainier is the most heavily glaciated peak in the contiguous United States, and as such provides excellent cold-water habitat for bull trout. However, as glaciers and snow levels rapidly decline in a changing climate, rivers on Mount Rainier may see higher water temperatures.

Studying the impacts of glacial retreat on cold-water habitat will be key to protecting bull trout as climate change progresses. As one part of this research, park scientists are working with several partners to create thermal infrared stream temperature data maps for entire Puyallup Watershed, highlighting Mount Rainier’s cold-water habitat.

Read more about this work in the “Mount Rainier: A Cold Water Refuge” Science Brief.

View watershed temperature webmaps in detail:
Thermal Imagery Web Map Puyallup Watershed
Longitudinal Temperature Point Data Web Map Puyallup Watershed

Webmaps created by Brian Zierdt, South Puget Sound Salmon Enhancement Group.Thermal Infrared Data: Puyallup River and White River, WA Thermal Infrared Survey, Technical Data Report, January 7, 2020 (Survey: July 26 – August 1, 2019). Quantum Spatial Inc.

Numerous tadpoles fill a shallow pond with muddy banks that is drying up.
Tadpoles in a shallow subalpine pond that is drying up.

NPS Photo

Aquatic Habitats & Amphibians

Amphibians depend on water for breeding and aquatic habitats are drying up earlier in the summer. Generally warmer, drier conditions can cause moist microhabitats, such as ephemeral ponds and intermittent flowing streams, to become too dry and unsuitable for native amphibians. Western Toads, a terrestrial species, migrate to breed and lay their eggs in subalpine lakes, which are being affected by climate change. On Mount Rainier, this egg deposition is timed with the spring snowmelt. Many of the breeding ponds and pools of water that toads rely on are drying up earlier in the season, resulting in mass mortalities of eggs, larvae (tadpoles), and metamorphs such as toadlets. A shift to earlier breeding may leave amphibians exposed to fluctuating weather conditions, such as cold storms in spring. Other amphibian species of concern include Van Dyke’s salamander and larch mountain salamander.

Scientists are working to study how climate change might continue to impact amphibian species of concern on Mount Rainier. Non-native fish, which compete with and prey upon native aquatic species are also being removed from park lakes to reduce impacts on amphibians and other species. Visitors are encouraged to learn more about fishing at Mount Rainier and how it can help with reducing non-native fish populations.


Debris Flows & Flooding

As glaciers retreat, they deposit massive amounts of rocky debris into river systems. This debris fills up river channels when the rivers can’t support the amount of sediment flowing in the water, a process known as aggradation. The river water is forced to change direction and create new channels. This is why Mount Rainier’s rivers have wide, rocky, braided riverbeds. Climate change is accelerating glacial recession and thus increasing the sediment available to rivers to transport downstream. This can lead to new river channels in adjacent floodplains that are in the path of buildings and roads. In addition to melting glaciers, climate change is increasing rain and flooding events. Warmer temperatures means that precipitation falls as rain instead of snow. This can result in rapid aggradation and debris flows.

Aerial photo of a rocky glacier terminus with water pouring out of a cavern in the ice.
A new cavern in the Tahoma Glacier created after an outburst flood on August 5, 2019, that generated a debris flow along Tahoma Creek.

NPS Photo

Hotter weather in the summer can also cause melting glacier water to build up quickly, and if it gets trapped in the ice, it could release suddenly in the form of outburst flooding, another cause of debris flows. Glacial outburst floods are the primary cause of glacially-originated debris flows in the park. Mount Rainier scientists are studying glaciers and river systems to better understand these dynamic forces and have developed a debris flow hazard system to determine conditions when debris flows may occur.

Remember, ANY river in the park is at risk of a debris flow. Rising water level, shaking ground and a rumbling noise may signal a debris flow or lahar. If you are near a river and notice a rapid rise in water level, feel a prolonged shaking of the ground, and hear a roaring sound coming from up valley (often described as the sound made by a fast–moving freight train), then move quickly to higher ground! A location 160 feet (50 m) or more above river level should be safe. Learn more about geohazards.

Flooding & Fish
Another side effect of an increase in extreme peak flows and flood events, is that they can scour redds (a spawning location on a riverbed) while fish eggs are incubating, damaging fish populations. Park scientists are conducting annual spawning surveys to track trends over time and location of spawning habitat. The park is also prioritizing the replacement of culverts throughout the park, including the White River Campground culverts as outlined in the Fish Management Plan. Culverts help combat high flows and removal of fish barriers.

A small lake with a small bank of snow on one edge in a dry rocky valley.
Frozen Lake, which supplies the water for Sunrise, with only a small snowbank remaining. Photo taken 8/9/21.

NPS Photo

Water Supply

The loss of perennial snowfields during the past thirty years, combined with the potential for lower annual snowpack and increased air temperatures, is decreasing water supplies. Mount Rainier National Park’s water supply primarily depends on streams and lakes fed by snowmelt and perennial snowfields. For example, the water at Sunrise comes from Frozen Lake, entirely fed by snowmelt. Warming temperatures correspond with shifts from solid to liquid precipitation (more rain, less snow) resulting in earlier snowmelt. This means there is less water later in the summer. Park visitation is increasing, putting more pressure on the limited park water supplies.

Mount Rainier National Park is taking steps to develop a range of water supply options and park management strategies to adapt to climate change, including:

  • Increased water storage capacity.
  • Groundwater investigations to potentially supplement stream and lake water sources.
  • Reducing park water usage.

Please do your part when visiting by conserving water!


Additional Research


Last updated: May 2, 2024

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