As Glaciers Melt, Mt. Shasta Could See More Mudslides

Mt. Shasta, at 14,179 feet, the second highest peak in the Cascades mountains and the fifth highest in California. (©Joe)
Mt. Shasta, at 14,179 feet, the second highest peak in the Cascades mountains and the fifth highest in California. (©Joe)

A giant mudslide sent mud and debris hurtling down the southeastern flank of California’s Mt. Shasta in late September. Experts believe glacial melting, hastened by a three-year California drought, loosened giant ice blocks at the small Konwakiton Glacier midway up the peak, dislodging earth and rocks dammed up under the ice.

U.S. Forest Service climbing ranger Jonathan Dove of the Shasta-Trinity National Forest was on a ridge above the mudslide when it happened. “It sounded like a freight train barreling down the canyon,” he told the Los Angeles Times.

Mt. Shasta’s September mudslide was the worst the area had seen in 20 years, according to U.S. Forest Service Hydrologist Steve Bachmann, who spoke with Bachman warned that another chunk of glacier could easily dislocate, shunting a new torrent of mud and boulders down the mountain.

Scientists attribute the accelerated melting on the Mt. Shasta glacier, in part, to a lack of insulating snow pack. And that’s bad news. Due to climate change, snowpack is expected to decline 25 percent to 40 percent statewide by 2050. Mt. Shasta, which is a dormant volcano in the Cascades mountain range, has the most glaciers of any mountain in California.

No one was hurt, and no homes were damaged from flooding, but the mudslide buried two roads in the tiny town of McCloud, in northern California’s Siskiyou County, under mud, large boulders and fallen trees. Authorities were forced to close the roads to traffic, and one of them will not likely be reopened until next year. The mudflows, which came down the appropriately named Mud Creek, also cascaded into McCloud River, popular with fishermen, and fed into Shasta Lake, which is only a quarter full due to drought.

McCloud River in summer. (©Carlos Wolters)
McCloud River in summer. (©Carlos Wolters)

Forest Service officials told the Sacramento Bee that the drought, combined with hot summer temperatures, may have created a small lake atop or within the glacier, causing a chunk of it to collapse, which then released the dammed up water in a small outburst flood. These glacial outburst floods have a name in Iceland: “jökulhlaup.” (Read more about them on glacierhub, here.)

Mt. Shasta’s Mud Creek has seen its share of mudslides in the past 100 years. The biggest occurred in 1924, when mud and debris spread over an area 8 miles by a half a mile, blocking the railroad tracks and severing water lines to the town of McCloud for two days. The mudslide made the front page of the local Redding Courier-Free Press six times in the weeks following the incident.

McCloud railroad. (©Drew Jacksich)
McCloud railroad. (©Drew Jacksich)

Glacier stories you may have missed this week – 10/6

California droughts and glacier melts lead to massive Mt. Shasta mudslide

“Experts believe glacial melting, accelerated by the drought, may have released “pockets of water” that destabilized massive ice blocks and causing the debris flow Saturday afternoon in Shasta-Trinity National Forest, officials said.”

Read more about Mt. Shasta mudslide in the Los Angles Times.


The culprit of glacier melting – pollution

“When Kaser’s team looked at ice cores previously drilled at two sites high in the western Alps – the Colle Gnifetti glacier saddle 4,455 m up on Monte Rosa near the Swiss–Italian border, and the Fiescherhorn glacier at 3,900 m in the Bernese Alps – they found that in around 1860 layers of glacial ice started to contain large amounts of soot.”

Read more about how pollution melts glaciers instead of rising temperatures in Climate Central news.


Cooling of the Earth increases erosion rates

“Every year, billions of tons of rock and soil vanish from Earth’s surface, scoured from mountains and plains and swept away by wind, rain, and other elements. The chief driver of this dramatic resurfacing is climate, according to a new study. And when the global temperature falls, erosion kicks into overdrive.”

Read more about cold climate shrinks mountains in Advancing Science, Serving Society (AAAS) news.

Glaciers are muddying rivers, with drought to blame
Rivers off of California’s Mount Shasta are increasingly becoming brown. (Eric Leslie/Flickr)

Water flowing off snow-capped mountains has the image of being absolutely pure, but the rivers and streams of California’s Mount Shasta are unusually brown, and geologists are pointing at drought as the cause.

News surrounding the drought in California inundates the media, but we often hear about dying crops and brown lawns. This time it’s the tourism and fishing industries that are up in arms.

Paradoxically, the heavy river flows are caused by the same climatic variations that have created drought throughout the state. A dry winter left California’s glaciers exposed to the sun, without their usual protective cover of snow. Hot weather in the summer is rapidly melting them, particularly on Mount Shasta, home to the state’s largest glaciers. The mountain’s porous volcanic soils can absorb some meltwater, but their capacity has been overwhelmed this summer, and the meltwater is causing debris flows, muddying rivers and streams. More commonly known as mudslides, debris flows are flows of water, rock, soil and other organic material that course downslope, becoming destructive torrents when they enter streambeds. They can muddy the waters of rivers that are usually pristine.
Saying California’s drought is spreading quickly is a small understatement. (Climate Central)

This year, the rapid melt of the mountain’s south-facing Konwakiton Glacier has left the McCloud River opaque with volcanic ash. These highly turbid rivers are not novel phenomena. In the past century, severe debris flows like the current one have been witnessed seven times, particularly in the 1924, 1926 and 1930, other dry years for the region, when debris flows blocked roads and railroads, rendering them impassible for days. During this period in the 1920s, the McCloud River was unfishable. The murky waters do not harm the fish, but simply make them nearly impossible to catch.
Fly fishing in California’s McCloud River is one of the many activities to be affected by brown rivers caused by drought. (California Department of Fish and Wildlife)

Fly fishermen, fly fishing tour guides, and local businesses that relying on tourism fear that the current drought, and the associated glacial melt, debris flows and cloudy waters, will be detrimental to the local economy during the fishing season this fall and in the future years. Some fly fishing groups have already cancelled tours that they had booked—another sign of the cascading effects of glacial melt around the world.

For another story on the effects of glacial melt on fisheries, click here.