NRCS helps Protect Lives and Infrastructure from Erosion in McGrath, Alaska

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MCGRATH, ALASKA---Erosion is an inevitable fact of life on the Kuskokwim River. The river is a force of nature. It ebbs and flows. It bends and straightens. It freezes and thaws. The river changes every year as the continuous cycle of winter to summer creates dynamic movements that transform the landscape.

The Kuskokwim is the second largest drainage in Alaska, stretching 900 miles from the Alaska Range mountains to the Bering Sea.

The people who live along its banks are well accustomed to the Kuskokwim's ways. The river is their life blood. It's their source for fish. It's their highway for transportation and commerce. It allows them to receive critical goods and fuel via barge. It's the source of drinking water for some communities.

But at times the river can also be their nemesis. It can threaten their lives, infrastructure, and property.

Streambank erosion on the Kuskokwim River threatens a home in McGrath, Alaska.

Spring Break-Up: Dynamic vs. Thermal

A dynamic break-up is caused when snowmelt runoff enters the river before the ice has a chance to melt significantly due to warming spring temperatures. This results in immense heaving forces on the ice, causing it to break into large chunks which can cause severe bank erosion when these chunks collide with the shore; or worse when they interlock and cause massive ice jams and associated flooding.

If warming spring temperatures or low snow accumulations allow the river ice to melt in place, that is referred to as a thermal break-up and is generally much less damaging than a dynamic break-up event. Though bank erosion can and does happen during any of the ice-free months on the river from May through October.

In addition to the risk of erosion caused by ice impacts or ice jams, bank erosion can be caused by rapid dewatering of the banks following a flood event; or by erosion of the bank toe due to flowing water velocity and forces; or by wave impacts if strong wind events occur during periods of high water.

McGrath, Alaska.

The City of McGrath, Alaska

The City of McGrath understands the challenges of living on the Kuskokwim. McGrath is a remote community off the road system located about 220 miles as the crow flies from Anchorage. It's only accessible by plane or boat. McGrath has 306 year-round residents. It's a checkpoint on the famous Iditarod Trail sled dog race and serves as an important communication, transportation, and supply hub for Interior Alaska.

McGrath touts having a safe, friendly small-town feeling with modern basic utilities including running water, electric power plant, and a dirt road system spanning 15 miles. Community amenities include a coffee shop, bar, library, public radio station, lodging facilities, churches, store, museum, and a health clinic.

Requesting Assistance

In 2007, Natalie Baumgartner, the city administrator at the time, requested assistance from the USDA Natural Resources Conservation Service (NRCS) to respond to severe erosion. The damage was caused by the coincidence of high winds and high-water-generating waves that severely eroded parts of the bank along McGrath and damaged the levee that provided flood protection to the city.

"The river was creating a lot of erosion; in some areas it had eroded two (residential) lots deep, so it was important for us to seek assistance," Natalie said. "I reached out to our Congressional delegation and was put in contact with NRCS to see if we could utilize their Emergency Watershed Protection (EWP) program. And the result has been beautiful."

Streambank erosion threatening homes and infrastructure in McGrath, Alaska.

Emergency Watershed Protection (EWP) Program

EWP is a recovery program that helps communities relieve imminent threats to life and property caused by floods, fires, windstorms, and other natural disasters.

EWP differs from other government disaster programs because it does not require a disaster declaration by the federal or state government for a community to receive assistance. The NRCS State Conservationist can declare a local watershed emergency and initiate EWP assistance in cooperation with an eligible sponsor.

The City of McGrath as the project sponsor worked with NRCS to install a rock riprap revetment to stabilize the streambank and protect homes and infrastructure.

The work was performed via a competitive federal contract with a private contractor.

Streambank stabilization project completed in McGrath, Alaska.

The rock revetment work was completed in two phases in 2010 and 2014; and protects approximately 2,000 feet of streambank and adjacent buildings and city infrastructure including City Hall.

In subsequent years, the City of McGrath requested more assistance through EWP to respond to additional erosion disasters that occurred elsewhere on the river.

In 2022, NRCS completed construction on a third phase of the project. Phase 3 built a bank key on the upstream end of the project to prevent the river from flanking the existing riprap revetments.

Phase 3 also built four stream barbs downstream of the riprap revetments that provide protection from bank toe erosion to approximately 2,000 additional feet of stream bank.

The stream barbs redirect the flow of water away from the bank to prevent further erosion.

Construction on a stream barb that redirects the flow of water away from the bank to prevent further erosion.

A significant reason the project was feasible in McGrath was that the City has its own rock quarry that is accessible by road, so rock could be trucked to the project site.

"We were losing 10 feet of river bank every year to erosion," said Lucky Egrass, McGrath resident and employee of McGrath Light and Power. "The erosion control project was critical for the City. If it didn't go in, the river would have taken out City Hall."

"It's hard to plan because it's constantly moving," said Mike Tierney, current Mayor of McGrath and resident for 45 years. "The rock riprap and the stream barbs are doing a good job to stop the erosion."

Planning for the Future

Looking forward, NRCS and the City of McGrath are working on a new project that will take a more proactive approach to protect the watershed. The proposed new project will seek funding from the NRCS Watershed and Flood Prevention Operations (WFPO) program. The project will be locally led and residents of McGrath will have opportunities to provide input at public meetings hosted by the City of McGrath as the project sponsor.

"The staff of the City of McGrath have been fantastic to work with and we are grateful for the relationships and partnerships with the City, MTNT (an Alaska Native Corporation), and other local residents that have allowed us to implement EWP projects," said Brett Nelson, NRCS state conservation engineer. "We are excited to work with McGrath and other villages in rural Alaska to help communities plan for the future."