Erosion continues to eat away at Talkeetna riverfront

Erosion along the riverbank of the Susitna River, near a popular lookout to see Foraker, Hunter and Denali mountains. (Photo by Jenny Starrs – KTNA)

At the end of Main Street in downtown Talkeetna, the Big Susitna River rushes by after merging with the Talkeetna River. It’s taking large swaths of riverbank along with it, threatening the existence of the Talkeetna River Trail and increasing the flood risk downtown.

“You can see all this power when these two rivers come together. It’s a lot of water,” said Pamela Ness during a tour of the area. She’s a code compliance officer for the Matanuska-Susitna Borough. “So it’s very cold, it’s very fast. There’s a ton of debris that has been eroded away, just sitting, catching everything. It’s a dangerous situation.”

Ness has monitored the river and the floodplain in Talkeetna for nearly a decade. Since 2017, she has seen the river move in more than 100 feet in the area at the end of town, just south of the rock dike at the confluence of the Talkeetna and Susitna Rivers. She says the process has sped up this summer due to large amounts of water coming down the Susitna and wiping out buffers like islands and trees that protect the riverbank. Without those buffers, strong back eddies are scouring off the silty bank and bringing it closer to the revetment at the end of town.

“The Susitna is hitting the Talkeetna head on,” Ness said, “and it’s so much force of the water, it’s actually pushing the Talkeetna back against this bank, and that’s what’s causing the erosion.”

Pamela Ness, code compliance officer for the Matanuska-Susitna Borough, consults aerial imagery to assess the river’s changes since 2011. (Photo by Jenny Starrs – KTNA)

The U.S. Army Corps. of Engineers built the 1,150-foot dike and the 1,650-foot revetment along the shoreline in the 1970s, and then the Borough took over its operation and maintenance. All the underlying land is owned by the Alaska Railroad, which has traditionally given a public use permit to the Borough to access and perform upkeep on the flood prevention structures.

In addition to the Borough, the railroad has three other active permits along that stretch of riverbank: one to Illume for green space for its commercial cabins, and then one to Talkeetna River Guides and one to Mahay’s Jet Boat Adventures to access the water.

“Obviously it’s eroding and it’s going to take all of that away, and it’s going to go to that back-up dike, is what’s going to happen,” said Israel Mahay, owner of Mahay’s Jet Boat Adventures. “You can see it going away. You got a whole river pointed right at the end of town. I’ve been watching this for years. I said this 10 years ago, I saw it happening.”

Mahay grew up in Talkeetna, and has been a riverboat captain on the Chulitna, Talkeetna and Susitna Rivers for 22 years.

“This is a very fast-moving, glacial-fed river. They change all the time” Mahay said. “You could have a river move a long ways. A long ways. And the only reason it hasn’t moved more is because of man, like with the railroad bridge and having the dike down and doing things so it doesn’t go into town.”

Mahay said the common sense solution is to put up a barrier to protect the area from washing out entirely, and to do it quickly.

“Obviously that’s eroding pretty fast, and we need to stop that from eroding, so to me, the common sense would be to put some sort of an erosion barrier down past town,” he said.

Whirling back eddies have caused large chunks of the shoreline near downtown Talkeetna to collapse. (Photo by Jenny Starrs – KTNA)

After a partial closure in late June and early July, the River Trail is back open — for now. Fences are up to protect the revetment from further damage and people from the undercut riverbank as they traipse along the popular Denali viewpoint. 

Ness is documenting the river’s encroachment toward town on a near-daily basis. She’s monitoring one spot especially carefully, where the ground between the nearby slough and the river has receded to only a 16-foot strip.

“We have a situation where it’s very close, so if the river erodes into here and gets into this slough, the new riverbank is going to be at the edge of the revetment over there,” Ness said. “And all of this is going to become river in here.”

The Borough says they will invite the Army Corps. to assess the state of the revetment sometime in the fall or spring, once the water goes down. They’re also looking into hiring an engineer to perform any emergency repairs that are needed. Longterm, the Borough hopes to apply for assistance from the Army Corps. under Section 205 of the Flood Control Act, which provides federal funds for small flood damage reduction projects. But that process often takes years, and also requires the Borough to put forward 35 percent of the funds for design and construction.

“A lot of Talkeetna was built on an old riverbed, so the river’s trying to go back there. And we’re trying to keep it from doing that, and I don’t know.” Ness paused as she looked at the river. “Hopefully it’ll go down, we can get a plan, put that plan into action.”

But she said even formulating the plan will take time. 

“Right now, there’s nothing you can do. We can’t see underneath, we can’t see how far undercut it is, we can’t see how much of the tow or the bottom of the dike has been damaged,” Ness said. “So it’s kind of a waiting game right now.”

In the interim, with so much water already in the river and the fall flood season approaching, Ness is counseling residents to be prepared for a flood event by getting together important documents and medications, anchoring down belongings and heeding Borough notifications and evacuation orders if necessary.

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