MSB declares disaster emergency for Talkeetna flooding, erosion

During a special session of the Matanuska Susitna Borough Assembly Tuesday afternoon, a resolution was put forward extending a local disaster emergency that had been made earlier in the day. The motion would extend that declaration to October 31 for the Talkeetna flooding.

Heavy rains in Talkeetna added to the already high volume where the three rivers— the Susitna, Chulitna, and Talkeetna Rivers—converge, causing damage to a rock revetment installed to protect the riverbank, creating a threat to homes and businesses in the area.

Earlier in the day, a local disaster declaration was declared by the MSB Borough Mayor, Edna DeVries, and MSB Manager Mike Brown, who told the assembly that there has been flooding, high waters, and erosion occurring over the past week, necessitating the need for the disaster declaration.

“It buys us 7 days. The resolution before you would extend that through October 31, and give us the authorities we need to go in and render some temporary repairs,” Brown said. He is aware that there may be some longer-term repairs, but those will take time to develop.

Tom Adams, the Public Works Director for the MSB told Assembly members that following a significant precipitant event at the end of August and into the early part of September, a number of roadways overtopped with flooding, but the situation in Talkeetna is especially concerning.

“At the beginning of the holiday weekend, Talkeetna experienced an overtopping of the dike and revetment that caused localized flooding in Talkeetna, with some depths of water requiring response from the Borough Department of Emergency Services to monitor the events there,” Adams said.

As the waters receded at the end of the Labor Day weekend, roadways were no longer overtop, allowing the civil engineers to go on site and assess the dikes and revetments—the fortifying rock and masonry protecting the riverbanks— in the affected areas, and they noted that specifically, a revetment at the end of Main Street had lost approximately 150 feet of stone facing itself.

On Wednesday, Adams said his department started to implement their emergency response plan, and that after speaking with the Talkeetna Fire Chief, who had reported that the city had also lost between 60 and 85 feet of land, in addition to the revetment, and that nearby cabins were now in jeopardy.

Adams and a representative from the US Army Corps of Engineers made a site visit and measured out a loss of 300 feet of revetment, and that land had started to erode into the Talkeetna and Susitna Rivers.

“This is not a unique event for Talkeetna,” he said, noting that the revetment has undergone several repairs over the past decade, with the most recent repair in 2020. “Dealing with a loss of over 300 feet of revetment is new. Typically, it’s a much smaller magnitude, and we have not lost as much land in a short amount of time as we have these past few days.”

Adams said that they have engaged a contractor to procure 900 tons of riprap in reaction to the revetment, erosion, and flooding, but it’s not quite enough. He said that estimating final figures is difficult at this point, but rough estimates point to 2,000 tons of loose stone used to form a foundation for a breakwater or other structure, known as riprap material.

“The water, while receding, is still flowing quite heavily and we are unable right now to obtain a depth of the river, which is a pretty significant variable with respect to the volume of riprap we need to place in the water.”

The emergency declaration will give the Public Works Department more time to obtain more materials, stage more materials on-site, and rebuild the revetment.

“Our reaction right now is more about protecting the riverbank from further erosion. We have highly silty-sand material out there and it’s very erosive, even under low-flow conditions. The concern is that as this riverbank continues to erode, we are susceptible to losing more of our revetment as it moves downstream, not only jeopardizing the cabins that are there now, that are within 20 to 30 feet of the riverbank, but there are facilities downstream that could be exposed to if further eroding occurs.”

Adams said he is predicting to do the work within the next two to three weeks, and once more material is procured, they are looking to physically place rock at the end of September and into the beginning of October, as long as the river continues to recede.

The measure passed unanimously.