Mat-Su officials want renewed review of Matanuska River dredging

What you need to know:

• Mat-Su Borough officials want the state to revisit whether dredging the Matanuska River could reduce flooding and erosion in the region. 
• Past studies show dredging would be costly and uncertain, with high upfront and ongoing maintenance costs and no guarantee of long-term effectiveness, borough officials said.
• Officials said selling gravel from dredging could offset costs, but inconsistent material quality and permitting challenges could make profitability unlikely.

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PALMER — Mat-Su Borough officials will ask state resource managers to once again review whether dredging the Matanuska River could help reduce local flooding and provide a source of funding through the sale of gravel pulled from the riverbed.

Matanuska-Susitna Borough Assembly members requested the review during a joint Mat-Su Planning Commission and Assembly meeting March 10. They said they are looking for ways to protect the riverbanks before erosion becomes an emergency.

“I’m wondering if this does get somewhere — even if the borough or state loses a little bit of money annually — but actually in the long run saves some money without having to do reactive work,” said Assembly member Michael Bowles, whose district includes erosion areas in Butte and Sutton.

State officials did not reply to a request for comment about such a plan.

Officials with the Alaska Department of Natural Resources, which oversees the river and mining operations, did not attend the session and were unable to call in due to a technical issue, borough officials said after the meeting.

The Matanuska River most recently flooded its banks near Butte last year, fully destroying a long-compromised revetment, flowing over a series of private properties and coming within feet of the Old Glenn Highway. State crews installed an emergency fix over about a quarter-mile section to protect a series of electric poles and the roadway.

An ongoing Alaska Department of Transportation study is set to examine how to protect the banks along the highway from further erosion in Butte and north past Sutton. State and borough officials said they have no authority to protect or alter banks along private property in the area. A federal property buyout program was available for certain properties through 2018, but not all owners accepted the offer.

Whether dredging is a viable way to control the Matanuska River has been a point of discussion since at least the 1950s, Borough Planning Director Alex Strawn said during the meeting.

A series of federal, state and local studies — at least seven since 1991 — show that while solutions for river control could include digging trenches and pits under the water to redirect flow, with annual maintenance to keep them from refilling with debris, there is no way to tell whether it would provide a long-term fix. The river’s movements are unpredictable, and the costs likely outweigh the benefits, according to the documents.

The most recent study, conducted in 2004, found the initial dredging operation would cost at least $20 million, while maintaining it would run about $2.9 million per year, according to the document.

Reselling gravel pulled from the river could help cover that cost, but relying on that option depends heavily on whether there is demand for it, officials said at the meeting, and the cost to transport it. 

The quality and type of gravel pulled from the river is typically inconsistent, officials with Anchorage Sand and Gravel said during the meeting, limiting its value. 

Any company that wants to extract it would also need about a dozen federal, state and local permits before starting operations, Strawn said.

A series of private operators have used river gravel for nearby projects over the last several decades, Strawn said, but he is unaware of any major extraction operation in Mat-Su that has successfully turned a long-term profit on such a project.

Assembly members Stephanie Nowers, BillGamble and Bowles spoke in support of asking the state to renew their review of whether to dredge the river. 

Assembly member Dee McKee and Maxwell Sumner spoke against the request. 

“There’s just three things that gravel needs to be: easy to get, it needs to be high quality, and needs to be close to where you need to use it,” Sumner said during the meeting. “And I don't really think this gravel source is any of those three.”

-- Contact Amy Bushatz at contact@matsusentinel.com