Surveys Suggest Jarvis Creek Won’t Overflow and Flood Fort Greely-area Training Facility

Apr 30, 2021

Jarvis Creek originates in uplands south of Fort Greely and runs along the installation's eastern perimeter before turning westward and emptying into the Delta River. When it overflows, its floodwaters often flow into and around Delta Junction.
Credit Tim Ellis/KUAC

Army officials say a military training facility near Fort Greely won’t flood this year with overflow from Jarvis Creek. That’s happened in years past, but experts who’ve been surveying the watershed that drains into the Jarvis say a program to monitor formation of a type of ice called aufeis in the area suggests it won’t cause the creek to overflow its banks this year.

Engineers and other experts with the Army and local Soil and Water Conservation District gathered recently at Fort Greely’s Allen Army Airfield to talk with the pilot and crew of an Army helicopter about a biweekly aerial survey of a watershed that originates in uplands just south of Fort Greely and empties into Jarvis Creek, which runs alongside the installation.

Members of the group that flew along on the April 20 aerial survey file into the terminal at Fort Greely's Allen Army Airfield after a flight from Fort Wainwright.
Credit Tim Ellis/KUAC

“… So we’ll run south, probably just south of where the aufeis starts to form,” says Earl McNabb, a project engineer with the Salcha-Delta Soil and Water Conservation District. He and the others were in the airfield’s terminal were preparing to fly up into the watershed and around the Jarvis Glacier at the top of the canyon in the eastern Alaska Range.

“Let’s go all the way up to the glacier and just do kind of a loop and we can see the watershed all the way down,” says Tom Douglas, a geochemist with the Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory.

Matt Sprau, chief planner for Fort Wainwright’s Environmental Division, said in an interview that the flights are part of a program to monitor the watershed for formation of aufeis, a type of layered ice that forms after successive flows of surface water in subfreezing temperatures.

High up in the watershed, Jarvis Creek's surface water flows under and around multicolored aufeis.
Credit Tim Ellis/KUAC

“It’s an area that essentially creates an ice dam on the river, due to various geological formations in that area,” he said, “and it has a tendency to overflow outside of the stream bank.”

Sprau says the Army and local Soil and Water Conservation District and other agencies have been surveying the watershed for years, especially during the spring, to see if the meltoff-swollen Jarvis Creek has jumped its banks. That’s happened in previous years, and it’s led to flooding in some training areas around Greely, especially the so-called Battle Area Complex. The BAX, like all the ranges around the installation, is operated by Fort Wainwright.

“We relay that information to Army leaders to understand what’s going on downrange, what hazards potentially exist, (and) if the training area is open and can be utilized by the troops,” Sprau said.

McNabb says he believes flooding is unlikely this year, because aufeis in the upper watershed doesn’t appear to be causing any significant overflow.

“We’ve had a lot of warm weather, and we’ve had a lot of wind,” he said. “So the snowpack, instead of all turning into accumulated runoff, a lot of it is just evaporating and leaving.”

Jarvis Creek flows north along the eastern perimeter of Allen Army Airfield, then turns westward and empties into the Delta River. But if aufeis diverts the flow, it can jump its banks and flow northward, toward Delta Junction.
Credit Tim Ellis/KUAC

Jeff Durham, the local Soil and Water Conservation District’s program director, says the aufeis monitoring began a few years after the BAX was built to determine whether the ice is accumulating and likely to cause flooding around the ranges and other areas downslope.

“They are a huge landowner is our community,” he said. “What they do in managing their land has a direct impact on all of us. They care about that.”

Durham says the monitoring program helps Army officials understand more about the watershed. He says it’s provided data that suggest development of the BAX and other facilities has not increased the risk of flooding around the installation, nor in the nearby town of Delta Junction.

“The concern for the city has always been ‘What is the Army doing to either exacerbate or lessen that?’” Durham said.

The monitoring program informs Army officials if aufeis is causing Jarvis Creek to overflows into the Battle Area Complex, or BAX, and the Combined Arms Collective Training Facility, or CACTF.
Credit U.S. Army Alaska

McNabb agrees that the BAX generally doesn’t increase the risk of flooding in Delta. But others, including longtime City Council member Lou Heinbockel, disagree.

“We have tried for years, as a community, to get a handle on that overflow situation,” he said in an interview Thursday.

Heinbockel says Fort Wainwright or the Soil and Water Conservation District should share data from the monitoring program. He says neither agency has told city officials about the program.

“No, not a word,” he said. “To my knowledge, we haven’t got a word.”

In response, a Fort Wainwright spokesperson said later Thursday that Army officials hope to brief the City Council about the program during its meeting on Tuesday.