COLEHARBOR – Following a late fall season of very low water, Lake Audubon has returned to its winter operating level.
Unlike its big sister, Lake Sakakawea on the west side of the U.S. Highway 83 embankment, Lake Audubon’s water levels are carefully regulated – 1,847 feet in the summer and 1,845 feet in the winter. By comparison, fluctuations of 10-20 feet a year can be expected on Lake Sakakawea.
However, this year Lake Audubon was an exception. Due to a pressing need for maintenance and repairs at the Snake Creek Pumping Plant, Audubon was lowered close to 1,842 feet this fall. The lower water level allowed workers to make necessary repairs, such as replacement of protective rock rip rap that had eroded away from the sides of discharge tunnels leading from Lake Sakakawea to Lake Audubon.
When work was completed in the early part of November, the Bureau-of-Reclamation-owned plant was fully utilized, pumping water from Lake Sakakawea into Audubon.
“It was 14 days of pumping, a massive amount of water.” Dustin Offerdahl, Snake Creek Pumping Plant manager
“It was 14 days of pumping, a massive amount of water,” said Dustin Offerdahl, Snake Creek Pumping Plant manager. “We used all three pumps 24/7. That had probably not happened since the early 2000s.”
Maintaining Lake Audubon’s water level within a 2-foot variance is because of an outlet into the McClusky Canal on the lake’s east side. A stable water level is necessary to facilitate a natural flow of water into the canal through control gates without a need for pumping.
The assurance of a stable water level is also beneficial to cabin owners on Lake Audubon who do not have to contend with major changes that effect docks and shorelines. It also means boat ramps do not have to extend deep into the lake to compensate for times of low water.
While workers had identified areas in need of repair prior to this fall’s drawdown, and completed those repairs, they also discovered more work may be necessary in the future.
"There was a lot more damage to a discharge wingwall than we thought. It is cracked about five feet further down than we knew. Offerdahl
“There’s some truth to that,” said Offerdahl. “There was a lot more damage to a discharge wingwall than we thought. It is cracked about five feet further down than we knew. We'll send divers in next spring and consult with an engineering firm to see what needs to be done.”
Fortunately, the crack in the wingwall is not believed to be so severe that it requires immediate attention.
“Sometime in the next three to five years,” said Offerdahl, adding that federal funding will likely need to be procured. “It may benefit NAWS. Perhaps share costs on a coffer dam.”
Offerdahl was referring to the Northwest Area Water Supply project which will be connecting a water pipeline to one of the three tunnels at the Snake Creek Pumping Plant. Currently the NAWS pipeline is in the ground near the Totten Trail on the east side of U.S. Highway 83. The Snake Creek plant is nearby but on the opposite side of the highway.
Annual inspections of the Snake Creek Pumping Plant are set to begin in January. According to Offerdahl, that means water inside the three tunnels will have to be removed. Air movers will be utilized to help dry the tunnels.
“Then we’ll actually have guys go in there and do inspections,” explained Offerdahl. “There will be some sandblasting and recoating. We’ll check everything.”