Working on bat time: Cottage Grove Ravine Regional Park work timeline driven by threatened species concern
The possible presence of a threatened species means that a small part of the Cottage Grove Ravine Regional Park capital improvement project must take place on bat time.
Starting next month, crews from S & A Land Clearing will begin cutting down select trees in the county park. Washington County commissioners approved a contract for the work Feb. 7.
The trees must be removed before new road and trail construction — part of a major renovation that will close the park for a year — can commence.
But the company must complete the work by March 31 in order to minimize the impact on a certain furry-winged creature that may have taken refuge in the park: the northern long-eared bat.
Ravine Park is a potential habitat for the bat, which is on the threatened species list due to the decimation of its population by a deadly disease called white nose syndrome. Under federal conservation rules administered by the U.S. Fish and Wildlife Service, tree cutting must take place at a specific time to avoid disturbing or killing young bat pups that may be roosting in the branches.
"The pup rearing season for these bats is June," said Grant Wyffels, project manager for Washington County. "They're considered to be in hibernation prior to this time. Their roosting period is outside of that March window.
"Basically all of Washington County is considered a zone of potential impact," Wyffels added. "This is a new rule. We want to do the right thing and we're following the rules of the permit."
Wayne Sandberg, deputy public works director and county engineer, said the March 31 deadline doesn't affect any other portions of the project.
"You don't have to have every single thing done by that date," he said. "You just can't cut anymore trees by that date. This is the first step in making some significant design improvements."
Those improvements include new trails and parking lot and a new entrance that will be built as part of a separate road improvement project by the county. The new road will allow motorists to access the park from County Road 19 and Keats Avenue. It would replace the current entrance on East Point Douglas Road south of Keats Avenue.
Once the tree cutting is complete, the South Washington County Watershed District will begin work on stabilizing the ravine that runs the length of the park to improve drainage and prevent erosion from flash floods.
Trees will be removed over an area that includes 7.4 acres near the park road, 5.8 acres near the ravine stabilization area and 2.6 acres in the ski trail area.
Some remaining "high quality" trees will be encircled with protective fencing to reduce the stress caused by construction, Washington County natural resources coordinator Dan MacSwain said.
"Those are large diameter oak trees," he said. "Twenty-inch-plus trees. A lot has gone into designing this system to reduce the impact within the park. Because of the tree survey data they were able to design around those nice high-quality trees."
The $119,641 cost of the tree removal and protection project will be split between the county and the watershed district, which will contribute $73,138 and $39,700, respectively. The county approved a cooperative agreement with the watershed district Feb. 7.