Threatened bats dictate flood levee timeline

CEDAR RAPIDS - Building flood protection won't take the winter off.

Credit the bats - more specifically, the threatened northern long-eared bat.

Tree cutters hired by the city will be taking down trees on 1.4 acres of heavily wooded land and on 2.4 acres with fewer trees to make way for the earthen levee that will be built in 2017 at the former Sinclair meatpacking plant in New Bohemia.

Rob Davis, the city's flood control project manager, said the trees must come down between now and March 31 as directed by federal regulation because the trees are potential habitat for the northern long-eared bat. One of several species of bats in Iowa, the northern long-eared bat has received protection as a threatened species under the federal Endangered Species Act.

It is a protection that the species enjoys in all 99 Iowa counties, though similar protection for the threatened Indiana bat covers only some counties in Iowa and not Linn County.

Davis said the city had two choices to comply with the federal rules: conduct a bat survey of the area where the trees are coming down to show they are not used by the threatened bat species; or cut the trees down during the time bats hibernate away from their spring-to-fall homes. The latter option is the easiest, he said.

Davis said a thick line of trees will remain along the river at the Sinclair site to continue providing wetland and bat habitat. It is the trees and vegetation behind the first line of trees that must go to make way for the levee, which will rise gradually about 17 feet to its top before gradually falling on the other side.

Part of the area where the trees will come down has been the site of a homeless encampment, which police shut down last week in response to complaints.

However, Davis said the tree cutting is because of the bat habitat and levee building and is not related to concerns of the homeless camp.

'We are trying to preserve as many trees as we can for the wetland habitat and the bat habitat and for the natural environment for users along the river,” he said. 'At the same time, we need to take out a certain number to protect the other interest - which is flood protection for the city.”

City arborist Todd Fagan said most of the removed trees likely are of 'pretty low value” in terms of tree species, although he said even low-value trees provide habitat, carbon sequestration and stormwater retention. The area that will remain in trees between the river and the base of the levee may contain higher value trees, Fagan said.

James Pease, emeritus associate professor of natural resource ecology and management at Iowa State University, said cutting trees in the winter should not harm any population of bats.

Pease said Iowa has nine different species of bats, but he said a disease, white-nose syndrome fungus, has killed the northern long-eared bat in sufficient numbers that it is now threatened. The disease has killed some 6 million bats since 2006 in the eastern part of North America, he said.

Pease said the northern long-eared bat is a 'colonial” species of bats rather than a 'solitary” species, which means that females form maternal colonies of up to several dozen females and their pups. Out of hibernation, they spend time in hollow trees or other natural structures. Solitary males and non-breeding females of the species are more apt to spend their time under the loose bark of trees, he said.

Pease said removing trees will prompt bats returning from hibernation next spring to search out other woodlands to have their young.

The timing of tree-cutting of bat habitat is tied to the arrival of cold temperatures, which send bats into hibernation in places where the temperature remains above freezing. That can mean caves in northeast Iowa or even Minnesota, where air inside the cave remains above freezing, Pease said.

He said he gets calls most years from people with bats in their houses. Typically, the bats have hibernated in an attic, and a cold snap wakes them up, sending them into the walls to seek a warmer spot, he said.

Cedar Rapids' Davis said five contractors have submitted bids to take down trees to make way for a levee. The bids range from $63,500 to $97,600, he said.

The winning contractor will be required to remove stumps with the trees, but Davis said it will be left to a subsequent contract for grading to remove roots from the levee site. Any voids, including those created by burrowing animals, can compromise the levee structure, Davis said.

The tree removal at the Sinclair site also will include the removal of 21 parking-lot trees from the city's Lot 44 along the river at about 10 Avenue SE. This will be the site of one of 11 pumping stations in the flood-control system. The stations will pump rain water over the levees and flood walls and back into the river at times when the river is high.

Construction on the Lot 44 pump station will begin in 2016. Once completed, it will provide some help during times of flooding even as the rest to the flood-control system is built out over the next 10 to 20 years, Davis said.

Also in 2016, he said work to move water and sewer lines along the river in Czech Village across from New Bohemia will take place so construction of an earthen levee from 17th Avenue SW downriver to the landfill can take place in 2017 along with the construction of the levee at New Bohemia.

In 2016, too, work will begin to raise the flood wall that protects the Quaker Co. plant so that it - like the entire system - protects against a flood of the size of the historic 2008 flood.

Davis said it would cost about $400 million to build the entire system at today's prices. However, it may cost $600 million in inflated dollars if it takes 20 years to build out the system, he said.