Dredges operating around the clock are pumping 10,000 cubic yards of sand per day onto Missouri River sandbars in preparation for summer nesting of the piping plover and least tern.
The endangered least tern and the threatened piping plover -- both roughly the size of a robin -- prefer vegetation-free sandbars for their nests. While both birds nest elsewhere, the U.S. Fish and Wildlife Service designated areas along the Missouri River as critical habitat for the piping plover.
The sand and pebble mixture offers camouflage, the shoreline and river provide a food source, and the sandbars offer protection from ground predators for both species, said Kelly Crane, manager of the Army Corps of Engineers' sandbar restoration project.
"We've permanently altered the river system, and if we can mimic more of the natural system, that's good," she said.
The corps' goal by 2015, in conjunction with recommendations from the Fish and Wildlife Service, is to provide about 11,900 acres of habitat on the Missouri River by building up existing sandbars, clearing them of vegetation and using flow levels when possible to create new habitat.
The Missouri River between Yankton and Sioux City, Iowa, bears the closest resemblance to the river's natural state before reservoirs were built and before management policies dictated downstream flow. The natural rise and fall of the river would create sandbars or scour existing sandbars of vegetation, providing nesting habitat for the birds.
It was that kind of river -- strong current, sandbars and dozens of tree snags -- that Galen Jons navigated Tuesday as he steered a boat upstream of the Vermillion-Newcastle, Neb., bridge and about 200 yards into a reinvigorated backwater area near a state game production area.
It was here that a dredge scoured the bottom starting last fall and pumped a slurry mixture nearly a mile away to a sandbar at mile No. 777 on the river.
"It's a win-win when you can restore an original habitat for fish and wildlife and create a sandbar at the same time," said Jons, a Yankton-based resource biologist for the corps.
Part of this 74-acre sandbar developed naturally in 1997 when exceptionally high releases from upstream Gavins Point Dam deposited sand here. Flows have never been as high since then, so part of the sandbar remains, but it's covered with vegetation and is less attractive to the least tern and piping plover. Areas of the sandbar without vegetation are frequently under water during the nesting period.
The corps will raise the level on part of the sandbar and just began the same process about a mile downriver at a 44-acre sandbar.
Here a second dredge is at work in the main river, lowering the cutterhead up to 4 feet into the riverbed and pumping the mixture to a nearby sandbar where bulldozers spread it out.
The dredges never dig deeper than the existing channel, part of an effort to "make as small a footprint as we can," Jons said.
The corps expects to add about 720,000 cubic yards of sand to the two spots this year at a cost of $5.6 million.
Human activity on the sandbars is restricted from mid-April, when the birds arrive, to mid-August, when they head south for winter.
The corps' Emergent Sandbar Habitat program entails four projects below Gavins Point Dam this year totaling about 200 acres at a cost of $10.2 million.