04 November 2009

Imperiled Species to Benefit From Sandbar Habitat Creation on Missouri River

The latest project by the U.S. Army Corps of Engineers to create an expanse of sandbar habitat for imperiled terns and plovers will get underway next spring on the Missouri River near the Niobrara River confluence.

The created sandbar will be 37 acres in size, and situated at Missouri River mile 842, across from the "Old Townsite boat ramp," near Niobrara, Nebraska, according to Corps officials.

This site was selected because of its former use by Least Terns and Piping Plovers, and since it has areas of natural sand accumulation, according to Kelly Crane, a biologist and manager of the Emergent Sandbar Habitat Program of the Corps. "There are already large, submerged sandbars at this location. When sandbars persist in an area for several years, vegetation encroaches to the extent where the birds will no longer use them. Birds can no longer easily see approaching predators and no longer feel safe and will abandon the sites. The Corps capitalizes on these existing, vegetated sandbars by performing vegetation removal and habitat enhancement."

"The 842 site and staging area as it looks today. 842.09 is looking from slightly upstream looking downstream from the NE side towards the SD side." Images courtesy of the Army Corps of Engineers.

A picture of the road to the staging area parking lot (the Niobrara Townsite Boatramp).

Tern and plovers have not used this sandbar for a couple years, Crane said.

"On September 25, 2009, a construction contract was awarded to Western Contracting Corporation of Sioux City, Iowa to construct a 37 acre sandbar," Crane said. "Dead vegetation will be cut and removed to the extent possible and the sandbar will be overtopped with approximately 1-2 feet of sand, as the contractor will dredge shallowly submerged sand and pump it on top of the sandbar. The sand will be reshaped to designated elevations so it will be at varying elevations suitable for nest sites of the plovers and terns.

"The contractor will begin work as soon as ice conditions leave Lewis and Clark Lake and can work until April 15th. April 15th is approximately the date when the terns and plovers will start making their way back to the area for the 2010 nesting season. The contractor will then suspend work until mid- to late-August 2010 when these birds will leave the area. The contractor must have all the work completed by December 2010."

"The contractor will use the Niobrara Townsite boat ramp area to stage and launch equipment," Crane said. "There will be a number of trucks that will transport the dredge, the dredge pipes, the dozers, scrapers, and other earth moving equipment. Barges will carry the equipment out to the sandbar complex."

The elevation of the sandbar will be high enough to "enable normal operation of the upstream system of dams, especially Fort Randall Dam near Pickstown, S.D.," according to a Corps press release.

A team of government officials decided where this new sandbar habitat would be established.

"The Emergent Sandbar Habitat (ESH) Program works with a multi-agency team from the U.S. Fish and Wildlife Service, the National Park Service (in reaches of the Missouri National Recreational River), state wildlife agencies and the Natural Resources Conservation Service when choosing sites for ESH construction," Crane said. "Members on the team from the Corps are engineers, biologists, project managers, construction representatives, real estate, and regulatory. The ESH multi-agency team usually meets in early spring prior to the birds' arrival in April to take a look at maps of the river reaches and Lewis and Clark Lake and to talk about past years' bird usage of each potential sandbar creation area.

"The team looks for areas in the river where the sand naturally accumulates. Sometimes these areas are partially emerged and sometimes these areas are completely submerged. From aerial photograph imagery we can see these naturally accumulating areas, even if they are shallowly submerged. The ESH program capitalizes on these accumulation areas. There are other selection criteria that have been identified over the years by various agency and public scoping comments used when choosing our sites. For example, we try to stay away from areas of high recreational usage, like popular picnicking sandbars. Once the birds utilize a sandbar, the Corps will restrict its use by the public during the time when plovers and terns are present. Examples of other selection criteria are, avoidance of the thalweg (main channel in the river), and avoiding sandbars that are attached to land to avoid any potential for mammalian predation.

"The team discusses potential localities and develops a prioritized list of sites for consideration. One of the goals of sandbar creation activities is to spread the habitat along the entire river section where these species breed, in order to avoid drawing a bunch of birds into one particular area that could be disastrously impacted by one hail storm, for example."

In 2009, summer thunder-storms had a deleterious impact on nesting activities of the plovers and terns, when hail destroyed nests and also caused bird mortality along a portion of the Missouri National Recreation River.

"There are currently two multi-agency teams that identify sandbar habitat for the ESH Program; one in North Dakota and one for Nebraska and South Dakota," Crane said in an email message. "The four reaches identified in the 2003 Amended Biological Opinion (BiOp) with habitat creation goals are 1). Below Gavins Point Dam, 2). Below Garrison Dam, 3). Below Fort Randall Dam, and 4). Lewis and Clark Lake.

"The entire process from site selection, design, National Environmental Policy Act (preparation of the Environmental Assessment), processing the Section 404 regulatory permit, selection of a staging area, to when construction actually begins is about 18 months," Crane said. "Construction contracts are awarded in the fall of the year so the contractor are poised to begin construction as soon as the birds leave the area in late August/early September. Construction cannot take place during the bird nesting season because there is a chance that if construction begins, the birds will choose the new sandbar as a nesting site and construction would have to be halted. The contractor works from approximately September until winter conditions prevent any further construction. Most projects can be finished within this time period, however, the contractor is allowed to complete the project in the spring if there is an early onset of wintry conditions in the fall."

The Army Corps of Engineers must provide habitat for the tern and plover under the amended Biological Opinion regarding the operation of the main stem dams on the Missouri River, which was issued by the U.S. Fish and Wildlife Service in 2003, according to a press release issued by the Corps for the Niobrara sandbar project. "Prior to the construction of the dams, bare sandbars were more abundant than they are today. Operation of the dams has altered the flows so that little new habitat is formed and the existing habitat is prone to erosion and vegetation encroachment."

Aerial Survey of Habitat

A recent aerial survey of riverine sandbars used by plovers and terns was done on September 16th 2009 by Corps officials to document the conditions of the habitat during this more normal flow regime.

The Corps has created several sandbar areas in recent years, and the survey was an opportunity to evaluate the conditions of these sites.

"These aerial surveys provide valuable information on any erosion that may be taking place on the sandbar and to assure the sandbars are performing as designed with areas of shallow water within the sandbars to provide additional plover forage opportunities," Crane said.

"The constructed sandbars are performing as designed and no areas of unanticipated erosion is taking place."

The Least Terns and Piping Plovers "have shown an immediate, favorable response to these habitat creation activities," she noted. "Both species utilize the newly created sandbars the first year they are available and continue to use the habitat until the vegetation becomes too thick for their tolerances. It is the Corps' responsibility to assure sufficient, barren sandbar habitat is available to the birds each year in all reaches. We are still behind the habitat creation curve and need to continue to create and maintain sandbars each year so we can assure compliance with the U. S. Fish and Wildlife Services Biological Opinion and to eventually recover populations of both birds on the Missouri River.

"The Niobrara sandbar project will continue the efforts of the Corps to improve and provide places for the plovers and terns to nest and successfully rear young which is essential for maintaining viable the Great Plains populations of these birds.

Pictures of riverine habitat created by the Corps of Engineers along the Missouri River.
Images and caption details courtesy of the Corps of Engineers.

River mile 761.3 is a 50 acre sandbar the ESH program built in the river below Gavins Point Dam in 2005.

RM 826 is a 200 acre complex built from 2006-2008 in Lewis and Clark Lake just downstream from the sediment deposition zone.

RM 791.5 is a 40 acre sandbar built in 2007. The picture is from the South Dakota side looking towards Nebraska.

RM 775 is a 44 acre sandbar built in fall of 2008 in the river below Gavins Point Dam, immediately downstream of the Vermillion Bridge.

RM 777.7 is a picture of the 15 acre backwater constructed in South Dakota in conjunction with the 76 acre sandbar.

RM 777.7_30 is a 76 acre sandbar complex built in the Missouri River immediately upstream of the Vermillion Bridge.

RM 795 is a 76 acre sandbar built in autumn of 2008.

RM 774 is a 49 acre sandbar built in spring of 2009 in the river below Gavins Point Dam, immediately downstream of the Vermillion Bridge.

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