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5. Environmental Documents

Title:	Upper Mississippi River System Environmental Management Program Definite Project Report/Environmental Assessment (SP-18) : Rice Lake Habitat Rehabilitation and Enhancement Project, Minnesota Valley National Wildlife Refuge, Scott County, Minnesota
Authors:	United States. Army. Corps of Engineers. St. Paul District.
Keywords:	Restoration ecology Environmental protection Environmental management Wetlands Minnesota River (S.D. and Minn.)
Publisher:	United States. Army. Corps of Engineers. St. Paul District.
Abstract:	Rice Lake is a shallow floodplain lake located on the right bank of the Minnesota River approximately 16.7 miles above the confluence of the Minnesota and Mississippi Rivers. Rice Lake lies within the Minnesota Valley National Wildlife Refuge. The lake covers about 170 acres, and ranges is depth from 18 inches to 3 feet during most growing seasons. Rice Lake provides habitat for migratory waterfowl, other migratory birds, and aquatic furbearers. Rice Lake can experience highly variable water levels from year to year, much of which is the result of high water events on the Minnesota River. During years of high water, the water in Rice Lake is too deep for the growth aquatic vegetation, especially emergent vegetation. During years of low water, emergent vegetation chokes the lake, reducing habitat value for waterfowl and other wildlife. It is estimated that currently, optimal water level conditions for aquatic vegetation occur about 3 out of 10 years. There is no capability at this time for the Refuge to manage water levels in Rice Lake to improve this situation. The Refuge has recently purchased a 40-acre agricultural field adjacent to Rice Lake. The opportunity exists to plant trees in this field in manner that will accelerate its reforestation and promote reforestation with a species mix similar to the native floodplain forest in this region. A short distance below Rice Lake is a 70-acre emergent marsh that is a perched wetland, maintained by a natural river levee. Erosion from interior drainage has created a breach in the natural levee, which if left unchecked, would result in drainage and a reduction is size of this wetland. The Refuge has constructed a temporary berm on the inside of the natural levee to stop the drainage of this wetland. The plan formulation process considered a number of alternatives for the habitat problems and opportunities in the Rice Lake area. For Rice Lake itself, the alternatives focused on providing the capability for the Refuge to manage water levels in Rice Lake to promote optimal growth of aquatic vegetation, especially emergents. Alternatives were identified and evaluated that would allow the Refuge to both draw down Rice Lake and to impound water in Rice Lake. For the agricultural field a number of planting options were considered ranging from species composition to measures that would enhance survival and growth of the trees, such as pretreating planting sites and the use of tree tubes, mats, and mulch. For the breaching of the natural levee two alternatives were identified. The first was to stabilize the river bank and the natural levee through the use of riprap, while the second was to reconstruct the temporary berm constructed by the Refuge to make it a more permanent solution. The alternatives that achieved habitat objectives in the most cost effective manner were selected for the recommended plan. The recommended plan for Rice-Lake is the excavation of a 2,530 feet long channel in and adjacent to the lake which would provide the Refuge the capability to draw down Rice Lake for habitat management purposes. At the outlet of the channel, a stop log control structure would provide the Refuge with the capability to raise Rice Lake water levels for habitat management purposes. It is estimated that with this water management capability, the Refuge will be able to optimize aquatic vegetation growth for migratory waterfowl and other wildlife approximately 3 out of 4 years, versus the estimated 3 out of 10 years that occurs now under unregulated conditions. The recommended plan for the agricultural field is to plant 2-year old seedlings of floodplain forest tree species. The species mixture would be an approximation that which occurs in the natural floodplain forest in this area. Some measures would be used on a limited basis to enhance survival and growth of the trees. These include mechanical and chemical pre-treatment of planting sites, and the use of tree tubes, mats, and mulch for a limited number of trees. The recommended plan for the natural levee is to reconstruct the temporary berm previously constructed by the Refuge to make it more permanent. An overflow spillway would be provided in the berm to prevent overtopping of the berm by interior drainage trees.
Description:	Definite Project Report with Integrated Environmental Assessment
Rights:	Approved for Public Release; Distribution is Unlimited
URI:	https://hdl.handle.net/11681/36880
Size:	204 pages / 5.79 MB
Types of Materials:	PDF/A
Appears in Collections:	Environmental Documents