The purpose of the Dredged Material Management Plan (DMMP) is to prepare a coordinated long-term plan for managing dredged material from Pool 6.
The Pool 6 DMMP study area is located between Lock and Dam 5A at river mile 728.5 and Lock and Dam 6 at river mile 714.1. The study area borders the city of Winona, Minnesota, at the upstream end and extends downstream of the village of Trempealeau, Wisconsin.
The U.S. Army Corps of Engineers operates and maintains the Upper Mississippi River 9-Foot Channel Navigation Project. Dredge material has many good uses, such as creating habitat and reinforcing existing infrastructure. The Corps also allows the public to access the material at certain sites at no cost. This use is termed “beneficial use.”
Maintenance dredging typically occurs at seven active dredge cuts in Pool 6. The annual average amount of material dredged in Pool 6 since 1981 is 25,000 cubic yards. Although a large capacity (1.3 million cubic yards estimated) will be dredged over 40 years, the amount of continuous “beneficial use” of the dredged material in Pool 6 allowed the Corps to develop a flexible DMMP that requires fewer real estate acquisitions, saving federal dollars.
The Pool 6 DMMP contains alternative plans that emphasize accommodating year-to-year placement rather than providing long-term storage capacity. The Corps selected a target year-to-year capacity of 168,000 cubic yards to provide ample space for the largest quantity of material likely to be dredged in one year.
The DMMP evaluated a list of potentially suitable sites and developed the federal standard or base plan for managing dredged material for a minimum of 20 years. The federal standard is defined as “the dredged material disposal alternative or alternatives identified by the Corps which represent the least costly alternatives consistent with sound engineering practices and meeting the environmental standards established by the [Clean Water Act’s] 404(b)(1) evaluation process…” (33 CFR 335.7).
Public review of the initial draft plan ended on April 10, 2020. The U.S. Army Corps of Engineers, St. Paul District reformulated the plan based on consideration of public comments received during the 2020 public review. A revised draft plan was completed in summer 2022 based on extensive coordination with the city of Winona and Winona County. A second round of public review was completed in July 2022 and comments are being addressed. Completion of the plan is anticipated for early 2023. Upon approval of the plan, potential real estate acquisitions will be phased over time, pending prioritization of parcels and availability of funds.
Congress authorized the Upper Mississippi River 9-Foot Channel Navigation Project via the Rivers and Harbors Acts of 1930 and 1932.
Expended to date $3,058,632.34