US Army Corps of Engineers
St. Paul District Website Website

Big Sandy Lake Dam Rehabilitation Project

Published Oct. 1, 2018
Updated: Sept. 20, 2019

Big Sandy Lake Dam is a significant hazard dam located on the Sandy River in Aitkin County, Minnesota, 1.25 miles upstream of the junction between the Sandy River and Mississippi River. The dam’s original purpose was to provide supplemental flow to the Mississippi River during periods of low river stages for navigation. Construction of the locks and dams downstream of Minneapolis in the 1930s reduced the need for upstream storage for navigation, and since then Sandy Lake Dam’s purpose has shifted to flood control, recreation, fish and wildlife conservation, and water supply. The dam is owned and operated by the U.S. Army Corps of Engineers in accordance with the 2003 Water Control Manual, Mississippi River Headwaters Project and the 2010 Mississippi River Headwaters Reservoir Operating Plan Evaluation Study.


Over its history, Sandy Lake Dam has undergone a series of modifications, repairs and periodic inspections. From 2011 to 2016, a series of above and below water inspections identified several features that had deteriorated to a point that repair or replacement were necessary to maintain the long-term stability of the structure. These deficiencies were highlighted in the Corps’ 2016 inspection report and include:

  • Upstream Timber Apron and Cutoff – poor or unknown condition, needs replacement.
  • Lock Curtain Wall – poor condition, needs replacement or repair.
  • Concrete – areas of poor condition, needs repair.
  • Log Sluice Bay – stop logs in poor condition and difficult to operate, needs replacement.
  • Slide Gates – operable but nearing end of typical service life, need replacement.

A preliminary engineering report (i.e., design analysis report) was completed in fiscal year 2019 for the listed repairs/replacements to summarize the evaluation and development of the recommended rehabilitation plan and present preliminary design and cost estimates for proposed repairs/replacements.


Drafting of plans and specifications for the Big Sandy Lake Dam rehabilitation construction project will be completed under contract by an Architecture and Engineering firm. The design phase of the project is anticipated to be complete in spring of fiscal year 2020. The project will advertise for construction upon receipt of funds, anticipated to be in the fiscal year 2021 budget.


Preliminary engineering report                        $346,000

Plans and specifications                                     $750,000

Construction                                                      $7,500,000
(Requested in FY 2020 budget)