Background/Discussion
Lake Manawa is a 785 acre natural oxbow lake that is owned, operated, and maintained by the Iowa DNR and located within Council Bluffs.
Iowa DNR is working to improve the water quality within Lake Manawa. Planned dredging creates additional depth and volume at Lake Manawa, both important to achieving long-term water quality goals. Historic lake dredging work deepened significant portions of the lake, and in 2016 an additional 500,000 cubic yards of material was removed. The resulting maximum lake depth is 22.5 feet; however large expanses of the lake still average between 6 to 7 feet of water.
The City of Council Bluffs owns or sponsors multiple levee segments, which encompass the City Federal Levee System, providing flood protection from the Missouri River, Mosquito Creek, and Indian Creek. In order to meet the criteria for levee certification, seepage improvements are necessary for several reaches of levee. These projects require significant amounts of borrow material and finding suitable material at a reasonable price has been a challenge for the program.
The DNR and City entered into the Cooperative Agreement to remove 500,000 cubic yards of material from Lake Manawa and temporarily stockpile it on state property. The City of Council Bluffs will use the stockpiled material for planned levee projects.
The agreement had a not to exceed amount of $1,500,000 to be paid by the City. This amount was based on a unit rate of $3/CY of sand material.
The dredge operation is now complete and the final stockpiled amount of material is 519,805 cubic yards. This amendment allows the City to acquire the additional 19,805 cubic yards at the same unit rate identified in the original agreement. The new not to exceed amount will increase by $59,415 with this amendment.