Background

Years of sediment deposition in the lower 2.5 miles of the Oconto River resulted in shallow water depths and limited public use of this tributary to Lake Michigan. Adequate water depth is vital to both recreational uses and the launching of large pleasure craft by one of the city of Oconto’s largest employers, Cruisers Yachts.

Approach

Foth completed a hydrographic survey and dredge prism design for the 2.5-mile stretch of river to determine dredge volumes for permitting and sediment staging. An evaluation was necessary to determine if hydraulic or mechanical dredging would be more feasible. Truck traffic hauling sediment through the city was not desirable, and small areas of hard sediments were present that were not conducive to hydraulic dredging. Foth coordinated efforts with the U.S. Army Corps of Engineers, Wisconsin Department of Natural Resources and the U.S. Fish and Wildlife Service to manage the dredging time frame and fisheries concerns, specifically salmon spawning. Finally, we prepared dredging designs and specifications, secured permits and provided construction oversight.

Results

Foth’s work enabled the successful dredging of 90,000 cubic yards of sediment, found beneficial use for the dredged material and cleared a navigable waterway for yachts exceeding 50 feet. We assisted the city in obtaining Harbor Assistance Program grants to help defray the cost of dredging this vital resource. The project was permitted to allow, and bid out to implement, mechanical or hydraulic dredging which resulted in competitive pricing and the flexibility to remove hard sediments by mechanical dredging means.  Hydraulic dredging implementation resulted in almost no truck traffic, thereby eliminating wear and tear on city streets. We used cost-effective sand segregation technology to obtain dredging materials suitable for beneficial use on local highway construction projects, eliminating the need for sediment disposal. The restored river, completed with the city’s limited financial resources, now provides greatly improved navigation for sport fishermen, pleasure craft and local industry.