County presents Arrowhead Cove dredging pilot: 11,000 cubic yards removed, lessons learned
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Summary
County staff and contractors reported results from a pilot dredging project at Arrowhead Cove on Deep Creek Lake: mechanical dry excavation removed about 11,000 cubic yards of sediment at a cost covered by the state, restored boating access and required significant staging, cofferdam work and upland restoration.
County staff on Feb. 3 presented a final report on the pilot dredging project at Arrowhead Cove on Deep Creek Lake, summarizing methods, outcomes and lessons learned from a project funded by the state.
Bruce Michaels of county staff described the project as a state-funded pilot to test whether mechanical dry dredging is an effective method to remove accumulated sediment from one of the lake’s sediment-impacted coves. Project activity began with staging-area preparation in October 2023; dewatering and cofferdam installation were performed in the fall/winter, excavation started Dec. 1, 2023, and work continued through January 2024.
Key findings and details:
- Volume removed: Staff reported removal of more than 11,000 cubic yards of sediment; the initial target had been about 15,000 cubic yards but funding limited the amount removed.
- Method: Mechanical excavation in the dry, after installing cofferdams and diverting Arrowhead Run through large-diameter hoses, followed by trucking excavated sediment to a staging field to dewater. County staff said the material was classified as clean and used as landfill cover, avoiding disposal costs.
- Cost and funding: The county said the project cost approximately $2.5 million and was entirely funded by the state for the pilot project.
- Benefits: The project improved boating and swimming access in the cove even during drought-level lake conditions; installed submerged aquatic vegetation (SAV) and in-water rock structures to support fish habitat.
- Constraints and lessons: Mechanical dry dredging was effective but expensive and weather-dependent; winter work created high cost and logistical complexity. Hydraulic dredging (work in open water) is cheaper and could allow work in summer but would affect recreational use during the season and may require different permits. The county released a lessons-learned report (posted on the county website) and described ongoing monitoring of habitat effects.
Ending: County staff said the project demonstrated dredging can remove accumulated sediment but that cost, timing and permitting are significant factors for future work; funding sources and public impacts will determine whether additional coves are targeted for dredging.
