J-Ditch Effluent Lagoon, located in Lake Fork, Idaho, is a crucial water management structure owned by the local government. This lagoon is regulated by the Idaho Department of Water Resources and plays a significant role in managing effluent from the surrounding area. Completed in 2001, the lagoon has a dam height of 41.5 feet and a storage capacity of 645 acre-feet, serving a drainage area of 0.1 square miles.

The J-Ditch Effluent Lagoon is designed as an earth dam with a core made of stone and foundations supported by rock and soil. With a surface area of 21.5 acres, this lagoon is inspected biennially due to its high hazard potential and fair condition assessment. Despite the absence of a spillway, the lagoon is equipped with valve outlet gates for water release. Furthermore, the risk assessment for this structure indicates a high level of risk, emphasizing the importance of regular maintenance and emergency preparedness to ensure its continued functionality in managing water resources in the area.