Grethe is a privately owned dam located in Walworth, Wisconsin, along the Bloomfield Creek. Built in 1969 by the USDA NRCS, this Earth-type dam stands at a height of 14 feet and has a length of 238 feet. With a maximum storage capacity of 53 acre-feet and a surface area of 50 acres, Grethe primarily serves recreational purposes.

Despite its low hazard potential and fair condition assessment, Grethe poses a very high risk due to its location and potential impact on the surrounding area in the event of a failure. The dam is regulated by the Wisconsin Department of Natural Resources (WIDNR) and undergoes regular inspections, with the last assessment conducted in October 2020. Emergency action plans have been prepared, although they have not been updated recently.

Grethe is a significant structure in the area, providing both recreational opportunities and potential flood control benefits. Enthusiasts interested in water resource management and climate resilience should keep an eye on the risk management measures and updates related to this dam to ensure its continued safety and functionality for the community.