Pleasant Valley No. 12, also known as Lucas Detention, is a private earth dam located in Winona, Minnesota. Constructed in 1968 by the USDA NRCS, this dam serves as a crucial flood risk reduction structure along the Pleasant Valley CR-TR. With a height of 30 feet and a length of 440 feet, Pleasant Valley No. 12 has a storage capacity of 30 acre-feet and a drainage area of 0.41 square miles.

Managed by the Minnesota Department of Natural Resources, this dam is regulated, permitted, inspected, and enforced by state authorities to ensure its structural integrity and functionality. The dam's hazard potential is considered significant, with a fair condition assessment as of April 2015. The last inspection date was in May 2019, with inspections conducted every four years to monitor its performance and safety. Despite its moderate risk level, Pleasant Valley No. 12 continues to play a vital role in protecting the surrounding area from potential flooding events.

Water resource and climate enthusiasts will appreciate the strategic location and design of Pleasant Valley No. 12, which showcases effective flood risk reduction measures in a high-risk area. With its uncontrolled spillway and buttress core type, this dam exemplifies efficient engineering practices to manage water flow and prevent potential disasters. As a significant structure in the St. Paul District, Pleasant Valley No. 12 stands as a testament to the collaboration between private owners, state agencies, and federal designers in safeguarding communities and ecosystems against the impacts of extreme weather events.