Holly Twp 9, located in Murray County, Minnesota, is a privately owned earth dam completed in 2007 for flood risk reduction on Plum Creek. Managed by AREA II MN RIVER BASIN PROJECTS, INC, this dam stands at 40 feet in height with a structural height of 50 feet and a total length of 400 feet. With a storage capacity of 186 acre-feet and a drainage area of 1.6 square miles, Holly Twp 9 plays a crucial role in mitigating potential flooding in the surrounding Walnut Grove area.

Despite its low hazard potential, Holly Twp 9 is subject to regular inspections by the Minnesota Department of Natural Resources, with the last assessment conducted in March 2016 deeming its condition as satisfactory. With a moderate risk assessment level of 3, the dam has not experienced any significant modifications since its completion. While the dam lacks certain features like outlet gates and locks, its uncontrolled spillway type ensures effective water discharge during periods of high flow. Overall, Holly Twp 9 serves as a vital infrastructure piece in the region's water resource management efforts.

As an essential part of the flood risk reduction infrastructure in the St. Paul District, Holly Twp 9 contributes to the overall resilience of the Plum Creek watershed. With its private ownership and state regulation, the dam is a key asset in protecting the local community from potential flooding events. By meeting state permitting, inspection, and enforcement requirements, Holly Twp 9 demonstrates a commitment to maintaining its functionality and ensuring the safety of residents in the surrounding area.