The Dutch Hollow Subwatershed Site M-4 in Danbury, Iowa, is a local government-owned earth dam completed in 1984 by the USDA NRCS. With a height of 33 feet and a length of 500 feet, this dam serves multiple purposes including fire protection, stock, small fish pond, and flood risk reduction. It has a storage capacity of 195 acre-feet and covers a surface area of 7.1 acres, with a drainage area of 0.66 square miles, located along the TR-Koker Creek.

Despite being classified as a low hazard potential, the Dutch Hollow Subwatershed Site M-4 has a moderate risk assessment of 3 due to its age and condition assessment being listed as "Not Rated." While the dam is state regulated, permitted, and inspected by the Iowa DNR, it lacks specific information on emergency action plans and risk management measures. The dam's spillway is uncontrolled, and it does not have outlet gates or associated structures, highlighting the need for further assessment and potentially updating safety protocols to ensure the protection of downstream areas and the environment.