Herwig Pond, located in Grasston, Minnesota, is a privately owned earth dam constructed in 1967 by the USDA NRCS. The dam, standing at 16 feet high and spanning 560 feet in length, serves various purposes, primarily as a water resource management structure for the Spring Brook river. It has a storage capacity of 50 acre-feet, with a normal storage level of 12 acre-feet and a surface area of 7 acres.

This low hazard potential dam has been deemed to be in satisfactory condition as of the last inspection in October 2016. The structure is regulated by the Minnesota Department of Natural Resources - Ecological and Water Resources division, with state permitting, inspection, and enforcement in place. Despite the moderate risk assessment score of 3, the dam has not required any significant risk management measures or emergency action planning as of the most recent data update in May 2021.

Overall, Herwig Pond serves as a vital component of water resource management in Kanabec County, Minnesota, providing flood control and water storage capabilities for the surrounding area. Enthusiasts of water resources and climate will find interest in the dam's design and construction details, as well as its role in maintaining water quality and quantity in the region.