Big Sandy Creek Watershed S-23, also known as Lasater South, is a vital flood risk reduction structure located in Matheson, Colorado. Managed by the local government, this earth dam was completed in 1959 by the USDA NRCS and is regulated by the Colorado Division of Water Resources. With a height of 22 feet and a length of 1267 feet, the dam provides protection to the Big Sandy Creek-TR and has a maximum discharge capacity of 1736 cubic feet per second.

Despite its low hazard potential and satisfactory condition assessment, the Big Sandy Creek Watershed S-23 poses a high risk due to its location and purpose. With a normal storage capacity of 158 acre-feet and a drainage area of 3 square miles, the dam plays a crucial role in mitigating potential flooding events in the area. Inspected every 3 years, the dam has a needle outlet gate and a spillway width of 202 feet, ensuring efficient water release during high flow periods.

In the event of an emergency, it is essential for local authorities to have an updated Emergency Action Plan (EAP) in place to guide response efforts. While the risk management measures and inundation maps for the dam are not currently documented, the structure remains a key asset in safeguarding the surrounding community from the impacts of extreme weather events and ensuring the sustainable management of water resources in the region.