Post Falls South Channel is a gravity dam located in Greenacres Subdivision, Idaho, on the Spokane River. Built in 1906, this hydroelectric dam stands at a height of 25 feet with a hydraulic height of 18 feet and a structural height of 25 feet. It serves multiple purposes including fish and wildlife pond, recreation, and hydroelectric power generation, with a normal storage capacity of 225,000 acre-feet.

With a hazard potential rated as high and a risk assessment indicating a very high risk level, the dam is under the regulatory oversight of the Federal Energy Regulatory Commission. It boasts a spillway width of 127 feet and features six vertical lift outlet gates. The dam's drainage area covers 3,784 square miles and its surface area spans 48,000 acres, making it a significant water resource structure in the region.

Despite its age, Post Falls South Channel remains a vital component of the water infrastructure in Kootenai County, Idaho. With its rich history and ongoing importance for both water management and energy production, this dam exemplifies the intersection of hydrology, engineering, and environmental stewardship in the face of changing climate conditions.