The largemouth bass (Micropterus salmoides) population in South Mill Creek Lake, a centrarchid-dominated, eutrophic small impoundment in West Virginia, was managed under a 305-mm minimum-length limit until 2007. Under this regulation the population was typified by consistently low proportional size distribution (PSD) values, low quality-length CPUE, excessive juvenile recruitment, and poor length structure. Therefore, in 2007 a protected slot limit (PSL) regulation (305–406 mm) was implemented to shift the size structure of the fishery. Spring (May) boat electrofishing surveys were conducted pre- and post-regulation (2003–2022) to evaluate fishery response under both regulatory regimes. The largemouth bass population of a similar system, Kimsey Run Lake, was sampled using the same methods over the same time periods. Relative abundance of quality-length fish, PSD, length structure, and growth rate increased for largemouth bass at South Mill Creek Lake under the PSL, while during this period Kimsey Run Lake population characteristics stayed relatively stable under a catch-and-release regulation. Annual mortality rate estimates at South Mill Creek Lake declined from 44.3% to 32.9%, although the change was not statistically significant. Creel surveys during the PSL period indicated angler approval and willingness to harvest sub-quality fish. Our results suggest that angler compliance with the new regulation has enhanced the quality of the South Mill Creek Lake population. Largemouth bass at Kimsey Run Lake continued to experience low growth rates and low annual mortality throughout the study. The protected slot limit regulation was considered successful and could be applied to other West Virginia small impoundment fisheries where large-mouth bass populations exhibit poor length structure.