The effects of a slot length limit of 381-533 mm and a daily bag limit of 3 fish on largemouth bass (Micropterus salmoides) catch and harvest, abundance, and size structure in Gibbons Creek Reservoir, Texas, a newly-opened heated impoundment, were monitored for 3 years, 1985-1988. Randomized creel surveys conducted from March through May each year were used to evaluate angler catch and harvest. Spring and fall electrofishing provided abundance and population structure data. Initial overharvest did not occur because 94% of all largemouth bass caught during the first 5 days of angling were protected from harvest by the restrictive limit. Total spring and fall electrofishing CPUE (catch per hour) increased from 1985 to 1988. CPUE increased for most length groups below and within the slot. The proportion of slot-length largemouth bass did not change after angling commenced although CPUE increased. The high slot limit was effective at preventing initial overharvest in a newly-opened impoundment and for maintaining a bass population structure dominated by large (>381 mm) individuals.