Lake Conroe is a 21,000-acre (85 km2) lake in Montgomery County, Texas, United States. Even though it is named Lake Conroe, only a small portion of the lake is in Conroe, Texas. Most of the lake is in unincorporated Montgomery County. The lake lies on the West Fork of the San Jacinto River, just west of Interstate 45 off of State Highway 105 in Montgomery and Walker counties. The lake runs through classic East Texas Piney Woods forests.