Lady Bird Lake is a major recreation area for the city of Austin. Its banks are bounded by the Lady Bird Lake Hike and Bike Trail, and businesses offer recreational watercraft services along the lakefront portion of the trails. Austin's largest downtown park, Zilker Park, is adjacent to the lake, and Barton Springs, a major attraction for swimmers, flows into the lake. Much of the landscaped beauty of the parks surrounding Lady Bird Lake can be credited to the former First Lady, Lady Bird Johnson, who, in the 1970s, focused her attention on the Town Lake Beautification Project. The City of Austin prohibits operation of most motorized watercraft on Lady Bird Lake. As a result, the lake serves as a popular recreational area for kayaks, canoes, dragon boats, and rowing shells. Austin's warm climate and the river's calm waters, nearly 6 miles (9.7 km) length and straight courses are especially popular with crew teams and clubs.