Once connected to the Gulf of California, waters within the Salton Basin extended nearly to Palm Springs. Deposits from the silt laden Colorado River sealed off the north end of the gulf in what is now Imperial County and formed Lake Cahuilla, which was considerably larger than the present day Salton Sea. Its ancient shoreline can still be seen on the hills west of the sea. After many thousands of years, Lake Cahuilla's waters receded, leaving a dry lakebed. The Salton Sea formed between 1905 and 1907, when the Colorado River was tapped near Yuma, Arizona, to allow irrigation waters to flow into the Imperial Valley, but storms and high waters washed through the canals and the river flowed almost unchecked into the Salton Basin. After much labor, mostly paid for by the Southern Pacific Railroad, the breech was closed in 1907. Water level within the sea is now maintained by agricultural runoff, inflow from the New, the Alamo and the Whitewater Rivers, and by rainfall. The sea is about 35 miles long by 15 miles wide, has a maximum depth of 50 feet, salinity slightly greater than the Pacific Ocean, and a surface averaging 230 feet below sea level. The Salton Sea Recreation Area was dedicated April 12, 1955.