"... Many springs flow from a six-mile stretch of the Columbia Slope between Marine Park in Vancouver and the Fisher's Landing area near Camas. Most of the springs flow from gravel deposits in the hillsides above the Columbia River.
Ellsworth Springs, west of the Interstate 205 bridge, was a source of drinking water for the city for many years. In 1973, the city stopped using the springs because of elevated nitrate concentrations, most likely from septic tanks in large areas of east Vancouver. From the late 1800s to 1973, Ellsworth Springs supplied as much as four million gallons per day of the city of Vancouver's drinking water.
In 1949, the U.S. Geological Survey found that Columbia Slope springs discharged approximately 35 cubic feet of water per second. Salmon and Lacamas creeks flow at about this rate during the summer. In a 1988 update, the Geological Survey found that Ellsworth and a few other springs near I-205 flowed at rates similar to those measured in 1949. The other springs had a 40 percent decrease in flow. The large springs that supplied cold, clear water to Vancouver Trout Hatchery had decreased to 5 and 20 percent, which forced the hatchery to drill wells in the late 1980s. ... "
Clark County "Water Resources & Clean Water Program" website, 2007.