Aquifers and Wells
Groundwater discharges from an aquifer near the surface supply an estimated flow between 50 and 100 cubic feet per second (1.4 and 2.8 m3/s) to the middle and upper sloughs. Rain infiltration and artificial sumps recharge this shallow aquifer. Geologists have identified four other major aquifers separated by relatively impermeable clays or other strata at various levels below the surface aquifer. The City of Portland's water bureau manages the Columbia South Shore Well Field that taps the deeper aquifers. As of 2004, 25 active wells drawing from depths ranging from 60 to 600 feet (18 to 180 m) could produce up to 100 million US gallons (380,000 m3) a day from the field. These were drilled between 1976 and 2003 to supplement the city's main water supply from the Bull Run Watershed during droughts or emergencies. The Rockwood Water People's Utility District (PUD) and the City of Fairview have also drilled three wells near the upper slough.
Read more about this topic: Columbia Slough, Hydrology
Famous quotes containing the word wells:
“There are many ways of discarding [books]. You can give them to friends,—or enemies,—or to associations or to poor Southern libraries. But the surest way is to lend them. Then they never come back to bother you.”
—Carolyn Wells (1862?–1942)