Communities may try to aid natural recharge rate into aquifers by using treated sewage, expert says<BR>
Communities in arid areas in northern Arizona may try to protect the groundwater supply by using treated sewage to recharge aquifers, according to a Tucson-based hydogeology consultant.
Effluent, which is wastewater after it is treated in sewage plants, may be used for aiding the natural recharge rate from rainfall, Mark M.
Cross said during a meeting of the Northwest Arizona Watershed Council Wednesday afternoon.
More than 10 people attended the meeting in the Kingman field office of the federal Bureau of Land Management.
Cross, principal with Errol L.
Montgomery & Associates Inc., said communities in the Phoenix and Tucson areas currently use reclaimed water – which has been treated – on golf courses.
During the winter, the reclaimed water recharges the aquifer.
He brought up the suggestion of using effluent for recharge purposes in response to a question from Kelly Winder, who works in his family's landscaping business.
"You can try to enhance natural recharge," Cross said.
"It depends on the rainfall."
He said the Golden Valley area has about 8 inches of rainfall a year, but only about 1 percent of the total reaches the aquifer.
The rest of the water is lost through evaporation or runoff.
The groundwater in the Kingman area gets recharged from sewage treated at the Hilltop wastewater plant operated by the city of Kingman, said Scott Yocum, Kingman's utilities superintendent.
The Hilltop plant northeast of the city treats about 1.6 million gallons of sewage a day and the downtown plant south of town handles about 300,000 gallons per day.
The city is expanding the infiltration basins at the Hilltop plant, and those basins enable the effluent to recharge into the aquifer, Yocum said.
Yocum told Cross that effluent discharged into aquifers must meet state and federal drinking water standards.
The city's groundwater is at least 500 feet below the surface.
Yocum said he does not know what the recharge rate is in Kingman.
The recharge rate in the Sacramento Valley aquifer in the Golden Valley area is 3,500 acre-feet of water a year, according to the Mohave County Planning and Zoning Department.
While most rainfall is lost through evaporation, the recharge rates from streams in southern Arizona ranges from 60 percent to 90 percent, Cross told the gathering.
He suggested increasing the recharge rate by capturing rainfall in arroyos with check dams.
He said the Colorado River would not be suitable for recharge purposes in the Kingman area because of its distance and the costs of transporting the water.
Storing water for recharge purposes in "water banks" is cheap, but building the wells to retrieve that water can be costly, he said.
Cross, who has worked in the field for 10 years, said communities should not worry about the loss of their water through aquifer recharges.
"Water levels rise in all directions," he said.
"You are increasing the amount of water stored in the recharge facility.
The guy downstream gets the effluent."