By Joy Hampton
The Moore American
MOORE — A recently released report will aid the state in planning for Oklahoma’s future water supply.
City wells, which tap into the Garber-Wellington aquifer, are an important component of Moore and Norman’s water portfolios. Moore has about 30 active water wells. One or two wells were destroyed in the tornado and may not be replaced.
If the aquifer is diminished more quickly than it can recharge, that could negatively affect the city’s ability to supply future water demand. But how much well water withdrawal is too much?
In conjunction with the Oklahoma Water Resources Board, the U.S. Geological Survey recently completed a study of the Garber-Wellington to answer that question and to provide data critical to future policy making. For Moore, the report is informative, but not critical.
“We’re slowly over time going away from wells,” said Moore City Manager Stephen Eddy.
When the arsenic standard came in several years ago, Moore and Norman shut down some wells.
“At the same time, we were beginning rapid growth,” Eddy said. “Right now we’re getting about half our water from Oklahoma City and I expect that trend to continue.”
Moore has worked toward being less dependent on the aquifer over time — the city does not have the land to build more wells.
“A few years ago we went through a very detailed study,” Eddy said.
At that time, test wells showed issues with water quality on the east side of Moore. Peak water usage during summer is also an issue.
Norman gets about one-third of its water from wells and has anxiously awaited the information from the aquifer study.
“This is part of the state water plan. Before you know what you can give away, you have to know what you have,” Norman Utilities Director Ken Komiske said. “The news is really pretty good.”
The Central Oklahoma or Garber-Wellington aquifer lies beneath 3,000 square miles of central Oklahoma that includes parts of Canadian, Cleveland, Grady, Lincoln, Logan, McClain and Oklahoma counties.
“Water from the Central Oklahoma aquifer is used for public, industrial, commercial, agricultural and domestic supply,” according to the report, which will go through public and political comments and review before recommendations for the state water plan are formalized.
Still, the data is in and revised withdrawal allowances for current and future wells seem likely. The analyses indicate that the pumping rate of two acre-feet per acre per year is not sustainable for more than 41 years if every landowner with a potential well in each acre in the central Oklahoma aquifer exercised the current temporary right to pump at that rate.
“This would be if we had everything equally spaced out and all pumped at the same rate, but life doesn’t work like that,” Komiske said. “In reality, we’ll have unequal areas of withdrawal.”
The Garber-Wellington aquifer provides a strong component of water needs for approximately 1.2 million people as estimated in the 2010 census. That population is expected to increase by 20 percent from 2000 to 2030, according to the report.
The study was done to determine how that growing population’s draw on the groundwater supply would affect the long-term aquifer storage. To answer that question and provide information that could result in strategic state policy, the USGS investigated the hydrogeology and simulated groundwater flow in the aquifer using a numerical groundwater-flow model.
“A multiple-well aquifer test was completed at a production well near Norman as part of this report to determine transmissivity and a storage coefficient for the central Oklahoma aquifer,” the report states. “Water levels were measured in 280 wells as part of this investigation between Feb. 17, 2009, and March 13, 2009.”
While the Garber-Wellington aquifer is not sustainable at the current level of allowed withdrawal, predictions for the future are better than expected.
Komiske anticipates revised withdrawal allowances will be somewhere between 1.1 and 1.5 acre-feet per acre per year. The model used in the study indicates these amounts could be sustainable for 50 years.
The model isn’t intended to be perfect, Komiske said, but provides a scenario for making predictions. For Norman, things are looking good for future well water supplies.
“Norman has the right to a lot of property because as subdivisions go through the platting process and expect the city to provide water, they give us their water rights,” Komiske said.
Norman will likely be able to bring new wells online as needed in developing areas, provided the funding is available. However, how future Environmental Protection Agency regulations regarding naturally occurring pollutants will affect the well water supply is yet to be determined.
While Moore is moving toward more dependence on Oklahoma City water purchases, Norman continues to look at treatment options — including potential treatment to eliminate or reduce arsenic and chromium 6, should the need arise.
The recently completed study did not “simulate effects from a predictive climate model,” so recharge was held constant “at the average flux for each cell that was specified for the 1987-2009 time period,” as stated in the report.
Climate is a factor, however, and with much of Oklahoma continuing to experience drought, the state plan can’t come into play soon enough.
“Drought is continuing to intensify over Oklahoma,” John Harrington, division director of the Association of Central Oklahoma Governments’ Water Resources Division, reported.
Harrington said this year has been shaping up as central Oklahoma’s second driest winter on record.