Archive for Wednesday, August 14, 2002

Tonganoxie Sandstone aquifer feeds water supply

August 14, 2002

In recent week's The Mirror has received numerous calls from citizens asking why, if there is a ban on outdoor watering, citizens who have private wells are continuing to water.

They are asking: Doesn't that water come from the same source as the city's well?

The answer, according to the experts, is: yes and no.

Yes, it is comes from the same aquifer as the city's water, and no, unless the domestic well is extremely close to the city's well, it probably won't have an effect on the city's well.

According to Tonganoxie's water plant supervisor, Kent Heskett, the city's well, which is off Fourth Street toward the east edge of Tonganoxie, is fed by an aquifer known as the "Tonganoxie Sandstone."

The aquifer, part of a 300-million-year-old river system, cuts an underground southwest-moving swath through eastern Kansas from south of Lansing to the Oklahoma border, and is recharged by rainwater.

Recent years' below-normal rainfall, coupled with Tonganoxie's growth, has resulted in a situation where more water is coming out of the well than is going in.

Allen Macfarlane, assistant scientist at the Kansas Geological Survey at the University of Kansas, said that's not a good sign.

"Depending on how much you're pulling out on an annual basis, or even on a seasonal basis, it may take several years for it to be replenished," Macfarlane said.

"If you've had several dry years in a row, one good wet year is not going to do it," he added.

Even under the best of circumstances, wells in the Tonganoxie Sandstone are anything but high-volume producers.

"Most of the domestic wells I've seen in the Tonganoxie yield anywhere from five to 10 gallons a minute," Macfarlane said. "City wells aren't much better, typically."

In contrast, Macfarlane said, agricultural wells in central or western Kansas can draw as much as, or more than, 1,000 gallons a minute.

Rex Buchanan, who also works for KGS, described the Tonganoxie Sandstone aquifer as "water saturated sandstone."

"Don't think of the Tonganoxie Aquifer as one big swimming pool that you could empty all of a sudden," Buchanan said. "You might pump heavily in one location and drop the water level substantially there, but that doesn't mean you're going to drain all the water out of it a few miles away."

It's possible domestic wells near the city's well could draw down the city's well level, Buchanan said. He said he'd guessed these wells would have to be within about a quarter-mile of the city's well to have an effect.

The availability of water will play a critical role in the area's future development. Water from rivers is as important as water from wells, Macfarlane said. Many Kansas rivers originate in the high plains. And, many of these rivers dry up during certain times of the year, he said.

"If you pay attention to how things have changed, historically, you can see that more and more sections of rivers in the western and central part of the state stay dry longer each year," Macfarlane said. "That means there's less and less water to come down those streams into eastern Kansas. There's a lot of storage in the reservoirs, but even those storages rely on the inflow."

Macfarlane said that's an important thought when it comes to planning on reliance on surface water.

"So what does the future hold?" he asked. "I'm not really sure, but it's certainly not going to one where we will find more water that's for sure."

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