Rex Buchanan can remember digging out old documents from the 1940s and 1950s that suggested the amount of water — particularly in western Kansas for irrigation — was unlimited.

“We pretty quickly perceived that wasn’t true,” said Buchanan, deputy director of the Kansas Geological Survey at Kansas University.

He spoke to about 80 people Wednesday night about water issues in the state, including the depletion of the Ogallala-High Plains Aquifer in western Kansas, as part of the Wild Science lecture series by the KU Natural History Museum.

The colors on the topographical maps Buchanan displayed painted a grim picture of aquifer water levels for some western Kansas counties.

Because of the region’s reliance on agriculture, irrigation accounts for a majority of the water use in the western half of the state. The problem is that some areas are seeing the aquifer’s levels decline 2 to 3 feet per year and being recharged with about only an inch of new water.

“It’s not too hard to figure out that it’s not really a renewable resource if you’re using it that way,” Buchanan said.

Some areas, like Scott and Wichita counties, could be coming dangerously close to depleting their water supply for major irrigation, while other counties to the south could have anywhere from 100 to 250 more years of the estimated usability, according to KGS maps.

The state is already seeing an effect on the agricultural economy and water-usage habits in some areas, Buchanan said.

Some people might think of the crisis resulting in western Kansas residents one day turning on the taps and nothing coming out.

“If cities do proper planning, and if people do proper planning, there’s going to be water out there for a long time for those types of purposes,” Buchanan said. “Large-scale irrigation is really the issue.”

In recent years, Kansas water officials have mentioned more regulation, especially on irrigation practices. Buchanan said it has been and will continue to be a complex issue with “no silver bullet.”

“This is a tough one. It’s a big problem, and it’s a hard one to solve,” he said.

The next discussion in the Wild Science series will be on biodiesel alternative fuel at 7 p.m. Jan. 7 at the museum, featuring Susan M. Williams, associate professor of chemical and petroleum engineering.