Brownie Wilson had plans to be a wildlife biologist before a genetics class drove him away from the field. Instead he drifted to geography: He liked maps.

Today he’s a mapmaker of sorts, only instead of accounting for the hills and valleys above ground, he and his colleagues at the Kansas Geological Survey are working to map the underground water system called the High Plains Aquifer. It’s is a massive freshwater reservoir that stretches from Nebraska into Texas and on which much of the region depends. Their work is helping to track the levels of the aquifer so that water users can make decisions that will affect generations to come.

On Tuesday night Wilson, a manager in the geohydrology section of the Survey, spoke about projections of water levels in the aquifer in central and western Kansas. Wilson’s talk was part of the Kansas University Natural History Museum’s “Science on Tap” series at Free State Brewery.

Wilson brought with him a slideshow of maps pointing to depletion levels, groundwater paths, water usage and a host of other factors of growing interest to farmers, water managers and state and local governments.

Wilson and researchers from the Kansas Geological Survey regularly fan across the region to gather data from the field. Month after month, year after year, they visit the same wells. With elongated steel measuring tapes they plumb wells to measure their depth.

The Survey uses those measurements to look at water levels over time, projecting into the future. Although those projections get geographically specific, Wilson tells those who worry over the levels in their neck of the state, “Don’t get caught up in the hard numbers.” Rather, he counsels folks to look at regional trends more broadly.

Since 1996 the Survey has recorded a steep decline in the aquifer’s depth, from negative 99.80 feet in 1996 to negative 113.09 in 2013. A map of water use across the state shows that in central and western parts of the state, where groundwater is especially important because of scant rainfall, irrigation is by far the most dominant use of water.

But it wasn’t all doom and gloom. Wilson had other maps showing the impact that 15 percent and 30 percent reductions in water use could have on the aquifer. They might not change the game entirely, but could significantly increase the lifespan of wells in the region. Wilson also pointed to voluntary agreements to reduce use among water rights owners in Kansas as hope that solutions can be found at the local level.