Warm weather and little snow so far this winter has meant ski areas around the Twin Cities have to make the flakes to open — and the third year of summer drought is having an impact on how ski hills and trails turn water into snow.

At the cross-country ski trails in Bloomington's Hyland Lake Park Reserve, low water levels in Hyland Lake and Bush Lake mean the ski area will take the unusual step of drawing groundwater to make snow.

"We're thinking about the long term, but trying to balance that natural resource protection and recreation," said Luke Skinner of the Three Rivers Park District, which runs Hyland Lake and several other ski areas in the metro.

The state Department of Natural Resources has advised against pulling water from Bush and Hyland lakes this winter, Skinner said, because the drought has brought water levels so low. Instead, the department approved using the groundwater-based system that the Hyland Hills downhill ski area uses to make snow for cross-country courses as well.

Skinner said the Nordic ski area at Hyland typically uses 14 million gallons of water to make snow. In recent years, he said the park district has cut water use at the trails to about 9 million gallons per season because of the drought.

That means a thinner snowpack and smaller trails, Skinner said, and a shorter season at many ski areas if the weather is too warm. Hyland Lake has yet to open its cross-country ski trails, which are usually busy by mid-December.

Despite spring-like temperatures last week, the park district made snow for Hyland Hills and the Elm Creek Park Reserve cross-country ski trails in Maple Grove. Both systems are fed by groundwater wells.

Daniel Scott, professor of geography and environmental management at the University of Waterloo in Ontario, said groundwater can be depleted if ski areas use it for snowmaking year after year. He said groundwater takes longer to recharge than surface water.

Using groundwater to make snow is not a sustainable practice, Scott said. "That's not something you want to see happening in the longer term."

Skinner emphasized that the drought — not snowmaking — is responsible for lower water levels in Hyland Lake and Bush Lake, but agreed drawing from the lakes is more renewable in the short term.

Scott has published several papers suggesting Midwestern ski areas will become more and more dependent on artificial snowmaking as the climate changes and winters warm. Higher costs, shorter seasons and more crowding, as skiers compete for lanes and trails on fewer skiable days, could spell trouble for snow sports in the decades to come.

He said the source of power for snow guns is a major factor in how sustainable artificial snowmaking will be — though the makeup of the local power grid is not really in the control of ski area operators.

Scott said he wants states to help local ski areas identify better sources of water to prevent lakes and groundwater from being drawn down too far. For example, he said, some ski areas use manmade reservoirs to capture snow melt in the spring, and use the same water to make snow in the winter.

Though snowmaking is water-intensive, Skinner said, not every year is dry. Before the last three years of drought, he said, there were three years of flooding, and plenty of water in the lakes to make snow. Skinner said he thinks making snow will help keep skiing alive in Minnesota even in the face of warming winters.