State Rep. Scott Odenbach, R-Spearfish, speaks in the South Dakota House chamber on Feb. 7, 2024. (Photo by Makenzie Huber/South Dakota Searchlight)

South Dakota lawmakers on Monday defeated a bill that would have tightened limits on groundwater pumping by eliminating an exception for some deep aquifers.

The vote in the House of Representatives was 16-49.

The bill, sponsored by Rep. Scott Odenbach, R-Spearfish, would require that annual withdrawals from any groundwater source could not exceed the source’s estimated recharge rate. It would do so by striking language in state law that allows an exception when pumping from lower than the Greenhorn formation, a layer of limestone found across the state. 

Odenbach told fellow representatives he brought the bill after increased population growth in western South Dakota raised local concerns about whether the state is adequately tracking drawdowns from Black Hills area aquifers.

Opponents, however, said the bill risked creating practical and financial problems for public water providers that rely on those aquifers, where recharge is difficult to estimate with precision. They cited uncertainty with the science, warning that eliminating the exception could force additional study and expensive monitoring wells. That could cause delays for growing communities. 

Rep. Kent Roe, R-Hayti, said “the Greenhorn exception does not allow over-appropriation. It simply recognizes the legitimate scientific uncertainties in estimating recharge rates for these deep, complex, bedrock aquifers.”

“The exception uses the word ‘may approve,’ not ‘shall,’ meaning it’s never automatic,” he said.

The bill had advanced out of the House Agriculture and Natural Resources Committee on a 9-4 vote last week.