SIOUX FALLS, S.D. (KELO) — Ron Duvall isn’t worried about South Dakota’s water supply.
Duvall serves as the state’s water rights permitting administrator and oversees the process, defined by state law, to help people obtain water. He has more than 35 years of experience in monitoring water use in the state and he agrees South Dakota is blessed with plenty of water.
“We want their water to be available for perpetuity,” Duvall told KELOLAND News. “If you manage it right, that’s possible.”
In South Dakota, all surface and groundwater is the property of the people living in the state. Surface water is the water you can see like streams, rivers and lakes, while groundwater is located below the surface and it makes up a majority of the water people use in their everyday life.
Duvall described how South Dakota’s water rights department has an observation well network of roughly 1,600 wells across the state where it actively measures groundwater levels. Some of the data from these observation wells goes back to the 1960s which helps the department look at how drought cycles and wet cycles affect the groundwater aquifers.
Duvall said a drought year like 2021 puts stress on all water resources. He noted the water rights office saw an increase of 121 water rights applications in 2021 and 80% were related to irrigation use. He said the 121 applications was up from 22 applications for irrigation permits in 2020 following a wet year in 2019. He said drought and crop prices impact the amount of irrigation applications the most.
“You do see declines during drought years when more pumping is occurring, whether it’s due to irrigation or municipal or rural water,” Duvall said. “Then you also see in those observation wells, those aquifers recover during more normal years or wet cycles even.”
Duvall credited state laws enacted in the 1970s for protecting aquifers. He said state law requires water rights to be managed by not allowing more water to be taken out of an aquifer than what it can recover on average.
“We’re using that observation well data and we’re using hydrology studies to estimate the amount of recharge,” Duvall said. “We got decades of measurements from our observation well network and it’s just not showing that sort of a decline.”
As of July 14, the state has 5,532 active irrigation permits for about 836,000 acres. Those permits are split between 2,999 that use groundwater and 2,473 that use surface water as a source for irrigation. Sixty are dual permits.
South Dakota’s use of the Ogallala Aquifer
Some of South Dakota’s groundwater comes from the Ogallala Aquifer, which is one of the world’s largest aquifers spanning eight states from S.D. to Texas.
Duvall said the state has issued 173 permits to take water out of the Ogallala Aquifer and 143 are for irrigation and the rest are for municipal or rural water system use.
The state also has 69 observation wells in place to monitor water levels in the Ogallala Aquifer in south-central South Dakota.
“Those, by and large, are stable,” Duvall said. “For the most part, we do not see a decline.”
Unlike South Dakota, other states using the Ogallala Aquifer for water have recorded greater water level declines. In 2016, the Ogallala Water Coordinated Agriculture Project started receiving funding to look at challenges from over-pumping the aquifer.
The Texas Water Development Board says declines of more than 300 feet have occurred in the last 50 to 60 years but the rate of decline has slowed.
Duvall said the declines in the Ogallala Aquifer are largely localized and a lot of it comes from more irrigation happening in warmer southern states. He again credited laws enacted in the 1970s to protect South Dakota from getting in a worse situation.
“A lot of these western states, they’re already behind the curve because they’re using more water than what’s going into their aquifers right now,” Duvall said. “In South Dakota, we haven’t gotten there and the idea is that we don’t get there because we’re using that observation well data and making sure that we’re not ever appropriating more water out than what the estimated average annual recharge is to it.”
Duvall described a hydrograph, data showing the rate of water flow in relation to time at a specific point, that has “stair step down” and it never recharges as the example South Dakota avoids. He said there are only two aquifers the state believes are fully appropriated.
“Based on hydrologic studies, we think we’re to the point where we’re taking out as much water as we dare without getting ourselves into the situation of a declining water table,” Duvall said.
Those two aquifers are the Tulare East James aquifer and the Tulare Western Spink Hitchcock aquifer and those have been fully appropriated since 2015. Both aquifers are located north of Huron.
Unlike aquifers, Duvall said surface water sources will have more shutoffs when the water flow level is low to protect downstream domestic uses and downstream senior water rights.
How to get more water in South Dakota
When someone submits a request for more water in South Dakota it needs to be for a source with unappropriated water amounts.
“You can’t unlawfully impair someone else’s existing water rights,” Duvall said. “It has to be a beneficial use of water and it has to be in the public interest.”
Duvall said when an application comes in, answers depend on what the data from the observation wells say about water levels along with how much water will be coming out.
He said there are two crew technicians that physically go from well site to well site to measure the water levels.
“That’s happening about every third week during the summer during the irrigation season,” Duvall said. “You don’t see as much fluctuation in those wells in the winter. So they really don’t get measured other than from the spring through early fall.”
The water rights observation wells are small and typically look like orange pipes in public right aways. Those wells are strictly for observation and data collection purposes and the water is not pumped or used in any way except to record the aquifers.
“Over the years, you see declines during droughts, you see peaks during wet cycles,” Duvall said. “But if you drew a line through all those points, it’s pretty much horizontal. It’s stable.”
