SIOUX FALLS, S.D. (KELO) — Nearly a million acres are covered by irrigation permits in South Dakota. It’s not unusual to see an irrigation system dropping water in a crop field in eastern South Dakota.

A South Dakota law and the South Dakota Department of Agriculture and Natural Resources help make sure that farmers aren’t wasting water or using too much, even in dry years.

State law 46-6-3.1 states that water withdrawn from a groundwater source cannot exceed the average estimated annual recharge of water to the groundwater source.

“We’re never gonna be taking out more than what the average annual recharge is,” said Ron Duvall, the water rights permitting administrator for the state DANR. “Now granted there will be years of drought where more water comes out than comes in but on average, we are not going to exceed the average.”

Duvall said the state law protects water sources to ensure that water is always available in the future.

“That (law) saves us from a lot of problems western states are having, where they’re taking more water out. I mean the horses are out of the barn, and now you are just trying to manage the decline,” he said.

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.

“Nowadays, most applications that we get in, the great majority are groundwater sources,” Duvall said. Older permits may have surface water as a source.

Surface water would be a river such as the James River. Groundwater is an aquifer below the ground.

Most of the permit holders are east of the Missouri River, he said.

Duvall said 836,000 acres may sound like a lot but when compared to some southern and states to the west, it’s not a large amount. Nebraska has about 9.8 million acres in 2020, according to the Nebraska Department of Environment and Energy.

Irrigated land in states such as Kansas and Texas is also in the millions.

Tom Pierce, the irrigation sales manager for Farmers Implement and Irrigation in Brookings, has worked with irrigation systems for almost 38 years.

The DANR will also inspect the irrigation system after a person receives a permit, Pierce said. The permit holder has five years to install a system, he said.

The holder of the irrigation permit must state the intended average annual use and source of water.

Duvall said the permit holder submits a record of water use each year to the DANR.

Monitoring systems help to determine if irrigation use is excessive, Duvall said.

The state has 1,600 wells across the state that are monitored. Those wells help to indicate the water supply in aquifers. They can also indicate any overuse of water by permit holders in specific aquifer management regions.

Equipment used to monitor flows in streams and rivers. DANR photo.

The DANR also monitors stream levels at specific sites in the state.

In general, permit holders do not want to waste water, Duvall said. But the DANR will investigate a report of water puddling in a field or pouring from a field, he said.

When is a permit needed?

A farmer will need to apply for an irrigation permit if he wants to irrigate more than one acre of land, Duvall said.

The application is reviewed on four criteria: the water source needs to be capable of supplying the system, the irrigation cannot impede on someone else’s water rights, the water must have a beneficial use, the water must be used in the public interest.

The DANR can approve the permit if the application is not contested. Duvall said contested applications are infrequent. A neighbor, for example, may contest an application. A contested application will go to the state water management board for review.

An approved active permit allows the holder to irrigate land, most of it cropland, even when it’s very dry or there are drought conditions. In short, that is the main purpose of irrigation, to ensure that crops are adequately watered during dry conditions.

“Obviously, precipitation drives (irrigation),” Duvall said.

The approved active permits are tied to the land. So if the land changes owners, the new owner has the permit, Duvall said.

And once a land owner gets a permit, they don’t want to lose it or give it up, Duvall said. It could take years to get approved

What’s the flow of water with irrigation?

Permit holders are technology savvy and can determine the moisture level in soils across their cropland, Duvall said.

Improvements in irrigation systems have made irrigation systems more efficient, according to the U.S. Department of Agriculture (USDA).

“One of the biggest changes is the efficiency of sprinklers…,” Pierce said. High-pressure systems were the norm years ago but the shift has been toward lower pressure “that use a lot less horsepower,” he said.

“Water efficiency is a really big deal,” Pierce said. The improved systems discharge water closer to the ground and the plant

“There is not as much evaporation and the wind doesn’t (affect) it,” Pierce said.

Another big change is software that allows farmers to operate a system with their cell phone or computer, he said.

A farmer can change the flow, the timing and other factors remotely.

“You could start it from Hawaii if you wanted to,” Pierce said.

Working to help conserve the Ogallala Aquifer, Kansas State University’s mobile drip system is retrofitted to existing center pivot irrigation systems, monitored and managed by mobile phone. Irrigating wheat in western Kansas with mobile drip saves 30-60% compared to conventional sprinkler irrigation. Photo by K-State Research and Extension/USDA.

The water dispersed in irrigation is measured in acre feet per acre.

Improvements along with some crop changes contributed to the average irrigation application rate from 1969 to 2017, the USDA said The rate declined from more than two acre feet per acre irrigated to just under 1 1/2 acre feet per acre irrigated.

South Dakota allows for up to 24 inches or two acre feet per acre.

 “The average use is eight or nine inches in East River,” Duvall said.

Most producers use a low-pressured irrigation system where the water is applied close to the ground at low pressure, Duvall said.

What’s the future water supply?

“The number of acres has been slowly increasing bit by bit. But there was a big jump in 2013,” Duvall said of the numbers since he started with the state in 1983.

The DANR had about five times the average number of applicants in 2013 after the severe drought in 2012, he said.

There were about 710,000 acres covered by irrigation permits in 2012.

So far, the DANR has closed permitted applications for the Beadle and Spink aquifer areas because the water levels are not adequate for additional permits, Duvall said. Those aquifers are considered fully appropriately, he said.

Those with active permits can continue irrigating in Beadle and Spink counties but the state hasn’t granted new permits, Duval said.

But, overall the water levels in aquifers are more than adequate, Duvall said.

“We’re fortunate for a couple of reasons, one is the statute (on not using more than recharge), to stop us from getting into trouble in the first place and secondly our population in this state is far less concentrated than some of the western states that do have problems. Do I see a looming issues on the horizon? I really don’t.”

The two aquifers for Spink or Beadle are fully appropriated and the Big Sioux aquifer is close but that includes a reserve store of water for future use, Duvall said.

Observation wells show stable or even rising water levels, Duvall said.

South Dakota’s water sources may be more sustainable than others.

The Ogallala Aquifer is one of the world’s largest fresh groundwater resources. It covers 175,000 square miles in eight states.

The USDA said in 2021 that part of the Ogallala aquifer could be exhausted of water within the century at the current rate of use.

By 2010, 30% of the aquifer’s water had been tapped, according to Kansas State University.

Multiple studies also state that farmers and others are working to reduce their water use and demand of the Ogallala Aquifer. The University of Nebraska said even more than 10 years ago that more farmers were switching to low-pressure irrigation to reduce water use.