Aquifers in the United States – Part 2

Christensen Well & Irrigation Inc. drills a 380-foot irrigation well in May 2014 into the Ogallala Aquifer northwest of Ainsworth, Nebraska. The well was designed to pump 900 gallons per minute for center pivot irrigation.

Part two of three: The Ogallala Aquifer

By Mike Price

Meeting today’s food production demand in the 21st century in the United States will depend on groundwater.

U.S. agriculture uses 49.5 billion gallons of groundwater per day, on average, for irrigation—65% of the nation’s daily total of 76 billion gallons. Sustaining the nation’s groundwater resources to meet agricultural needs requires wise use, pumping efficiency, locally adapted management, resource monitoring, and managed recharge of groundwater storage to assure future supplies.

A joint commitment to begin an educational campaign for the agricultural irrigation community was announced on World Water Day, March 22, by the Irrigation Association and the National Ground Water Association at the White House Water Summit. The goal is to help the nation’s 121,000 farms enhance water efficiency and reduce energy consumption of their 476,000 irrigation wells.

About 170,000 irrigation wells extract groundwater from the Ogallala Aquifer, which extends across eight states from South Dakota to Texas, in one of the most productive agricultural regions in the world—serving not only the United States but large parts of the world’s food production.

In part two of Water Well Journal’s three-part series examining major aquifers in the United States, we shift our focus to the Ogallala Aquifer.

The Ogallala is the leading geologic formation in the High Plains Aquifer System, which underlies 174,000 square miles.

Though there exists several other minor geologic formations in the High Plains Aquifer System, such as the Tertiary Brule and Arikaree and the Dakota formations of the Cretaceous, these units are often referred to as the Ogallala Aquifer.

The Ogallala supplies water for 20% of the corn, wheat, sorghum, and cattle produced in the United States.

The Ogallala can hold more than enough water to fill Lake Huron and part of Lake Ontario. Ninety percent of the water pumped out is used to irrigate crops.

The Ogallala is a very complex aquifer system composed primarily of unconsolidated clay, silt, sand, and gravel. The Ogallala varies, offering a mix of confined and unconfined aquifers, with virtually all recharge coming from rainwater and snowmelt. The High Plains has a semiarid climate, so recharge is minimal.

Generally, the Ogallala is found 50 to 300 feet below the land surface, and the saturated thickness varies greatly as well. The average thickness is about 200 feet, but it exceeds 1000 feet in west-central Nebraska. Both the saturated thickness and areal extent of the Ogallala is greater in Nebraska and account for two-thirds of the volume of Ogallala groundwater, followed by Texas and Kansas, each with about 10%.

Drilling Challenges

Cody Christensen and his staff have a unique viewpoint of drilling in the Ogallala.

Located in northeast Nebraska in Hartington, Christensen Well & Irrigation Inc. typically drills on the eastern fringe of the Ogallala. When the company heads west to drill in the heart of the Ogallala, it is usually subcontract work for Cody’s childhood friend, Tonny Beck, owner of Beck’s Well & Irrigation Inc. in Ainsworth, Nebraska. Beck is located in northcentral Nebraska.

The Ogallala geology typically consists of 1 to 2 feet of topsoil and then sand, Cody says, forcing him to set a surface culvert to keep the hole from caving in underneath the drill rig. Outside of this safety precaution, the Ogallala pales in comparison to drilling in his area of northeast Nebraska which bears glacial till, blue clay, and rock before reaching sand and gravel.

“I don’t think I’ve ever hit a rock out in the Ogallala formation,” says Cody, who has drilled in the formation since the early 1990s and manages the company with his three younger brothers.

“We basically put our drill bit on, drill a hole, and never see it until the hole is done.”

Christensen Well & Irrigation has one reverse drill rig for irrigation wells and two straight rotary rigs for test holes for irrigation and domestic or stock wells for pastures. The standard depth for an irrigation well in the Ogallala is between 300 and 350 feet. For an average center-pivot 133-acre circle, the average gallons per minute is 800-900 in the Ogallala compared to 600-700 gpm in northeastern Nebraska due to its heavier soils.

Typically, Christensen Well & Irrigation uses a three-man crew when drilling in the Ogallala, and they average a dozen to 15 jobs a year for Beck’s Well & Irrigation. Cody has reduced manpower needed by streamlining the drilling process.

To construct a well in the Ogallala, 50,000 to 100,000 gallons of water is needed. In the past, Cody pumped water from another well which required four men to lay pipe and pick it up at the end of the job. Today, they use a hose reel they purchased in 2012 to transport water to the well they’re developing, which now takes only one man to lay out the hose.

The rig setup was also updated in 2012. Originally built on a trailer, the rig is now on a tandem axle truck with hydraulic outriggers on it. Where it used to take at least three men an hour to set up the rig now takes one man about 10 minutes.

Timing is a factor when developing a well. Beck is pretty adamant once Cody drills a well and gravel packs it—no matter what time of the day it is, a test pump is installed.

“We feel it’s very important to pump the drilling fluid out of those holes immediately after drilling,” Cody says. “We’ve just had great results doing that. You might not think it’d be a great big deal to wait four or five hours until the next morning, but we feel it’s in our best interest and the customer’s best interest to do it that way.”

Drilling in the Ogallala over the years has taught Cody to use a finer slotted well screen along with a high-quality gravel pack around the well casing. He found placing the gravel down the borehole using a hopper assembly lets the gravel flow even and consistent, resulting in a high success rate of pumping pure water with no sand or formation.

“A lot of the wells that are made out there the sand can be fine,” Cody says, “and if you don’t use the right screen or the right gravel pack, you can end up with wells that pump sand and they’ll do it their whole lives.”

Water Quality

The Kansas Geological Survey says the quality of Ogallala water is particularly high because the sands and gravels of the formation have a low solubility and act as a filter to help purify the water.

The Ogallala Aquifer. Image courtesy Kansas Geological Survey.

The No. 1 contaminant issue Cody and Beck are concerned with and treat is nitrates, a contaminant the sands and gravels do not help clean up.

In north-central Nebraska and east of it, dryland farming (meaning without irrigation) dates back 80 to 90 years. The first 70 of those years farmers didn’t pay attention to how they applied fertilizer, Beck says. Because of the soil types, leaching occurred and now nitrate issues exist in the shallow aquifers. Fortunately for most of Beck’s area there are combining zones and better water quality in lower aquifers.

But it’s not uncommon for Beck to need to drill into the deep sand for quality water. He recalls drilling a 310-foot residential well recently where at 70 feet the gravel formation had 25 parts per million nitrate.

High nitrates are affecting the housing market in parts of Beck’s area. Home sellers are unable to receive a loan from the U.S. Department of Agriculture Rural Development due to high nitrate levels; conversely, the new homeowner can’t get a mortgage without a decent water quality test. Oftentimes customers prefer Beck to redrill the well for homes up for sale rather than install a treatment system. Beck estimates he does a handful of these type jobs each year.

“People have high nitrate water in their gravel formation they’re pumping out of,” Beck says, “and when the well was drilled in the 1960s or 70s nobody was paying attention to that.”

In western Kansas, the Ogallala is up to several hundred feet thick in places; it is thickest in southwestern Kansas. In places, tens to hundreds of feet of the Ogallala are saturated with good quality water.

However, the impact over overuse has caused significant concern. Take for example a small city in western Kansas which during recent evaluations identified a loss of 60 feet of saturated thickness in their wells, according to Ned Marks, PG, owner of Terrane Resources Co. in Stafford, Kansas.

Michael Schnieders, PG, PH-GW, president of Water Systems Engineering Inc. in Ottawa, Kansas, says recharge has occurred within the Ogallala, but it is limited and localized—not widespread or sustained. In some areas, a change in water quality has been identified as being attributable to the water level declines. These are localized changes due to interaction with saline waters or from poor well design and influences with either upper or lower aquifers.

For example, according to Marks, there is evidence of intrusion by the Arkansas River alluvial aquifer directly attributed to poor well design and insufficient grouting.

Water Level

The condition of the Ogallala Aquifer varies significantly depending on the location and whether the aquifer is able to be recharged from precipitation.

Water level declines in southwest Nebraska have led to aggressive management by the Natural Resources Districts (NRDs) to limit the amount of water that can be pumped annually. They have successively made major reductions in the amount and rate at which the aquifer is declining.

Cody Christensen (pictured) and his three younger brothers manage Christensen Well & Irrigation, which was established by his parents, Bill and Connie, in 1973. Photos courtesy Christensen Well & Irrigation.

Positive news from the 2015 Nebraska Statewide Groundwater-Level Monitoring Report reveals much of the state is beginning to recover from the 2012-2013 drought.

From spring 2014 to spring 2015, water levels began to rise after significant declines resulting from an extended period of drought from early 2012 through summer 2013. Above-normal precipitation for much of Nebraska and better water-use practices accounted for the rises. The average change from spring 2014 to spring 2015 was a rise of 0.53 feet.

Although these one-year rises are good, many parts of the
state remain below 2012 levels, according to the report. Eastern Nebraska saw some of the largest rises—with some wells recording rises of 10 to 15 feet. Rises in these areas are the result of above-average precipitation and reduced need for irrigation pumping.

It is expected in spring 2016 water levels will continue to
rise throughout much of the state as was seen in spring 2015, particularly in eastern Nebraska where flooding was common.

The effect of climate change on U.S. irrigation and water
levels was summarized by the U.S. Department of Agriculture in a 2015 paper, Climate Change, Water Scarcity, and Adaptation. Irrigated acres are expected to decline as the country warms. This is because either more rain reduces the need for irrigation, or less water constrains the ability of farmers to irrigate. In some cases, dryland farming may become more profitable.

For Cody, a historical study of rainfall amounts and the effect
on water levels left a lasting impression on him following a 2008 presentation by a representative of the Upper Big Blue Natural Resources District in southeast Nebraska.

The representative showed data from the 1950s comparing rainfall to water levels in the district and did the same for 2008. Cody says the graphs mirrored each other: If there was heavy rainfall, the water level was up; if it didn’t rain, both were down. Tens of thousands of irrigation wells were added in the district from the 1950s to 2008, he says, and the graphs did not change.

“This representative concluded, in that particular area anyway, irrigation has little to no effect on groundwater levels,” Cody says. “Those were his exact words—little to no effect.”

Cody says this is true in northeast Nebraska and west of his area toward north-central Nebraska where Beck is located.

Beck says the saturated thickness in his region has been stable where he saw small changes even during the 2012 drought. The average declines in Beck’s region were less than 3 feet during the drought with saturated thickness between 150 and 400 feet, which he says are minimal declines.

“Precipitation drives water levels in our region, and for the most part, irrigation has a minimal effect on the aquifer levels,” Beck says. “Unfortunately, irrigation is the only thing that can be regulated or controlled and so all of the pressure to manage water levels and stream flows is put on that segment even though much of it is up to Mother Nature.”

In the North Platte NRD in western Nebraska, average precipitation is 14-16 inches a year. It has had its fair share of dry years with 2012 seeing only 6 inches, but in 2015 the district recorded 25 inches, according to John Berge, general manager of the North Platte NRD in Scottsbluff, Nebraska.

The North Platte NRD has 800 monitoring wells—more than most states have and well more than other Nebraska NRDs—to measure static water levels three times a year in the spring, summer, and fall. Along with measuring static water levels, the district has put into place multiple regulations based on Nebraska’s legislative bill, LB 962 in 2004, which deemed the river basins over-appropriated in terms of groundwater expansion. The district is in the midst of striving to meet specific obligations to maintain the ability for downstream appropriators.

The district has a mix of aquifer systems, with the Ogallala on the eastern portion of it and an alluvial aquifer along the North Platte River and Arikaree formations in the outlying areas.

On allocation alone in 2015 due to heavy precipitation, Berge says there was more than 17,000 acre-feet of credit back to the North Platte River.

“In a district that has as few irrigated acres as we do, that is a very significant number,” Berge says.

Overall, the Ogallala Aquifer in Kansas is in decline, according to Schnieders, particularly in the western part of the state. There is little new development occurring; however, the changes occurring are in the review, assignment, and transfer of water rights.

Second to the loss of quantity in Kansas, Schnieders says the driving issue is management. There is increased activity by the five Groundwater Management Districts, but they are limited in their ability to mandate or enforce change. What progress has been made is a result of a shareholder mentality and bringing all parties reliant on groundwater to the table to discuss the elephant in the room—aquifer levels. With some exceptions, the bulk of proactive conservation efforts at this time are being driven by the municipalities.

Marks works closely with municipalities in evaluating their current and future groundwater options. “With water rights impairment, is there regional decline? Over-development? Drought? Yes, yes, and yes,” Marks says.

Schnieders agrees. “Future usability will require major changes to crop management and selection. Until that becomes the new norm, little change is expected.”

Restrictions for Developing High Consumptive Use Wells

Nebraska’s 23 NRDs use groundwater regulations in different combinations and to different degrees depending on their respective geographic areas of concern.

The majority of the state that has the Ogallala Aquifer under it is under some form of restriction for developing any additional new high consumptive use wells, which is a well that pumps more than 50 gpm. This decreases the ability to drill high capacity wells unless they are a replacement well or if water rights have been purchased and transferred to a new location.

Well drilling moratoriums and moratoriums on expansion of acres for irrigation were put in place more than a decade ago in some districts. The NRDs have voluntarily done this to collect data on stream flow and groundwater levels with the goal to slowly release acres to be developed for irrigation drilling.

Cody, who is serving as this year’s president of the Nebraska Well Drillers Association, understands the NRDs’ goal to preserve and protect the Ogallala, but he is frustrated with their inaction. He cites three NRDs in eastern Nebraska which have had relatively the same water level records over the last 30 years despite adding irrigation wells during that timeframe. He wants the NRDs to improve their ability to make use of the data they have received and also release more acres to be developed.

The North Platte NRD instituted a well drilling moratorium for the entire district in 2002, and in 2004 implemented a moratorium on the expansion of acres. It has flowmeters on every regulated well. Among other measures, the district is considering regulating the entire district. It manages 3.5 million acres, where 350,000 are irrigated with 80,000 acres falling outside of impact to rivers. For continuity’s sake and to protect the delicate aquifer systems, the district might look to manage them too.

The first increment of the North Platte NRD’s Integrated Management Plan with the Nebraska Department of Natural Resources is to return 8000 acre-feet to the North Platte River annually by 2019. The next step is to be fully appropriate, which hasn’t been defined yet but is assumed to be much higher than 8000 acre-feet.

“Because of the soil and crop types we have and the allocation we have to maintain and precipitation we generally receive, I don’t see a situation certainly in my lifetime where we’re going to allow further groundwater development in this district,” Berge says. “Now there are other districts around the state that still allow well drilling or allow acre expansion. We’re just not one of them. We don’t have that luxury.”

A Look Ahead

Irrigation and groundwater, the issue focus of this month’s Water Well Journal, will likely always be a hot button issue in Nebraska.

The past five years irrigation was strong in the state, Cody says, due to high grain prices and high land prices and dry weather. In 2012, Cody had 23 employees where 90% of drilling was for irrigation. Today, he has 10 full-time employees and there will be between 40% and 50%
irrigation drilling, with the rest being domestic or stock wells for livestock and pastures.

In north-central Nebraska, Beck serves a mature irrigation market. Plugged well screens and old tired pumps needing repair or service work is common. Much of the irrigation equipment, Beck says, has been in use for 35 to 40 years now.

“We’re kind of hamstrung with being able to add to what we’re already doing if we can’t do any additional development,” says Beck, who served as the 2013 Nebraska Well Drillers Association president. “It’s kind of put our economy in a holding pattern.”

Since the October 2013 Governor’s Conference on Water, Kansas has been guided by Governor Sam Brownback’s “Vision for the Future of Water in Kansas.” In 2014, Kansas undertook a campaign of “Stakeholder Outreach” to boost awareness and develop a partnership attitude.
From reports, the campaign involved more than 400 meetings, seminars, and workshops for communities, civic groups, professional organizations, and interested citizens—a significant effort to raise awareness of the importance of water to the state as well as the challenges facing its availability and use.

Cody discusses with the general public in northeast Nebraska how the Ogallala Aquifer works. Due to increased media coverage over the last decade, Cody believes the public is prone to overreact if they read the Platte River or a stream or creek is running low.

“Basically, as long as we get our average rainfall throughout the state, typically our streams are always running, which means our groundwater aquifer is overflowing,” he says.

Cody, who will turn 42 on May 31, is nervous about the next five years. To survive, the company has diversified with Cody’s brother, Casey, offering his electrician services outside of wiring a water well, such as service/repair of the numerous electrical irrigation systems in the area. They’ve begun selling water distillers made in Lincoln, Nebraska, even though most folks don’t need one due to the high quality of water. It might keep them somewhat busy though.

“I’ve been doing this long enough and there always seems like there is something to do and worrying about it definitely doesn’t help the cause,” Cody says, “but that’s human nature, I guess.”

Mike Price is the senior editor of Water Well Journal. In addition to his WWJ responsibilities, Price produces NGWA’s newsletter and contributes to the Association’s quarterly scientific publication. He can be reached at Read parts one and two.