Drought highlights irrigation conservation

This year’s drought is having a severe impact in the western states. It actually began last year, when regular monsoons failed and the amount of snowpack was greatly reduced.

Of the 17 most affected states, Arizona is the worst hit, along with Utah, Colorado, Nevada and New Mexico. Some prime agricultural areas in Washington and Oregon are also affected. The drought’s effects on California are especially significant, since agriculture is a major driver of the state’s economy.

News stories report zero water allocations to some California farmers from already stressed surface water systems and aquifers, and some producers are destroying thirsty almond orchards, plowing crops under or simply deciding not to plant. Consumers can expect to see price increases on California-grown vegetables and other ag products in the coming months.

The drought has reached into the upper Plains states, with North and South Dakota the most affected. According to a state climatologist, 91% of the North Dakota is in severe, extreme or exceptional drought. About 72% of South Dakota is in severe or extreme drought, according to the latest updates by the National Weather Service.

Some moderate drought areas reach into northern Minnesota, while the rest of the state and parts of Wisconsin are experiencing abnormally dry conditions, according to the drought map. So far the middle Plains states have been less affected.

Missouri River irrigation

Drought conditions continue to affect the upper Missouri River Basin above Sioux City, Iowa (upper basin), according to the latest report by the Missouri River Water Management Division of the Corps of Engineers’ Northwest Division. July runoff in the upper basin was only 34% of average. July runoff above Fort Peck Dam was the lowest in 123 years of record-keeping. “Reservoir inflows in July have been declining due to the warmer and drier conditions in the upper basin,” said John Remus, chief of the U.S. Army Corps of Engineers’ Missouri River Basin Water Management Division.

While the primary purposes of the six-dam system on the Missouri River include maintenance of navigation and hydropower, farm irrigation needs were also part of the Pick-Sloan Missouri River Plan that resulted in the dams being built. The original plan that called for irrigating 5.4 million acres was downsized to 3.8 million acres in 1958 and 2.9 million in 1986. About 2 million acres are irrigated from the river today, with irrigated crops including alfalfa, wheat, hay, barley, oats, sugar beets, potatoes, corn and cherries.

Conservation

The good news is that for decades, farmers have been steadily becoming smarter and better irrigators. They haven’t had a choice. In the 1970s, awareness began to hit home that the aquifers supplying water to the central Plains were being depleted faster than they could be recharged. Today we know that climate change is affecting the frequency of droughts and floods, so water supply is even less predictable. The rate of depletion is not the same in all areas. Some parts are doing better than others, but all must become better water managers.

At the Ogallala Aquifer Summit in 2018, charts showed water withdrawals from most parts of the aquifer to have been more or less flat since 2000—this over a period when acreage, plantings and yields were increasing. In other words, irrigators began learning how to make every drop count.

Nebraska: Future of water management?

Nebraska is a pioneer and model for other states in its water management policies. It is naturally rich in rivers and groundwater, with much of the state being underlain by the Ogallala Aquifer, part of the High Plains Aquifer. Maps of the Ogallala Aquifer show Nebraska’s part as the most replenished and losing the least amount of water.

The “center-pivot revolution” in irrigation increased irrigated acres in the state from 1 million to about 9 million acres beginning in the 1960s. But lax water rights regulation at the time meant that pumping was too uncontrolled. Some small streams and rivers went dry. So the state began reforming its water regulation system, culminating in the Nebraska Groundwater Protection Act in 1980.

Nebraska is the only state that regulates water allocations through Natural Resource Districts based on river basins instead of political boundaries. It helps that Nebraska is blessed with many rivers and 24,000 miles of flowing rivers and streams—more groundwater than in any other state. Each NRD allocates both surface and groundwater based on need. It’s a rational system much different from California’s water rights regime, a complex hybrid tangle of senior and junior water rights holders grandfathered in over time, sparking many legal disputes. In 2014, California began pruning this system with the Sustainable Groundwater Management Act.

The clarity of Nebraska’s water management is important for the entire region’s farmers because Nebraska is a net water exporter to its neighbors—more water leaves the state than enters it. Under the Republican River Compact of 1942, Nebraska supplies water to eastern parts of Colorado and eastern Kansas.

Technology is helping. Irrigation equipment makers are providing apps that allow farmers to turn irrigation systems on and off from their phones, according to what soil sensors tell them. Lee Orton, executive director of the Nebraska State Irrigation Association, points out that even older, less efficient spray irrigators can be improved by replacing nozzles with more efficient drip nozzles. Not all farmers can afford these systems, though. Irrigation systems are a huge investment.

Becoming a more efficient irrigator is not without ironies and difficulties. Some less efficient methods of irrigation return more flows back into the aquifers as they leak down from fields or irrigation canals. More efficient methods can result in less recharge to water stores.

The state sets strict limits on both surface water and groundwater for each of the 26 irrigation districts. “My grandfather used to turn on the pump and leave it on 24/7,” said Orton. “Today, farmers that used to withdraw 3 feet [of water] are using 10 or 11 inches—and getting better results.”

In less water-favored parts of the Midwest, some farmers are moving to less thirsty crops—from irrigated to dryland wheat, for example. Less-thirsty cotton has been moving north, and more efficient water usage has helped increased the popularity of sorghum.

David Murray can be reached at [email protected].