The Ogallala Aquifer, a vast underground water reservoir, stretches across approximately 174,000 square miles beneath the Great Plains. It underlies parts of South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, New Mexico, and Texas. This aquifer serves as a primary water source for agriculture and communities throughout the High Plains region. It supports about 27% of all irrigated land in the United States and provides approximately 30% of the groundwater used for irrigation nationally. The aquifer also provides drinking water to 82% of the 2.3 million people residing within its boundaries.
Understanding the Aquifer’s Decline
The Ogallala Aquifer formed over millions of years from ancient meltwater and rainfall, with sediments deposited from erosion in the Rocky Mountains. Water slowly accumulated within these porous materials. The aquifer recharges very slowly, with less than an inch of precipitation annually reaching it on average. Rates range from 0.024 inches per year in parts of Texas and New Mexico to 6 inches per year in south-central Kansas. This slow replenishment means that the water within much of the aquifer is considered “fossil water,” accumulated over geological timescales.
Extensive groundwater pumping for irrigation is the primary reason for the aquifer’s current decline. Large-scale extraction began significantly after World War II, driven by the adoption of center-pivot irrigation systems and automotive engines to power wells. Farmers widely adopted these technologies to grow water-intensive crops such as corn, cotton, and alfalfa in the semi-arid High Plains. While agriculture accounts for approximately 95% of the water withdrawn, municipal and industrial demands also contribute. This widespread pumping has led to withdrawal rates that are 3 to 50 times greater than the aquifer’s natural recharge rate in some areas.
Varying Timelines for Depletion
There is no single date for the entire Ogallala Aquifer to run dry, as depletion rates vary significantly by region. Some areas, particularly in the southern and central parts, have experienced substantial, irreversible declines. For instance, parts of Texas and Kansas have seen water levels drop by 100 to 200 feet, with some areas in the Texas Panhandle experiencing declines of up to 256 feet. Many wells in these regions have already gone dry or become economically unfeasible to pump due to increased pumping depth.
Factors influencing these regional timelines include local pumping rates, the aquifer’s thickness, and underlying geological formations. The aquifer is generally thinner in the south, making it more susceptible to rapid depletion, while Nebraska holds the thickest and most expansive parts. For example, water levels in Nebraska have shown less decline, and in some localized areas, have even risen. This contrasts sharply with areas like western Kansas and the Oklahoma Panhandle, where declines of over 28 feet and 70 feet respectively have been observed since predevelopment.
Impacts of Water Scarcity
Continued decline of the Ogallala Aquifer poses challenges, particularly for the agricultural sector. Farmers in affected areas face reduced crop yields and may need to shift towards less water-intensive crops or revert to dryland farming practices. The increasing depth to water also leads to higher pumping costs, which affects the economic viability of irrigated agriculture. Some land may eventually be taken out of production entirely if water becomes too scarce or expensive to access.
Economic implications extend beyond individual farms. Economic downturns and job losses can occur as agricultural output diminishes. Rural communities, particularly those built around irrigated farming, face declining populations and reduced economic activity. Beyond human impacts, environmental effects include the loss of wetlands and disruption to ecosystems and wildlife that depend on groundwater-fed streams and habitats. Endangered species like the whooping crane, pallid sturgeon, and piping plover face impacts from reduced water availability.
Approaches to Water Stewardship
Efforts to manage and conserve the Ogallala Aquifer’s water resources are underway, focusing on strategies and innovations. Improving irrigation efficiency is a primary approach, with technologies like precision irrigation, drip systems, and mobile drip systems delivering water efficiently. Deficit irrigation, which strategically reduces water application during less critical growth stages, also conserves water with minimal yield loss. Remote sensing using satellite and drone imagery allows farmers to assess crop water needs precisely across large areas.
Promoting drought-resistant crop varieties and incentivizing dryland farming where feasible are additional strategies to reduce reliance on aquifer water. Water-saving agricultural practices, such as no-till farming and improved soil health management, also contribute by enhancing water retention and reducing runoff. State and local water management districts implement regulations on pumping and develop water conservation plans. Programs like Local Enhanced Management Areas (LEMAs) in Kansas demonstrate how reduced water pumping can be achieved while maintaining agricultural income. Initiatives also explore artificial recharge and the conservation of playa lakes as natural points for aquifer replenishment.