Without an adequate solution to the region's groundwater problems, the United States Geological Survey (USGS) and the National Water Management Center (NWMC) project the Grand Prairie's Alluvial Aquifer will be too small for commercial use by 2015.
Currently, more than 90 percent of the water needed for crop irrigation is being withdrawn from the Grand Prairie's Alluvial Aquifer. A main source of agricultural water since 1904, the Alluvial Aquifer annually provides millions of gallons of water but is quickly being depleted. In fact, the water table in the aquifer has been declining at the rate of about one foot per year and since 1915, faster than natural recharge.
In 1937, water from the Alluvial Aquifer was only some 50 feet beneath the surface of the land. Today, the South Central Water Management Center (SCWMC) reports that water is 105 feet below the surface.
This de-watering of the Alluvial Aquifer has caused a cone of depression in it that resembles a long trough, which centers around Stuttgart, Arkansas and extends northward to Hazen, Carlisle and Lonoke. Recent studies have shown that the cone of depression is lengthening and now stretches nearly to England, some 35 miles northwest of Stuttgart.
Well depths of 120 feet and more below the surface are common in many locations throughout the cone of depression. In some areas, drilling into the deeper Sparta Aquifer is necessary for adequate supplies of water.
Pumping from the Alluvial Aquifer has increased the length of the cone of depression and the environmental problems now facing the region are compounding.
The National Weather Service (NWS) in conjunction with the U.S. Drought Monitor (USDM) has this region of Arkansas listed as "D3 Drought-Extreme." The region is in its third consecutive year of an annual rainfall deficit.
The Alluvial Aquifer currently is being recharged by the White River on the eastern border of the region, the Arkansas Rivers on the west, and Wattensaw Bayou from the north. However, that natural recharge is only replenishing about 67 percent of the total amount of water being demanded from this regional portion of the aquifer, so at the current rate of withdrawal the aquifer's decline continues.
In recent years, individuals from the Grand Prairie area have touted the deeper Sparta Aquifer as a suitable groundwater source once the Alluvial Aquifer's supply is depleted. However, the Sparta Aquifer does not have the capicity, has extremly slow recharge and is expensive to pump. The sparta is also the region's only reliable source of safe drinking water and most public water systems within the Grand Prairie depend solely on the Sparta Aquifer.
Arkansas state law places the public's need for drinking water above irrigation, or other commercial water need. However, the Sparta Aquifer is already being tapped for uses other than drinking water and its level has been declining since 1986 at the rate of about one-foot per year.
The U.S. Congress authorized the Grand Prairie Area Demonstration Project (GPADP) in 1991 to protect and preserve the Alluvial and deeper Sparta Aquifers found beneath the surface of the Grand Prairie area. This project was created to allow the continued irrigation of agricultural crops, slowing further depletion of aquifers, while providing greater benefits to the millions of waterfowl that annually migrate through the region.
The GPADP will utilize on-farm reservoirs and tailwater recovery systems for more efficient, individual management of surface and irrigation water. Farmers will have about 88,000 acre-feet of additional water storage capacity for on-farm irrigation use once the project is complete. These reservoirs and their companion recovery systems will enable growers to recycle at least a portion of the water used for irrigation.
Recaptured tailwater will be directed back into the on-farm reservoir through a system of ditches, pipes and pumps. Farmers again have access to at least a portion of their original on-farm water supply for crop irrigation and without having to continually pump additional supplies from the ground.
Other Project Benefits
- Protection of the Sparta Aquifer, the primary source of the Grand Prairie's drinking water
- Adequate water capacity to seasonally flood more than 38,000 acres of harvested rice-fields to provide a high quality food source for waterfowl
- The reintroduction of native prairie grasses along project canals
- Establishment of fisheries in canals while enhancing existing stream fisheries
- Increase in wetlands which attract waterfowl and other wildlife
- Creation of habitat for shorebirds and fish
- Decrease agricultural runoff which means less chance of crop chemicals tainting rivers and streams
- No negative impact on area waterfowl because pumping water from the White River, through the distribution network and into on-farm reservoirs would be conducted primarily during the summer and not during the waterfowl hunting season
- Allow time for the Alluvial Aquifer to recharge
- Slow or halt the drying of many wetlands along the White River
- Maintain farm property values
- Maintain the tax bases for communities in the area
- Maintain the area's agricultural economy, including farm production, agribusiness, farm jobs, public services, urban and rural populations at current levels
The first contract between a Grand Prairie farmer and the local White River Irrigation District (WRID) and the Natural Resource Conservation Service (NRCS) for an on-farm water storage and management system was signed October 16, 2000. This marked the official beginning of construction for the GPADP. Local farmers are currently constructing on-farm features.
Final approval of more than 100 additional, on-farm water plans are expected to be complete sometime during 2001. These on-farm conservation features will cost approximately $80 million with the federal government covering 65 percent of the total cost.