Playa Recharge Summit
Playas recharge the Ogallala Aquifer — that is the message PLJV has been promoting for the past 10 years. As a result, landowners are more aware of the connection and have started asking specific questions about aquifer recharge before deciding whether to conserve or restore their playas. They want to know how much groundwater recharge goes through playas, how long till it reaches the aquifer, and will that water benefit them directly. So, PLJV went looking for answers.
In 2015, with funding from the Great Plains Landscape Conservation Cooperative, PLJV held a Playa Recharge Summit to discuss the link between playas and the aquifer with 14 scientists and researchers who study various aspects of playas including hydrology, wildlife ecology, economics and communications. During the meeting, the participants came to agreement on how to answer landowners’ questions based on the most recent scientific knowledge.
Amount of Recharge Through Playas
Playa experts agree that playas recharge the aquifer at the rates described in the 2009 USGS Circular: Recharge Rates and Chemistry Beneath Playas Literature Review (USGS recharge report; http://pubs.usgs.gov/circ/1333/), which gathered and reviewed all the scientific literature about recharge to the High Plains Aquifer. According to the report authors, “Reported recharge rates beneath playa floors range from about 0.01 to more than 10 in./yr, whereas most interplaya settings in croplands and rangelands have recharge rates reported to range from about 0.01 to 1 in./yr.” The scientists at the Summit supported using an average of 3 inches per year across the region in calculating recharge rates through playas.
As the USGS recharge report indicates, recharge rates vary based on a number of factors including depth to aquifer, soil type, amount of soil saturation, evaporation and transpiration. Recharge rates also vary during the playa wet/dry cycle. According to the USGS report, most of the recharge happens when the soils are dry and have formed large cracks. Water runs off the landscape and into the cracks, eventually making its way to the aquifer. Then when soils become saturated and the cracks seal, recharge continues to happen through the clay soils at at the edge of the playa where the clay soils meet the upland soils. Recharge during this time happens at a much lower rate.
The USGS recharge report concludes that “properly functioning playa wetlands … are thus important for the overall recharge contribution to the southern High Plains aquifer.”
Time to Recharge Through Playas
In general, water recharging today through playas will be available for our children and/or grandchildren. The time it takes for recharge to reach the aquifer and be available for extraction varies depending on depth to the aquifer formation and underlying soil type. If it is shallow, water will recharge in months to years. If the depth is approximately 100 feet, it will take years to decades. If the depth is approximately 200 feet, water will recharge in decades. At the deepest locations, recharge could take a century to reach the aquifer.
Quality of Recharge Through Playas
The benefit of a healthy playa—a playa with a grass buffer and no hydrological modifications such as pits or ditches—goes beyond simple recharge. Research shows that water reaching the aquifer through playas is of higher quality than that going through other pathways. This happens in two ways: first, as rainfall and runoff travel toward the playa, the surrounding grasses trap sediments, which can carry contaminants into the playa; then, as the water moves through the clay floor of the playa, a second ‘cleaning’ process occurs as the soils beneath the playa remove nitrates and other dissolved contaminants. The result is high quality water reaching the aquifer that can then be used by those living on the land.
Direct Recharge Benefits to Landowners
When a landowner takes actions to increase recharge on his/her property, that water benefits him/her directly. Although water in the aquifer does flow horizontally, flow rates are extremely slow (½-1 mile per 10 years). Thus, the water is functionally compartmentalized in a given area.
More Information & Resources
Download PLJV’s Playas & Recharge Communication Kit (11.4 MB), which includes communication tips, sample messages, ready-to-use flyers and podcasts. You may also download the files individually.
- Communicating About Playas and Recharge Tip Sheet (115 KB)
- Groundwater Recharge Through Playas: What the Scientists Say (6.6 MB)
- Playas and the Ogallala Aquifer Fact Sheet (1.5 MB)
- Playas Provide Clean Water for Future Generations podcast (2.2 MB)
- Playas Provide Direct Recharge Benefits to Landowners podcast (2.2 MB)
Contact Anne Bartuszevige for a copy of the full Playa Recharge Summit Report.