We grew up on the High Plains thinking of those occasionally muddy pasture depressions as “buffalo wallows” or “mud holes.” Turns out, scientists are learning those playas play a significant role in recharging the Ogallala aquifer. They are the most numerous wetland in the region, more than 75,000 of them, and they’re an important source of water — both for people and wildlife.
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Growing up on a western Kansas farm, I remember my father pointing-out those depressions in the pasture that always held rainwater for a while following a storm. My dad called them “buffalo wallows.” Others called them “mud holes.” Those seasonal ponds, known as “playas,” or “rainwater basins” in central Nebraska, are a regular and frequent feature of the high plains landscape. They are the most numerous wetland in the region, more than 75,000 of them, and they’re an important source of water — both for people, and wildlife.
In recent decades, many researchers, representing a variety of disciplines, have begun studying these wetlands, according to University of Kansas geologist Bill Johnson:
“There’s a number of people that are focused on these; they’re coming from all different directions. I think the one that’s really important now, for a lot of people, really relates to what everybody’s interest is rooted in — what’s their connection with the groundwater?”
Johnson has been investigating playas more than 30 years. He says scientists now have evidence playa wetlands are a primary source of recharge to aquifers such as the Ogallala — that vast but diminishing source of groundwater so vital to life on the semi-arid plains.
Playas are shallow, round water catchment areas found at the lowest point in a watershed. These basins have a layer of clay soil that enables recharge, says Ken Rainwater, who directs the Water Resources Center at Texas Tech.
“Even though soils in the playa bottoms are clay, they dry out and desiccate with big cracks between rainfall events. So when you have your first flush of water coming into the playa, when you have enough rainfall, it’s real easy for water to go down through those cracks and head down through the clay toward the aquifer below.”
New Mexico Rancher John Wood has what might be the largest playa in New Mexico at 160 to 200 acres, on his land north of Clovis. “We can get a three-inch rain and the next morning it would be gone. It goes somewhere, and I think it goes down.”
As the clay absorbs water, it expands, sealing the cracks, and filling the basin with water from rainfall and runoff, and providing water, food and shelter for birds and other wildlife. But just as we’re learning their importance, so are we learning that playas are under stress. Ken Rainwater of Texas Tech says many have lost capacity to not only recharge groundwater but also to filter and clean water going down into the aquifer because they’re clogged with sediment — sediment transported from cultivated fields by rain runoff. And some growers, not understanding the benefits playas provide, farm right through them, lessening their function.
“We’re not trying to go get anybody in trouble; we’re not trying to tell people you are doing things that are wrong. We’re just trying to understand how these complex processes on our planet work so that maybe we can have a better future.”
The more we learn about playas, the more we understand the importance of these so-called mud holes to the people and wildlife sharing this landscape. Healthy playas provide groundwater recharge and improve the quality of water flowing into the aquifer. Establishing native grass buffers around a playa helps to filter out soil and agricultural contaminants present in runoff, preventing sediment accumulation and allowing the playa to do its job. Contact your local Natural Resources Conservation Service Center for more information about technical and monetary assistance to help with playa conservation.
You’ve been listening to Playa Country, a weekly show about the wildlife, people and landscapes of the western Great Plains. This program is made possible by the Playa Lakes and Rainwater Basin Joint Ventures.
Original broadcast: August 2012