What’s the Problem With Pits?

 

Healthy, functioning playas provide important habitat for ducks, geese and other wildlife, and are areas of focused recharge to the Ogallala Aquifer. But many playas have been modified through tilling and pitting. Filling a pit allows rainwater and runoff to reach the large cracks in a dry playa floor—which is essential for recharge to occur—rather than collecting in the pit. The shallow water that spreads across the playa also allows plants and insects to flourish, which in turn provides important food and habitat for migrating birds and other wildlife.

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This is Playa Country — a weekly look at the wildlife, wetlands and prairies of the western Great Plains, and the people who manage them — brought to you by Playa Lakes Joint Venture, an organization dedicated to conserving birds and bird habitat.

It’s an amazing world, and scientific research presents new information every day, and sometimes new science makes us have to re-think actions we took based on older knowledge. So it is with playa lakes, the shallow, ephemeral “mudholes” or “buffalo wallows” as they’re sometimes known, that dot the High Plains.

Angela Safranek is a rangeland management specialist with the U.S. Forest Service at Pueblo.

“In the 70s and 80s, people would look at playas and when they would see those playas fill up people thought, ‘well if we dig those holes a little bit deeper we’re going to be able to have more water in that deeper hole and it will hold for longer because it’s not going to evaporate as fast.’”

That’s exactly what many crop producers and ranchers did — thinking it would give them a longer lasting supply of water for livestock or crops. But we now have a better understanding about the hydrology of playas, and what happens when you “pit” a playa.

“Instead of making a deeper hole and a bigger basin, the playas just drained and didn’t hold water very well at all anymore, to the extent that we weren’t getting the recharge to the aquifer.”

Scientists have learned that, not only do playa wetlands recharge the Ogallala Aquifer, these small but numerous wetlands are a primary source of recharge. I talked to a scientist who knows about it. Ken Rainwater, with the Water Resources Center at Texas Tech in Lubbock.

“Playas are a source of focused recharge. The water is collected long enough for part of it to go down into the subsurface and head toward the aquifer.”

By filling a pit in a playa, the water is able to reach the large desiccation cracks that are found all over the playa floor, which is essential for recharge to occur. 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.

Grady Grissom ranches in southeast Colorado, and had a 25 to 30 acre pitted playa on his grassland. He filled the pit, the water spread out, restoring natural plant life.

“And when playa water gets spread out over vegetation, then you have an explosion of bug life. That’s what the migrating birds need.” Grissom says a year later, the playa was full of water and hosted some visitors. “There was over 100 cranes that came in and spent about 10 days.”

Anne Bartuszevige, Conservation Science Director with Playa Lakes Joint Venture, says there’s a whole community of wetland plants that need the very shallow water found in a healthy playa.

“If the playa is never wet because the water is concentrated in a certain area, then those plants just don’t ever grow. Those plants, when they mature, they have seeds. And the seeds are what are eaten by the ducks. If you don’t have those plants growing, you don’t make those seeds, and then those ducks don’t have that food.”

These playa wetlands are below the Central Flyway, that major migration route birds fly between wintering grounds in the Gulf of Mexico, and their nesting grounds of central Canada. Migrating birds need a lot of calories, and seek rest stops featuring lots of plants and bugs to eat. The good news about fixing pitted playas is, it’s cheap and easy.

“When the pits were dug, the soil piles are right next to it. We can just put that same soil back in.”

If you have a pitted playa, technical help and cost-share funding is available to rehab the wetland and set up alternative water sources for livestock. Contact your USDA service center and ask about restoring playas through the Continuous Conservation Reserve Program, or a Wetlands Reserve Easement, and how the Environmental Quality Incentives Program can help bring water to the rest of the pasture.

This Playa Country episode was made possible by the Playa Lakes and Rainwater Basin Joint Ventures, and a grant from the Wildlife Conservation Society’s Climate Adaptation Fund, which was established by a grant from the Doris Duke Charitable Foundation.

Original broadcast: March 2015

Posted: February 15, 2016
Topics: Playas