what are playas? · the smallest playas are less than 1 acre, and the largest playas are greater...

T H E Q U I C K & D I R T Y V E R S I O N

What Are Playas?

Playas are small, ephemeral wetlands…

at the lowest point of their own watershed...

that are keystone ecosystems...

and

recharge

the High

Plains

(Ogallala)

Aquifer...

in the western Great Plains.

T H E D E T A I L S

Wait, There's More

Small

The smallest playas are less than 1 acre, and the largest playas are greater than 300 acres, with an average size of ~7.3 acres. 33% of playas are less than 1 acre.

Ephemeral

Playas fill with run-off from large precipitation events (>2 inches in 24 hours) and are wet for a few weeks to a year or more. One study estimated that playas were wet on average once out of every 11 years.

Watershed

Each playa has its own watershed (e.g., no inflow or outflow). The landcover in this watershed greatly determines the health of a playa. Grassy watersheds are better than cropped watersheds because excess sediment is not generated.

Watershed

Playas are mainly in cropland (49%), which includes CRP, and grassland (39%), including pastures. The rest are in shrubland, developed areas and other types.

Keystone Ecosystems

Playas support 185 species of birds, 350 species of plants, 37 mammal species, and 13 amphibian species. They are migratory stopover habitat in the Central Flyway and critically important for waterfowl, shorebirds and waterbirds.

Recharge the High Plains Aquifer

Recharge is 10-100 times greater under playas than inter-playa areas

How Recharge Happens

Recharge occurs through playa basins and along the perimeter. When rainfall or associated runoff reaches the playa, water penetrates the clay layer through large cracks, which eventually swell shut and become impermeable as the clay absorbs more water.

Playas in the Western Great Plains

State Number Average Size (Ac) Range (Ac)

Colorado * 8,047 5.5 0.01 - 248

Kansas 22,045 3.7 0.08 - 464

Nebraska 21,900 1.2 0.01 - 79.5

New Mexico * 2,231 14.3 0.04 - 1,241

Oklahoma * 2,886 4.7 0.01 - 600

Texas 23,041 17.0 0.01 - 841

*Playas were mapped using mostly SSURGO and LANDSAT data; thus these figures tend to omit many small playas compared with National Wetland Inventory data used in other states (NE, KS, TX).

Threats The #1 threat to playas is culturally-accelerated sediment accumulation from row crop agriculture and over-grazing, also hydrologic modifications (pitting, ditching, berms, roads) and energy development.

What We Can Do

Conservation Programs �  Farm Bill - CRP (CP-23a), WRP, EQIP �  Easements �  NAWCA grants �  Local Conservation Partnerships �  Farm Bill Biologists �  Ogallala Initiative �  Playa Conservation Initiative

Conservation Practices �  Grass buffers around playas (native grasses are best) �  Sediment removal �  Pit filling �  Watershed management

The Full Story

�  Playas of the Great Plains, by Loren Smith Copies of this book have been distributed to the Management Board. If you do not have a copy contact the office, and we will send one to you.

�  USGS Recharge Rates and Chemistry Beneath Playas of the High Plains Aquifer—A Literature Review & Synthesis Download from http://pubs.usgs.gov/circ/1333, or request a copy from the PLJV office.

�  Playas of the Great Plains, USA This article is being reviewed for publication in the Encyclopedia of Wetlands: Wetlands of the World. Link coming soon.