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Lake Wister

Lake Wister is the source of water that PVIA treats and distributes. As such, both the amount of water in the lake and the water quality of the lake are of central concern.

The Lake Wister reservoir currently covers 6,300 acres, with an average depth of eight feet. Lake Wister was created in 1949 by the closing of Wister Dam. PVIA has been using water from Wister to supply to the Poteau Valley region since 1969. While Wister has proven itself a reliable source of drinking water, water quality suffers from excessive loads of nutrients and sediments entering the lake from its watershed. Nutrients cause more algae to grow, which in turn leads to increased expense in treating the water, to low dissolved oxygen levels in the summer (bad for fish and other aquatic life), and other problems. The growth of certain types of algae (blue-green, also known as cyanobacteria) can cause drinking water to taste or smell bad at certain times of the year.

The sediment entering the lake contributes to turbidity (cloudiness) of the water and it gradually filling the lake in. Based on the most current estimates, Lake Wister is losing around 475 acre-feet of capacity each year do to sedimentation. That equals almost 1% of the lake’s capacity, which means in 20 years, the lake will hold 20% less water than today.


PVIA is leading several efforts to improve water quality at Lake Wister. Current projects include:

Lake Wister Water Quality Modeling in Support of TMDL Development

PVIA began development of a computer model of Lake Wister in 2014, contracting with Dr. Thad Scott, a limnologist (lake specialist) then at the University of Arkansas to lead that effort. Dr. Steve Patterson at Bio x Design worked with Dr. Scott as PVIA’s ecological restoration consultant. Dr. Scott moved to Baylor University in 2016, where the modeling work was completed.

The modeling report has been reviewed by PVIA and by the Oklahoma Department of Environmental Quality, and revised in response to their comments.

A copy of the Lake Wister Water Quality Modeling in Support of Nutrient and Sediment TMDL Development report may be reviewed or downloaded here.


Best Management Practices for Construction and Maintenance of Dirt and Gravel Roads, on February 28, 2013, at Lake Wister.

Reducing soil erosion from unpaved roads in the watershed. One of the main sources of soil erosion in many watersheds is sediment that enters streams and eventually the lake from eroding dirt and gravel roads. PVIA partnered with the Choctaw Nation and the Nature Conservancy to sponsor a workshop highlighting techniques of road construction and maintenance that can help reduce erosion, while saving money in the long run because the need for road maintenance is reduced.

For more information on the workshop and these techniques, click here.