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Thursday, Nov. 27, 2014

Stocking restriction lifted on Bull Shoals and Norfork tailwaters

Thursday, December 11, 2008

Due to improved dissolved oxygen conditions on the Bull Shoals and Norfork tailwaters, the stocking restrictions have been lifted.

Matt Schroeder, Arkansas Game and Fish Commission Trout Management Biologist, explained that destratification is a result of decreasing temperature and increasing density of the top layer (epilimnion) of Bull Shoals Lake. "When surface temperature and density of the epilimnion reach that of the bottom layer (hypolimnion) the lake mixes or turns over," Schroeder said. "Once these two layers are mixed with the aid of wind, the bottom layer of the lake is again recharged with dissolved oxygen."

Because the intakes of the dam are located in the same area, dissolved oxygen in the tailwater discharge improves as well, Schroeder said. "Around the same time Norfork Lake also began to destratify. However, this process is taking longer to develop and at times the dissolved oxygen levels in Norfork Tailwater is still below state mandated level 6.0 parts per million. As of Nov. 22 the level has consistently been around the 6.0. If this trend continues for the rest of this week, we can infer that Norfork Lake has also destratified."

Greers Ferry Lake, however, is further away from destratification.

The dissolved oxygen level in the Greers Ferry tailwater has continued to fluctuate with patterns of generation and has continued to decline overall during periods of non-generation.

"The Trout Program along with AGFC District Biologists will continue to monitor the dissolved oxygen levels of Norfork and Greers Ferry tailwaters with direct measurements and readings of USGS gauges. Once it has been determined that these lakes have destratified and the resulting D.O. conditions have improved the stocking restrictions will also be lifted from Norfork and Greers Ferry tailwaters," Schroeder stated.



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