Dissolved Oxygen

Dissolved oxygen levels are very low in our Arkansas tailwaters this year. I don't remember it being this low in the past. Debri left suspended in the lakes from the spring 2008 floods may have something to do with it. Stocking has been suspended in the upper sections below the reserviors because of unusually low DO levels. The charts in the image to the right (click to enlarge) show the October 2008 DO and temperatures for all five White River basin reservoirs. The Table Rock and Norfork DO levels drop to near zero at around 60 feet. The others still have varying levels of DO stratified throughout the water column. But they're all near zero at the bottom of the lake.

The following images include a 2008 time lapse view of the DO and temperatures for each of the five reserviors. The bright red line is the March 2008 readings. That's the lowest point in temperature and highest point for DO in the annual stratification of the water column. Follow the two charts in sequence and you can see the DO dropping as the temperatures rise near the surface. As temperatures fall through the winter the DO levels will begin to rise again. The changing temperatures through the water column is commonly refered to as "turnover". But as you can see from the charts, it takes several months for the lakes to actually turn over. There's a link to daily tailwater DO levels on the Generation Tables page. Follow the link under Fish AR & MO to get there.