This is what the ncdnr guy said a couple of weeks ago....
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Aug 5th, 2010 - 9:18 AM QuoteReply Is Duke Power holding the "smoking gun" that started the striper kill?
Based on the comments from the wildlife commission guy, sounds to me like this all started when Duke released the lower level cold water and the dissolved oxygen levels plummeted. The fish were shocked and they died. Some might have died eventually due to the heat wave, but Duke's draw down seems to be a tipping point.
Obviously none of the hopeful comments he made back in July actually came to pass. I copied his comments below.
"Also, a new variable was added to the equation this year. Duke needed to pull water from the hypolimnion by running the lower level intake in order to meet their thermal discharge requirements of their NPDES permit. The use of the lower level intake is not [unusual]; however, in the past they were able to wait until later in the summer when large fish were not occupying the hypolimnion. The hot weather and water temperatures have not allowed that to happen this year. Duke began running the lower level intake Monday afternoon and they have been running hydroacoustic, DIDSON (sonar), and water quality surveys ever since. Water quality data have indicated that the use of the lower level intake has decrease DO in the hypolimnion faster than in past years. For example, DO decreased 0.5 mg/L from Monday to Wednesday and this type of decrease usually takes 6-7 days. However, as of yesterday, DO in the hypolimnion was still slightly greater than 2.0 mg/L.
While a few deaths have been observed this week, we hope that 1) the decline in DO in the hypolimnion occurred before too many striped bass congregated down lake or 2) the rapid decline in DO in the hypolimnion was a cue or forced striped bass out of the hypolimnion to "brave" warmer water temperatures. That said, hydroacoustic data from yesterday indicated that a number of larger fish were still occupying the hypolimnion near the dam. Therefore, it is likely that this event will continue; however, we hope it will be similar in scale to 2009 as compared to 2004."