On groundhogs and water levels: What will reservoirs look like on Memorial Day?

February has arrived and Groundhog Day has come-and-gone. So this makes me a little late in giving my annual prediction on how the three Corps of Engineers’ Savannah River reservoirs will begin the 2015 tourist season.

Now whether my prognostication will be any better than those of large, furry rodents is to be determined. Will I be better than Punxsutawney Phil (Pennsylvania), Gen. Beauregard Lee (Georgia), Jimmy the Groundhog (Wisconsin) or those pesky prairie dogs of my west Texas childhood? Time will tell.

In my past forecasts, I correctly predicted conditions about half the time but I’m getting better – which is about the same as the groundhogs crawling out of their holes. At least I won’t bite the ear of a local mayor as happened in Sun Prairie, Wisconsin, this month. So here goes…

I didn’t use a crystal ball or my shadow to make this foretelling, but rather forecasts from the National Weather Service for rainfall and discussions with Savannah District water managers for inflow and outflow expectations.

As of this writing Hartwell, Russell and Thurmond reservoirs continue on the rise, as does the winter guide curve for Hartwell and Thurmond. (Russell has one guide curve year round.) The rising levels have ‘chased’ guide curve for some weeks but remain about one foot below the daily guide curve. As noted in last week’s posting, winter rainfall gives more runoff into the reservoirs than the same rainfall would in the summer. However, the rainfall in January did not reach average levels. As of this writing we remain in Drought Level 1 conditions which limit discharges from the system.

The National Weather Service predicts dry and wet spells through the next 14 and 30 day range. Some precipitation will be above average, some below. The 90-day outlook shows equal chances for above or below average rainfall. What does this mean? It means 2015 matches an ‘average’ year.

Average years have reservoir levels slightly below full summer pool (660 ft-msl at Hartwell, 330 ft-msl at Thurmond). Average rainfall, average runoff, average, average, average.

So at this time it looks good – very good, in fact – for reservoir levels to reach or remain just slightly below full summer pool on Memorial Day at Hartwell and slightly below at Thurmond. We must keep Thurmond no higher than 329 ft-msl for worker safety while ongoing gate repairs continue.

All in all, a good place to start the summer. Just two or three extra rain storms in the meantime and the levels could be even better.

I’m not sure whether I saw my shadow for this posting. I’m not sure what difference it makes, either. I just know I feel good for the start of the season. Until then, I think I’ll crawl back into my hole.

~Billy Birdwell, Corporate Communications Office

About US Army Corps of Engineers Savannah District

The U.S. Army Corps of Engineers Savannah District oversees a multi-million dollar military construction program at 11 Army and Air Force installations in Georgia and North Carolina. We also manage water resources across the Coastal Georgia region, including maintenance dredging of the Savannah and Brunswick harbors; operation of three hydroelectric dams and reservoirs along the upper Savannah River; and administration of an extensive stream and wetland permitting and mitigation program within the state of Georgia. Follow us on Twitter @SavannahCorps and on Facebook.com/SavannahCorps
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