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.

Courtesy corp of engineers

Top 6 Tips for De-Winterizing – Is Your Boat Ready For Spring?

In October 2013 we announced an initiative to assess our flood storage capacity to test the possibility of reducing our current flood storage allotment. More specifically, the study will provide information that will better define the present need for flood storage in the basin. In the announcement we estimated the study would take approximately 12 months. Based on recent updates from the Hydrologic Engineering Center (HEC), the organization conducting most of the study, the results will be delayed about six more months.

To recap, the assessment will look at two things:

1) the ability of the projects to contain the Probable Maximum Flood (PMF), which however unlikely, is the greatest rain event the basin could ever expect; and

2) the ability of the projects to contain a number of smaller and more likely periods of rainfall intensity, from 10- to 500-year rain events. The assessment models intense rain events, and how runoff occurs in the basin with the present level of development. It will compare impacts of each of these rain events using our current 4-foot drawdown with impacts of lesser amounts of flood storage (smaller winter draw downs). The idea is to assess how much flood storage we need and identify what kind of risk we are taking if we reduce the winter drawdown and then get the inevitable large spring rain. If the study indicates that all the present flood storage is not needed, additional studies could be performed to determine how much storage is economically justified.

Update on the Savannah River Basin Comp Study (Interim 2)

In February we provided an update on the progress of the Comp Study. We estimated then, that the draft report would be ready for review in about 12 months (putting us at approximately February 2015). An updated estimate on completion of a draft report for public comments is about January 2016.

After we ran an initial data set through the models, the Corps and the study sponsors agreed that we needed to add data from 2013 to our inflow dataset to have more accurate results.  We are obtaining that information to make sure we capture the recovery of the system from the most recent drought, possibly the new drought of record, which occurred from 2011 to 2013. Georgia Environmental Protection Division (GAEPD) is now collecting the needed data and when their work is complete, we will run the reservoir simulation models again to evaluate each of the six proposed alternatives.

Other work continues. The Nature Conservancy (TNC) has been performing research and held a workshop to help define parameters for Alternative 3: “Release Based on Environmental Flow Restriction.” TNC is finalizing their report from that workshop and they will then update the ecosystem functions model to incorporate additional environmental criteria that we will use to evaluate each alternative.

To recap, the purpose of this interim is to answer the following questions:

1) How low can we reduce daily outflows at the Thurmond Dam during drought conditions?

2.) How long can we sustain these minimum outflows before significant negative impacts would occur to the downstream economy and environment?

This portion of the study will examine value, risks and impacts of six alternative operating protocols for the current Drought Contingency Plan. You can see summaries of these alternatives here.

~Russell Wicke, Corporate Communications Office Chief

– See more at: http://balancingthebasin.armylive.dodlive.mil/2014/11/19/compstudy/#more-1805