On watermelons and water levels

Summer in the Southeast means many things. Heat and humidity come to mind first, of course, but so do things like lazy Sunday afternoons, fishing trips, water skiing, firefly chasing and eating watermelon under a shade tree.

In the upper Savannah River Basin, it also usually means less rain and declining reservoir levels. Besides less rain, the heat means more water evaporates from the reservoirs and the plants along the shore suck more water out of the reservoirs to keep themselves green.

As our commander, Col. Marvin Griffin, noted in his July 13 post to this blog, abnormally hot, dry weather drives many factors that lead to a decline in reservoir levels. He also noted we have plans for dealing with this situation: the Water Manual and the Drought Contingency Plan.

While some have criticized both, the plans prove effective over and over. They strike a balance in managing our resources among a variety of users, whether the basin has too little rainfall, too much rainfall, or “just right” rainfall.

The Corps of Engineers and our partners from Georgia and South Carolina natural resource agencies along with The Nature Conservancy, continue to study the river and the management of it. For details on the status of the Comprehensive Study, refer to our June 8 blog post.

The current interim phase has limited scope. It seeks to answer two basic questions: How long can we reduce daily outflows from Thurmond Dam during drought and how many days can we reduce them before significantly impacting the environment. We are evaluating six alternatives to the current Drought Contingency Plan:

  1. Extreme Drops: This alternative considers extreme reductions in outflows for each drought trigger. For example, the model considers a reduction of releases to 3,500 cubic feet per second (cfs) in Drought Level 1. In Drought Level 2: 2,500 cfs. In Drought Level 3: 1,500 cfs.
  1. Higher Drought Level Elevation: This alternative considers redefining the elevation at which Drought Level 3 occurs. Currently, Drought Level 3 is defined as 14 feet below summer full pool with a minimum outflow of 3,800 cfs (3,100 cfs in November-January). This alternative would define Level 3 at 8 feet below summer full pool, with a minimum outflow of 3,600 cfs.
  1. Release Based on Environmental Flow Recommendations: This alternative incorporates a wider variation in outflow volume based on seasons, conditions, available rainfall and environmental requirements. The alternative’s intent is to define the underlying goal of water management that provides greater benefits to the environment.
  1. 3,600 CFS Constant: This alternative reduces all outflows immediately to 3,600 cfs at the first drought trigger and maintains this outflow until the reservoirs rise two feet above the first drought trigger. During the months of November through January, the outflow would drop to 3,100 cfs.

Alternatives 5 and 6 are combinations incorporating elements from these first four alternatives.

Some have asked, “Will the Comp Study actually change the Drought Contingency Plan? If so, how?”

We don’t know the answer to either of those questions and we won’t know for a while yet, as noted in the June 8 post. The study may find that the “No Action Alternative” takes the best overall approach. This would leave the drought plan as it is.

After our complete analyses we’ll see if one of them would be a better overall approach than our present plan. If so, we’ll send our recommendation to our South Atlantic Division office in Atlanta for approval. Until we complete our analyses, we just don’t know if one of the alternatives will be better.

However our findings and recommendation turn out, state and federal natural resource agencies, which along with the Corps guard this precious resource, will be involved. As normal we will seek public comments before making any final decision.

Ultimately, the only real solution to drought is more rainfall, (but not too much – we don’t want to end up fighting floods).

Keep watching this column for updates.

Oh, and if you have a cool watermelon under a nice shade tree, let me know. I want to stop by.

~ 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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