Savannah River Dams to make controlled spillway releases due to recent rains

Due to recent above-normal rainfall in the upper Savannah River Basin, Savannah District anticipates a need to operate the spillway gates early on the morning of Dec. 31 at the three major dams in the Savannah River system: Hartwell Dam, Richard B. Russell Dam and J. Strom Thurmond Dam.

Once spillway gates are opened they will likely remain opened for five to seven days, until water from the recent storm event can be safely evacuated from the reservoirs making room for future storms. Although high volumes of rainfall are causing these conditions, water managers said there is no cause for concern, and that the dams and reservoirs were designed and equipped to handle this kind of eve0115Dam03_t300nt; they are well within their operating parameters.

Normal access to dam sites may be restricted due to road closures and limited staffing. Typical viewing areas will be closed as a precautionary measure. The road to the Hartwell Power Plant will also be closed to vehicle traffic. Project offices will be coordinating with Georgia and South Carolina law enforcement officials to regulate traffic flow near the dams.

Record-breaking December rainfall is the cause of increased water levels at all three reservoirs. The scheduled operational releases will increase flood storage capacity allowing the reservoirs to manage additional rain and inflows.

Above-average precipitation began in October when the upper basin received more than 200 percent of normal rainfall for the month. The large volume of inflow caused lake levels to rise beyond normal levels. Throughout this time water managers continued to aggressively operate the system via controlled releases in order to make room for additional rainfall.

November rainfall continued in high volumes, exceeding 200 percent of normal again, keeping water levels into flood storage despite release rates matching safe downstream capacity. December rainfall has continued at about 200 percent of normal and reservoir levels are expected to exceed normal flood storage, which will require operation of spillway gates with controlled releases to sustain flood storage capacity in the reservoirs.

Officials advise caution to people who might be near the Savannah River below Thurmond Dam for the next several days. Based on the forecast from the National Oceanic Atmospheric Administration (NOAA), the Savannah River below Thurmond Dam may exceed channel capacity if current rainfall causes a significant increase in local inflow. In other words, the Savannah River below Thurmond may see higher and faster flows with additional rainfall.

“Safety remains our Number 1 priority throughout this high-water event,” said Col. Marvin Griffin, Savannah District Commander. “Although we’ve experienced above-average rainfall in the past 90 days, the system is well equipped to handle much higher water volumes than what we are seeing now. Nevertheless, just like in all high-water events these conditions will result in circumstances that require caution for those in the surrounding areas, especially below Thurmond Dam where local inflows are unregulated.”

Potentially hazardous conditions resulting from high water and increased flows include floating debris, submerged retaining walls and higher river velocity downstream of Thurmond Dam. Additionally, high water is also a possibility in properties between Stevens Creek Dam and Thurmond Dam. As lake levels rise, some Corps managed recreation areas upstream near the reservoirs will be closed for public safety reasons as facilities become unusable.

Daily updates will be posted on the Savannah District Facebook page and the district’s Twitter feed: @SavannahCorps.

For more information on impacts to specific areas around the lakes, please contact the Hartwell Project office at 888-893-0678, or the J. Strom Thurmond Project office at 800-533-3478.

~Russell Wicke, Chief of Corporate Communications Office

– See more at: http://balancingthebasin.armylive.dodlive.mil/#sthash.U4nUZcbQ.dpuf

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November clouds precipitate like it’s 1948

It’s probably best that the last two weeks in November were the polar opposite of the first two record-drenching weeks. However, I must admit, it was interesting – exciting even – to watch the rain gauges rise.

Each of the sub-basins exceeded its monthly average early on but quickly fizzled out.

Still, that early precipitation was enough Rainfall Chart_Template-Novto propel the sub-basins into record highs for November: Russell received 9.4 inches, besting its previous record of 8.9 inches set in 1948; for perspective, its monthly average is just 3.6 inches.

Likewise, Thurmond and Hartwell collected 7.4 and 9.0 inches, respectively, posting third place numbers for the past 67 years. (Thurmond, which averages 3.4 inches, saw its wettest years in 1992 (8.6 inches) and 1957 (7.8 inches), while Hartwell, which averages 4.6 inches, received a whopping 12.7 inches in 1948 and 9.8 inches in 1992.

Probably more intriguing than the record-setting precipitation is that these “anomalies” weren’t even part of climatologists’ El Niño-related, wetter-than-average-winter predictions, which are expected to begin later this month.

If those predictions are realized, though, the water managers aren’t the only ones who will be thankful for the relative dry spell in late November.

– See more at: http://balancingthebasin.armylive.dodlive.mil/2015/12/02/nov-precipitates-like-its-1948/#more-2241

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Local weather systems in tune with fiscal calendar

The Savannah River Basin sputtered its way through September but somehow still landed close to par. This feat seems even more astonishing – if watching rain gauges can be considered astonishing – when you consider the entire basin collected more than one third of its monthly average rainfall on a single day, Sept. 25.

The rest of the month was a different story.

Hartwell, which received 4 inches Rainfall Chart_Septlast month (84 percent of its average, 4.7 inches), received less than 1/10th of an inch for 23 of September’s 30 days. One tenth of an inch is like a toddler’s spittle and probably just as annoying if you’re counting on rain.

Russell and Thurmond weren’t much better; they had 8 and 7 days, respectively, out of 30 where the total rainfall exceeded 1/10th of an inch in a 24-hour period.

Click here to see the hourly data for the sub-basins in September.

Both fared better than Hartwell with respect to their averages (Russell received 3.4 of its 3.7-inch average, while Thurmond got 3.7 inches – just over its average of 3.6).

And after all the hard work of collecting every little drop in September, Hurricane Joaquin and an associated low-pressure system brought a windfall of rain in October.

In fact, the storm delivered an average of more than 5 inches across the sub-basins, which was almost enough to bring the basin out of Drought Level 1. Almost.

When taken in context, two forces came together and in four days ameliorated a deficit for the Savannah River Basin – just in time for the new fiscal year.

– See more at: http://balancingthebasin.armylive.dodlive.mil/2015/10/09/local-weather-systems-in-tune-with-fiscal-calendar/#more-2193

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