What do nine spillways open on Table Rock Dam really mean?

It generally means water is being released from Table Rock Lake through the Spillways of Table Rock Lake Dam under the White River Basin Water Control Plan (Plan), revised as of December 1998. The number of spillways open doesn’t mean much; however, the amount of water going through the dam’s Spillways does!

Nine gates open at Table Rock Dam

The goal of the Plan is to capture, store and get the water that could cause flooding into Bull Shoals Lake until it can be safely released downstream. According to the U.S. Army Corps of Engineers (USACE), the Plan, “simply stated, says releases from Beaver are dependent upon the elevation in Table Rock and Bull Shoals Lakes; releases from Table Rock are dependent upon the elevation in Bull Shoals Lake; and releases from Bull Shoals and Norfork are dependent upon the seasonal regulating stage at Newport, Arkansas.”

The USACE Dam Safety Facts for Table Rock Dam state that the ten spillways can pass 558,000 cubic feet per second (CFS) or 55,800 CFS PER spillway per second. It is possible to open each of the ten spillways incrementally. In addition, 15,100 CFS can be released through the dam’s four turbines. As this article is being written, at 10 a.m. on April 15, 2025, the nine spillways open on Table Rock Dam are releasing 8992 CFS. In addition, 6452 CFS are coming through the dam’s turbines for a total release of 15444 CFS.

When the elevation of Table Rock is between 915 and 920, and Bull Shoals is below 684, the Plan requires the release of 15,000 CFS until it drops below 915. Typically, just the turbines are used, but two are down for maintenance, requiring the supplemental use of the spillways to get to the 15,000 CFS the Plan calls for. Lake elevations between 921 and 931 call for a release of 20,000 CFS, requiring both the spillways and turbines.

When the lake level rises “above, or predicted to exceed 931, the Plan requires regulation to obtain the most effective flood modification with the designated surcharge storage space.” There is no set CFS release, and it depends on the amount of inflow to Table Rock Lake.

People often ask, “Why doesn’t the USACE use forecasts to pre-release before rain?” The USACE Dam Safety Facts for Table Rock Dam says, “Regulation during storm periods is based on runoff predicted from the rain that has occurred and can be measured. Rainfall forecasts are not sufficiently accurate to base operational decisions on them. Because rainfall forecasts are inaccurate, pre-releasing would put downstream users at risk if rain developed in the uncontrolled areas instead of upstream of the dam. Conversely, we are also asked by some users to stop releases from the dams before a rainfall begins. This can also cause issues since we would be holding water in the flood pool, which lessens our ability to reduce peak downstream flows from large rainfall events.

Another commonly asked question is, “Why not lower lake levels in the winter to prepare for spring rains?” That same source says, “While lowering lake levels in the winter to prepare for spring rains does in effect increase the size of the flood pool, at the same time it takes away from hydropower and water supply storage. The Corps does not have legal authority to do this. The current allocation of storage for flood damage reduction as approved by Congress. Changing that allocation would require Congressional action.

“Also, that is a very risky suggestion because there is no way to forecast long-range how much or how little rain will fall. If the Corps artificially lowered lake levels in the winter and spring rains did not come, a shortage of water to generate electricity, meet the needs of water utilities or provide viable recreation opportunities could ensue. The water supply and power users pay for that storage. If the drought progressed, instead of recovering, lake levels could continue to drop and cause an extreme water shortage.”