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Six White River Basin lakes are operated together as a system to reduce the frequency and severity of floods. These lakes are Beaver, Table Rock, Bull Shoals, Norfork, Greers Ferry and Clearwater. Beaver, Table Rock and Bull Shoals lakes are in a row along the main stem of the White River in Arkansas and Missouri. Norfork Lake is on the North Fork River, which empties into the White River near the town of Norfork in north central Arkansas. Clearwater Lake is on the Black River near Piedmont, Missouri. The Black River's confluence with the White River is near Jacksonport, Ark. Greers Ferry Lake is on the Little Red River near Heber Springs, Ark. The Little Red's confluence with the White River is near Georgetown, Ark.
Yes. Both the Corps and SWPA are following the missions entrusted to them under the law.
The water control 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. Release criteria for the lakes was developed more specifically based upon the pool elevation, pool elevation of downstream lakes, the time of year, and downstream river conditions.
From 1 December through 14 April - Regulate to 21 feet except, if a natural rise exceeding 21 feet occurs, regulate to the lesser of the observed crest or 24 feet.
From 15 April through 7 May - Regulate to 14 feet except, regulate to 21 feet, from 15 April through 30 April, and 18 feet, from 1 May through 14 May, if the four-lake system storage exceeds 50% full.
From 8 May through 30 November - Regulate to 12 feet except, regulate to 14 feet from 15 May through 30 November, if the 4-lake system storage exceeds 70% full.
Release a minimum of firm power and in extreme cases zero if a significant reduction in critical downstream flood conditions is possible.
Prorate the flood control releases between Bull Shoals and Norfork to maintain equal percentages of available flood control storage in NF and the BV-TR-BS.
Release a maximum of 32,500 cfs from BS and 10,500 cfs from NF subject to a 50,000 cfs flow limit at Batesville.
Curtail secondary power generation releases exceeding firm power until six days after the crest at Newport. Secondary power releases should provide that stages above the regulating stage continue to recede until the regulating stage is reached.
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 was 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.
The Corps does deviate from the water control plan from time to time when necessary to meet the objectives of the system while not creating significant adverse impacts. The impacts depend on the location, nature of the deviation, and its duration. In general, the water control plan is a compromise among the users of the system who possess an allocation of water. What is optimal for one user of the system will not be optimal for another user of the system. All users accept some risk. When a deviation is approved, typically, one user group moves closer to its optimal conditions while others are moved further from theirs.
Proposed changes to the operating plan would require authorization and funding by Congress to study the impacts. All user groups would have input on changes they desire, even though each change to benefit one group would have a negative impact on another group or groups. These impacts would need to be communicated to all stakeholders in the basin and a new plan developed and coordinated before it could be implemented. In the end, substantial changes in operations are unlikely because of the substantial impacts they would cause, and there is no way to predict the outcome of less significant changes (who wins, who loses).
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.
The design of the dams included a minimum flood control release when the lake has flood storage in use. That minimum flood release is typically passed through the turbines. For example, if rain causes the regulating stage at Newport to be exceeded, the Corps will continue releases from Bull Shoals and Norfork powerhouses but will limit them to a combined total of about 5,050 cubic feet per second. This minimum release is made to continually free up storage space and enable the dams to reduce the peak should a large, infrequent flood event occur. This release is typically passed through the turbines to gain the benefit of generating electricity while evacuating flood storage.
Conversely, when the lakes are below conservation pool, no minimum flood control release is required because there is no stored floodwater to evacuate. However, in the near future we will see minimum releases even when the lakes are not storing floodwater because Congress authorized minimum flows at Bull Shoals and Norfork to improve water quality in the tailwaters.
Analysis of over 60 years of hydrologic data has proven that major floods develop from the accumulation of storage in the lakes from persistent, repeated rain storms that do not allow enough time in between to evacuate flood storage. In other words, flood storage is most always filled at the lakes by several smaller storms rather than by one large storm. So using that long-term perspective, the Corps prepares for the future by making releases whenever possible any time flood storage is in use.
As the White River basin has developed, the request for operations keyed to specific interests has intensified, and at times these requests are for conflicting operations. Farmers request lower river stages; navigation interests request sustained rivers stages; downstream fisheries want sustained low level cold water releases; hydropower interests would like sustained high pool levels; those concerned with downstream flood control would like low pool levels; still others would like constant pool levels. The water control plan managed by the Corps is a compromise to distribute the benefits fairly among all stakeholder interests.
It is a matter of balancing flood storage among the lakes in this interconnected system to best prepare for a variety of scenarios if more rain falls. This is a key part of the water control plan. It helps to understand that Bull Shoals Lake has more than twice the flood storage capacity of Beaver and Table Rock combined. The flood pool at Bull Shoals is 41 feet deep. By comparison, the flood pool at Table Rock is only 16 feet deep, and the lake is much smaller. Let's say we've had heavy rain and Bull Shoals is 15 ft high. It still has more than two-thirds of its flood storage capacity available to capture more rain runoff. When Table Rock Lake is 15 feet high, it is 99 percent full and a fairly small rain event could cause it to spill and flood homes and businesses downstream. So we have to start bringing Table Rock Lake down first.
Yes. These lakes were among dozens Congress ordered the Corps to build in the Mississippi River Valley to reduce flood damage and loss of life. This was primarily in response to the great flood of 1927, which swelled rivers across the entire Mississippi River Valley. That year incessant rainfall soaked 31 states and two Canadian provinces. This and subsequent floods in the 1930s and 1940s prompted legislation that led to construction of the Corps dams in the White River Basin. These lakes also work in conjunction with a system of levees, which provide additional reduction in flood damages. Since they were constructed, the White River Basin lakes and levees have prevented an estimated $960 million in flood losses.
The Corps attempts to balance the percentage of flood storage available in the three lakes on the main stem of the White River (Beaver, Table Rock, and Bull Shoals) with the percentage of flood storage available in Norfork. This better ensures the full use of available flood storage when needed. Computer simulations of 60 years of river data show that maintaining equal percentages of available flood storage between the 3-lake sub-system and Norfork Lake best provides flood damage reduction to the lower White River valley.
What do we mean by balance? If Norfork is using 85 percent of its flood storage capacity, we make releases try to balance the average flood storage capacity in use at 85 percent across Beaver, Table Rock and Bull Shoals. This does not mean we try to hold each of these three lakes at 85 percent full, it is the average among these three lakes. Keep in mind, Beaver provides supplemental storage for Table Rock and is much smaller. Table Rock protects homes and businesses immediately downstream of the dam. Bull Shoals Lake is larger than Beaver and Table Rock combined and has more than double the flood storage capacity. Bull Shoals works with Norfork Lake to reduce flood peaks in the lower White River Valley. For example, holding flood water in Beaver's flood pool when there is flood control storage in use at Table Rock and/or Bull Shoals provides the additional flood storage for Table Rock. This ensures that Beaver Lake fills first and empties last. Evacuating storage from Table Rock provides the maximum downstream protection and ensures that if rain continues, Table Rock and Bull Shoals will be in balance as both begin reaching their maximum capacity.
Beaver Lake provides supplemental flood storage for Table Rock and Bull Shoals. The releases from Beaver Lake are limited to 1,000 cubic feet per second daily average release when either Table Rock or Bull Shoals is more than 2 feet into the flood pool. Once the current pool elevations for both Table Rock and Bull Shoals are within 2 feet of their conservation pool elevation, releases can be increased from Beaver Lake.
Beaver Lake is first in the 3-lake chain (Beaver, Table Rock, and Bull Shoals). If we release floodwater stored in Beaver into Table Rock and Bull Shoals while they are already storing floodwater, we use up more storage capacity in those two lakes. If additional rain falls in the Table Rock and Bull Shoals drainage basins, they will fill even more, while Beaver Lake's flood pool sits empty and unable to help. Once the water leaves Beaver Lake, we cannot put it back. On the other hand, if more rain falls in the Beaver drainage basin and fills its storage capacity, we can simply move some of the floodwater into Table Rock and Bull Shoals at that time. It is in accordance with the water control plan, which has been carefully thought out and reviewed multiple times over the years. To do otherwise would increase flood risks all along the White River downstream of Beaver Dam.
The Corps has a water management Website at www.swl-wc.usace.army.mil. Real-time data, project operating data, and daily reports are a few of the items available. Also, the White River Water Control Plan is available on this site. In addition, our personnel make annual presentations to local elected officials and emergency managers from jurisdictions along the rivers. At other times, presentations are made to various stakeholder groups at their request. The Reservoir Control staff also fields numerous phone calls from the general public, media, and congressional staffs throughout the year
Yes, exactly as designed. The six lakes working in conjunction with levees downstream in the river basins prevented an estimated $116.3 million in flood damage. Even though some of the lakes filled to record levels in April that year, peak discharges downstream were actually tempered by operating the spillway gates. When the spillway gates are opened, they temporarily create or induce additional flood storage because water can be stored to a higher level. Since the flow coming into the lake was greater than the amount released, the lake rises while the downstream flood peak is reduced.
For instance at Beaver Lake, the peak flow coming into the lake was 110,000 cubic feet per second, but the peak flow released at the dam was only 92,400 c.f.s. At Table Rock, the peak flow coming into the lake was about 252,000 cubic feet per second, but the peak flow released from Table Rock was only 48,300 c.f.s. Further downstream, the peak flow coming into Bull Shoals Lake was 198,000 cubic feet per second and the peak flow released was 35,500 c.f.s. Norfork Lake also made a large spillway release. Peak inflow to Norfork was about 115,000 cubic feet per second and the peak flow released was 81,700 c.f.s.
Although the releases from each dam were many more times larger than the typical hydropower release, the dams performed exactly as designed by reducing the peak flow released into the White River basin, which lessened the extent of downstream flooding and undoubtedly contributed to saving lives. From the information above, had Bull Shoals and Norfork not been in place and the flood peaks coincided, the flow in White River could have exceeded 300,000 cubic feet per second which is much higher than the 117,000 c.f.s that was the combined release from the two dams.
The spillway is designed to pass 342,000 cubic feet per second. Engineers can conceive of conditions that could lead to flows up to 1.3 million c.f.s. at the dam, but this would be an extremely rare flood event.
Jacksonport levee protects Jacksonport, Diaz, and a large agricultural area. The Newport levee protects the City of Newport. The Village Creek, White River & Mayberry levee protects an agricultural area in Jackson & Woodruff Counties. Kitty Burns levee protects agriculture. Des Arc levee protects the City of Des Arc. The De Valls Bluff levee protects the City of De Valls Bluff. White River Levee District levee from Augusta to Clarendon protects agriculture in Woodruff, Prairie and Monroe Counties. Clarendon Levee District levee protects the City of Clarendon. The White River backwater levee protects agriculture in Phillips & Desha Counties
Flood damage reduction lakes work by capturing runoff in their flood pools during heavy rain. After rivers downstream begin receding, water is released in a controlled fashion following pre-determined operating plans. Without the lakes, all that water would roll downriver at one time. Flood crests would rise higher and spread over more land, thus causing more damage and possibly loss of life. The water stored in the flood pool must be evacuated in preparation for the next storm as quickly as downstream conditions permit without creating additional flooding. The difficulty with repeated rain is engineers are not always able to release all the water captured in the flood pool between rains. This can cause lake levels to rise with each new rainfall. When that occurs, it can sometimes take many months to empty the huge volumes of water from the flood pools and return all the lakes to their conservation pools.
It is worth noting the lakes are not intended to prevent all flooding. The lakes have limitations that Mother Nature can exceed, and from time to time does. Therefore, downstream property owners should be judicious in how they develop land within the flood plains. Floods are not as frequent because of the dams, and when they do occur, they are typically not as severe as they were before the dams were built. But there will still be occasions when significant floods occur downstream of these dams. Planting crops on land that floods on occasion might be profitable in the long run. Building a home or business on that same land might not be. Farming, running a business, or having a home in the flood plain of a river is a risk that each landowner accepts.
When Congress instructed the Corps to build the White River Basin lakes, they also told the Corps to include storage for hydroelectric power generation at five of them; Clearwater Lake does not have hydropower. Water supply storage was also included at Beaver Lake, and Congress gave the Corps authority to reallocate limited amounts of storage in each lake for additional water supply. The storage space that holds water for hydropower generation and water supply primarily comprises what is referred to as the conservation pool. Basically, the conservation pool creates the lakes and provides the ancillary recreational opportunities. In recognition of these opportunities, Congress also instructed the Corps to provide public access at each lake, hence the Corps parks. Most recently, some storage is being reallocated at the direction of Congress to provide minimum flows below Bull Shoals and Norfork Lakes.
In a nutshell, the White River Basin lakes were built to store water for hydropower and water supply during average weather and to store floodwater during wet weather. Therefore, the lake levels are weather dependent. Levels can range from very high during abnormally wet weather to very low during drought. This is how the lakes were designed, and it is how they provide benefits to repay the taxpayer investment in them. Just this decade, weather patterns have created both drought (2005-2007) and flood conditions (2008-2009).
The Corps does not have the legal authority to manage lake levels for recreation. The Corps is bound under the law to follow the White River Water Control Plan, which dictates how the system is operated.
This plan has a lengthy history. In 1942, the Basis of Design for Definite Project Report was developed, which included the original studies for the method of operation for Bull Shoals and Norfork. This report helped establish the size of the flood and conservation pools in each lake. In 1952, the Plan of Flood Regulation for Bull Shoals and Norfork Reservoirs was developed. This reports described the proposed plan of regulation for Bull Shoals and Norfork. In 1954, the Master Manual for Reservoir Regulation of the White River Basin was first developed. This described the operating criteria for Bull Shoals, Norfork, and Greers Ferry. In 1963, the Reservoir Regulation Manual for Beaver, Table Rock, Bull Shoals, and Norfork Reservoirs was developed. This was revised in 1966. In 1993, the Master Manual for Reservoir Regulation for White River Basin was developed. No changes to the Water Control Plan were made, only basin conditions were updated. The economic analysis showed that changing the allocation of storage for purposes other than flood control, hydropower, or water supply was not economically justified. In 1998, after years of additional study, a revision to the water control plan was made that lowered the regulating stages on the White River.
The key is that rainfall amounts and consumer demand for electricity determine releases from the dams either through power generation, spillway gates, or conduits. At times, water may be released through all three. In 2005, 2006 and 2007, this region experienced below normal rainfall and drought. Because there was less water coming into the lakes, there was less water released from the dams, but some power generation was still necessary to meet consumer demands for electricity. Therefore, most lakes experienced lower lake levels. By comparison, 2008 and 2009 were wet, flood-producing years, and with so much water coming into the lakes, lake levels remained high much of the time until all the stored floodwater could be released in a controlled fashion according to the Water Control Plan. The early part of 2010 was pretty wet, and lake levels again rose. However, dryer weather prevailed by late spring, and as captured flood waters were released, lake levels began returning to their conservation pools.
Conditions in the lake and conditions downstream of the dam help dictate releases. When a lake is in its conservation pool, Southwestern Power Administration determines the releases within certain limits. They are subjected to 7-day and 28-day drawdown limits, along with having a minimum release requirement to ensure trout survival during the warm months. SWPA is also subject to maximum release limits based on downstream conditions during high water. The maximum release is determined by the Corps Water Control Plan. Since the lakes are operated as a system, it gets still more complex. For instance, Beaver Lake releases are determined by conditions in Table Rock and Bull Shoals lakes downstream. Below Bull Shoals, Norfork and Greers Ferry lakes, releases are determined based on river levels miles downstream of the dams. The Corps will release water stored in the flood pools of Bull Shoals and Norfork based on the White River stage at Newport to empty the lakes as quickly as possible.