B. Everett Jordan Lake is a U.S. Army Corps of Engineers multi-purpose lake in Chatham County. Construction on the dam started in 1967 and Jordan Lake completed filling in 1982. As seen in Figure 1, the dam is located on the Haw River just downstream of the confluence of the Haw and New Hope Rivers, with most of the Lake's storage in the New Hope basin.
The Lake is designed to provide for water supply, recreation, flood control, fish and wildlife management, and low-flow augmentation. As is typical for multi-purpose reservoirs, the Lake's storage volume is divided vertically into several "pools" which are keyed to lake level elevations. Specifically, there is a flood pool, which provides for flood control storage; a conservation pool, which provides for water supply and low flow augmentation; and a sediment pool, which provides for the accumulation of sediment.
The top of the conservation pool corresponds with the normal lake level of 216 feet mean sea level (MSL). At this elevation, Jordan Lake covers 13,900 acres. As Figure 2 shows, usable water in the lake at its normal elevation amounts to a total volume of approximately 140,400 acre-feet and is referred to as the conservation storage. Approximately 45,800 acre-feet in conservation storage, or about 15 billion gallons, is designated to provide water supply. This amount of storage is estimated to be able to furnish approximately 100 million gallons per day (MGD) during most of the severest droughts.
In addition to water supply, the Lake's conservation storage provides 94,600 acre-feet for downstream flow augmentation to benefit water quality and economic development. The low flow augmentation storage is used to maintain a minimum flow of about 388 MGD (600 cfs) at Lillington. The minimum streamflow recorded by the USGS at Lillington prior to Jordan Lake's impoundment was 7.1 MGD (11 cfs). Storage and releases for flow augmentation are provided in addition to storage for the 100 MGD water supply. Withdrawals from the water supply storage pool have no impact on the low-flow augmentation storage pool.
The State of North Carolina has been assigned the use of the entire water supply storage in Jordan Lake and, under G.S. 143-354(a)(11), can assign this storage to local government having a need for water supply storage. The North Carolina Administrative Code (15A NCAC 2G.0500) describes the specific procedures to be used in allocating the Jordan Lake water supply storage.
Allocations fall into two categories. Level I allocations are made based on 20-year water need projections and when withdrawals are planned to begin within five years of receiving the allocation. Level II allocations are made based on longer term needs of up to 30 years.
Initial allocations of water supply from Jordan Lake were made in 1988. At that time, 42 percent of the water supply pool was allocated; however, some original allocation holders have since released their allocations. Currently, 44 percent of the water supply pool is allocated. Note that allocations are actually a percentage of the water supply pool and not a rate of withdrawal. However, for convenience allocations are frequently expressed in MGD, since 100 percent of water supply storage has an estimated safe yield of 100 MGD.
Existing rules limit water supply allocations that will result in diversions out of the Lake's watershed to 50 percent of the 100 MGD total water supply yield. The EMC may review and revise this limit based on experience in managing the Lake and on the effects of changes in the Lake's watershed that affect its yield. Currently, 28 MGD of the 100 MGD yield is approved to be diverted out of the Lake's watershed.
Costs and Repayment
Jordan Lake was financed and constructed by the Federal government through the U.S. Army Corps of Engineers. Storage space for municipal and industrial water supply was included at the request of state and local officials with the understanding that the costs associated with this water supply storage would be paid for by the actual users. North Carolina statute (G.S. 143-215.38) authorized the State, acting through the EMC, to assume repayment responsibilities for these costs. The costs associated with providing water supply storage in Jordan Lake fall into three basic categories: capital costs, operating costs, and administrative costs.
The total annual cost for each one MGD allocation out of Jordan Lake varies with a number of parameters, including when the allocation is received, when water is actually withdrawn, the length of the payback period, and variable annual operating expenses. An additional administration charge of $250 is added to each annual bill regardless of the total number of MGD allocated.
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|Last Modified: 12.18.2009|