Agenda - 06-02-2004-9c - Laserfiche WebLink

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C Insofar as the West Fork Reservoir is concerned, the Capacity Use Agreement does not specify any limit on Hillsborough withdrawals from the reservoir. With the exception of the requirement for an instream flow contribution, the agreement treats water from the reservoir as if it were an outside the Eno basin water supply similar in character to treated water supplies that Hillsborough has in past times purchased from OWASA or the City of Durham , West Fork Reservoir Construction of the Phase I reservoir (impounding approximately 786 million gallons of water when filled to an elevation of approximately 633.0 feet MSL, surface area of 204 acres) was essentially completed in the fall of 2000, The net fifty year safe yield of the Phase I reservoir (not including releases for instream flow) has been estimated to be 1,8 millicn gallons per day, giving the Town a total raw water availability of approximately 3.2 mgd under the first stage of Eno River Capacity Use Agreement withdrawal limitations. Note: the term "50-year safe yield" represents a statistical projection or extrapolation that essentially means that, at a daily draft of 1.8 million gallons, there is a 700% probability that the reservoir will be completely depleted once in a 50 year period and/ora 2°/ probability that it will be depleted in any given year. The TQWn began filling the reS8rV01r in early 2001 after a resolving several problems that allowed water to leak out of the reservoir through its intake/release structure. In spite of the severe drought of 2002, the reservoir has been filled to capacity since December 2002. Releases from a partially filled (approximately 60-70%) reservoir during the summer and early fall of 2002 helped prevent the total draw-down of Lake Orange during the drought of 2002 and afforded the Town a reliable supply of raw water when its Eno allocation had been significantly reduced and no water was available for transfer from either the City of Durham or OWASA, The plethora of permitting requirements imposed an the construction/development of the reservoir by permitting authorities (US Army Corps of Engineers, US and NC Fish and Wildlife, NC Division of Land Quality- Dam Safety section, NC Division of Water Resources) include only one condition which modifies the terms and conditions of the Eno River Capacity Use Agreement. Hillsborough is required to constantly release an amount of water, ranging from 4,0 cfs (2.6 mgd) to 1.0 cfs (650,000 gallons per day [gpd]) to the Eno, based on the time of year and the amount of water impounded at the time of release. The 4.0 cfs is measured near the outlet from the dam intake/release structure occurs during the month of April if the reservoir is filled to 60 percent or more of its capacity, The 1.0 cfs minimum release (which includes an additional release to account for in-channel lases) is measured at the Hillsboro gage irrespective of the time of year ar quantity of water stored in the reservoir. The Gapacity Use Agreement has been modified only to incorporate the minimum 1,0 cfs release into the total instream flow requirement. There are no dam/reservoir permitting conditions requiring that Hillsborough use the water in the West Fork reservoir to do anything other than supplement its previously existing Eno River raw water supply. According to the Capacity Use Agreement, the Eno water supply is and has been available with only one restriction during high flow periods (total withdrawal cannot exceed an amount that equals the first stage of Eno water restrictions plus water supply available from a source outside the Lake Orange/Eno system) and with limitations during periods of low flow instream flow. There are no requirements that s