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

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Eno River Capacity Use Agreement According to the 1987 Capacity Use report, the historical roots of the impetus to evaluate and control water use in the Eno basin stemmed from the total dewatering of the Eno riverbed below Lake Ben Johnson (Hillsborough's run of the river reservoir and raw water intake location) for prolonged periods "particularly after 1977". In 1979, Orange County established a water resources task force to address water supply issues, The task force report issued in 1981 alluded to the possible designation of the Eno as a capacity use area, Growth, rising water demand and riverbed dewatering problems continued unabated in subsequent years, In July 1986 the County adopted its water conservation/drought ordinance which limited water use by individual water customers/consumers on the basis of the amount of water storage remaining Lake Oranges and, in November 1986, the BOCC formally requested that the NC Division of Water Resources initiate a full capacity use investigation. The capacity use investigation culminated with the completion in September 1987 of the "Report on the Eno River Area Capacity Use Investigation", This report recommended, among other things, that the entire Ena basin upstream of the confluence of the Eno and Little Rivers in central Durham County be designated a surface and ground water capacity use area, During the period of time between the completion of the report and May of 1989, the stakeholders in the Ena water use issue (Orange County, Town of Hillsborough, Orange-Alamance Water System, Piedmont Minerals, and NC Division of Water Resources [DWR]) entered into a voluntary "Eno River Capacity Use Agreement" which dealt only with surface water use at and upstream of Hillsborough, In accordance with the provisions of the Capacity Use Agreement, Hillsborough, Orange Alamance and Piedmont Minerals have voluntarily committed to a process in which limitations on the quantity of raw water withdrawn from the Eno are initiated by a specific naturally occurring low instream flow condition. That is, when natural instream flow (flow not supplemented by releases from Lake Orange) falls below a daily average of 10 cubic feet per second [cfs] or approximately 6,5 million gallons per day [mgd] for seven consecutive days, the first level of withdrawal limits are implemented, Each of the individual withdrawal allocations is specified as a daily withdrawal (ex. Hillsborough at 1,51 mgd) but is actually calculated as a daily average over aseven-day period (for example, Hillsborough's daily withdrawal rates could [and often do] vary between 0..9 mgd and L8 mgd over aseven-day period but still average 1,5 mgd or less for the week). Individual withdrawal allocations from the Eno River are further reduced according to water levels (and water storage remaining) at Lake Orange (for example, Hillsborough's allocation is reduced to 1,36 mgd when the Lake Orange water level drops to two feet below full). Orange County's role in the agreement is to coordinate the overall operational activities related to water withdrawals; to release water from Lake Orange as necessary to meet the withdrawal demands; and to maintain a minimum rate of instream flow (1,7 cfs [1.1 mgd] specified to be an instantaneous minimum flow target) in the river as measured at the Hillsborough gage (a USGS operated stream flow gage located south of Town, below the last point of withdrawal but above the point where the Town discharges treated wastewater into the river).