Orange County NC Website
~~ <br />In the months and years since the agreement was first ratified, it has been modified in <br />terms of operational requirements to allow for reasonable controls and to account for <br />instream releases from Hillsborough's West Fork Reservoir. Specific operational changes <br />include: 1) modifying the law instream flow trigger (requiring seven consecutive days of <br />low instream flow) initiating withdrawal restrictions and the high instream flow trigger <br />(requiring seven consecutive days of high instream flow) curtailing withdrawal restrictions; <br />2) allowing withdrawing entities to share unused portions of their allocations with sufficient <br />notice; and 3) allowing essentially unlimited water withdrawals during periods of restriction <br />when short-term (at least 24 hours) but high (above 10 cfs) instream flows exist as a <br />consequence of intense and prolific thunderstorms; and 4) providing for higher instream <br />flows by requiring and instream flow contribution from the west fork reservoir. <br />Over the fifteen years that the Eno River Capacity Use Agreement has been in effect, the <br />specified system of controlling withdrawals and releases has worked fairly well. In general, <br />capacity use restrictions are in effect for a period ranging, on average, from early July to <br />late December, Significant deviations to the usual low flow (dry) period include the <br />summer/fall of 1989 and 2003 which were sufficiently wet that Capacity Use restrictions <br />were not implemented at all and the drought of 2002 when the low flow period spanned <br />from the beginning of April until the end of October. <br />There have been occasions numerous occasions when operational difficulties have been <br />encountered in the effort to limit withdrawals and maintain instream flow. Often the <br />outcome of these difficulties has been a period of time when there was either too much or <br />too little water was released for instream flow. Many of the problems have been related to <br />equipment failure: the water release gates at Lake Orange and power outages and other <br />failures at the USGS stream flow gage, for example, There have also been instances <br />where excessive amounts of water were withdrawn for weeks at time., <br />The processes of adjusting the release of water from Lake Orange (it is often 24 hours or <br />more before such adjustments become evident as an increase or decrease in flow at the <br />Hillsborough gage) and predicting when the users must reduce their Eno water <br />withdrawals and supplement their water demand by other sources are often unwieldy and <br />inaccurate.. However, regardless of the various operational problems, stream-watch <br />monitoring of macro-invertebrate populations and water quality parameters in the Eno <br />River below Hillsborough has shown the river to be more healthy during dry times than the <br />upper reaches of the Little and Flat Rivers, which have much larger drainage areas and no <br />water withdrawals upstream of the monitoring paints, Addition indications of the efficacy <br />of the Capacity Use Agreement may found by evaluating how the system worked during <br />the 2002 drought in which this area, including the Eno basin, experienced the most severe <br />draught conditions evident in more than 75 years of official rainfall/streamflow record <br />keeping, Although a critical water supply shortage was narrowly averted, the drought <br />eventually came and went without completely emptying Lake Orange and with several <br />months of water supply (sufficient to meet at least Hillsborough's demand) remaining in <br />the West Fork reservoir. <br />4 <br />