Agenda - 10-21-1986 - Laserfiche WebLink

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-t -2- • Piedmont. Minerals withdraws 0.25 mgd, 3 or 4 days a week with none drawn the rest. Most of this is lost in process or from evaporation ,from their sediment ponds. - : . The 3.2 miles of river between Lake Ben Johnson and the wastewater outfall is the section of river most impacted by abnormal low stream flows. The Eno River. State. Park begins several miles below the outfall and has. - the river flow augmented by this approximately 0.8 mgd of effluent. Over twenty miles downstream, ' Durham, who operates a wastewater treatment plant "_ . discharging to the Eno has found its 7Q10 dropping from 2.6 cfs in the _ • early 1970's to 0.6 cfs in recent years, due totally to the out-of-basin • transfers. in the upper Eno. . From 1977 through 1985 there have been increasing times of NO flow in the Hillsborough section of the Eno, reaching over 12 weeks in 1985. This year, in recognition of the increasing impacts of these low to no--flows, a strong effort was made to assure a high flow condition, as it turned out, in the face of a potentially very serious drought condition. Reservoir management strategies were developed by Orange County with assistance from the Division - of Water REsources and ways were found to release water through the dams to maintain some stream flow. These efforts were marginally effective, in part because of opposition ._ from several sources to the maintenance of ANY stream flow, and in part because of the learning process of managing, for the first time, a reasonably complex . system of dams and water withdrawls. Water conservation regulations were proposed, established, and then modified to reduce stream flows below the 7Q10 at various stages keyed to the level of water in the Lake Orange impoundment. By early June flow had reached 7Q10. From mid June to present the daily levels have been below 7Q10, as low as 0 to 20% for many days (except for 1-2 days several times from rainfall in August).