Agenda - 04-06-1981 - Laserfiche WebLink

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AGENDA ATTACHMENT 7 MANAGERS REPORT WEED INFESTATION OF LAKE ORANGE Shortly after Christmas I received a complaint from a person owning pro- perty on Lake Orange concerning weed infestation at the Lake. This person asked would the County take the necessary steps to resolve the problem. In the summer this weed covers a large portion of the Lake's surface, and seriously interferes with recreational activities there. I asked the Extension Service for assistance with this problem. The weed was not readily identifiable, but now they are satisfied it is the "Southern Naiad". The weed is not native to this area and is not located in nearby waters. Since Lake Orange is a water supply, treatment of the condition, if that is the course selected, will be difficult. There are three possible methods of treating this condition: 1 . A winter water drawdown of some six to eight feet. As the Lake is the primary source of the water for Hillsborough and the Orange Alamance Water System, this procedure is a calculated risk. This winter we are experiencing a severe drought. A drawdown of six to eight feet during the winter months to allow the weed to freeze, (it only grows in shallow water) results in removing about one half the water in the Lake. If the winter is not severe not much is accomplished. If the spring is dry we enter the summer with only a partly charged Lake. If a winter drawdown were done we might consider deepening the Lake along the shoreline to three feet. This action would eliminate most of the problem but would be prohibitively expensive. 2. Chemical Treatment: This treatment is moderately costly ($8000-10,000, 'for chemicals alone) but also introduces a hazardous material into the community water supply. The treatment should be applied during the spring just as the weed starts to grow. To reach the entire weed crop the Lake should be nearly full . Yet this is the wettest time of the year. As the treatment continues for a ten day period we cannot know with reasonable certainty a hard rain will not cause the Lake to over- flow and introduce quantities of chemically treated water into the drinking water system.