Blue-green algae in Lakes Hickory and Rhodhiss are causing unpleasant taste and odor in public drinking water in Hickory, Longview, Lenoir, Valdese, and Granite Falls. Also affected are drinking water systems that purchase water from these municipalities, including the towns of Conover, Claremont, Maiden, Catawba, Hudson and Sawmills, Alexander County Water System, Caldwell County Water Systems, Joyceton Water Utility, Baton Water Authority, Icard Township Water Corporation, and Triple Community Water System.
Because of the concerns about unpleasant taste and odor, the water treatment plants that get their water from Lake Rhodhiss are all using activated carbon to improve the taste and odor of public drinking water. In addition, as the number of algae in the lake decrease, the taste and odor should improve.
Blue-green algae (also known as cyanobacteria) are microorganisms normally found in the environment. An algal bloom occurs when the number of algae rapidly increases. Some types of blue-green algae can produce toxins that can harm fish and other animals. Some of the toxins can affect humans by harming the liver and/or central nervous system.
The State Laboratory of Public Health and the Harmful Algal Blooms Program in the N.C. Division of Public Health have tested water samples from Hickory and Lenoir for one algal toxin, microcystin (a liver toxin). No microcystin toxin was detected in those samples. Additional toxin testing may be done depending on the persistence of the bloom, whether health effects are reported and what the predominant algal species is.
The blooms in Lake Rhodhiss and Lake Hickory might have occurred because of hot weather, lack of rainfall, and calm water with high levels of nutrients (phosphorus and nitrogen). After recent rainfall, it appears that the bloom may be decreasing in density. Besides causing taste and odor problems for drinking water systems that draw from the lakes, blue-green algae may also create a scummy film on the lake’s water, which poses problems for people swimming in the lake. People who swim in the affected water may experience skin rashes or irritation.
Follow these simple precautions around blue-green algae blooms:
• People and pets should not swim in waters containing large amounts of blue-green algae.
• If you come into contact with algae-filled water, simply rinse off with fresh water as soon as possible. In some cases, skin irritation can occur from prolonged skin contact with algae.
• Swim in designated areas, and make sure children are supervised at all times when they are near water.
Blue-green algae are not known to have caused severe illness in people in North Carolina. However, if the algae are producing toxins, animals and humans could become ill by consuming untreated water. Treated drinking water is not considered a health risk. Also, swimmers in waters with blue-green algae might develop an irritating skin rash. Symptoms of algae-related illness may include fever, nausea, diarrhea, or vomiting. If you become sick after swimming in or drinking water from Lake Rhodhiss, contact your local health department immediately. For taste and odor concerns about your drinking water, contact your local water utility.
For more information about drinking water, visit the Public Water Supply Section’s Web site at or call the main office at (919) 733-2321. For more information about blue-green algae, contact the Harmful Algae Blooms Program at (888) 823-6915.