N.C. Department of Environmental Quality’s Division of Water Resources (DWR) advises the public to avoid contact with green or blue water in Lake Norman due to algal blooms that have lingered in the area since June 16.
Algal blooms have been observed at multiple locations on the lake in Catawba, Iredell, Lincoln and Mecklenburg counties. Reports have been concentrated at northeastern portions of the lake. Algal blooms may move due to wind and wave action.
DWR investigated blooms at five locations, and determined the blooms are dominated by Dolichospermum. Previously known as Anabaena, Dolichospermum belong to the algal group cyanobacteria, also known as blue-green algae. Cyanobacteria blooms usually appear bright green, but when a bloom starts to decay, the color can change to a milky blue. Decaying algae may produce a strong, foul odor that can impact a large area.
Dolichospermum can produce microcystins, a type of algal toxin that may cause adverse health effects in humans and pets. Rapid, preliminary testing of samples collected on June 17 did not detect microcystins. However, toxin production is dynamic and can begin and end quickly. It is not possible to tell just by looking at a bloom whether toxins are being produced or not. Monitoring is ongoing, and any new developments will be reported on DWR’s Algal Bloom Dashboard as soon as they are available.
N.C. Department of Health and Human Services, Division of Public Health (DPH) routinely encourages the public to avoid contact with large accumulations of algae and to prevent children and pets from swimming or ingesting water in an algal bloom.
DPH suggests the following steps to safeguard against algal blooms:
- Keep children and pets away from water that appears bright green, blue, discolored, or scummy.
- Do not handle or touch large mats of algae.
- Avoid handling, cooking, or eating dead fish that may be present.
- If you come into contact with an algal bloom, wash thoroughly.
- Use clean water to rinse off pets that may have come into contact with an algal bloom.
- If your child appears ill after being in waters containing an algal bloom, seek medical care immediately.
- If your pet appears to stumble, stagger, or collapse after being in a pond, lake, or river, seek veterinary care immediately.
Algae are a natural occurrence in all waterbodies, but certain environmental conditions can cause rapid algal cell growth, leading to algal blooms. These conditions include increased nutrients, such as inputs of nitrogen and phosphorus, elevated temperatures, increased sunlight and low or no water flow.
To report an algal bloom, contact the nearest DEQ regional office or submit a report online. To view reported algal bloom events, visit DWR’s Fish Kill & Algal Bloom Dashboard.
To learn more about algal blooms, visit the DWR website. For more information on the potential health effects from algal blooms, visit the DPH website.