Understanding Blue-Green Algae in Lakes and Rivers
By David L. Russell, PE, ASP
Blue-green algae, scientifically known as cyanobacteria, are harmful microorganisms that thrive in nutrient-rich waters. While often mistaken for algae, these bacteria multiply rapidly under the right conditions, creating toxic algal blooms. These blooms can disrupt ecosystems, harm aquatic life, and pose health risks to humans and pets.
At Global Environmental Operations in Lilburn, GA, we specialize in water quality consulting, assessment, and treatment solutions to help communities manage harmful algal blooms and restore safe, usable water.
Why Blue-Green Algae is a Problem
Cyanobacteria produce toxins that can cause:
- Skin irritation, allergic reactions, and rashes.
- Neurotoxic and liver-toxic effects in humans and animals.
- Bad taste and odors in drinking water.
Even small amounts of phosphorus and nitrogen in runoff can fuel massive blooms. For example, phosphorus concentrations as low as 0.0056 mg/L can trigger harmful cyanobacterial growth.
Causes of Algal Blooms
The main contributors include:
- Runoff from fertilizers used on lawns, farms, and gardens.
- Discharges from sewage treatment plants and biosolids.
- Uncontrolled urban stormwater runoff.
Communities were rarely designed to control phosphorus (P) and nitrogen (N), which makes nutrient pollution a growing concern.
How to tell the difference between algae and cyanobacteria.
One quick test has been developed by Kansas State University. The jar portion of the test requires a (1 quart) sample of suspect water put in a clear plastic or glass container with a top. The top should not be airtight because the green stuff in the water can produce gas that could
rupture the container. Also, you don’t want the material on your skin.
If there is a green sediment on the bottom of the jar after overnight refrigeration, it’s algae. But if there is a floating green layer on the top of the water, it is probably cyanobacteria. If you have questions, see the photos below.
Solutions for Blue-Green Algae
Managing algal blooms requires both prevention and treatment. Some effective strategies include:
- Community-Based Prevention
- Reduce fertilizer use and avoid over-application.
- Support stronger nitrogen and phosphorus standards for runoff.
- Chemical Treatment Options
- Controlled use of copper sulfate, alum, or lime can reduce blooms.
- Applications may cost $3,000 or more for small lakes and often require permits.
- Advanced Technologies
- LG Sonic ultrasonic systems: Floating solar-powered platforms that disrupt algae growth over areas as large as 124 acres.
- Aeration systems: Circulating water to improve oxygen levels and reduce algae growth.
These approaches can be combined for long-term lake recovery.
How To Take Action
If your community faces issues with blue-green algae blooms, the first step is proper analysis and planning. At Global Environmental Operations, we provide expert consulting, nutrient monitoring, and treatment design to restore safe, healthy water systems.
📞 Contact us at 770-923-4408 and ask for Dave to learn how we can help your lake or river.