Algae are a natural component of any lake or pond system. However, harmful algal blooms (HABs) are quickly becoming increasing challenge to safe water habitats and clean water sources. The most common are cyanobacteria – also known as blue green algae. Large concentrations of algae blooms can threaten a pond system’s chemical balance and create conditions that could be toxic to humans or wildlife. Environmental changes or pond nutrient (nitrogen and phosphorus) imbalances in the water can encourage and intensify toxic algae.
Many cyanobacteria blooms can produce toxins (cyanotoxins) that cause immediate (sometimes long-term) damage. For this reason, many states are adopting the U.S. Environmental Protection Agency’s (EPA) cyanobacteria guidelines to help pond owners and operators protect the health and safety of residents, their pets, livestock, and wildlife. Similarly, Health Canada also publishes extensive information and research.
While blooms happen naturally, an imbalance of phosphorus and nitrogen, in particular, can accelerate an algal bloom’s growth significantly. Pollutants from construction runoff, fertilized yards and golf courses, road wash, stormwater runoff, pet waste, and decomposing leaves, grass clippings, and other organic materials also contribute to nutrient imbalances in the water.
Higher temperatures and increased sunlight in summer months also can encourage algae blooms, especially in standing water, which is warmer than circulating water and can act like a breeding ground. A lake or pond usually takes on the color of the algal species within it. Algal blooms often are green or blue-green, although golden-brown algae, or diatoms, are common and can give a lake or pond a brown or cloudy appearance.