August 21 – Sept. 30, 2020Vol. 22, No. 11

It's Not Easy Going Green

by Dr. Danielle Wain

Even if you don't live on North Pond, you might have heard that North Pond recently experienced a significant bloom of cyanobacteria (blue-green algae). So why did this happen?

Lakes are natural systems and algae plays a key role in maintaining the ecological health of the system. Algae are the base of the food chain. They are eaten by zooplankton, which are eaten by small fish, which are eaten by big fish. But when there are excessive nutrients, particularly phosphorus, in a lake, the algae growth can get out of control, leading to an algal bloom. When there are extended periods of hot weather, cyanobacteria in particular can thrive.

Cyanobacterial blooms have the potential to be toxic, so it is key to take action to avoid these! Excessive algal blooms decrease water clarity, turn lakes green, impair recreation, habitat, and reduce property values. You can find more detailed information and resources about the impacts, prevention and management of algal blooms at

For most lakes, the primary source of phosphorus is the watershed, the surrounding land that drains into a lake or other waterbody. When it rains, some water seeps into the ground, but a lot of it runs off the surface and into the lake, bringing sediments and phosphorus with it. Phosphorus sources are different in each lake but can also come from s septic systems, the atmosphere, and lake sediments that have accumulated phosphorus under certain conditions.

So what can be done about it? The old adage, "An ounce of prevention is worth a pound of cure," applies here. The best way to reduce the phosphorus in your lake is to protect the shoreline from erosion and runoff. This means fixing any sites on your property where sediment might be entering the lake. Talk to your lake's LakeSmart coordinator to learn how to create buffers between your property and the lake to absorb the phosphorus. Support or implement projects that prevent erosion from roads. Individuals can take many small actions to protect the lake to help avoid big, complex and expensive actions to remediate algal blooms after they happen.

In the meantime, the North Pond Association, the 7 Lakes Alliance-Colby College Water Quality Initiative, the State, and others are working together to monitor various aspects of the current bloom. We are also collecting data to help determine where the phosphorus is coming from so that a management plan can be developed. For more information on this, watershed management plans for other lakes, and LakeSmart contacts, visit

Danielle Wain is Lake Science Director for the 7 Lakes Alliance.

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