What is a harmful algal bloom?

By CORRINA PARNAPY

Lake Champlain, like some other Adirondack lakes, experiences harmful algal blooms. These blooms can close beaches, impact drinking water and deter people from recreating. Organizations and agencies on both sides of the lake are working to stop what causes these blooms and protect our water resources.

Q: What is a harmful algal bloom?

A: A freshwater harmful algal bloom (HAB) is an excessive amount of algae, primarily blue-green algae (cyanobacteria), that causes harmful effects to organisms, water quality, recreation or the economy. Blue-green algae is natural within our waterways and forms of algae are the base of the aquatic food web, but when blue-green algae blooms it can cause toxic conditions. HABs are an indicator of excessive nutrients such as phosphorus, though nitrogen can also trigger them. Road salt, heavy metals and warming waters can compound the problem. Cyanobacteria can be toxic to both wildlife and humans.

Q: What can prevent harmful algal blooms?

A: The only way to prevent a bloom is by targeting and stopping the source of excessive nutrients. But it is not phosphorus alone that causes the bloom. Other factors can occur beyond the lake or the nearshore area. Any activity that takes place within a watershed can influence water quality. Even those who don’t live along the waters or recreate in them can have an impact.

Protecting water quality starts at the highest peak of a watershed. Protecting the streams from erosion (sediment with phosphorus) by following sound forestry practices and maintaining connectivity (aquatic organism passages) to downstream sections is vital. Headwater streams flow into larger streams and rivers that can be found within suburban and urban areas, as well as near farms. These streams can be protected with proper storm-water and agricultural management. Adequate permeable surfaces, upgraded septic systems, rain gardens and homes that are not over-built for the property can help. Vermont requires protective agricultural practices, called RAPs, and offers agency assistance to farmers.

Maintaining adequate shoreline and riparian buffers along waterways helps filter pollutants before they enter our water resources.

Q: Who is working on this problem?

A: Many organizations and agencies are dedicated to implementing projects that reduce the nutrients that make their way into Lake Champlain and feed the algae. In Vermont, the Lake Champlain Committee has run a citizen cyanobacteria monitoring program with the Lake Champlain Basin Program for years, according to Lake Champlain Committee Executive Director Lori Fisher. The state and the Lake Champlain Basin Program also work with landowners to reduce phosphorus runoff.

In New York, programs in the Lake George watershed – one source of Lake Champlain’s water – have likewise reduced nutrients.

The Lake George Association in recent years has undertaken dozens of storm-water projects that either remove sediment from streams or infiltrate storm water into the ground where nutrients can bind to soil particles Executive Director Walt Lender said. One such project, called the West Brook Conservation Initiative, diverts runoff from 90 acres through an engineered wetland that is removing 85 percent of the phosphorus and 92 percent of suspended solids.

Another organization, the Fund for Lake George, has a program focused on identifying point-source problems and assisting property owners with halting runoff and tracking impacts, as well as jointly working with RPI and IBM under the Jefferson Project to utilize state of the art technology to identify sources of nutrients. Federal officials are also working to develop a warning system.

In 2018, Gov. Andrew Cuomo prioritized protecting Lake Champlain, Lake George and other state waters that have had or could have harmful algal blooms. Leading professionals from across the state drafted action plans.

Q: Will reducing phosphorus fix the problem?

A: Once long-term water quality protection measures have been put in place and phosphorus reduction is started, an immediate reduction in HABs is not certain. Waters that regularly experience HABs will also contain sediment that is rich in phosphorus and other nutrients. The release of phosphorus from the bottom during spring and fall turnover can contribute a significant portion of nutrients and delay recovery.

In addition, increased water temperatures from climate change can cause a higher occurrence of HABs, increasing intensity, frequency and distribution. Warming waters coupled with increased nutrient addition can compound toxic HABs.