Blue-green Algae Bloom Update

10/19/2012

The blue-green algae bloom in the Charles River has now subsided.

Blue-green algae, or cyanobacteria, are aquatic bacteria that can produce toxins which are harmful to humans, dogs and other mammals. If you see water that looks bright green or contains bright green strands avoid contact with the water as much as possible and wash contacted areas after exposure. Common reactions to the toxins include rashes, eye irritation, and possible gastrointestinal distress.

Blue-green Algae News

Blue-green algae in the Charles River watershed

Blue-green algae (also known as cyanobacteria) has been present in Eastern Massachusetts and the Charles River for years, but the issue has recently become a concern due to the type and quantity of blue-green algae that is present. CRWA is part of a collaborative effort working to develop a protocol for monitoring blue-green algae levels in the river during the summer months, and notifying the public of potential risks from the toxins blue-green algae can produce in the water. We are committed to providing the public with information on blue-green algae conditions through our daily water quality flagging program.

One of the common blue-green algae found in the Charles River is Microcystis, which grows naturally in calm, warm, shallow water that is rich in nutrients (nitrogen and phosphorous). Microcystis secretes a toxin when it dies, and accumulations of this toxin can pose a health risk to humans and animals. Unfortunately, there is not a direct correlation between visible algae in the water and toxin levels, so it can be difficult to determine when the water is safe. We are testing for both blue-green algae cell counts and toxin levels on a regular basis, and advise river users to use caution if blue-green algae is visible, particularly in large quantities. Click here for a simple field guide to help identify blue-green algae.

The Massachusetts Department of Public Health defines a bloom as the presence of any of the following:

• cyanobaceria concentrations >70,000 cells/ml of water

• cyanotoxin levels >14 parts per billion (ppb)

• presence of a visible cyanobacteria scum or mat

 

A sample warning sign posted by MA Department of Conservation and Recreation an dMA Department of Public Health during severe blue-green algae blooms

A combination of factors, such as excess nutrients, warm temperatures, and sunlight, encourage blue-green algae growth. The presence of nutrients, such as phosphorus, is mainly due to runoff from large impervious surfaces in urban areas (streets, parking lots, lawns) and from direct discharges such as wastewater treatment facilities. Click here to learn more about the impact of phosphorus in the Charles.

Blue-green algae becomes a serious problem when it grows in abundance, preventing light and oxygen from getting into the water. In the Charles, severe algae blooms are usually caused by heavy rainstorms that bring an enormous influx of nutrients to the river, followed by hot weather that leads to warm water temperatures, creating perfect conditions for algae growth. Direct discharges of heated water likely contribute to blue-green algae growth as well.

CRWA Works to Prevent Blue-green Algae Blooms

CRWA projects help prevent blue-green algae blooms by addressing the key contributors:

• high nutrient levels
• warm water temperatures
• low streamflow.

CRWA works on several fronts to monitor and address blue-green algae growth in the Charles River. While there are currently no recognized methods to eliminate the cyanobacteria from the water, blooms can be prevented by reducing the river’s nutrient levels and water temperature.

Water Quality Monitoring - CRWA has taken a lead role in monitoring the water quality of the river. Once a month, more than 60 volunteers gather at 35 sites along the river to collect water samples, measure depth and temperature, and record river conditions. The data collected is used to identify problems in the river and trends in water quality, and to track the progress of efforts to clean up the Charles. CRWA staff also collect water quality data from potential pollution “hot spots” and from tributaries to the river in an effort to track down possible sources of pollution.

Flagging Program - Our daily water quality flagging program presents the daily flag colors of the river's health, which signify whether or not the river is safe for boating at nine boating locations from Watertown to Boston. Flag colors are based on bacteria levels, blue-green algae counts, and rainfall-based prediction models. A blue flag indicates suitable boating conditions; a red flag indicates potential health risks.

Pollution Reduction - CRWA has spearheaded a project to quantify the nutrient levels that negatively impact the Charles River and to identify the sources of these nutrients. Working with the Massachusetts Department of Environmental Protection and the U.S. Environmental Protection Agency, CRWA has spent five years collecting streamflow and water quality data to create a Total Maximum Daily Load (TMDL) for the Charles River. The TMDL report analyzes the pollution contributions from different sources and establishes the amount of pollutant the river can sustain and still meet water quality standards. Sources of excess nutrients, such as phosphorous, include stormwater runoff from urban areas (streets, parking lots, lawns), direct discharges to the river, such as from wastewater treatment facilities, and releases from the sediments accumulated at the bottom of the river. The information from the report is used to identify areas of the river where nutrient levels are high and establish priorities for remediation. The most promising approach to restoring the river’s nutrient balance appears to be cleaning up polluted stormwater runoff, most of which reaches the Charles with little or no treatment at all.

Environmental Advocacy - In addition to using scientific research to protect the Charles River and its watershed, CRWA works to reform state water law, policy and practice to preserve aquatic habitat and maintain streamflows. Among its current legal initiatives, CRWA is working to protect aquifers and maintain summer flow levels, which will reduce temperatures and improve water quality, and to prevent excessive discharges of hot water into the river. Higher water temperatures are known to exacerbate toxic algal blooms, harm fish populations and decrease water clarity.

Thanks to determined advocacy by Conservation Law Foundation and CRWA, the Gen On Energy, LLC cogeneration plant in Cambridge  is switching to a closed-loop system.  The plant will capture most of the heat generated by the plant and distribute it as steam through a new pipeline to be built across the Craigie Dam. The modifications  will enable the company to drastically reduce the amount of water it withdraws from the Charles River, removes heat from the plant, and double the amount of steam it can sell to heat buildings in Boston.

Blue-green Algae in the Charles River Resources

CRWA's algae sampling for 2008 has been conducted with support from REI.