Mystic Daily Boating Advisory

Beach closing information is updated every morning by the Department of Conservation and Recreation (DCR) at 6AM at this hotline number: 617-626-4972.

How safe is it to boat today?

Estimates of water quality conditions are generated by an automated bacteria prediction model and by additional cyanobacteria testing during the boating season. The predictions are made each day at 5 AM and are valid for the remainder of the day. For more on what the estimates mean and how they are arrived at, see the questions below. Click on the icons on the map for recent past predictions.

Mystic River

Mystic Valley Parkway (Rt 16)


Malden River

Revere Beach Parkway (Rt 16)


Upper Mystic Lake

Shannon Beach


What do the categories mean?


Boating is probably safe! The chances that E. coli bacteria levels exceed state recreational standards are low, and there is no evidence of a cyanobacteria bloom.


The chances that E. coli bacteria levels exceed state recreational standards are high, or there is evidence of a cyanobacteria bloom with concentrations exceeding state safety guidelines.


There is no evidence of elevated bacteria levels, but screening values indicate a possible cyanobacteria bloom.

Not Available

Current predictions are not currently available due to missing data or other system error.

What causes these risks?


High bacteria concentrations can result when wastewater, which normally goes to a wastewater treatment plant, gets mixed with rain water in the stormwater pipe network and travels directly to rivers.  Mechanisms include illicit connections, leaking or broken infrastructure, and combined sewer outflows. All these problems are common in urban areas, and fixing them is an important priority for our organization and for federal and state regulators.  For more information on bacteria in our rivers and lakes, see our annual EPA Water Quality Report Card.

The second condition that can trigger a boating advisory is high confirmed levels of cyanobacteria.  Cyanobacteria, or blue-green algae, release harmful toxins into the water that can affect the nervous system, liver, skin, and overall human health. Cyanobacteria blooms are most common during late summer.  Blooms are usually short-lived, but during blooms contact with water is discouraged for pets and people.

How does it work?

Whether you’re rowing, kayaking or swimming, we want users of the Mystic to be able to make informed decisions about their activity. The Recreational Risk Assessment Project is all about communicating water quality conditions in a way that’s easily understood.  

In the first stage of this project, we collected and analyzed water quality samples for bacteria (Enterococcus or Escherichia Coli) and other parameters.  80 bacteria samples were collected from three sites between April and September in 2015 and 2016. We then used this data, along with additional bacteria data from the municipalities and the state, to develop models to predict water quality conditions in three areas of high recreational use. The models use real-time precipitation data and other variables to generate daily predictions of conditions.

We share these predictions with the public via our Twitter feed @SafeMystic and on this webpage above.

Project Partners

  • Dr. Jeffrey Walker (Walker Environmental Research LLC), Modeler and Website Developer

  • Dr. Nathan Sanders, Project Statistician & Mystic River Watershed Association Policy Committee Co-Chair

This project is funded by Massachusetts Environmental Trust.