Friends of Casco Bay researcher Mike Doan launches a continuous monitoring station in Harpswell on March 31. The station. along with one soon to be placed in Portland Harbor, will continuously collect data that will be used to determine the health of the bay. Contributed / Friends of Casco Bay

Two new continuous monitoring stations will enable Friends of Casco Bay to more completely track the health of the entire bay and how it changes.

Friends of Casco Bay has three decades of data on the bay’s health, but the new stations in Cundys Harbor in Harpswell and in Portland Harbor will provide a snapshot of the health of the bay today, tomorrow and into the future, according to Executive Director Cathy Ramsdell.

Friends of Casco Bay Executive Director Cathy Ramsdell and researcher Doan collect water samples in Portland Harbor. A new continuous monitoring station will data hourly. Contributed / Friends of Casco Bay

“Continuous monitoring is important because gathering data at high frequency intervals is critical to looking at things scientifically. The data has to stand up to statistical analysis,” Ramsdell said. “We have been monitoring the bay for 30 years. We have a good sense of where it is healthy and where it is not healthy. The question we struggle to answer is how is the bay changing.”

Changes in temperature and acidity level, for example, adversely impact cold water species, such as lobster and other shellfish, according to Ivy Frignoca, the baykeeper for Friends of Casco Bay.

The stations collect data hourly on temperature, acidity, dissolved oxygen, carbon dioxide, chlorophyll, dissolved organic matter, turbidity, salinity and water depth.

Made possible by a recently completed $1.5 million fundraiser, the new stations will join the the South-Portland based group’s continuous monitor station off Yarmouth, which has been operating since 2016. The money, Ramsdell said will fund the stations,  for the next decade.


The station in Harpswell was installed in late March. The second station will be launched in Portland Harbor this month.

“This is about understanding the health of the bay,” said Friends of Casco Bay Research Associate Mike Doan. “To do that, we need three sites spread across the bay.”

Doan said although the Yarmouth site, “generally a healthy site with good water quality,” is centrally located, it doesn’t provide a full picture of Casco Bay, which stretches from Cape Elizabeth to Phippsburg.

“It is a huge bay,” he said. “It is not the same from one end to the other.”

The Cundys Harbor monitor will capture data from the eastern section of Casco Bay where there are a lot of aquaculture operations and where the Kennebec River basin, which drains water from approximately one-fifth of the state’s land mass, meets the ocean. The station in the western section around Portland, Ramsdell said, will capture data in “the busiest section of Casco Bay and arguably one of the busiest sections of waterway in the state.”

“The goal is to be able to continually monitor three regions of the bay that are quite a bit different from each other,” she said.


The data from the stations will be added to the data Friends of Casco Bay staff compiles between April and November in 22 sites across Portland Harbor, as well as the data that comes in from the organization’s close to 300 volunteer Water Reporters.

All this data will help Friends of Casco Bay track changes in the bay and pick up on trends before they become problematic.

Frignoca told the Forecaster one way the bay is changing is the water is getting warmer and more acidic.

The increase in temperature in Casco Bay, she told the Forecaster in a recent interview, means many of the cold water species that the bay has long supported are relocating. Lobsters are moving further offshore and shrimp numbers have been drastically reduced.

It has also meant the invasive green crab has a bigger stronghold on the ecosystem. The crabs, which are native to the northeast Atlantic Ocean and Baltic Sea, eat clams and mussels and have “decimated the shellfish population and habitat,” she said.

The warmer water also means increased algae blooms, which, along with decreased ph levels, results in more acidity in the water. That acidity reduces calcium levels, which according to some studies, can result in shellfish with smaller and less hearty shells.


Nitrogen pollution in runoff flowing into Casco Bay is also impacting water health, Doan said.

“There is still a lot we still have to learn, but there are alarming signs,” Frignoca said.

The changing water chemistry concerns Ramsdell.

“We have concerns moving forward about the water chemistry being able to continue to support a good, robust ecological and economical resources in the bay,” she said.

The data from the stations will be published at, shared with scientists, water monitoring networks, as well as the Department of Environmental Protection and Environmental Protection Agency.

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