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History of our Water Quality Monitoring Program

While we are always excited to share our current science efforts, which you can read about here, the projects we have done over the past 28 plus years is important, even if we are not continuing them today. These programs taught us a lot about the health of the Bay and have informed the work we currently do.

Our Water Quality Monitoring, launched in 1993, initially was designed to address:

How healthy is the Bay? Where are the problem areas?  

Spatial, episodic monitoring by staff and volunteers provided a “snapshot” of the environmental health of the Bay. Staff and volunteers all measured dissolved oxygen, temperature, salinity, water clarity, and pH (the level of acidity of the water).

In addition, staff scientists measured total nitrogen and dissolved inorganic nutrients, water depth, and chlorophyll fluorescence, a measure that provides an estimate of phytoplankton abundance. Chlorophyll is the green pigment in plants that traps the energy of the sun for photosynthesis. 

Staff scientists sampled water quality from surface to seafloor by boat year-round

From 1993-2017, staff scientists collected water quality data from the surface to the bottom every month at ten profile sites across Casco Bay. In some months, especially during the winter, bad weather prevented us from getting to all ten sites. We did manage to visit three of the ten sites every month of the year for over 24 years. We call these three our sentinel sites, and we continue to monitor these:

  • Broad Sound, our “deep water” site
  • Clapboard Island, Falmouth, our “suburban” site
  • Fort Gorges, our “urban” site in Portland Harbor

Volunteer Citizen Stewards sampled surface waters from shore from April through October

The data were collected by volunteer citizen scientists, whom we trained to rigorous specifications (using a Quality Assurance Project Plan). These stewards used Secchi disks and water quality test kits specifically designed by us as “Casco Bay kits” with the help of LaMotte Company.

After pulling up buckets of seawater at their shoreside sites, volunteers carefully mixed chemicals, titrated, and flocculated, to get measurements for dissolved oxygen, salinity, pH, temperature, and water clarity. They would devote more than an hour at a time to monitor their assigned stations, at appointed times in both the morning and afternoon, on ten Saturdays from April through October.

Their data enabled us to identify when and where we were most likely to find water quality variations throughout the sampling season. These data, along with other staff collected data, helped us address our early questions, “How healthy is the Bay?” and “Where are the most challenged regions of the Bay?”

These data have:

  • Provided critically important baseline data; we continue to build on this data set at key sites around the Bay
  • Buttressed our advocacy and community outreach to tighten environmental protections for Casco Bay 
  • Enabled us to create an annual Health Index of the Bay using Citizen Stewards data
  • Identified areas where further study is needed
  • Showed that the water quality of certain areas of the Bay have consistently remained healthy or challenged:
    • Portland Harbor, the New Meadows embayment, and Harraseeket River mouth showed the poorest water quality

Broad Sound, Maquoit and Middle bays, and the offshore waters around Halfway Rock showed the highest water quality

We appreciate all of the volunteers that made this program possible. You can read more about the program and see the list of volunteers who took part here.

Why we changed our Water Quality Monitoring program

This long-term monitoring has provided critically important baseline data and showed that the water quality of certain areas of the Bay has consistently remained healthy or challenged. After more than 25 years, we realized we were not learning new information. Given the constraints of   time and funding, we assessed options and determined that we needed to shift our efforts to engage volunteers in new, more inclusive efforts, while significantly increasing the amount of data collected by staff using modern technologies.

We needed to address a new question: How is the Bay is changing?

This question inquires about trends in data, and detecting trends requires robust data sets.

In order to collect statistically-sound data we needed to increase the frequency of our monitoring.

Episodic snapshots of the Bay cannot provide the data needed to address the question: How is Casco Bay changing? More comprehensive, continuous data may help us begin to understand how climate change, excess nitrogen, and the changing chemistry of Casco Bay may be impacting the ocean food web.

We want to offer “low-threshold” volunteer opportunities to engage more community members in our work

Nabbing Nitrogen in 2016 taught us that many people are eager to help monitor the health of the Bay in short bursts of data collection efforts, rather than through the intensive training and time commitment required by our previous Citizen Stewards Program.

New technology enables us to collect data more efficiently

Our staff members continue to monitor 22 sites every 3 weeks, from May through October, using a data sonde to measure multiple water quality parameters simultaneously. An unattended data sonde and a carbon dioxide sensor collect data hourly at a continuous monitoring station, year-round.