THREE BAYS WATER QUALITY MONITORING PROGRAM

It has been clear to citizens that portions of the Three Bays System are declining in quality. In general, areas with potentially lower circulation (such as Prince Cove) tend to have lower water quality and are more sensitive to impacts from nutrient loading. Not surprisingly, these also tend to be most likely the areas with the most significant nutrient inputs. As a result of public concern the Three Bays Water Quality Monitoring Program was initiated in 1999. In this collaborative effort, Three Bays Preservation Inc. provides the support, coordination and oversight of the program through its director, Lindsey Counsell and CMAST provides technical guidance, analytical support and data interpretation.

The monitoring program uses both volunteers and staff for the field data collection efforts. The sampling teams are equipped and trained prior to sampling and given refreshers as needed during the field season. Analysis of samples collected from the effort and compilation of field and laboratory data provide an ecological overview of water quality conditions within the system. The methods employed are directly comparable to other data collection efforts associated with CMAST which involve over half of the embayments in Massachusetts.

The sampling teams conduct field measurements of physical parameters as well as collect water samples for subsequent nutrient analysis by the Coastal Systems Laboratory at CMAST. The physical parameters include: total depth, Secchi depth (light penetration), temperature, pond state, weather, wind speed and direction. Samples are also collected and "fixed" in the field for Winkler Titration to determine dissolved oxygen content. Laboratory analyses include: plant available forms of nitrogen and phosphorus (nitrate + nitrite, ammonium, ortho-phosphate), organic forms of nitrogen and carbon (dissolved organic nitrogen, particulate organic nitrogen, dissolved organic nitrogen and particulate organic carbon), the primary phytoplankton pigment, chlorophyll a, as a gauge of algal biomass and salinity. Samples for physical parameters are measured at surface and bottom or in depth profile if low tide water depths reach 3 meters. Nutrient samples are generally collected at mid-water except in deep basins where profiles are collected. These parameters form the basis for evaluating the nutrient related health of a coastal embayment. In addition, samples for the indicator of potential pathogen contamination, fecal coliform numbers, are collected from 6" (15 cm) depth at each station and assayed by a membrane filtration technique by the Barnstable County Department of Health and Environment laboratory.

The following measurements were conducted on each sampling (O = On Site; L = Lab):

Physical Measurements:
(O) Total Depth
(O) Temperature
(O) Light Penetration (Secchi depth)

Chemical Measurements:
(L) Nitrate + Nitrite
(L) Ammonium
(L) Dissolved Organic Nitrogen
(L) Particulate Organic Nitrogen
(L) Total Dissolved Nitrogen
12. Chlorophyll & Pheophytin a
(L) Phosphate
(O) Oxygen Content
(L) Salinity
(L) Chloride
(O/L) Periodic Sulfide

Sampling is monthly and concentrated from May - November, when nutrient related water quality declines are most prevalent. Fourteen stations within the estuary (Figure 1A) and five within the Marstons Mills River System (Figure 1B) are occupied during each event. Stations were selected to provide adequate spatial coverage with replication within the larger sub-embayments.

Data is compiled and reviewed by the laboratory for accuracy and evaluated to discern any possible artifacts caused by improper sampling technique. Modifications to the Program are made based upon annual review. Modifications are only made if data quality is compromised, useful long-term data is created by consistent sampling of a fixed network of stations through time. CMAST is finalizing a Quality Assurance Project Plan (QAPP) for the program in which details of sampling and analytical procedures are provided. All analytical methodologies have been previously approved for use by EPA, MCZM, NOAA and NSF.

As the program progresses, additional "special projects" are being undertaken to identify problem areas or to support interpretation of the monitoring data. Based upon 1999 results (see below) the Program has begun monitoring river discharge volume from the Marstons Mills River (with partial support from a Cape Cod Commission Grant). In addition, moored instruments to monitor dissolved oxygen and chlorophyll have been deployed within Prince Cove to better elucidate the level of nutrient related decline in this over fertilized system.