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Bruce Hooke collecting water samples above Rising Sun Dam in Providence.

Water Quality Monitoring

In partnership with URI Watershed Watch Program the Watershed Council monitors water quality at three sites on the lower Woonasquatucket River from May through October. See below for the sites monitored, what's monitored, and the data

Sites Monitored: The Watershed Council is directly involved in monitoring three sites on the lower river. The water quality of many of the lakes and ponds in the upper part of the watershed is also monitored under the URI Watershed Watch program by volunteers not associated with Watershed Council. The data for all of the Watershed Watch sites are available on the Watershed Watch web site. Most of the data for the sites we monitor is also posted here (see below). The sites monitored by Watershed Council volunteers are (listed from north to south down the river) (click on the plus symbols for more information about each site):

  • Greystone Mill Pond, Johnston/North Providence:
    • We started monitoring at this site in 2005 and have been monitoring every year since then. This site is above the most urban part of the watershed but it is below the outfall for the Smithfield Sewage Treatment Plant. In 2008 we shifted from collecting our samples below the dam to collecting our samples above the dam so be cautious about comparing data for this site from 2008 and after with data for this site from previous years.
  • Rising Sun Dam, near Donigian Park, Providence:
    • Our first site - Watershed Council volunteers have been monitoring the water quality every year at this site since 2003. The water samples are collected just above the dam. Below this dam the river starts to be influenced by the tides from Narragansett Bay.
  • Waterplace Park, Providence:
    • We started monitoring at this site in the heart of Providence in 2008. This site is more complicated than the other sites since it is heavily influenced by tidal action from Narragansett Bay. Water quality in this part of the river is vital for fish that need to move through this area to migrate between the bay and the freshwater river upstream of here. Also, everything that flows down the river eventually passes through Waterplace Park on its way to the bay.

What's Monitored: The key factors we monitor for are (click on the plus symbols for more information):

  • Dissolved Oxygen:
    • Dissolved oxygen is important to the health of animals that live in the river because they need air to breath too. If the dissolved oxygen drops below 3 mg/L aquatic animals cannot survive. Between 3 and 5 mg/L it is hard for organisms to function, and above 5 is good. Oxygen levels are generally higher in the spring when the water is cold, because cold water can hold more oxygen. For more information visit the URI Watershed Watch website and, in particular, read this PDF document on dissolved oxygen. To run the dissolved oxygen tests the volunteer monitor collects two samples and runs two tests on each sample. The four results are averaged to get the final dissolved oxygen value for that date. The test used is the modified Winkler titration test.
  • Water Temperature:
    • Since the water temperature determines how much oxygen the water is capable of holding, water temperature is also an important factor. Many aquatic organisms are also sensitive to water temperature. So, we record the water temperature whenever we test for dissolved oxygen.
  • Weather:
    • The weather conditions also influence the dissolved oxygen levels. A windy day can churn the water's surface and introduce more oxygen into the water. Sunlight increases the rate of photosynthesis of plants in the water, which adds oxygen to the water.
  • Salinity:
    • At Waterplace Park we test for salinity whenever we test for dissolved oxygen. Since Waterplace Park is heavily influenced by the tide the salinity varies depending on whether the tide is coming in (flood tide) or going out (ebb tide). Salinity is important for determining which organisms can survive in a water body but it is also very useful for interpreting other data. For example, if we see high salinity readings on a given date then we know that a significant percentage of the water we are testing comes from the bay rather than river, which influences how we interpret the results.
  • Bacteria:
    • The quantity of bacteria in the water is the standard measurement used in most cases to determine whether it is safe to fish and swim in a water body. Once a month during the monitoring season we bring water samples to URI for them to test for bacteria. The results are generally available on the Watershed Watch website within a few weeks and are usually posted here on our website shortly thereafter. In 2006 Watershed Watch began testing for the bacteria group enterococci, instead of fecal coliforms. This change was made because the US EPA identified enterococci as a better indicator of the risk of contacting gastrointestinal disorders as a result of coming into contact with the water than fecal coliforms. As a result of this finding, RI DEM and RI Department of Health are also switching to using enterococci as their standard for recreational contact (swimming). The Rhode Island standard for freshwater used for recreation is 61 enterococci (count per 100 ml). For more information visit the URI Watershed Watch website and, in particular, read this PDF document on bacterial monitoring.
  • Nutrients:
    • When we collect samples for the bacteria testing we also collect samples for nutrient testing and deliver these along with the bacteria samples to the Watershed Watch lab at URI. The nutrient samples are testing over the winter after the end of the monitoring season. Watershed Watch tests for a variety of nutrients, including: ammonium-nitrogen, nitrate-nitrogen, dissolved phosphorus, total Nitrogen and total phosphorus; and for related factors such as pH and alkalinity. Nutrients play a key role in the health of a water body. Aquatic organisms need some nutrients to survive but water too rich in nutrients can create algae blooms and similar problems. For more information about nutrients, see the documents available on this page of the URI Watershed Water website.

The Data: To see the data for the sites we monitor click on the links below.

These data, along with data on other sites in the watershed and across the state are also available at the Watershed Watch website.

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