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Projects > Water Quality Monitoring - Summer 2008

The Spruce Creek Water Quality Monitoring project is being conducted for the second summer to establish a water quality baseline of existing conditions. The data generated from this monitoring project will be compared to Maine water quality standards to better understand Spruce Creek's water quality, determine its current stress level, look for troubled spots, provide an objective basis for corrective action, and enable us to confirm improvements as we proceed with Best Management Practices and restoration projects.

With the help of Paul Mitnik and Malcolm Burson from the Maine DEP, we've again received approval of our Spruce Creek Quality Assurance Project Plan. Monitoring for dissolved oxygen, salinity and temperature started June 12. Every other week (on a Monday or Tuesday) a team of two goes out and monitors six sites in Spruce Creek, three above the Rt. 1 Bridge and three below, at the low and high tides.

The data collected in 2008 (along with previous years' data) will enable us to establish a water quality baseline and will be compared to Maine DEP standards in order to better understand Spruce Creek's current stress levels and provide an objective basis for corrective action. We are grateful to the University of Maine Cooperative Extension and Presumpscot River Watch for loaning us their expensive equipment in our first two years, as well as to the Kittery Sewage Treatment Plant where we go to have our equipment cross checked and to our dedicated volunteers. We are especially grateful to the EPA and their loan of a YSI85 meter through their Equipment Loan Program.

Spruce Creek Low %DO Occurrences 2005-2007

What We're Measuring

The level of dissolved oxygen (DO) in a body of water is one of the best indicators of its health and its ability to support aquatic life. Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. The ideal dissolved oxygen concentration for many fish is between 7 and 9 mg/l. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills. Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Seasonal and daily fluctuations in dissolved oxygen can be quite large. Early summer morning measurements of DO show the worst case scenario on the river because warm water holds less oxygen than cold water and because during the dark nighttime hours the aquatic plants are consuming oxygen rather than releasing oxygen into the water as they do through photosynthesis during the daylight hours. For more information on how dissolved oxygen is an indicator of water quality, please see the University of Rhode Island Watershed Watch factsheet on dissolved oxygen and temperature or visit http://www.vic.waterwatch.org.au/fortheteacher/manual/sect4b.htm.

Most aquatic organisms are poikilothermic - i.e., "cold-blooded" - which means they are unable to internally regulate their core body temperature. Therefore, temperature exerts a major influence on the biological activity and growth of aquatic organisms. To a point, the higher the water temperature, the greater the biological activity. Fish, insects, zooplankton, phytoplankton, and other aquatic species all have preferred temperature ranges. As temperatures get too far above or below this preferred range, the number of individuals of the species decreases until finally there are few, or none. Temperature is also important because of its influence on water chemistry. The rate of chemical reactions generally increases at higher temperature, which in turn affects biological activity. An important example of the effects of temperature on water chemistry is its impact on oxygen. Warm water holds less oxygen that cool water, so it may be saturated with oxygen but still not contain enough for survival of aquatic life. Some compounds are also more toxic to aquatic life at higher temperatures. Temperature is reported in degrees on the Celsius temperature scale (C). For more information, check out http://waterontheweb.org/under/waterquality/temperature.html.

Salinity is simply a measure of the amount of salt dissolved in the water. Salts are substances such as common table salt (sodium chloride, NaCl), limestone (calcium carbonate, CaCO3) and many others. They are picked up by the water as it runs over and through the rocks and soils of the catchment. Low levels of these salts are vital to the growth of aquatic plants and animals but high levels can cause problems for aquatic life and for human uses such as crop irrigation. Aquatic plants and animals need the natural salts contained in waters for growth. Some species are adapted to the low range of salts found in soft waters while others need the highest levels found in hard waters. However, if salinity increases above the normal range of a particular water the natural community will become stressed and, as levels increase, species will start to disappear, depending on their degree of sensitivity.

The percent dissolved oxygen saturation is a good calculation of the health of the water. The oxygen holding capacity of water is a function of temperature and salinity. It is possible for water to hold >100% capacity when the input of oxygen from algae or plants is greater than the transfer of oxygen to the air.

Tidal water is classified as SA, SB, SC from best to worse. Spruce Creek is classified as SB (tidal sections) and B (non-tidal sections). In terms of  DO, the minimum standard for SB is 85% saturation at any time. The minimum standard for B is 75% saturation or 7 mg/l whichever is greater.

Spruce Creek %DO Saturation (2008)

View all of the 2007 Water Quality Monitoring Data.

View all of the 2006 Water Quality Monitoring Data.

View all of the 2005 Water Quality Monitoring Data.


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