Our volunteer based water quality monitoring program focuses on the final 3-mile long stretch of the Spicket River as it flows from Steven’s Pond at the Methuen line, to its confluence with the Merrimack River. On the third Tuesday of each month, Groundwork staff and a team of volunteers head out to test a number of different aspects of the Spicket’s water.
Temperature - What is it? - Many aquatic organisms have tight temperature requirements in order to survive. Temperature also impacts the amount of oxygen available in the water. As water temperature increases, its ability to hold oxygen decreases. - In urban areas - Removal of trees along the banks of a river and nearby blacktop can increase water temperature.
pH - What is it? - A measure of the concentration of hydrogen ions in a solution. pH is measured along a logarithmic scale from 1 to 14. pH values below 7 are considered acidic, values above 7 are basic (or alkaline), while a pH of 7 is neutral. According to the EPA, water with a pH in the range of 6.5-9 is considered tolerable for most aquatic life. Slight changes in pH can have wide reaching impacts to an aquatic ecosystem, as pH becomes too high, or too low many organisms have serious trouble living, foraging, and reproducing. - In urban areas – pH can be dramatically altered by chemical runoff from industry, automobiles, and lawn products.
Conductivity - What is it? - A measure of the water’s ability to pass an electric current. An increase in dissolved minerals, ions, or particulate matter can cause conductivity to rise. Conductivity levels typically fall between 300 and 700 us/cm in fresh water systems. - In urban areas – Salts and other particulate matter may enter a stream through stormwater, increasing conductivity.
Dissolved Oxygen (DO) - What is it? - The amount of oxygen present in the water. Aquatic ecysosytems, like terrestrial ones, both produce and use oxygen. All aquatic organisms require oxygen in order to undergo cellular respiration, and photosynthetic organisms produce oxygen. Dissolved oxygen quality criteria are as follows: >9.5 mg/L (AA - excellent), >8.0 mg/L (A - good), >6.5 mg/L (B - fair), and > 4.0 mg/L (C - poor). - In urban areas – DO is closely tied to water temperature and flow. In areas where water becomes stagnant or too warm, DO levels drop.
Turbidity - What is it? – Turbidity is a measure of the suspended and dissolved particulate matter in the water. The more turbid water is, the cloudier that water appears. High turbidity can lead to an increase in water temperature and a subsequent decrease in dissolved oxygen. It also dramatically changes the environment for aquatic organisms, it can make it more difficult to find food, clog gills, and smother eggs. Turbidity levels greater than 8 NTU (turbidity units) is considered unhealthy to aquatic life. - In urban areas – Particulate matter enters urban streams most often through storm water runoff, bank erosion, and excessive algal growth.
Nutrients (Nitrogen and Phosphorus) - What is it? – Nitrogen and phosphorus are vital components of all life. In terrestrial ecosystems nitrogen is generally the “limiting factor”, while it is phosphorus in aquatic ecosystems. High levels of nutrients in stream water lead to unchecked growth of algae, a problem known as eutrophication. As algae grow and die, decomposition of the algae reduces dissolved oxygen and can cause a “dead-zone”. Nitrate levels greater than 40 mg/L are considered unsafe for freshwater aquatic organisms, while the EPA recommends that total phosphorus not exceed 0.1 mg/L in streams and rivers. - In urban areas – Nitrogen and phosphorus most often enter streams through storm water runoff and combined sewer overflows (CSOs).
Bacteria (E. coli) - What is it? – Bacteria present in the guts of most terrestrial organisms. Presence of E. coli in a river environment generally points to sewage contamination and can lead to illness or disease. According to the EPA for healthy water quality the 30-day mean of E. coli should not exceed 126 organisms/100 mL, while a single sample should not exceed 406 organisms/100 mL. - In urban areas – Contamination by E. coli is most often caused by combined sewer overflows (CSOs), where sewer drainage and storm water drainage mix and enter the stream water.