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<br />Stream Velocity <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />This is a measure of the velocity (meters/second) of the stream measured at the <br />surface in midstream. This varies greatly depending on the width and depth of the stream. <br />This is not an indica~ion of flow rate (volume of water/second). <br /> <br />Dissolved Oxygen <br /> <br />This measurement is given in mg/L and percent saturation. The percent saturation <br />is a measurement of the amount of oxygen present divided by the amount of oxygen that <br />can be dissolved at the ambient temperature. Running water or water with abundant plant <br />life is normally at 100% saturation. The fact that the brook is below this amount is not <br />unusual during the fall. Production of oxygen through photosynthesis decreases and use <br />of oxygen increases as aerobic detritovores begin decomposition of leaf litter and other <br />organic matter. <br /> <br />pH <br /> <br />This is a measure of the acidic or basic character of the stream measured by the <br />amount of H+ atoms present. pH is measured on a logarithmic scale where 7 is neutral, 1 <br />is highly acidic and 14 is highly basic. Trott Brook is well within the neutral range. pH is <br />a highly variable measurement and can be impacted quickly through the activity of <br />organisms within the stream, precipitation or anthropogenic pollutants. The Anoka Sand <br />Plain has a large amount of calcium and magnesium cations (Bloom, 1996) which act as a <br />buffer against acidification of the brook. <br /> <br />Conductivity <br /> <br />Measuring the conductivity of a stream can provide an indication of the amount of <br />total dissolved solids found in the water. This, in turn, can be an indication of the <br />contribution of groundwater to the stream. Water that is higher in conductivity can be <br />indicative of higher contributions of groundwater to the stream flow. The conductivity <br />values measured at Trott Brook are considered high. Calcium and magnesium are most <br />likely the most predominant dissolved solids. This high concentration of calcium can also <br />be evidenced the large concentrations of mollusks that can be found in the stream. <br /> <br />4 <br />