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• 5. Measure the gage heights to the nearest 0.01-foot and calculate <br />the flow using the equations on Table C-2. Only the upstream <br />gage height needs to be used if free-flowing conditions are <br />present. <br />6. Remove the flume. <br />C. 3 MEASUREMENT OF VERY LOW SPRING FLOWS <br />Some of the spring flows are lower than can be accurately measured with a <br />cutthroat flume and yet are still large enough to produce a discrete flow. <br />In these cases, the spring discharge can be measured by alternate means. <br />One relatively easy and accurate way is to create a small dam and use a <br />piece of hose or tubing to concentrate the discharge from the dam. This <br />allows for accurate flow measurement as well as providing a means of <br />collecting a representative water sample. The procedure for using this <br />method is as follows: <br />1. Select a location in the flow path with sufficient slope to <br /> allow the tubing to freely flow. <br />2. Place the tubing in the flow path and create a small dam <br /> covering the upstream end of the tubing up to but not including <br /> the open end of the tubing. If a water sample is to be <br /> collected, try to cause as little turbidity as possible upstream <br /> of the end of the tubing. <br />• 3. Place the downstream end of the tubing at such a height that a <br />container can be completely filled without moving the tubing. <br />4. Allow the discharge from the tubing to stabilize. If a pond is <br /> created by the dam, the discharge will stabilize when the level <br /> in the pond stabilizes. <br />5. Place a small container under the discharge end of the tubin <br />q <br /> and measure, at least three times, the number of seconds (T <br />} <br /> required to fill the container of known volume (V in ounces). <br />6. Calculate the discharge using the following formula: discharge <br /> (gpm) = 0.469 x V/T. <br />7. Record the flow rate to the nearest 0.1 gpm on the Data <br /> Collection Form. <br />• <br />C-2 <br />