Laserfiche WebLink
<br />structure allowed efficient capture offish during draining. When Old Charley Wash was drained, <br />a 6.4 nun screen was placed in front of the downstream water control valve to prevent fish from <br />escaping. In addition to providing a stable bottom to collect fish, closure of the drain valve on <br />the second dike allowed periodic fish removal prior to complete draining. This feature allowed <br />documentation of fish movement out of the wetland during the draining process in 1996. <br /> <br />Chapter One: <br />Water Quality and Zooplankton <br /> <br />Methods <br />Physical, chemical, and zooplankton data were collected in Old Charley Wash in the <br />spring and s~er months between 1994 and 1996. Maximum depth, surface water <br />temperature, alkalinity, conductivity, turbidity, surface dissolved oxygen, and zooplankton <br />volume/densities were measured. Maximum depth was determined by subtracting the known <br />difference of the bottom of the wetland to the staff gage reading on the outlet drain structure. <br />Water chemistry variables were measured using a Hach DREL/2000 Water Quality Kit <br />(Conductivity was measured with a Hach model 44600 Conductivity/TDS meter). Water <br />temperature and chemistry variables were recorded at a single location near the center of wetland <br />at each sample date. During 1996 dissolved oxygen was measured with an OxyGuard MkII <br />meter and data was collected from both the water surface and just above the bottom of the <br />wetland. Dissolved oxygen readings were not made for the May sampling periods in 1996 due to <br />equipment malfunctions. Water quality data were collected from sub-surface samples during <br />daylight hours in 1994 and as close to dawn as possible in 1995 and 1996. Data collection <br />started between the second and fourth week of May. Data were collected weekly while the river <br />and wetland were connected and biweekly thereafter. <br />During 1994, zooplankton sampling effort in Old Charley Wash was subdivided into <br />three sections in an north-south gradient. Zooplankton was collected from arbitrarily selected <br />open water locations in each of three sections of the wetland between May and October. In <br />addition, zooplankton volume was.also measured from a backwater habitat in the main channel <br />just adjacent to Old Charley Wash. During 1995 and 1996, a grid was overlaid on a map of Old <br />Charley Wash. Each grid was numbered and zooplankton samples were collected from three <br />randomly selected off-shore cells. Sampling occurred at about 2 week intervals in 1994 between <br />24 May and 22 September. During 1995 and 1996 sampling occurred weekly when the wetland <br />was connected to the river and biweekly thereafter. Sampling ranged between 31 May and 14 <br />September in 1995 and between 14 May and 8 July in 1996. <br />Zooplankton was collected with a 10 cm diameter plankton net with 243 micron mesh. <br />Zooplankton samples were taken during daylight hours by submerging the net under the surface <br />and pulling the net just under the surface through a known distance (8 m). At each of three <br />zooplankton collection sites, three samples were taken by pulling the net from three different <br />directions without disturbing the area. During 1994, zooplankton was recorded by volume in the <br />field. Zooplankton samples were placed in a graduated (0.1 ml) centrifuge tube and treated with <br />a few drops of 10% formalin. Zooplankton quickly settled and volume of zooplankton was <br />recorded. During 1995 and 1996 samples were preserved in a 5% formalin solution and taken <br /> <br />11 <br />