Swains Flat Sub Basin Main Stem at Rainbow Bridge Monitoring Site

 

       RAINBOW BRIDGE at the US GEOLOGICAL SURVEY STATION

The US Geological Survey Gaging Station measures stage and discharge on a continual basis every 15 minutes.

Two views of the Rainbow Bridge

 

            Main Stem Van Duzen River at Rainbow Bridge – Both sides of the tree

            Karen Bromley recording observations and data at Rainbow Bridge.

       The Van Duzen Watershed Project monitored at the Main Stem at Rainbow Bridge during the 07 Hydrologic Year with Dave Slyter and Sal Steinberg taking turbidity and discharge. During the 08 Hydrologic Year, monitoring was taken over by Isaac Mikus, a local resident of the area who works with California Department of Fish and Game, and who measured turbidity, discharge, and suspended sediment slightly west of the bridge.

       In order to become more safety conscious when monitoring during storm events, Dave Slyter devised the Slyter stick with three prongs for the hach cells, a timer, and a pouch for the pad, pencil, and orange peels. We were able to use this device on the Main Stem at Rainbow, the Main Stem at Weare’s, Grizzly Creek, and Yager Creek.

Dave Slyter’s Slyter Stick

Isaac Mikus began to monitor in the 08 Hydrologic Year at Rainbow Bridge and Grizzly Creek taking turbidity and suspended sediment samples.

            Isaac taking turbidity samples at Main Stem Van Duzen at Rainbow Bridge.

          

                   Isaac taking suspended sediment samples at Rainbow Bridge Monitoring Site.

        The site at Rainbow Bridge and the site at the Weare’s Mainstem will offer the project the opportunity to analyze the main stem from several focus areas. In the 07 Hydrologic Report, The amount of turbid material carried in Yager Creek was surpassed only by that amount recorded for the main stem Van Duzen River at Weares. It is interesting to note that Grizzly Creek carried more material per second than the main stem Van Duzen River at Rainbow Bridge. In the Maximum Average Turbidity for the Main Stem at Rainbow (810 NTU’s) was 53% lower than the Maximum Average Turbidity at Main Stem Weare (1517 NTU’s).

           

            In Karen Bromley’s report on water quality in the Lower River Basin, bi monthly temperature ratings were taken from Oct.2006-April 2008. Seven day moving averages for continuous temperature monitoring were collected from 6/7/07 to 9/21/07. During summer 07, the Main Stem Van Duzen at Rainbow Bridge had the highest maximum weekly average temperature over 22 degrees Celsius. Water quality criteria developed by the Environmental Protection Agency recommends that the maximum weekly average temperature (MWAT) threshold should not exceed 18 degrees Celsius during the summer months for coho salmon and 19 degrees Celcius for steelhead/rainbow trout.  Temperatures in Yager Creek, Main Stem Rainbow, and the Main Stem Weare exceeded the recommended MWAT threshold for the entire continuous monitoring period.

For more information access our monitoring report at www.fovd.org

View of Rainbow Bridge from downstream