AWWA ACE70949

This powerpoint presentation begins by providing a brief overview of the Colorado River Aqueduct system in southern California, and the significant threat of quagga mussels to the lower Colorado River system. The objectives of this 2-yr study on the 4 reservoirs of the Colorado River Aqueduct were to: improve understanding of veliger distribution within the reservoirs of the Colorado River Aqueduct; identify the limnological factors governing veliger abundance, distribution and fate; and, develop in-lake control strategies to minimize their spread and limit their impacts to reservoirs, conveyances and other infrastructure. Approach methodology included: in situ measurement of water column properties using Hydrolab Surveyor and DataSonde4a; plankton tows using a Wisconsin closing net for zooplankton and veliger abundance and distribution; and, veliger enumeration and size distribution using cross-polarized light on a Nikon E600 compound scope fitted with a micrometer; water samples were collected using a Kemmerer sampler near the center of the epilimnion, thermocline and hypolimnion; chlorophyll a and dissolved and total nutrient concentrations determined on samples; hydroacoustic measurements of sediment properties, fishery and zooplankton using a BioSonics DTX echosounder with 200-kHz split beam transducer; and, water current velocities determined using drogues fitted with GPS loggers and with an RDI 600-kHz Workhorse Sentinel ADCP. Seasonal trends and spatial trends are presented. Includes figures.