Quagga Mussels on the Lower Colorado River
Parker Dam Activities
Parker Dam is the most heavily mussel-colonized Reclamation dam on the lower Colorado River. Heavy colonization began in late 2007, and in early 2008, the population of quagga mussels was large enough to plug the dam's domestic water line and foul the water surrounding the generator seals. The gates on the dam's spillway were also heavily colonized.
An aggressive mussel management program was implemented at Parker Dam in early 2008. Actions include:
- Placing one-foot-square steel plates under water in the dam’s forebay to monitor mussel presence and density. The plates, suspended by rope or cable, are spaced at 10 foot intervals, from the water surface to within five feet of the lake bottom.
- Replacing all 3/8-inch basket strainer screens with 1/8-inch screens, to evaluate their effectiveness in removing adult mussels or mussel debris from the water stream.
- Installing two "bio-boxes" to monitor mussel settlement in cooling water pipes. The "bio-boxes," aquarium-like structures through which cooling water is routed, can be visually inspected for mussels. If mussels are found, the water supply pipe might be flushed with hot water to kill them, or mechanically cleaned to remove them.
- Monthly inspections of the dam's exterior trash racks and domestic water line inlet, and physical removal of the mussels as necessary.
- Installing a 50-micron filter on the domestic water line to evaluate how effective this filter is in removing zooplankton and quagga mussels from the water stream flowing through the pipe. A 100-micron filter will also be tested to evaluate its effectiveness.
In addition, copper-containing metals and other metal coatings -- such as galvinizing or metalizing, anti-fouling, and easy release coatings -- are being tested at Parker Dam to determine their effectiveness in preventing mussels from attaching to different surfaces. Similar research is underway at Central Arizona Project and Metropolitan Water District of Southern California facilities on Lake Havasu, and in Reclamation’s laboratory facilities in Denver.
Updated: December 2008