An aquatic invasion that Arizona wildlife and utilities officials have been dreading is now under way. A harmful species of mollusks that disrupts ecosystems and can spread throughout entire river systems has been discovered in the Colorado River waters from Lake Mead downstream to Lake Havasu.
The Dreissena species of mussels, which includes two closely related mussels, the zebra and quagga, can ruin boat motors, clog water intake pipes, negatively affect hydroelectric power operations, and affect water delivery systems.
These small invasive mussels, which originally came from Eastern Europe, have been causing multimillion-dollar problems in the Great Lakes and the Mississippi River Basin. The Colorado River lakes are 1,000 miles farther west than any previously known colonies of these species.
Mussels were first spotted near Arizona on Jan. 6 at the Las Vegas Boat Harbor at the southern end of Lake Mead. Since then, they have been confirmed to exist in other locations on Lake Mead, plus downstream lakes Mohave and Havasu in the Colorado River ecosystem.
“These invasive mussels are a serious threat,” said Larry Riley, fisheries chief for the Arizona Game and Fish Department. “(They) can reproduce and spread rapidly, and are often difficult to detect until they have become well established. A long list of agencies and organizations are cooperatively mobilizing to address this threat.”
More recently, divers have found quagga mussels at the Central Arizona Project intakes at Lake Havasu and officials fear this mollusk could spread into central Arizona lakes.
The CAP canal is one pathway for mussels to spread into central Arizona, but they can also hitchhike on boats coming from the Colorado River lakes that have already been infested.
“Quagga mussels could spread into Lake Pleasant, if they haven’t already,” Riley said. “These prolific invaders pose a significant, multi-million-dollar threat to our lakes, rivers, streams and water systems.”
The Central Arizona Project canal provides water to the interior of Arizona and stretches into the Phoenix and Tucson areas. Lake Pleasant on the northern edge of Phoenix is filled each year with CAP water.
Efforts are under way to examine this long canal stretching across the state to determine if these mussels have established themselves.
Bob Barrett, a spokesperson for the Central Arizona Project, emphasized that quagga mussels do not pose a threat to the public health or to the water supply. “We’ll do whatever it takes to keep the water flowing. If they begin to build up, we’ll scrape them off.”
The Arizona Game and Fish Department, National Park Service, California Department of Fish and Game, and the Nevada Division of Wildlife are urging all recreational water users to take positive action to avoid spreading this aquatic invasive species. Boaters (including personal watercraft, canoe and kayak users), divers and anglers should take the following precautions:
• Drain water from your boat motor, livewell and bilge on land before leaving the immediate area of the lake.
• Flush the motor and bilges with hot, soapy water or a 5-percent solution of household bleach.
• Inspect your vessel and trailer, removing any visible mussels, but also feel for any rough or gritty spots on the hull. These may be young mussels that can be hard to see.
• Wash the hull, equipment, bilge and any other exposed surface with hot, soapy water or use a 5-percent solution of household bleach.
• Clean and wash your trailer, truck or any other equipment that comes in contact with lake water. Mussels can live in small pockets anywhere water collects.
• Air-dry the boat and other equipment for at least five days before launching in any other waterway.
• Remove any mud or vegetation from your boat or trailer. Mussels can hide and hitchhike in this material.
• Do not reuse bait once it has been in the water.
• Clean sensitive gear (diving and fishing gear) with hot water (140 degrees) or a soak in warm saltwater (1/2 cup of iodized salt per gallon of water) and air-dry before use elsewhere. These precautions will also help minimize the chance of spreading blue/green and golden algae, which have infested the Salt River lakes of Apache, Canyon and Saguaro.
Zebra mussels vs. quagga mussels
• Zebra mussels are freshwater bivalve mollusks that typically have a dark and white (zebra-like) pattern on their shells, but may be any combination of colors from off-white to dark brown. They are usually paler in color near the hinge. Zebra mussels are rounder in shape than quagga mussels. They are usually about an inch or less long, but may be larger. When healthy, they attach to hard substrates.
• Quagga mussels are more triangular in shape and may have a varied color pattern. They are less than an inch long, but are extremely prolific. A single mollusk is capable of producing up to a million microscopic larvae in a year. They can be found at much lower depths than zebra mussels, which is not good news for the deep reservoirs found in the West.
and www.azgfd.gov for more info.