PUEBLO, Colo. -- Recent sampling efforts between the Colorado Division of Wildlife and Colorado State Parks personnel have detected the presence of zebra mussels at Lake Pueblo State Park.

Two adult mussels and one immature specimen were found on substrate sampling gear, and the larva was found by performing plankton tows.

Although zebra mussels do not pose a known threat to human health, biologists are concerned that zebra mussels may cause ecological shifts in the lakes they invade, with consequences to valued wildlife resources.

Because these invasive mussels attach to hard surfaces like concrete and pipes, they will affect canals, aqueducts, water intakes and dams, resulting in increased maintenance costs for those facilities.

Additional sampling at Lake Pueblo State Park to determine the degree of infestation and exact mussel species is planned for this winter and spring. State Parks and the DOW are planning a concerted effort to notify recreational users at Pueblo Reservoir, and other state parks, about the potential impacts of zebra mussels.

The Pueblo State Fish Hatchery, which receives its water supply from Pueblo Reservoir, will undergo an assessment regarding options to prevent the spread of adult mussels and/or larvae. Sampling inspections have been conducted to determine if zebra mussels or larvae are present in the hatchery unit. To date none have been detected.

Pueblo Hatchery raises a variety of warm and cold water species of fish (walleye, bluegill, crappie, channel catfish, smallmouth bass, wiper, rainbow, cutthroat X rainbow hybrid, and brown trout) and distributes these fish across the state each year. No fish are planned to be stocked from the Pueblo Hatchery until April this year. Effective water treatment options exist to eliminate zebra mussel adults and/or larvae prior to the fish being stocked.

All boaters and other water craft recreational users should take simple, precautionary steps every time they go to a lake, river or stream.

The primary method of overland dispersal of these mussels is through human-related activities. Given their ability to attach to hard surfaces and survive out of water, many infestations have occurred by adult mussels hitching rides on watercraft. The microscopic larvae also can be transported in bilges, ballast water, live wells, or any other equipment that holds water.

These mussels can settle in massive colonies that can block water intake and affect municipal water supply and agricultural irrigation and power plant operation. In the United States, Congressional researchers estimated that zebra mussels alone cost the power industry $3.1 billion in the 1993-1999 period, with their impact on industries, businesses, and communities more than $5 billion.

Many of these aquatic hitchhikers can harm people's boat as well. These invaders will attach themselves to boats and can cause damage to boat motors if they block the flow of cooling water through the engine.

Before leaving a lake or other waterway, always:

CLEAN the hull of your boat.

DRAIN the water from the boat, livewell and the lower unit of the engine.

DRY the boat, fishing gear, and equipment.

INSPECT all exposed surfaces.

REMOVE all plant and animal material.

The DOW and Parks personnel have been conducting field sampling efforts for several years to evaluate waters across Colorado for the presence of aquatic invasive species. These efforts are targeted toward locating and monitoring potential introductions of invasive species that can be environmentally and economically detrimental to the state, its wildlife and recreation resources.