If they were just a little larger, these snails and mussels invading and/or threatening Utah waters could well be the evil aliens in a B movie classic. A single snail or mussel can reproduce into millions in a very short time.

They look harmless, like a stubby, empty cornucopia. They are smaller than a fly, very unobtrusive and very slow moving.

At this point, quagga mussels have not been found in Utah but are very close and very much a threat. They were found a year ago in nearby Lake Mead in Nevada.

A single quagga mussel can produce up to a million offspring a year. Extrapolate that and you've got several trillion relatives being produced in a couple of years.

Utah does have the New Zealand mud snail. It's found in a number of waters, including the Green River, Provo, Ogden, Logan and Bear rivers. Most recently it was found in the Loa State Fish Hatchery.

The New Zealand mud snail needs no mate. It is asexual and can produce a new generation of hundreds of young every two months.

For now, snails are only a threat to fish. Fish eat them but get no nutritional value and can grow skinny and die.

If Utah gets quagga mussels, then not only fish but boats and pipes and docks and any other object dropped in the water overnight are threatened.

They group in layers and in large groups, and once in place, they are harder to remove than hardened concrete.

The problem with both snails and mussels is they are so small they can hide in the groove of a shoe or in a speck of mud or in the outdrive of a motor and can live for long periods out of water.

And once a water is infected, there is no cure.

One of the ways they move about out of water is as passengers on the soles of shoes and waders and in mud stuck to shoes and vehicles. They can also hide in hard-to-reach places on boats and trailers.

Consensus is snails were carried to a number of waters along the Wasatch Front by fishermen. It is unlikely the carriers knew they were carrying snails.

The quagga mussels have not hit Utah yet. There were some signs they had made it to Lake Powell, but later tests proved negative.

The mussels were found in Lake Mead, and it's not uncommon for boat owners to visit Mead and then Powell within a 30-day period, which is considered a safe waiting time.

The point is, of course, that people need to be aware of the threat and take the time and make the effort to avoid spreading the problem.

This means for boaters who have been in waters with quagga mussels, either wash down the boat and let it sit for at least five days prior to launching or wash the boat down in scalding-hot water. Washing stations have been set up near Lake Powell ramps and at locations near Quail Creek and Sand Hollow in southern Utah.

The hope is that boat owners won't find these things too much work and launch without proper cleaning.

With snails, the precautions are similar to those recommended for whirling disease.

These include washing and disinfecting things like waders and fishing gear and washing mud off shoes and vehicles.

It's really not too much to ask that people be aware of the problem and take precautions. A little work now could save big headaches in the future.

E-mail: grass@desnews.com