"Until we figure out what we need to do to make sure we don't spread the snails, we'll simply keep the hatchery closed down," Donaldson added.

In the past, both Colorado and California have been forced to close sections of rivers in order to stop the spread of the snails.

It is believed that the infestation of rivers along the Wasatch Front was a result of fishermen.

As with whirling disease, people need to be aware of the snails and be prepared to take steps not to spread them to other locations. One thing fishermen can do is wash their waders when they move between waters and put them in the sun to dry thoroughly. If the snails are kept moist, they can live for several weeks out of water.

The New Zealand mud snail can be found on both gravel and cobble substrates and aquatic vegetation. They look like tiny, black pebbles.

The Loa hatchery is located in the town of Loa, which is also where whirling disease was first detected.

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