Most crayfish are strictly aquatic creatures. In low-lying areas near ponds or waterways, however, they may burrow beneath the surface of lawns to find underground water, leaving behind chimneys--tall muddy tubes that stick above the grass. At night the crayfish emerge from the soil to roam about the lawn. During the day crayfish tunnels bake and harden in the sun, where they pose tripping hazards and dull lawnmower blades. The easiest way to get rid of the chimneys is to dispatch the crayfish and collapse the tunnels, according to the U.S. Fish and Wildlife Service.
Poison the crayfish. While no pesticide is Federally registered for use on crayfish, gardening expert Walter Reeves recommends mixing up one of two solutions: 1/4 cup of household bleach or a half-strength turpentine solution that is 2 qts. of turpentine, 1/4 lbs of soap powder and 1 qt of water. Pour either mixture into each chimney. Homer Swingle, Auburn University Fish Culturist, recommends dropping three pellets (or 1/2 tsp.) of lye, or sodium hydroxide, per chimney.
Close the opening of soft chimneys by pushing their tops down into the hole with your shoe or the back of a spade. Crumble the tops of hard chimneys so they fall into the hole.
Keep crayfish from entering your lawn from the surrounding area. There are two options for keeping crayfish out of your lawn for good. One option is to raise the grade of the entire lawn 6 to 8 inches. You'll need to remove the grass, mix the top 6 inches of soil with 6 to 8 inches of horticultural-grade sand or sandy soil, then replace the grass. Crayfish avoid sandy, well-draining, dry soil that is further from the water table than the surrounding soil. The second option is to erect a solid wood or stone fence around your property to create a physical barrier.