Question
What can I do to stop crawfish from building these mounds of mud in my back yard?

Answer
These can be tough. The following link contains a document that will help you sort out your options. http://icwdm.org/handbook/reptiles/Crayfish.asp  Short of reducing the moisture in the soil, there is precious little that can be done.

Finally, we are always looking for high resolution (3 mg or higher) images of wildlife damage). If you would like to share some photos with us and you can take them safely, we would be grateful. You may send them to [email protected]  (our server can handle e-mails that are 10 mg or smaller.)

Disclaimer: As with any activity, remember that animal damage control comes with its own risks and problems which can include but are not limited to legalities, health threats, and personal liabilities. Be sure to follow all state laws governing wildlife and make sure you have a thorough understanding on how to resolve the animal damage complaint. My advice is only as good as your understanding of me and my understanding of your situation. If you have any questions be sure to write back.