The answer to 'why is my irrigation system mud' is that a muddy irrigation system is typically caused by a leak or break in the system. This allows water to seep into the soil, creating muddy conditions around the affected area. Common symptoms include standing water, soft or spongy ground, and visible leaks or cracks in the pipes or components.
The solution often involves locating and repairing the leak or break, which may require digging up a section of the irrigation system. This is a task that can be done DIY if you have some plumbing experience, but it's generally recommended to call a professional irrigation technician. They have the tools and expertise to quickly diagnose and fix the issue, preventing further damage to your lawn and landscaping.