The answer to 'why is my sprinkler system mud' is that your sprinkler system is likely clogged or has a leak, causing water to seep up through the soil and create muddy conditions around the sprinkler heads. This can happen due to a buildup of debris, a broken sprinkler head, or a crack in the underground pipes.
Common symptoms of a muddy sprinkler system include standing water, soft or spongy soil around the sprinklers, and reduced water pressure or coverage. To fix the issue, you'll need to identify and address the root cause, which may involve cleaning the system, replacing damaged parts, or repairing any leaks. While some basic troubleshooting and minor repairs can be done DIY, it's often best to call in a professional landscaping or irrigation specialist, especially for more complex problems.