The answer to 'why is my irrigation system mud' is that your irrigation system is likely clogged with dirt, debris, or mineral buildup. This can cause the water flow to be restricted, leading to muddy or pooling water around the sprinkler heads or other components.
Some common causes of a muddy irrigation system include broken or damaged sprinkler heads, a cracked or leaking pipe, excessive mineral buildup in the system, or improper system drainage. Symptoms may include wet, muddy areas, low water pressure, and sprinklers not reaching their full coverage area.