Muddy? It depends on if you think the trails are saturated or not. Does a storm like this saturate the soil or was there enough rain in the past to do so?
/ˈsætʃəˌreɪtɪd/ Show Spelled[sach-uh-rey-tid]
soaked, impregnated, or imbued thoroughly; charged thoroughly or completely; brought to a state of saturation.
Sorry, I'm a water resources engineer and I've been asked this question twice already today so not trying to offend anyone. Even clay soils need a certain amount of moisture to turn to mud.