I'm planning a trip for this month, Where is there a wash station for the boat at the park or nearby?

No. The closest that I can think of is Moon Lake Park. It don’t have a wash station but you could use their boat ramp for free & dip it in fresh water

I did not find a spigot anywhere near the boat ramp and I did look. There are a few private marinas nearby who might oblige you. FYI I'm from South Florida and the trend here is to actually remove washing stations and spigots in order to increase thru-put and decrease conflict... Heart-breaking.