They should put signs up to let you know but u need permission first to use them
From their website: "Private use of the sports fields requires prior permission from the sports association. Information on cancellations or changes of all sports association practice/game schedules occurring on sports fields in Precinct 4 parks must be directed to the individual association: Sports associations do not provide Precinct 4 with game schedules, cancellations, or changes of their activities." I would advise calling.
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