The state Department of Environmental Protection says more than 1,200 horses are being kept on property where manure-laden stormwater is impacting the Neshaminy Creek watershed.
The DEP says the owners of the Parx Casino and Parx Racing facilities in Bensalem, Pa., also must implement a water conservation plan, improve efforts to manage waste water and make other changes.
The DEP says it's been working with Parx officials for more than a decade to bring them into compliance, but that a March inspection uncovered numerous violations.
A Parx spokeswoman did not comment when contacted by The Associated Press on Thursday.
