As Allegheny County, PA / Division 6: Parks and Recreation
Chapter 650 Park Rules and Regulations, subsection 650-1 Prohibited activities states:

B. Shrubs, flowers, trees, grass, turf, soil or rock formations.
(1) Picking, cutting, breaking, digging, defacing or injuring in any way.

C. Buildings, structures or park facilities.
(1) Damaging, defacing or misusing in any way.
  
D. Waste paper, garbage and refuse.
(1) Scattering or depositing except in appropriate receptacles.
(2) Failing to clean up and place all picnic waste paper, garbage and refuse in receptacles provided for that purpose. 
(3) Depositing in park receptacles waste paper, garbage or refuse except for that generated in the park by normal or permitted park activities such as picnicking.
  
E. Animals, birds and fish.
(1) Except as specifically authorized by the Parks Department, molesting, trapping, hunting, capturing, killing or injuring any bird or mammal.
(2) Abandoning animals or birds within the park.
 
F. Lakes, streams and fountains.
(1) Wading, swimming or diving.
(2) Discharging of any type of waste or toxic materials into, or otherwise contaminating, any lake, stream or fountain.

And as it is impossible to guarantee containment of helium-filled balloons, the release of which defaces and contaminates the natural environment, and can injure and kill wildlife, we hereby move to permanently ban the use of ANY AND ALL helium-filled balloons in ALL Allegheny County Parks and impose fines up to the legal state maximum for possession of such within Allegheny County Parks.