Using stormwater service or receiving final approval of improvements authorized by a plumbing permit, whichever first occurs, will automatically initiate appropriate billing for stormwater services as established by section 6.600 of this code. If development of a parcel does not require a plumbing permit, the creation or modification of any impervious surface from which stormwater may be discharged into city stormwater system shall initiate the obligation to pay the stormwater service charges.