Generally speaking, placing fill dirt, construction debris, or other materials is not allowed with any watercourse, whether it is a creek that runs year round or a dry wash. The drainage function of all watercourses must be preserved so that they have sufficient capacity to convey stormwater runoff. Any alteration to a watercourse requires a permit and a plan prepared by a civil engineer that meets the requirements of the City Code, including the General Engineering Standards (Article 3).
It depends. Fences are not allowed across drainage easements or within FEMA designated floodways, but may be allowed in other situations where it would not adversely affect the function of the watercourse.
Drainage culverts underneath public roadways are maintained by the Streets Maintenance Division, whose hotline number is 777-1666. Driveway culverts and culverts or pipes on private property are the maintenance responsibility of the property owner or Home Owners Association.