Part 10 — Copper Controls

(a) Pools, spas, and fountains. Discharges from pools, spas, and fountains that contain copper-based chemicals are prohibited from entering the storm drain system. Owners of pools, spas, and fountains shall either install a connection to a private sanitary sewer, including a connection for filter backwash, or divert the discharge for use in landscaping. Discharge diverted for use in landscaping shall not overflow the landscaped area.

(b) Sources. Each industrial source in the city shall have BMPs in place to minimize discharge of copper to the storm drain system, including consideration of roof runoff that might accumulate copper deposits from ventilation systems on site.

(c) Roofing materials. Copper metal roofing, copper granule containing asphalt shingles, and copper gutters shall not be permitted for use on any residential, commercial, or industrial building for which a building permit is required. Copper flashing for use under tiles or slates and small copper ornaments are exempt from this prohibition. Replacement roofing and gutters on historic structures are exempt, provided that the roofing material used shall be pre-patinated at the factory. For the purposes of this exemption, the definition of "historic" shall be limited to structures designated as

Category 1 or Category 2 Buildings in the current edition of the Palo Alto Historical and Architectural Resources Report and Inventory.

(d) Sites requiring copper controls shall comply with all applicable BMPs described in city regulations and otherwise prescribed by the Director.

(Ord. 5671 § 2 (part), 2025)