Porterville, CA Outdoor Lighting: Dark Sky Rules (2026)

Section 300.07.A states the purpose in explicitly astronomical terms: the shielding rules exist to minimize outdoor artificial light that could harm the environment, astronomical research, amateur astronomy and enjoyment of the night sky, not just to control glare for neighbors. That purpose becomes a design standard in Section 300.07.E, which requires every fixture to meet the Illuminating Engineering Society of North America's "Cut Off" or "Full Cut Off" criteria and to be shielded according to Table 300.07(B).

The shielding table sorts fixtures by lamp type. LED and fluorescent fixtures need full shielding plus filtering; high-pressure sodium and quartz lamps need full shielding with no filtering requirement; low-pressure sodium, described in the code as the source preferred for minimizing light pollution affecting astronomical observations, needs neither; and mercury vapor fixtures are not permitted at all. Maximum fixture height is separately capped by Table 300.07(A), from sixteen feet in residential districts up to fifty feet in recreation and park districts.

The rules apply going forward: Section 300.07.B limits the requirements to fixtures installed after the ordinance's effective date, and a property is grandfathered unless fifty percent or more of its existing fixtures get replaced, at which point the whole installation has to come into compliance. Fixtures under 4,050 total lamp-source lumens, fossil-fuel-combustion lighting, and temporary construction or emergency lighting are exempt outright.