By George P. Hassett

The first cable access broadcast in Somerville featured a dog peeing and a Marine enlistee swearing. But today, programs on Somerville Community Access Television are more likely to be produced by teens with positive messages or immigrants communicating in their native tongues.

Beginning today, SCAT celebrates 25 years of community programming as the state’s oldest public access station (the channel also features the oldest public access program in the world, Dead Air Live, which dates back to the early 1970s before SCAT, when the Somerville Media Action Project broadcast from Davis Square).

The week-long celebration kicks off with the ‚ÄúHaitian Arts Potpourri‚Äù on Monday and closes Thursday with ‚Äúthe week’s big extravaganza,‚Äù says SCAT Executive Director Wendy Blom, a creative arts festival featuring poetry, live music and belly dancing. In between, an open house and a talent showcase featuring ‚ÄúSomerville’s talented teens who perform hip hop, poetry and more in front of a live studio audience‚Äù take over the airwaves.

Thursday’s festivities will start with a half hour set by renowned fiddler and Somerville resident Matt Glaser, who has performed at Carnegie Hall and with Bob Dylan.

Blom said SCAT cablecasts programs in six languages other than English. Approximately 30 percent of programs are in other languages, serving Somerville’s diverse immigrant population, she said.