ROME — If an ancient legend is to be believed, Rome was established on the banks of the Tiber River, where the mythical founders of the city, Romulus and Remus, were rescued and suckled by a she-wolf. For centuries, the waterway — once even deified as the god Tiberinus — bolstered the city’s greatness.

More recently, however, the Tiber’s fortunes have been something less than godlike.

Great stretches of the riverfront walkways that abut the high travertine embankments built after disastrous flooding in 1870 have been abandoned to the dubious artistic talents of graffiti taggers. Joggers and cyclists must dodge litter, overgrown vegetation and improvised encampments of homeless people, despite decades of promises by city officials to clean up the river’s banks.

The river’s filthy waterfront and murky waters are a painful reflection of the more widespread neglect and degeneration that has been increasingly blemishing Rome’s beauty, the inattention a symptom of turbulent — at times corrupt — governance on the part of inadequate city administrations.

Faced with the city’s inaction, which it justifies by citing a lack of means and money, several associations of do-gooders have been taking matters into their own hands. Some of these groups have adopted the Tiber as a neglected resource to promote, develop and defend through a variety of initiatives.