(TNS) — During severe winter storms, Cold Springs Creek above Montecito turns into a torrent of mud, uprooted trees and shed-size boulders as it drains three square miles of sheer mountain front.

The only thing protecting the people, homes and businesses below is a low dam that the Army Corps of Engineers built in 1964 at the mouth of the creek's canyon, forming a basin between the steep banks to catch the crashing debris.

Over the decades, the basin filled up with sediment and grew thick with brush and trees.

Over the years the Cold Springs Creek basin has repeated a cycle of filling and cleaning. By 2017, the basin was almost unrecognizable.

Few officials gave much thought to the condition of the old structure — or to that of the 16 other basins built along the mountains' edge from Santa Barbara to Carpinteria — until the Thomas fire last December left the slopes bare and vulnerable to rapid erosion. On Jan. 9, a storm unleashed mudslides that ravaged Montecito, killing 23 people, destroying 130 homes and causing hundreds of millions in damage.

An eight-month Times investigation found that government officials did not heed decades-old warnings to build bigger basins that could have made the mudslides far less catastrophic — and that Santa Barbara County failed to thoroughly empty the existing basins before the disaster, drastically reducing their capacity to trap debris.

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