A spillover started at a major dam near Houston Tuesday, while Texas is still being devastated by Hurricane Harvey.

Addicks Reservoir spilled over for the first time in its history after catastrophic rainfall and flooding hit Texas.

As spillover was expected a few hours before it happened, Harris County Flood Control meteorologist Jeff Lindner warned that it would "dramatically affect" Houston's northwestern neighborhoods.

Following the beginning of spillover, Linder said that six neighborhoods were being monitored by authorities, and advised residents to leave the area if they have the opportunity.

Linder added that the spillover was in "uncharted territory" because the dam's spillway has not been activated for 70 years, which made predicting the exact impact nearly impossible.

Hurricane Harvey rolled over the Texas Gulf Coast Saturday, smashing homes and businesses and lashing the shore with wind and rain so intense that drivers were forced off the road because they could not see in front of them.

A Texas judge said there was one confirmed death from Harvey in the coastal city of Rockport. The Austin American-Statesman reported later Saturday that Aransas County Judge C.H. "Burt" Mills Jr. also says 12 to 14 people were injured by Harvey, which came ashore Friday night as a Category 4 hurricane but has since been downgraded to a tropical storm.

The fiercest hurricane to hit the U.S. in more than a decade came ashore late Friday about 30 miles (48 kilometers) northeast of Corpus Christi as a mammoth Category 4 storm with 130 mph (209 kph) winds. It weakened overnight to Category 1.

Harvey came ashore as the fiercest hurricane to hit the U.S. in 13 years and the strongest to strike Texas since 1961's Hurricane Carla, the most powerful Texas hurricane on record.