Waterlogged Houston is confronting two new crises.

This waterlogged city confronted two new crises Tuesday as the floodwaters from now Tropical Storm Harvey pushed this region’s infrastructure to the breaking point.

To Houston’s west, rain waters began to slosh over a key dam built back in the 1940s to control flooding in the city; meanwhile, the ever-rising San Jacinto River threatened to snap petrochemical-filled pipelines and inundate homes and freeways as the stream swells to record size.

“Please, please be alert. Please be on notice,” Houston Mayor Sylvester Turner said Tuesday morning. “The situation remains dynamic.”

The reservoir and San Jacinto crises have been building up as Harvey’s deluge moves downstream towards the Gulf of Mexico — toward and through Houston.

On Tuesday morning, officials with the Army Corps of Engineers said water from the flood control reservoir behind the Addicks dam was flowing into its spillway. Efforts by Army Corps engineers to head off the overflow by opening the dam’s floodgates had failed.

The reservoir is expected to continue to spill until Sept. 7. The amount of water coming over will start slowly and pick up until the reservoir crests on Thursday. Authorities say it will slowly decline after that.

Additionally, the Army Corps said it expects the Barker reservoir, which sits next to Addicks, to start spilling over by Saturday. However, officials said the amount of water spilled there would be far less than Addicks.

Most of that water is expected to flow into Buffalo Bayou — the flooded river that runs the length of the city toward the Gulf of Mexico — but government engineers and scientists were still calculating the impacts.

“People want exact answers right now and they want to know exactly what they want to do. My own house is in the spillway region of this reservoir,” Harris County Flood Control’s top meteorologist Jeff Lindner told reporters, asking for continued patience as government scientists and engineers raced to forecast the impacts of the dam releases. He said they hoped to have the models late Tuesday evening, after deadline.

“We have never faced this before, we have uncertainty in how the water is going to react as it moves out of the spillway and into the surrounding area,” he added.

However, Lindner emphasized the current controlled releases have not increased flood levels in Buffalo Bayou so far.

New figures released Tuesday put the scale of the disaster — and the challenge confronting officials — in perspective:

Nearly a third of Harris County’s 1,800 square miles is covered by flood waters.

The Harris County Flood Control District estimated 1 trillion gallons of water had fallen on the county.

All that rain upped sea level in the Houston Ship Channel by an astonishing 12 feet.

Those massive amounts of water helped fuel the crisis at the reservoirs and complicate efforts to open the floodgates, Army Corps engineers said Tuesday.

Officials first announced plans to release some water from the two dams as early as Sunday, following Harvey’s torrential rains overnight Saturday. Initially, Army Corps officials planned to slowly open the gates at Addicks at 2 a.m. on Monday and Barker at 11 a.m. The goal, they said, was to ramp up the water flow from both to about 8,000 cubic feet — or about 60,000 gallons — per second, combined, by Monday evening.

Then, right before midnight, the Army Corps informed county officials the controlled releases would begin shortly, hours earlier than expected.

On Monday, officials revealed the flows from the dam were only about half of what they initially wanted — roughly 4,000 cubic feet. They acknowledged the possibility water could overflow and publicly identified neighborhoods near the spillway that could be affected.

By Tuesday, that possibility became a reality as water began sloshing over the Addicks dam. Army Corps engineers also announced the flow rate had finally reached 7,300 cubic feet per second.

At Red Haw Road and Park Row, right below the Addicks reservoir, a fleet of first responders showed up Tuesday afternoon with rescue gear and flatbed boats.

“It’s never flooded here,” said Eric Peterson, 47, after climbing out of the boat. “I’ve lived there all my life. My father lived here for 60 years.”

To Houston’s east, the San Jacinto River continued to rise, surpassing the levels last seen during the historic October 1994 flood.

The surging water threatened more homes at risk, reportedly spilled across Interstate 10 and U.S. 59, and threatened to snap petrochemical-carrying pipelines that stretch across the river. During the historic 1994 flood, two pipelines snapped, spilling fuel that ignited a mile-long stretch of the river.

“There is disastrous flooding taking place along the West fork and East fork of the San Jacinto River,” Lindner said. “We have exceeded — by almost 2 feet — the historic record.”