The Trinity River levees in downtown Dallas have flunked an important review by the U.S. Army Corps of Engineers, casting more doubt on plans to build the Trinity Parkway toll road.

The findings released Tuesday will also trigger a new federal review of the city's flood risk, which could mean higher insurance rates for property owners in the Trinity's flood zone and more roadblocks to other development.

The corps inspected 170 aspects of the levees in late 2007, and found 34 "unacceptable." City officials said they learned of the findings only this week and have scrambled to make sense of a draft of the report, which won't be finalized until March 31 or later.

The problems highlighted in the report range from small flaws that can be almost immediately addressed to larger ones that could involve substantial changes.

Some of the larger problems involve questions about added risk of flooding relating to the placement of pillars on some of the bridges spanning the Trinity River. And the new Dallas County Jail's basement was dug into a levee, violating corps regulations and perhaps requiring significant changes.

But no accurate estimate of the fixes required – or the impact on the Trinity Parkway project – can be made until the city and the corps go over the findings in detail, Mayor Tom Leppert and other officials said Tuesday.

"It's too early to know," Leppert said, even as he promised that the city and its partners, including the North Texas Tollway Authority, would continue to push forward to meet a May deadline to have 30 percent of the $1.8 billion toll road designed. He has said he wants the toll road built by the end of 2013.

But Michael Morris, director of transportation for the North Central Texas Council of Governments and one of the road's top supporters, said the news could eventually mean a halt to the toll-road work.

"It's a big deal," he said.

And critics of the roadway, including Dallas City Council member Angela Hunt, who in late 2007 led an unsuccessful ballot initiative to take the four-and-six-lane toll road out of the Trinity River Corridor, say the findings ought to be red flags.

"What's it going to take to get them to give up on this road?" Hunt said. "We already have an unsafe levee system, even without pouring tens of millions of tons of concrete into our floodway."

NTTA chairman Paul Wageman said his agency will press ahead with design work.

"We're going to move forward with a design, do everything we can to hew to the deadline and by the May or June time frame have it to the corps so they can walk it through their process," he said. "That's going to be our focus. This is an issue that the city needs to address with the corps."

The May design deadline is critical because the corps must still decide whether the roadway will interfere with the city's flood protection. It can't make that decision until at least 30 percent of the road's design is done. Brig. Gen Kendall Cox, commander of the corps' Southwest division, and others said it's too early to tell what impact Tuesday's decision will have on the corps' review of those issues.

Morris noted that work already done on the toll road could actually help make resolving problems with the levees easier. "If we weren't thinking adding a transportation solution near the levees, we wouldn't have all that data that we have collected," he said.

The corps inspected Dallas' levees in December 2007, and Kevin Craig, the Trinity River project manager for the corps, said Tuesday that the agency has been working ever since to finish its final report.

"The simple answer is that didn't happen as quickly as we would have liked," Craig said. "We certainly wanted to make sure we were doing it right."

Now that the 34 items have been rated unacceptable, the corps and city engineers will inspect each one more thoroughly to determine what must be done to remove each flaw.

"Some of the items may turn out to be 'unacceptable' but it's possible some may not," Leppert said in prepared statements. "But let me be clear – if something is confirmed to unacceptable, we are committed to fixing it."

The corps has been busy inspecting hundreds of levees across the country since Hurricane Katrina's devastation of New Orleans. About 240 levees across America have flunked.

The unacceptable finding will trigger a review by the Federal Emergency Management Agency, Cox said Tuesday. FEMA certifies levees to protect against what is known as a 100-year flood – a flood which has a 1 percent chance of occurring each year. If the agency determines that Dallas' levees no longer provide adequate protection, it could decertify the levee system and redraw the city's 100-year flood maps.

If that happens, property owners could see big rate increases in their flood insurance. In some extreme cases, FEMA has prohibited nearly all development in flood zones after levees were labeled unacceptable.

After the corps labeled as unacceptable some of Sacramento's levees that line the Sacramento River, FEMA decertified them. As a result, the city has halted development in what had been expected to be its fastest-growing district.

While toll road supporters insisted that work on the Trinity Parkway would move forward, even Leppert said the report raises a host of uncertainties.

"Things come up when you are building a big project," Leppert said.

Hunt noted that in addition to the levee problems, the projected cost of the road has soared.

"I frankly think they would put the toll road ahead of the safety of the citizens of Dallas," she said.

Leppert and others said safety and flood control were always the top priority. Morris said his agency would not "do anything to jeopardize the flood control aspects of this project."

Wageman acknowledged that the costs for the project have soared since 1998, when voters first approved a bond package to pay for Trinity River Corridor improvements, including a new toll road. The road was originally estimated to cost about $350 million, with the city pledging $84 million toward that amount, he said.

Eleven years later, Wageman said, the cost is at least $1.8 billion, far more than the agency can expect to be able to pay with funds borrowed against future toll revenues.

Staff writer Rudolph Bush contributed to this report.

Now that the Army Corps of Engineers has found the levees unacceptable, does that mean Dallas residents are no longer safe from major floods?

No levee offers 100 percent safety. The Trinity River levee system is designed to protect against an 800-year flood, or a flood whose probability of occuring each year is approximately 1 in 800. That's a very rare, very large flood. The Corps defines "unacceptable" this way: "An unacceptable rating means a project has one or more deficient conditions that can be reasonably foreseen to prevent the project from functioning as designed, intended, or required." Brig. General Kendall Cox, the Dallas-based commander of the Corps' Southwest Division, said Tuesday that the new rating does not mean the levee has become less safe, only that it no longer passes, according to the grading scale established by the Corps since Hurricane Katrina.

Does that mean the Corps has raised the standards to which levees are supposed to perform?

Absolutely not, says Cox. A better analogy would be that the Corps has changed the grading scale, meaning that it takes just one "unacceptable" rating among scores of items inspected to classify the entire levee as "unacceptable." Of 170 items inspected in the Trinity levee, 34 failed to meet standards.

What's next?

The Corps will continue looking at the 34 areas of concern between now and March 31, when they expect to issue the final report for the once-every-five-years inspection. The city and the Corps will also work toward determining how serious the problems are and how involved the fixes will be. Meanwhile, the Federal Emergency Management Agency will likely begin a review of the levees’ strengths and their level of protection against a less severe but more likely flood, called a 100-year flood.