At the control center of the New York Independent System Operator on Carman Road, specialists oversee the state's power transmission system. A two-story-high schematic diagram covers one side of the room, with New York's major power pathways represented by multicolored lines.

A dysfunctional line turns into a string of colored lights. Last week, only a couple of lines were lit, showing there was little to be concerned about.

On Aug. 14, though, the whole board was aglow.

That summer day, a power line in Ohio drooped into a tree, triggering a blackout that rapidly blanketed most of New York, Ontario, eastern Michigan and northern Ohio, and parts of Pennsylvania, New Jersey, Connecticut and Vermont.

The blackout left an estimated 50 million people without power, and cost an estimated $4 billion to $10 billion in the United States.

Today, the cause of the blackout is known: mistakes and conditions that caused a cascading surge of power to sweep through the complex electric grid, prompting transmission lines and generators to shut down.

But a year later, many in the industry say that if the same thing were to happen, New York still might be left in the dark.

"Could we withstand exactly the same thing that happened last year?" William Museler, president and chief executive of NYISO said at his Carman Road office. "Maybe, maybe not."

While some specific problems have been corrected, the larger situation that allowed the blackout to take place still exists, several experts said.

One of the reasons the blackout spread was that problems in the Midwest went unfixed. Standards for running the transmission system in New York are generally agreed to be the best in the country. But as the nation's power grid becomes increasingly interconnected and interdependent, a glitch across a border can have a big impact here at home.

"We are as strong as the weakest link in this whole interconnection of energy systems," said state Assemblyman Paul Tonko, D-Amsterdam, chairman of his house's energy committee.

Yet federal legislation to make standards mandatory and enforceable has stalled.

The transmission system is not robust enough to withstand major power swings, because over the years the amount the country has spent on the network has declined. Meanwhile, demand for power has grown with the population and the proliferation of power-hungry technology.

"The system is overloaded and has been for years," said David Newman, a physics professor at the University of Alaska Fairbanks who has been modeling transmission systems. "The bottom line is, we're going to have another failure. I don't know when, but we will." Things that the utilities industry can do on its own, it is doing, said Jim Owen, spokesman for the Edison Electric Institute, a Washington, D.C.-based association of investor-owned power companies.

There is a big focus on what's called "vegetation management," to make sure trees and plants don't interfere with electrical systems, he said. The North American Electric Reliability Council, an industry reliability group based in New Jersey, has been conducting readiness audits of regional transmission controllers.

One of the problems last summer was a lack of communication among different transmission regions. For example, NYISO had no idea what its counterpart, the Midwest Independent System Operator, was doing.

Today, NYISO and MISO have direct lines of communication, NYISO's Museler said. And operators here have access to data from a larger area of the grid -- they can see beyond the boundaries of New York state, which lets them know about disruptions coming down the pike.

"If operators see something potential looming, they can do things to strengthen the system," he said. "But the real cause of the problem has not been addressed. The biggest danger is that people can continue to not follow the rules." When the power line in Ohio touched a tree and cut out, the electricity began to flow through other lines, which in turn shut down from overload -- a pattern that would repeat again and again.

"It should have been a very localized problem," said Ralph Fehr, an electrical engineering professor at the University of South Florida and a power systems expert.

The line was maintained by Akron, Ohio-based FirstEnergy Corp. The U.S.-Canada Power System Outage Task Force, created by President Bush and former Canadian Prime Minister Jean Chretien to investigate the blackout, found that, among many other problems, the company lacked emergency blackout plans.

The North American Electric Reliability Council found that FirstEnergy and other institutions violated several of the council's reliability standards, but there are no penalties for that.

"All of the guidelines and regulations have been pretty much voluntary," Fehr said. In the past, peer pressure has worked as a regulatory tool. But utilities have found that they can make more money by pushing transmission systems to the limit, he said.

"It's like driving without a seat belt," he said. "It doesn't mean you're going to die, but if you get into an accident there's a greater chance."

If anything can be done to stop a blackout, it's requiring that New York's standards be implemented nationwide, said Gavin Donohue, president and chief executive of Independent Power Producers of New York, an Albany-based trade group.

He's not alone in his view. From NERC to NYISO, Gov. George Pataki to Assemblyman Tonko, there have been calls to make the rules of the road mandatory.

"Which means Congress has got to do their job," Donohue said.

The massive energy bills that have been proposed -- and stuck -- in Congress for the past few years have included provisions that would give the Federal Energy Regulatory Commission power to enforce national standards. The comprehensive bill, which encompassed ethanol subsidies and liability protections for makers of the fuel additive MTBE, passed the House last year but was filibustered, mostly by Democrats, in the Senate.

"We're nowhere," said Sterling Burnett, senior fellow for the National Center for Policy Analysis, a Dallas-based research organization that promotes alternatives to government regulation. "You're not going to see it before the national election, that's for sure."

This year, a group of senators, including New York Democrats Hillary Rodham Clinton and Charles Schumer, co-sponsored a separate bill that deals just with the reliability issue. But that, too, has stalled.

The "shock value" of the blackout should have been enough to make some major policy changes take place, said Tonko, who is introducing a resolution in the Assembly to remind Congress and the White House that reliability standards are still needed.

"One year later, no progress," he said. "It's not an anniversary worth celebrating."

Burnett is not sure mandatory standards would solve things, and said it needs to be easier to build transmission lines.

"The truth is, if you really want to reduce the possibility of a blackout, you increase your number and sources of types of energy, and you improve the transmission grid," he said. Some people mistakenly believe that the blackout was about not having enough electricity. But on the day of the blackout, New York had enough extra generating capacity to power about 3 million homes.

Instead, it was partly about not having extra room to handle the power fluctuations that started in the Midwest.

"Over the last decade, we spent two-thirds less to enhance and maintain the transmission system," said New York Attorney General Eliot Spitzer. In that time, investment in New York State went from just under $300 million to $90 million a year, he said.

Consolidated Edison Inc. is making major upgrades to transmission lines in Westchester County that connect to New York City, NYISO's Museler said. But other projects, such as a proposal to build a major line from the Capital Region to the city, have been unable to find financing.

Next year, NYISO will put out a report with a 10-year view of New York's electricity situation, he said. It will include recommendations for the transmission system.

At this point, the system looks good through 2008, Museler said. But energy projects can take several years to complete, and there's nothing new in the pipeline.

"At some point, we're going to have to put some more money into this," he said. "It's just like roads or airports."

Adding generating capacity to the system can make it more flexible, Museler and others said.

Reducing the amount of demand can help buy time. Energy-saving projects such as the New York Energy Smart Program, a partnership between the New York State Energy Research and Development Authority and the state Public Service Commission, are reducing power consumption somewhat. But the amount of power used in the state has climbed each year, according to NYISO.

Newman, at the University of Alaska, said his studies show that fixing small problems could just forestall larger catastrophes, enabling the system to operate closer to overload.

"Any given blackout is caused by a trigger," he said. "A squirrel crawling into a transformer and getting fried. A tree."

The way to avert the darkness is spending billions to make the electricity system redundant, he said. "You can't control all the squirrels." FACTS:Blackout's impact The blackout of Aug. 14, 2003, swept through the Northeast after a power line in Ohio sagged into a tree limb. Measures for preventing future blackouts have been proposed, but no major reforms have taken hold. Estimated number of people affected by blackout: 50 million Estimated New Yorkers affected: 15.9 million Estimated U.S. cost: $4 billion to $10 billion Blackout began: Shortly after 4 p.m. eastern time New York's system fully restored: 10:30 p.m.

Aug. 15 Sources: U.S.- Canada System Outage Task Force, New York State Department of Public Service, Electric Consumer Research Council, New York Independent System Operator