Twenty-five years ago this week, the tanker Exxon Valdez struck Bligh Reef in Alaska, causing what was then the largest oil spill in U.S. history. Its accident is refocusing questions about the risks of the oil business as a large spill this weekend fouls Galveston Bay and new efforts aim to drill far offshore in the Arctic.

The Exxon Valdez spewed about 11 million gallons of oil — roughly what 17 Olympic-size swimming pools could hold — into the pristine Prince William Sound. The oil spread to 1,300 miles of shoreline, killing hundreds of thousands of fish, birds and other wildlife.

“What I remember most is the weeks going by without any real response on the water,” recalls Marilyn Heiman, then working for the Alaska State Legislature. “What little (cleanup) equipment they did have was obsolete and covered in snow.” She says thousands of fishing and tourism jobs were lost.

“Our wild fishing way of life collapsed overnight. Herring and wild salmon runs disappeared and have never fully recovered,” Dune Lankard, a native Eyak Athabaskan fisherman said last week.

The damage isn’t completely gone. “You can still see the oil if you dig just below the surface in some areas,” says Heiman, who now directs the Pew Charitable Trust’s U.S. Arctic program. “In the intertidal zones, you can still see the oil on the water when the sun hits it,” she says, causing otters to get re-oiled.

Heiman says the oil spill killed an estimated 250,000 seabirds, 2,800 sea otters, 300 harbor seals, 250 bald eagles, at least a dozen killer whales and billions of salmon and herring eggs.

“It was, without a doubt, a disaster,” says Charles Ebinger, director of the Energy Security Initiative at the Brookings Institution, a Washington-based research group. He recalls the sight of birds unable to fly, because they were covered in oil, and the challenge of cleaning up a spill in a remote, cold part of the world.

“It is remarkable … the cleanup was relatively successful,” Ebinger says, adding most wildlife have also recovered.

The March 24, 1989, spill, however, has had a lasting impact. It prompted Congress to pass the 1990 Oil Pollution Act to improve the nation’s ability to prevent and respond to oil spills, including a requirement that tankers have double hulls. In addition, Alaska requires that tankers departing Valdez have an escort response vessel.

Still, other accidents have happened. Nearly four years ago, on April 20, 2010, the BP-operated Deepwater Horizon oil rig exploded in the Gulf of Mexico, killing 11 workers and triggering the largest oil spill in U.S. history.

On Saturday near Texas City, a barge collided with a ship in the busy Houston Ship Channel and one of its tanks ruptured, spilling what Coast Guard officials say is up to 168,000 gallons of oil into Galveston Bay.

As the Exxon Valdez spill marks its 25th anniversary, oil companies are looking to develop offshore oil and gas in the Arctic. This new oil push began several years ago when global oil prices soared and the U.S. Geological Survey reported that the Arctic held 13% of the world’s undiscovered oil resources and 30% of natural gas ones — 84% of which are offshore.

Global warming has added to this impetus by causing the loss of more summer sea ice, making the region’s waterways more accessible. “It is creating the prospect of new maritime routes that would shorten transportation time,” to Europe and Asia, says Ebinger, co-author of a Brookings study, “Offshore Oil and Gas Governance in the Arctic,” to be released Wednesday.

“There is an increased push to drill offshore into ever deeper and riskier frontier waters of the Arctic,” Heiman says.”Those waters are ice-covered for eight to nine months of the year and in almost complete darkness for nearly three of those months. Even during the summer, when the ice pack has mostly receded, the Arctic experiences high seas, wind, freezing temperatures, dense fog, and floating ice hazards.”

Even more challenging is the lack of major highways, airports, and ports, Heiman says, adding cleanup technology has not improved much in the last 25 years.

U.S. companies, notably Shell in 2012, have encountered technical setbacks in their forays into offshore drilling in the Arctic, but that’s not stopping other countries from moving forward.

“The Russians are proceeding apace,” Ebinger says. “They see the Arctic as critical in their future oil and gas development.” He and Heiman say the U.S. government needs to do more to address the challenges posed by the Arctic’s development. The United States is slated to assume the chairmanship next year of the Arctic Council, a forum for eight Arctic nations to discuss regional issues.