A summary of May 10 events related to the vast oil spill from the Deepwater Horizon

Events May 10, Day 21 of a Gulf of Mexico oil spill that began with an explosion and fire on April 20 on the drilling rig Deepwater Horizon, owned by Transocean Ltd. and leased by BP PLC, which is in charge of cleanup and containment. The blast killed 11 workers. Since then, oil has been pouring into the Gulf from a blown-out undersea well at about 210,000 gallons per day.

HOW CAN THEY PLUG THE GUSHER?

Top hats and junk shots are on the list of possible next steps as BP, casting about after a 100-ton containment box failed, settles in for a long fight to stop its uncontrolled oil gusher a mile under the Gulf of Mexico. Engineers at BP PLC were wrestling with a shopping list of ways to plug the well or siphon off the spewing crude, including a smaller containment box, dubbed a top hat, and injecting shredded rubber and other debris into the well as a stopper, called a junk shot.

SANDBAG DROP

Helicopters were dropping large sandbags in Louisiana to try to protect the Lafourche Parish marshes from the massive oil slick. The spill began creeping farther west of the Mississippi River last week. About a dozen Louisiana National Guard soldiers affixed straps to one-ton sandbags to ready them for pickup. About 300 sandbags are expected to be used as a makeshift boom to protect the coast.

COST SO FAR

BP — which is responsible for the cleanup — said Monday the spill has cost it $350 million so far for immediate response, containment efforts, commitments to the Gulf Coast states, as well as settlements and federal costs. The company did not speculate on the final bill, which most analysts expect to run into tens of billions of dollars.

SPILL AMOUNT

An estimated 3.9 million gallons of oil have spilled since the explosion on the Deepwater Horizon. At that pace, the spill would surpass the 11 million gallons spilled in the Exxon Valdez disaster by Father's Day.

WETLANDS

Battered by hurricanes, weakened by erosion and flood-control projects, the sprawling wetlands that nurture Gulf of Mexico marine life and buffer coastal cites from storm surges now face another stern test as a monster oil slick creeps ever closer. About 40 percent of the nation's coastal wetlands are clumped along southern Louisiana, directly in the path of oil that was still gushing Monday from a ruptured underwater well. Roughly 3.5 million gallons has escaped in the three weeks since an oil rig explosion, and some is bearing down on the marshes as workers rush to lay protective boom.

WATERMEN

For watermen across the Gulf Coast, waiting is now a way of life. Waiting to see where the slick will land. Waiting for crab and shrimp zones to reopen. Waiting to make some money. Many wait all day in hopes of being loaded up with boom to keep oil out of untainted waters, only to leave without work.

BP's INFLUENCE

With millions of dollars invested in campaign donations and an all-star lobbying team, BP executives could give an advanced class in how to build influence in Washington. But with millions of gallons of leaking oil bearing down on Gulf Coast beaches and bayous, they could also teach how to lose it. Even pro-oil Republicans are demanding answers. At least for the moment, it appears that whatever clout BP has accrued, the oil company is unlikely to get delicate handling from lawmakers investigating the oil rig disaster when oversight hearings begin this week on Capitol Hill.

SHAREHOLDER SUIT

A BP shareholder has filed suit against the corporation's executives because of the offshore rig disaster that led to the oil spill in the Gulf of Mexico. Filed in federal court in New Orleans on Friday, the lawsuit by Pennsylvania resident Katherine Firpo accuses BP PLC of ignoring safety issues on rigs such as the Deepwater Horizon. And the suit accuses BP of pursuing cost-cutting measures at the expense of safety, while lobbying authorities to decrease safety regulation.