EXPLAINER: What's happening with the California oil spill?

HUNTINGTON BEACH, Calif. (AP) — Oil has been washing up on some Southern California beaches since a leak in an underwater pipeline from an offshore platform sent tens of thousands of gallons of heavy crude into the ocean waters. The spill fouled the famed sands of Huntington Beach, known as Surf City USA, and could keep the ocean and shoreline closed there and in some other communities to the south for weeks.

Here's a look at what happened, who's involved and the aftermath:

WHAT HAPPENED?

Boaters off Orange County and residents of Newport Beach started reporting a petroleum smell in the air and oily sheen on the water Friday afternoon, Oct. 1.

The following morning the Coast Guard confirmed a spill. The sheen on the ocean was miles wide and crude started washing ashore in sticky, black blobs. The leak occurred about 5 miles (8 kilometers) offshore at a depth of about 98 feet (30 meters) and came from a pipeline owned by Amplify Energy. The Houston-based company also owns and operates three nearby offshore platforms that pipe oil into Long Beach.

Oil first washed up in Huntington Beach, including Talbert Marsh, a sensitive wetland. Crude was later spotted down the Orange County coast, in Newport Beach, Laguna Beach and Dana Point. By Thursday tar balls were reported washing up in Carlsbad, in San Diego County.

HOW MUCH OIL LEAKED?

It’s still a mystery.

Amplify Energy publicly said no more than 126,000 gallons (477,000 liters) flowed from its pipe. But the company also told federal investigators the total may be 29,400 gallons (111,300 liters). On Thursday, the Coast Guard announced its own estimate of at least about 25,000 gallons (95,000 liters) and no more than 132,000 gallons (500,000 liters).

David Pettit, a senior attorney at the environmental group Natural...