Bloodworks Northwest is sending out an urgent appeal for donors with type O blood after their inventories dipped to emergency levels earlier this week.

Normally, Bloodworks Northwest and their locations in Bellevue and around King County keep a four-day supply of type O blood on hand. However, the organization announced yesterday that their supplies had dipped “alarmingly low” and they only have a one-day supply on hand.

“We expect donations to fall by about 15 percent during summer — with schools and colleges on break and donors on vacation,” a Bloodworks Northwest spokesperson said in a statement. “This year, the drop off has been closer to 25 percent.”

Type O negative blood is considered the universal blood type and can be transfused to any patient suffering from trauma when they are rushed to a hospital with no time to type that person’s blood. Nearly half of the population has type O blood.

Across the country, blood donation organizations are experiencing a shortage in supply, Bloodworks Northwest added.

Bloodworks Northwest will be located at 1021 112th Ave. until Aug. 29. They will move into a new location on 132nd Avenue Northeast on Aug. 30.

There will be a community blood drive in Mercer Island on Aug. 18. InPeak Properties organized the drive, which will be held from 11 a.m. to 5 p.m. (but closed from 1 to 2 p.m.) in the McDonald’s parking lot on Southeast 27th Street. Islanders can donate in the comfort of the air conditioned bloodmobile bus, burn about 650 calories just laying there and get free cookies.

This morning, nearly 250 swimmers and kayakers crossed Lake Washington during the 19th annual Swim for Life, a fundraiser to support the expand the cord blood bank and support bone marrow donation. Last year’s event raised $90,000.