A woman tests the water at Portland's East End Beach in this BDN file photo. The city announced late Friday afternoon that the beach is reopened after its most recent bacteria test came back showing levels well below the state beach closure limit.

Portland announced late Friday afternoon it has reopened a city beach that had been closed for 36 hours due to elevated levels of bacteria.

The East End Beach was closed until 4 p.m. Friday, a city official said — roughly 36 hours after an estimated 1 million gallons of partially treated sewage overflowed a wastewater treatment tank and began pouring into Casco Bay.

[One million gallons of ‘partially treated’ sewage spills into Casco Bay]

A first water sample taken Thursday showed levels of bacteria above the state beach closure limit, city spokeswoman Jessica Grondin said. The city made its decision on whether to keep the beach closed for the remainder of the day when the test results came in from a second sample later in the afternoon.

The second sample revealed 10 colony forming units of bacteria per 100 milliliters of water, well below the 104 colony forming units per 100 milliliters that stands as state beach closure limit, Grondin said.

Grondin characterized the earlier bacteria level as “slightly elevated” and said that such increases can be cause by heavy rain, which Portland saw Thursday.

Follow BDN Portland on Facebook for the latest news from Greater Portland.