PORTLAND, Ore. -- Poet's Beach on the Willamette along the South Waterfront is officially open to swimmers, but not everybody is raring to go for a swim.

Despite reassurances from city officials that the Willamette is clean, it can't completely shake its dirty reputation with some people

But both state and federal scientists who test the river maintain it is clean enough for swimming.

Hydrologists with the U.S. Geological Survey have been monitoring Willamette River water quality for the last 25 years.

In recent years, they began testing it every two weeks for a variety of contaminants.

"We sample for 250 different pesticides and four different metals," said hydrologist Stewart Rounds.

And their findings?

"When it comes to toxins we have not found anything to indicate it would be unsafe," Rounds said.

The Oregon Department of Environmental Quality also tests the area for contaminants. It also said the levels found are so low, they pose no human health risk.

The DEQ said the real concern for swimmers is bacteria, like E. coli, in the water.

The City of Portland tests for that weekly and finds bacteria levels also well within safe limits.

"We've put a lot of time, energy and money cleaning up this river," said Mayor Ted Wheeler.

The DEQ admits because it costs so much to do the testing, it can only test for many of the contaminants once every seven years.

Willamette Riverkeeper is pushing for increased state funding for more frequent testing.