The Human Access Project had the Willamette tested for toxic algae and found no measurable trace.
Willie Levenson with the organization said the project paid for the testing itself.
"There was some question mark as to whether or not the algae issue was confined to the Ross Island Lagoon and if downtown was safe," he said.
The samples were taken at the entry point at Poet's Beach and Tom McCall Bowl, the exit point.
"We worked very closely with Oregon Health Authority and (the Department of Environmental Quality) in picking our sampling points and following procedures to get the water tested," he said.
The float takes about 45 minutes to one hour to complete. Levenson said the water is nice and warm at 74 degrees.
"The water temperature is great for getting in the water," he said.
The float will feature an inter-tube parade, a band barge, a marching band and water slides.
He said the annual float is a celebration, which encourages Portlanders to have an improved relationship with the river.
"Some people wind up doing the float more than once because it's so fun," said Levenson.