(AP) — Authorities say more tests are needed to determine how long water from the swollen Platte River will pose a health risk.

The Platte has been filled with Colorado floodwater that contained debris, chemicals and raw sewage. The flow down the South Platte hit record levels in western Nebraska, but the flooding threat ebbed when the South Platte joined the North Platte and became the Platte. Department of Environmental Quality spokesman Brian McManus said tests show bacteria levels in the Platte River near the central Nebraska towns of Brady, Cozad and Overton were 10-15 times the amount that poses a higher risk of causing an illness.

McManus says more tests must be completed before state officials can determine how long the health risk will continue.