An operational failure at the The Dalles Wastewater Treatment Plant combined with rain resulted in the discharge of 416,000 gallons of treated but non-disinfected wastewater Wednesday evening through early Thursday morning into the Columbia River, likely exceeding the plant’s limit for E.coli.  One of the plant’s ultraviolet light disinfection channels was brought online Wednesday evening, but the UV disinfection system was not fully enabled for that channel.  Plant staff brought the system back online this morning.  Samples are being taken at pre-arranged locations in the river to provide data on the effect of the discharge on water quality in the river.  Warning signs advising no water contact have been placed along both sides of the river from The Dalles Riverfront Park to West Mayer Park boat launch on the Oregon side and from the Dallesport Boat Launch to the Klickitat Sandbar on the Washington side, and will be removed once sample results indicate the river water is safe for contact and public use.  Questions can be directed to the Public Works Department office at (541)296-5401.