(Lake Oswego, OR) -- The Portland Bureau of Environmental Services is warning people to stay out of the Willamette River downstream from Lake Oswego's Foothills Park. During maintenance work at a pump station, a mobile generator failed and allowed 30-thousand gallons of partially treated wastewater into the Willamette River. Environmental Services is warning people to stay out of the water near the park through Friday. The cities of Portland and Lake Oswego both use the treatment plant and they're working on plans to replace it.