December 30, 2009

Study needed on Mill Creek E. coli
Biosolid fertilizer is not the source, say water experts

By Keri Brenner
The Chronicle

     Environmental groups plan more sophisticated testing next year on Mill Creek in The Dalles and three other gorge waterways to determine why they all tested high for E. coli contamination this summer.
     “Once there’s a program that shows high levels, we want to keep monitoring it,” said Brett VandenHeuvel, executive director of Hood-River-based nonprofit Columbia Riverkeeper. “That’s especially true if there have been some changes in management, such as replacing sewer pipes or enforcing new buffer zones from the creeks.”
     This year’s testing, the first of its kind on Mill Creek by Columbia Riverkeeper, failed to show any clear source of E. coli “hot spots” — even though bacteria levels at Mill Creek’s 10th Street sampling site were as much as 415 percent above that deemed safe by the Oregon Department of Environmental Quality.
     Kate Merrick, coordinator for The Dalles Watershed Council, said the sample collections she and volunteers did were limited to city road crossings, St. Mary’s Academy and Thompson Park.
     “We only walked to places with public access to collect the samples,” said Merrick, a staff member at Wasco County Soil and Water Conservation District.
     “Mill Creek is almost all private ownership,” Merrick added. “One thing we could do next year is to contact private landowners to see if we can get permission to sample on their property.”
     The extra sample sites could help pinpoint the source of contamination through a process called “bracketing,” or taking samples above and below a specific area to narrow down the focus, she said.
     Merrick, who also coordinates watershed councils in Bakeoven, Fifteenmile and Mosier, said a decision on next year’s sampling strategy will be made by the nine-member board of The Dalles Watershed Council. The next board meeting is Jan. 14, she said.
     “This first year was really just a screening year,” Merrick said. “It showed us where we need to follow up.”
     Potential contamination sources could include leaky septic systems, broken sewage pipes or agricultural runoff that carries animal wastes.
     Local officials said they are ruling out The Dalles Wastewater Treatment Plant as another potential source of the contamination. The plant spreads its treated sewage biosolids on area hay fields as fertilizer, but plant managers say it’s unlikely that runoff from the spreading is causing the E. coli contamination in Mill Creek.
     The sewage biosolids are so heavily treated and strictly monitored that, by the time they are spread on farmland, they contain less than the minimum safe levels for volatile solids, said Kim Barte, the plant’s project manager.
     The term “volatile” solids refers to organic compounds such as E. coli bacteria.
“We use an anaerobic bacteriological digester on the solids, keeping them heated at 98 degrees for 30 days, to effect a required average minimum 38 percent reduction in volatile materials,” Barte said. “We test that every day to make sure we are meeting the required reduction level.”
     Last year, The Dalles plant had an average 60.5 percent reduction in volatile solids — well below the required minimum, Barte said. Anaerobic bacteriological
digestion is a speeded-up version of what actually happens in nature when organic materials are composted and become available as fertilizer, he said.
     In addition, the biosolids land application cannot be closer than 100 feet to any waterway or closer than 200 feet to a well, according to Dave Anderson, the city’s public works director.
     The Dalles’ biosolids land application program enrolls 10 landowners and is done at 17 hay fields — all downstream from the city’s Wicks water treatment plant, Anderson said. There are no biosolids land applications, animal grazing or industrial development upstream from Wicks, Anderson said.
     “We do everything we can to have the highest quality water come into our water treatment plant,” Anderson said. “And then we still treat it to remove contamination from the elements or any animals.”
     Columbia Riverkeeper first added E. coli testing in Hood River in 2008 after volunteers said they noticed a sewage smell, VanderHeuvel said. In that year, an extreme level of contamination was found in Hood River’s Indian Creek.
     The extreme level was pinpointed as coming from a leaky sewer pipe at Hood River Valley High School. School officials fixed the pipe immediately, VandenHeuvel said.
     “They were happy we found it,” he added.
     Columbia Riverkeeper added the Mill Creek E. coli testing this year. The environmental agency’s annual testing program runs from May to November and spans 120 spots along the Columbia River and its tributaries. In addition to E. coli, the agency tests for issues such as pH levels, temperature, turbidity (water clarity), dissolved oxygen and metals content, VanderHeuvel said..
     In addition to Mill Creek, this year’s testing found high E. coli levels in Hood River’s Indian, Phelps and Whiskey creeks.
     A strong presence of E. coli bacteria in a body of water is an indicator linked to a potential human or animal waste contamination. Drinking or swimming in such water could cause nausea, diarrhea, cramps, headaches or other symptoms.