Tuesday, November 30, 2004
MONMOUTH -- A seasonal increase in nitrate concentration in Monmouth's primary source of drinking water has officials weighing options that would bolster the city's water supply and production in the future.
"We're producing healthy water right now," City Manager Jim Hough said. "What we're talking about is the capacity.
"We're noticing during the summer time that we're bumping up against our ability to maintain the water supply so it keeps up with demand."
Possible solutions include developing and tapping new well sources, upgrading the efficiency of existing water system equipment or building a treatment plant to remove contaminants from some previously tested well sites.
No timeline has been established for implementing those items, but the city will be examining the feasibility of each of them during the coming months, Hough said.
Monmouth gets most of its potable water from the "Marion County well" located across the Willamette River. Nitrate concentration has been an issue with the well since it was activated in 1978, according to an engineering report completed on behalf of the city in October.
Nitrates are a chemical found in most fertilizers, in manure and waste discharge from septic tanks, and can be carried through the soil into groundwater.
Consumption of nitrates can reduce the ability of the body's red blood cells to carry oxygen, and result in a condition in infants called "blue baby syndrome."
The U.S Environmental Protection Agency sets nitrate standards for drinking water at 10 milligrams per liter (mg/l). The Marion County well averages about 5.3 mg/l. That number increases, however, to 13 mg/l between February and May.
The lowest levels are in the summer and fall. The cycle is believed to stem from the application of fertilizers on nearby farmland early in the year, combined with the slow movement of groundwater, the report said.
Russ Cooper, operations manager for Monmouth Public Works, said the city treats the Marion County water by blending it with cleaner water from two other wells it uses in Independence.
Cooper said there's never been a case of illness involving nitrates in the city's drinking water. And only once in 22 years has the city had to issue a public notice for high nitrate concentrations.
The main problem is the toll the treatment process takes on water production.
"We have to throttle back the production out of the Marion County well to blend with the Fourth Street wells, and that decreases the total amount of water we're able to produce," he said.
In the future, an increase in nitrate concentration in the Marion County well during the summer months could hinder the city's ability to produce enough water to meet demand.
Water use in the average Monmouth household is 100 gallons a day per person during the winter. It climbs to nearly 240 gallons during peak use in July and August, Cooper said.
Combined production in Monmouth's wells is about 20 million gallons during winter months. It's 58.7 million gallons in July.
Building a water treatment plant at Monmouth's well field in Independence would cost more than $1 million. The system would take in water from the Marion County well and pump it through a pipeline back to Monmouth.
Having such a facility could allow the city to use two wells -- one along Independence Highway, the other in the Buena Vista area -- that had been tested in the past, but later abandoned because of severe iron, bacteria and nitrate concentrations.
Hough said the city could increase output of its wells by refurbishing the pump and other equipment. The Marion County well has a production capacity of 1,200 gallons per minute.