MONMOUTH -- Monmouth officials are developing a new potable water source across the Willamette River from Independence.
They and their Independence counterparts may also abandon a potential joint project in which the towns would tap the river by building a surface water treatment plant.
Those were some of the revelations included in an update of Monmouth's water system master plan, which touches on current production capacity, future demand and planned improvements slated through 2030.
Monmouth residents consume about 1.1 million gallons a day during non-peak months. Most water is drawn from a municipal well east of the Independence Bridge in Marion County.
The city has a total production capacity of 2.16 million gallons per day (MGD) -- with 1.73 million MGD coming from its main well, and the balance from two smaller wells on 4th Street in Independence.
"The community has grown beyond its ability to work with one water source," Ed Butts, water engineer for Monmouth and Independence, told City Council at a work session last week.
"It's gotten to the point where I have concerns about it on high consumption days.
"It's a good source," he continued. "But you don't want to put all of your eggs in one basket."
Regarding new sources, Butts touched on a potential well being tested near the primary well in Marion County.
The city will trade municipally-owned residential lots to the owner of the well property if the site proves out.
Monmouth and Independence are also discussing a joint well field near the river.
Last August, the towns received surface water rights on the Willamette at a single diversion point -- along an old railway siding about half a mile south of the Independence Bridge.
Each city would have had the right to 4.46 cubic feet of water per second -- or 2.88 million gallons a day.
An early proposal discussed the two cities building a surface water filtration plant similar to one in Wilsonville.
But officials now plan to modify the surface water permits to a groundwater designation after discovering promising results from test wells running parallel to the river on the west side.
One well conformed with all EPA standards except for coliform bacteria, which can be dealt with, Butts said.
Developing both sources would cost roughly $2.6 million during the next few years -- and would spare the cities from having to invest as much as $15 million to $20 million for the filtration plant planned, said Public Works Director Craig Johns.
It also eliminates the need for a $1.5 million treatment facility city leaders had signed off on in 2005 to reduce nitrate levels in the water supply, Butts said.
Nitrates are chemicals found in manure and fertilizer that can be carried through the soil into groundwater.
Monmouth's Marion County well shows nitrate level spikes during the winter. Officials have resolved the problem by blending its water with water from its supplement wells. This, however, creates a production risk during peak water consumption months.
"One of the greatest legacies we could leave for Monmouth is a secure water source for the future," Johns said.
The city is also addressing options for the distribution and storage elements of the water system:
* Monmouth's 29.3-mile waterline -- 60 percent of which is Asbestos-concrete pipe installed in the 1960s -- is nearing the end of its lifespan. The pipe still functions and isn't in immediate danger of failure. But more structural testing is needed, and Butts recommends that staged replacement of the line is included in the final master plan.
* An additional 2 million gallons of water storage capacity could be created by building new reservoirs on Cupids Knoll and near the Fourth Street well field in Independence.