BELLINGHAM - City residents can expect utility rates to rise steadily in the years ahead to cover the costs of maintaining and upgrading water and sewer systems.

"There's definitely pain here," consultant Gordon Wilson told the City Council's public works committee at a Tuesday, Sept. 4, meeting.

Wilson and Public Works Director Ted Carlson gave the council committee a report on a new rate study - an outline of likely future utility system costs and the money that homeowners and businesses will have to pay to cover those costs.

In 2013, the combined water and sewer charge on city utility bills for homeowners could rise $3 to $4 per month, partly depending on whether a home has been converted to metered service. Increases will tend to be lower for the average metered home.

But the cost-and-revenue projections call for additional increases in that same range in every year after that, through 2018. In 2018, metered homeowners would be paying an average of $98.79 per month for water and sewer service that costs $71.49 today, if the City Council adopts the proposed new rates.

How much will your bill go up? There's no simple answer to that question.

Most city residents are still paying a flat, unmetered fee for water service, with a combined water-and-sewer charge that is now $85.86 per month for unmetered homes, including the $12 watershed surcharge for Lake Whatcom protection measures and utility tax.

If your home is still unmetered in 2016, your monthly water and sewer bill would rise gradually to $107.41 per month in that year, although that bill would drop for the average after the metered rate takes effect.

Meters are being phased in around the city, and all homeowners will be paying a bill that will be partly based on household water usage by the beginning of 2017.

But water service is just a portion of the city's bill, which also contains charges for sewer and stormwater. Sewer rates are headed up too, and a rate study of stormwater costs and revenue needs is expected to be completed soon.

City residents get a utility bill every two months. Council members have occasionally expressed interest in converting to a monthly billing system to spread out the impact on household budgets, but that idea now appears dead, after city staffers told the council that the conversion alone would cost the city about $300,000.

The proposed water and sewer rate increases will get some scrutiny from City Council before they are imposed, but the three council committee members at Tuesday's meeting indicated they are likely to approve rate hikes at or near what consultants and engineers are recommending.

Council member Seth Fleetwood asked Carlson what would happen if the council chose to deny the increases.

Carlson replied that some costs, such as the $10 million being spent to install water meters citywide, are mandatory under state law. In other cases, the reliability of the city's water and sewer system could be at risk if the city chooses not to raise enough money to cover maintenance costs.

"We're taking a more conservative approach here," Carlson said. "We need to put more back into our system. ... We understand there will be pushback from customers."

Council member Stan Snapp noted that city water engineers are planning to spend millions on a pre-treatment system at the city's water treatment plant to reduce the impact of summer algae blooms in Lake Whatcom, the city's water source. In 2009, a major algae outbreak clogged the city's water filtration system, reducing its output and forcing mandatory water use restrictions.

Snapp observed that city officials have been trying to reverse the phosphorus levels in the lake that are feeding the algae blooms, in hope of avoiding these kinds of expenses.

Carlson said he didn't want the reliability of city water service to depend on hope that the city's anti-phosphorus efforts will be successful.

"We're just not certain that the protections and restriction plans will be quick enough," Carlson said.

Carlson also told the council that pre-treatment systems to remove algae will reduce the amount of potentially harmful chlorine byproducts in city drinking water.

Bob Bandarra, superintendent of operations at Public Works, added that algae blooms in the lake restrict the water filtration capacity every year, even though there has been no recurrence of the 2009 crisis.

Council members Snapp and Gene Knutson said they had been expecting even bigger proposed rate increases, and they were relieved.

"This is much more modest than I was expecting," Snapp said.

Reach JOHN STARK at 715-2274 or john.stark@bellinghamherald.com . Read the Politics Blog at blogs.bellinghamherald.com/politics.