The way sewage rates are levied for many Sonoma Valley residences has been changed to take into account how much sewage they actually discharge, out of fairness and as a way to promote conservation.
"It is perceived as being more fair than a flat fee," said Spencer Bader, business division manager for the Sonoma County Water Agency, which runs the Sonoma Valley County Sanitation District.
Under the new structure, two-thirds of those ratepayers are seeing charges that are flat or less than before.
A third, however, are seeing rates increased, and for some the increase is substantial.
"I don't think as ratepayers we were given what our rates would go to," said Mayor Joanne Sanders, who's own home saw a 49 percent increase. "I don't think there was a lot of information given to the public about the potential of getting hit with 50 percent rate increases."
The sanitation district this year has a $13.2 million budget, a 5.5 percent increase over the 2011-2012 budget, which allows for sewage plant and system upgrades, Bader said.
Bader said the increase is in line with incremental increases over the past decade necessary to pay for $13.3 million in upgrades made since 1998 and for $13.6 million in upgrades being done this next year.
The district provides sewage services to 17,000 businesses and residences, both single-family and multiple family, in Sonoma and the Valley of the Moon.
Under the rate formula for the 2012-2013 budget year, there is a flat fee of $772, with the 5.5 percent increase.
However, there is now also a second tier of fees for 8,752 residences that take both sewer and water, which measures water use in January and February to set sewer rates.