With little discussion, and unanimous approval, city council members in Sonoma started a process to significantly raise water rates in the city. The action Wednesday sets in motion ten years of annual rate increases, totaling a cumulative 53.4 percent. The average monthly bill would rise for just shy of $43 a month to more than $104. Teresa Jurotich, a consultant from the firm Raftelis, which performed a study and devised the rate plan, said without the increases, the city’s water fund would dry up.