McCall voters will be asked on Tuesday to approve a $16.5 million bond issue to pay for improvements to the city’s drinking water system.Approval will require 50% of voters to be in favor of the proposal, plus one more voter for a simple majority.The $16.5 million bond would be used to increase the storage capacity and disinfection capacity of the city’s water treatment plant, which is located in Spring Mountain Ranch and serves all city water users.The improvements are needed to keep up with increasing water demand in McCall, which during the summer peaks at more than 3 million gallons per day.The city’s Water Fund does not have enough money to fund the upgrades, which must be complete by 2027 to meet standards set by the Idaho Department of Environmental Quality, the permitting agency under which the treatment plant operates.The McCall City Council chose earlier this year to seek a bond issue to fund the work instead of adopting rate increases that could double residential bills, which currently average $70 per month.The bond money would be repaid over 20 years through fees added to monthly bills paid by 5,900 city water accounts.