D.C. Water customers could see their bill rise by 12.3 percent under a proposal to be voted on in July.

As Short Articles About Long Meetings first reported, the biggest line item increase would be the Clean Rivers Impervious Area Charge, which covers the cost of the federally-mandated, sewer overflow Clean Rivers Project.

The new Clean Rivers Impervious Area Charge (CRIAC) is a fair way to distribute the cost of maintaining storm sewers and protecting area waterways because it is based on a property’s contribution of rainwater to the District’s sewer system. Because charges are based on the amount of impervious area on a property, owners of large office buildings, shopping centers and parking lots will be charged more than owners of modest residential dwellings.

The average bill would increase by $9.45 after October 1, according to a D.C. Water’s budget overview [PDF].

The DC Water Board of Directors, which will vote on the proposal in July, will hold a public hearing on May 14 at 6:30 p.m. Proposed rates can be seen here.