Issaquah committee backs staff plan to align duplex and single-family water and sewer rates; King County sewer minimum to be recalibrated

The Issaquah Mobility and Infrastructure Committee on July 15 reviewed a utility rate study and indicated support for staff recommendations to align duplex and single-family bimonthly rates for water and sewer, recalibrate the minimum sewer-volume assumption to match King County’s Residential Customer Equivalent (RCE) of 15 CCF, and continue the current stormwater rate structure.

The study, presented by city staff member Matt and consultant Sergei, updates a 2020 comprehensive rate study and covers rate-setting steps for water, sewer and stormwater for the next five years. Sergei summarized the three-step process as "revenue requirement, cost of service, and rate design" and said that "there's not a 1 size fits all solution" when deciding how much to recover through fixed versus variable charges.

Why it matters: the committee is setting policy direction now so staff can present a final summary and formal rate adoption later this year. The city plans a summary presentation to the Mobility and Infrastructure Committee on Sept. 16 and aims to adopt the rate ordinance at the Oct. 20 regular council meeting; if adopted, changes would be implemented beginning in 2026.

What the committee reviewed and recommended

- Align duplex with single-family rates (water and sewer): Staff proposed consolidating duplex billing into the single-family rate schedule for both fixed and volume structures starting in 2026. Sergei said duplexes and single-family homes have "fairly similar" fire-protection sizing and usage patterns, which underpins the recommendation to collapse duplex rates into the single-family schedule. The presentation noted there are about 87 duplex accounts on the system; most of those would see small bill changes and a minority of outliers could see larger adjustments.

- Recalibrate sewer minimums to King County RCE (15 CCF): For sewer, staff described current practice as a city local fixed charge plus a King County pass-through for treatment. The presentation said King County’s pass-through equals about $116.56 per residential equivalent (based on a 15 CCF bimonthly assumption). Staff recommended adjusting minimum assumed volumes for non-single-family customers to align with King County’s 15-CCF RCE so the city recovers the pass-through at a minimum. As Sergei explained, the approach ensures the city "at least recover[s] for the base 1 unit" while continuing to bill incremental use when consumption exceeds that floor.

- Stormwater: staff recommended continuing the current structure (charges per equivalent service unit tied to impervious area) and applying straightforward percentage adjustments to meet the revenue requirement.

Projected bill impacts and equity considerations

Staff presented class-specific phase-in scenarios and examples showing how the changes would affect customers. For water, converting duplexes from a 4-block to a 5-block structure and aligning fixed charges with single-family rates will produce mixed effects: low-usage duplex customers (roughly up to 8 CCF bimonthly) would generally see bill decreases, mid-range users small changes, and high-usage accounts increases of up to about 10% or more; very high outliers could see larger increases. Sergei noted the design intentionally places somewhat higher marginal charges on the top tiers to incentivize conservation.

For sewer, the proposal moves the King County treatment pass-through into a fixed component for single-family and duplex accounts (so those connections carry the fixed King County portion), while multifamily and nonresidential customers will continue to have mechanisms tied to consumption with a recalibrated minimum to 15 CCF. Staff said current local fixed sewer charge is $20.76 bimonthly and that King County’s pass-through equates to about $116.56 for a residential equivalent; the current per-CCF pass-through for some nonresidential billing was described as roughly $7.77 per CCF.

Committee discussion and non-rate issues

Committee members asked how conservation incentives would affect multifamily and renter-occupied units that do not receive individual bills. Deputy Council President Dimitchell (title as identified in the meeting) and others raised the concern that renters often lack direct price signals. Director Moon, the city’s public works director, said the city participates in Cascade Water Alliance conservation programming and that the city plans targeted outreach to very high-usage accounts: "We participate in all their drought management and conservation efforts," Moon said, and added the city will perform direct outreach to outlier accounts to help reduce peak summer use.

Council members also asked whether the rates account for recent storm-related costs (the presentation referenced the city’s response and some reprioritization after a recent "bomb cyclone"). Director Moon said the utility funds did not absorb the majority of those emergency costs, that staff had reprioritized or deferred some capital projects to manage cash flow, and that the proposed rates are intended to keep utility funds healthy over time rather than to retroactively reimburse a single event.

Committee response and next steps

Committee members voiced support for the staff recommendations during the meeting; there was no formal roll-call vote recorded in the transcript. Matt stated the staff recommendation is to follow the two policy statements (align duplex and single-family rates; recalibrate sewer minimums) and to continue the stormwater structure. Staff will return to the Mobility and Infrastructure Committee with a rate-study summary and findings on Sept. 16, followed by an anticipated council adoption action on Oct. 20 at the regular council meeting.

Ending

City staff and the consultant will use the committee’s direction to prepare the final rate study and ordinance language for council consideration in October. The committee adjourned at about 7:31 p.m.