The board of commissioners of Water District 19 is considering a policy change that would allow a few residential customers to supply both their main residence and an accessory dwelling unit (ADU) with one water service unit (share) if certain water-saving requirements are met. Presently a customer needs two water service units — one for the principal residence and one for the ADU (sometimes referred to as a mother-in-law or granny suite).
Many other water purveyors in the state follow such a policy, and it could have some important benefits for both current customers and those on the waiting list to obtain water service from the district.
If permitted under King County land-use codes, some current customers — Island residents, not developers — would be able to add an ADU of up to 1,000 square feet without having an additional water unit. Other existing customers who had been required to have two water service units for existing ADUs can install water-saving fixtures in the ADU and sell their now-excess water unit back to the district, thus conserving water, saving residents the bi-monthly base charge and providing them with several thousand dollars for their unnecessary water service unit. These units could then be made available to the next people on the waiting list.
Finally, people who are on the waiting list solely to build an ADU could proceed with their plans and drop off the waiting list, letting others move up on the list.
The district has been in a moratorium on issuing new water units since 1996 (although a number of unused water service units have been returned to the water district over the years and offered, in turn, to the next people on the waiting list). The limited water resource on the Island has long been a difficult problem for most Island water purveyors in providing new water services. During hot summers, peak water usage can exceed the resources available.
Despite spending millions of dollars drilling nine wells and expanding our surface water treatment plant, we physically can’t produce the volume of water to which we have the technical right from the state Department of Ecology.
The nature of the deep aquifer is such that while relatively modest flows can be readily accomplished, no matter how large a well or pump we install, larger amounts simply aren’t available. Furthermore, the two creeks that provide the bulk of our water have greatly restricted flows in the summer, when peak capacity is demanded by the district’s customers.
Despite the clear restraints on our ability to sustainably produce enough water to lift the moratorium on all new development, there are reasons to believe the district can alter its present policies and allow customers to build ADUs on a single water service unit without exceeding our ability to supply water to our existing customers and without setting back our ongoing efforts to eventually get water service to all the members of the waiting list.
First, the new Beall well — with its projected peak capacity of about 80 gallons per minute — is expected to come online later this year. Secondly, the Department of Ecology is expected to approve the use of the existing Morgan Hill Well to add about 35 gallons per minute to our peak capacity. Finally, proven and systemic conservation activities over the past four years have lowered peak consumption considerably.
The impact of this proposed policy change on water demand would be minimal; industry data suggests an ADU (which is limited by King County in both size and number of water-using fixtures) uses much less water than a full-sized residence. Further, it is estimated by the engineering firms that have produced our last two system plans that fewer than a dozen ADUs would likely be added per year.
The proposed district policy would require the installation of water-efficient fixtures and would prohibit any additional landscape irrigation. The expected small growth in demand could be more than offset by the projected conservation advances we are continuing to make in District 19.
The expected bottom line from this proposed policy change would be to benefit the district customers and those on the waiting list who desire to construct an ADU for a relative, a caregiver or a tenant and to add, however incrementally, to the stock of affordable housing on the Island without endangering our ability to supply water to our existing customers — which, after all, must be our number one priority at the district.
— Steve Haworth is a commissioner on Water District 19’s board.
District 19 meets
Water District 19’s commissioners will consider the proposed policy at their meeting at 6:30 p.m. Tuesday, June 9, in Fire Station 55’s emergency operations center.
