Senate clears bill to allow detached ADUs in rural areas with limits on size, siting and water monitoring

The Washington Senate on Tuesday approved House Bill 1345, a measure to let counties planning under the Growth Management Act authorize one detached accessory dwelling unit (ADU) per parcel in rural areas outside urban growth areas, subject to size, siting and infrastructure limits.

Under the bill, detached ADUs must be no larger than 1,296 square feet, be located within 150 feet of the primary residence, share the same driveway and meet applicable water and septic requirements. Counties would be required to enforce penalties for unpermitted units, track how many are built and cap how much rural population growth can be attributed to these ADUs.

Republican Senator Keith Gaynor told the Senate he supported the bill as a way to help people better utilize their land to create housing opportunities. "We certainly want to have every opportunity we can for people to better utilize their land," he said.

Republican Senator Keith Wagner spoke in opposition, saying the bill would put additional monitoring requirements on water use for ADUs and primary homes and cited average residential water usage estimates as part of his concern.

The Senate recorded a voice vote of 33 ayes, 15 nays and 1 excused; a presiding officer declared House Bill 1345 passed. The program reported that 29 Senate Democrats and four Republicans supported the measure in that chamber; it now heads to the governor's desk for signature.