Updated: Friday, August 3, 2007 2:09 PM PDT

New water rules that will sharply curtail some new exempt wells in the Walla Walla River basin were signed Thursday.

State Department of Ecology Director Jay Manning put his signature on the amendments, which will now be sent to the state Office of Code Reviser, said Hedia Adelsman, Ecology executive policy advisor.

Among the changes made by the new rules are requirements that new exempt wells drilled in certain areas be limited to 1,250 gallons a day for single residences and that they may not be used for irrigation between May and November unless owners provide ``bucket-for-bucket'' mitigation to replace withdrawals.

The areas affected will be lands zoned for lot sizes of 10 acres or less in the county. About 3.7 percent of the land in Walla Walla County is under that zoning, according to the county Community Development Department.

Concerns over the mitigation requirements led to a conference call in June between Manning, Walla Walla and Columbia County commissioners, state legislators and others. Officials at that time agreed to work to create a ``water bank'' to let landowners obtain water for irrigation during restricted months.

The plan worked out by local and state officials calls for the Washington Water Trust, a nonprofit agency based in Seattle, to acquire water on behalf of Ecology. Residents would then be able to pay a one-time fee to use up to 1,000 gallons a day for irrigation from May through November.

The amendments also establish minimum in-stream flows, require new exempt wells to be metered and limit stock-watering based on parcel sizes.

Adelsman said today the new rules should go into effect Sept. 5, 30 days after the signing.

A question-and-answer guide on the new rules will be posted on the Ecology Web site and printed versions will also be distributed to the county Community Development Department and elsewhere, such as real estate offices, Adelsman said.

A public workshop on the new amendments is being planned to be held sometime in September, Adelsman said. A specific date has not yet been set.

WHAT WAS SIGNED?

Amendments to the state water rule for the Walla Walla River Basin. Among the changes are restrictions on new exempt wells in certain areas. Restrictions include how much water can be withdrawn and a requirement for ``bucket for bucket'' mitigation to replace water used for irrigation between May and November.

WHO IS AFFECTED?

People in the Walla Walla River Basin who want to drill new exempt wells in the shallow aquifer in areas zoned for minimum lot sizes of 10 acres or less.

WHO IS NOT AFFECTED?

People with existing water rights or who have an exempt well that is now in use, people who can obtain a water rights transfer or those who can drill into the deep basalt aquifer.

WHAT IS AN EXEMPT WELL?

A well exempt from state water-right permitting requirements (RCW 90.44.050). Such wells are intended to provide up to 5,000 gallons of water per day for livestock, domestic use in single homes or small groups of homes, watering non-commercial lawns or gardens up to a half-acre and industrial purposes.

WHY AMEND THE RULE?

According to Ecology, restrictions are needed to address the impact of new exempt wells on existing water rights and on efforts to protect and restore stream flows in the Touchet, Walla Walla and Mill Creek/Yellowhawk Creek system.

ON THE NET

ecy.wa.gov/programs/wr/instream-flows/wallawallabasin.html