(the Washington Department of Ecology has authority to set minimum stream flows in the Skagit River system to protect fish, game, birds, recreational, and aesthetic values; Ecology promulgated a rule subjecting new water uses to shutoff when stream flows fell below a certain minimum; after the county brought an action alleging that the new rule would inhibit development, Ecology issued an amended in-stream flow rule to provide that new uses of water for domestic, municipal, commercial and industrial, agricultural irrigation, and stock watering would not be subject to shutoff; the Tribe challenged the validity of the amended rule, arguing that it conflicted with water code provisions prohibiting the withdrawal of water when such withdrawal would impair minimum flows; the lower court denied the Tribe’s petition for review, but the Supreme Court reversed, declaring that the amended rule was invalid; the Court found that a minimum flow set by rule was an existing water right that could not be impaired, the exception for “overriding considerations of the public interest” found in RCW 90.54.020(3)(a) was to be construed narrowly; Ecology had improperly reallocated in-stream flow to encourage development; such policy change could only arise through legislative action).