An irrigation district hopes to persuade the Oregon Supreme Court its planned reservoir was wrongly blocked due to a misinterpretation of in-stream water rights law. The state’s highest court is considering whether a reservoir proposed by growers from the East Valley Water District would unlawfully inundate stream flows meant to protect cutthroat trout. The irrigation district argues the legal controversy doesn’t just affect its proposed dam near Silverton, Ore., but would upend how water rights are administered throughout the state.