Idaho Code § 36-908
The department may install and maintain screening and bypass devices in any gravity-fed diversion taking or receiving one hundred twenty-five (125) cubic feet of water per second or less from any stream or lake in this state in which fish may exist or are placed or planted, to prevent said fish from leaving such waters. For such purposes, the department may install, maintain, repair, relocate or reinstall all such screens, gratings, or other devices and all bypasses thereto. No screen or other device shall be installed which will diminish the flow of water in such diversion. It shall be unlawful for any person to interfere with, tamper with, damage, destroy or remove any fish screening or bypass device installed pursuant to this chapter.
Idaho Code § 36-908