Oregon Revised Statutes Water Resources: Irrigation, Drainage, Flood Control, Reclamation § 541.055

(1) Any person or irrigation, drainage, water improvement or water control district organized pursuant to ORS chapter 545, 547, 552, 553 or 554 that owns, operates or maintains any irrigation, drainage, water supply, water control or flood control works shall be liable for damage caused by seepage and leakage from such works only to the extent that such damage is directly and proximately caused by the negligence of the person or irrigation, drainage, water improvement or water control district organized pursuant to ORS chapter 545, 547, 552, 553 or 554 and not otherwise. Damage resulting from extraordinary and unforeseen action of the elements, or attributable in whole or in part to the wrongful interference of another person or irrigation, drainage, water improvement or water control district organized pursuant to ORS chapter 545, 547, 552, 553 or 554 with the irrigation, drainage, water supply, water control or flood control works, which may not be known to the person or irrigation, drainage, water improvement or water control district organized pursuant to ORS chapter 545, 547, 552, 553 or 554 for such length of time as would enable the person or irrigation, drainage, water improvement or water control district organized pursuant to ORS chapter 545, 547, 552, 553 or 554 by the exercise of reasonable efforts to remedy the same, shall not be recovered against the person or irrigation, drainage, water improvement or water control district organized pursuant to ORS chapter 545, 547, 552, 553 or 554.

(2) An action or suit under subsection (1) of this section must be commenced within two years from the date when the damage is first discovered or in the exercise of reasonable care should have been discovered. However, in no event shall any such action or suit be commenced more than four years from the date the damage actually occurred.