Abstract
Almost any development of land is likely to alter the flow of water draining from the land to the possible harm of neighboring property. Washington has traditionally applied both the common enemy doctrine allowing diversion of diffuse surface water drainage with impunity and a strict liability standard prohibiting injurious obstruction or diversion of watercourses and natural drains. A reasonableness doctrine applied consistently and uniformly to all drainage water however characterized, would provide recovery to landowners suffering from an unreasonable invasion of excessive water depriving them of the free use and enjoyment of their property. A reasonable use doctrine would balance the reasonableness of the defendant 's conduct and use of land against the results of the harmful interference with the flow of both diffuse and channeled waters. It would be appropriate for the Washington legislature to adopt a unified standard of reasonableness for water drainage law. (Murphy-IVI)