The Cudia City Wash

Action by a group of Phoenix, Arizona, homeowners against the Salt River Valley Water Users' Association when their homes were damaged by water escaping from the Arizona Canal. The Arizona Canal is operated by the association as agent for the Salt River Valley Agricultural Improvement and Power District.

The canal traverses the valley in which the homeowners live and intersects at least four major natural washes, including the Cudia City Wash. During normal rainfall, surface runoff collects in these washes and then flows through the canal. However, during extremely severe storms, the washes overflow and flood the surrounding ground. When a storm is anticipated, the association follows storm-control procedures designed to enable the canal system to accept and safely carry off as much excess runoff as possible. Ordinarily, these procedures are sufficient to prevent dangerous overflow. However, several of the valley's brief, high-intensity summer storms have been severe enough to cause major breaches in the canal. The records of the association showed that in 1939 and 1943 a desert storm produced runoff that broke the canal banks in several places.

On June 22, 1993, a severe rainstorm occurred in the Cudia City Wash area. The storm was one having a 100-year return frequency, that is, a storm so severe that it could be expected to occur, on the average, only once in 100 years. During the storm the association went into its storm-control procedures. Nonetheless, when the water from the Cudia City Wash hit the canal, there was so much water in the canal and the wash that it created a backflow, causing water in the canal to flow upstream, overtopping the south bank of the canal, eroding the bank in three places, and causing a wall of water to hit the area in which the plaintiffs reside. The water traveled swiftly, carrying great amounts of mud and debris and possessing sufficient kinetic force to knock down houses and carry away automobiles and horses. The flood waters caused serious damage to the plaintiffs' homes and other property.

Plaintiffs' complaint alleged that the association owed the homeowners a duty to use reasonable care in operating the canal to minimize the destructive effect of desert storms and that the association was negligent in designing and following procedures in the event of severe storms.

At trial, plaintiffs seek to introduce a two-page document that purports to show in graph form the amounts of rain that fell at various points in the Salt River Valley during the storms of 1939 and 1943. This document was found in the association's files and was produced upon plaintiffs' request. The purpose of offering this document is to show that the association knew, or should have known, that storms similar to the June 1993 storm have occurred with some frequency in the valley. The document is unsigned and undated. Is the document admissible?