Santa Barbara Channelkeeper v. City of San Buenaventura

*1180 The Ventura River watershed is home to Southern California steelhead trout, a species listed as endangered since 1997. Defendant City of San Buenaventura (City) has been diverting water from the Ventura River *1181 since 1870, but plaintiff Santa Barbara Channelkeeper (Channelkeeper) sued the City and alleges that the City's current diversions are "unreasonable" because of the effect they have on the fish during summer months, when water levels are low. Nobody disputes that the City holds water rights that would otherwise allow it to divert this water, but under the California Constitution there "is no property right in an unreasonable use" of water. ( Joslin v. Marin Municipal Water Dist. (1967) 67 Cal.2d 132 , 145, 60 Cal.Rptr. 377 , 429 P.2d 889 ( Joslin ).) Thus, adjudicating Channelkeeper's allegations requires the court to determine whether the environmental consequences of the City's water diversion act to cap the City's water rights at a level below its current usage.

The City not only asserts the reasonableness of its own water use, it has cross-complained against other entities who also draw water from the Ventura River watershed, alleging that their water use is…