California likely has long and detailed regulations detailing the process to dispose of dirty water. Expect heavy fees and permits to allow the disposing of the environmental hazard. Once the inspector signs off, you can proceed to dump the water. Note, your water is "known to the the state of California to cause reproductive harm and other birth defects".
That's enough of me being a smart butt... If it's just dirty water from the outside it's about like driving your car in the rain or power washing under the hood. You didn't dump the battery acid out did you? I guess you could let the water evaporate and dispose of the solids somewhere...