The report said that years ago city planners had planned to build a facility that turns salt water into fresh water, but financial woes made that impossible.
In this sentence should turned be used instead of turns?
The report said that years ago city planners had planned to build a facility that turns salt water into fresh water, but financial woes made that impossible.
In this sentence should turned be used instead of turns?
I think the only form of the verb that does full justice to both the past-ness of the planning and the non-reality of the desalinization is would have turned. On this construction (would have plus past participle), see this former question.