With broad local support for San Diego’s envisioned water recycling program, Mayor Kevin Faulconer touted the plan again last week — this time as one of his top-funded efforts to fight climate change.

However, his strategy for pulling off the so-called Pure Water program isn’t a done deal. An agreement between local green groups and government officials that threaded the way for the project’s approval has hit a snag in recent months — one that could unravel regional backing for the program or end up costing residents billions of additional dollars.