Green Valley's biggest water company is proposing to nearly double the size of a planned pipeline to import Central Arizona Project water into the growing area, as part of an agreement to bring in CAP water for the Rosemont mine.

The proposal released last week calls for a pipeline that would bring in more than quadruple the amount of water the original pipeline would have brought - 30,000 acre-feet compared with 7,000.

That would eliminate or come close to eliminating the groundwater overdraft now plaguing the Green Valley area because of pumping for mines, farms, homes and golf courses. The overdraft has been pegged at 30,000 to 40,000 acre-feet. The newly proposed pipeline, about 9 miles long, would be 36 inches in diameter compared with 20 inches in the original proposal.

But the pipeline proposal faces a big unknown: making sure it stays full as population growth brings more water-users into Arizona over the next 20 years. That will put more pressure on the CAP's Colorado River supply, which already is over-allocated. The pipeline's backers hail this as a landmark opportunity to bring in a new water supply.

The Star had the orginal story.  Here's a copy.