* Benchmark Dec contract sinks to 76.10 cts/lb
* July/Dec spread widens in heavy trade as expiry nears
* Exchange inventories hover near 10-month highs, ICE data shows
NEW YORK, June 17 (Reuters) - Benchmark cotton futures sank to a 4-1/2-month low on Tuesday in heavy, spread-related trade as forecasts of wet weather in Texas, the top U.S. producing state, reinforced expectations of a fresh injection of supplies in the new crop year.
The most-active December cotton contract on ICE Futures U.S. fell as low as 76.10 cents a lb before ending off 0.8 cent, or 1 percent, at 76.32 cents a lb.
Trading volumes were heavy in spread-related dealings that shot the July contract as high as 90.37 cents a lb, the front month's strongest level since late May, before closing up 2.41 cents, or 2.7 percent, at 90.06 cents a lb.
The premium of the July contract, which represents this year's crop, above the December contract, which represents the upcoming 2014-15 crop, shot to 13.74 cents a lb from 10.53 cents previously. That was the highest such premium since 2011.
The day's choppy trade and the sharp rise in July prices were seen as evidence of that large delivery was likely against the contract, which expires on July 9, and reinforced worries over tight nearby supplies.
Even so, forecasts of wet weather in Texas raised expectations that farmers in the key U.S. growing region will boost output after battling a multiyear drought.
"For the first time in years, we have lots of water in the ground. We are looking at the prospect of a good crop out here," said Jobe Moss, a broker with MCM Inc in Lubbock, Texas.
The U.S. Department of Agriculture last week raised its outlook for U.S. inventories to hit a six-year high by the end of July 2015 as it upped the crop forecast for the world's top exporter.
ICE stocks slipped to 416,692 bales on Friday from 418,240 bales previously, exchange data showed on Monday. That compared with May's ten-month high of 431,160 bales, data compiled by Reuters showed. (Reporting by Chris Prentice, editing by G Crosse)
