UPDATE 1-Lower 48 US July natgas output up slightly from June

* July production at 72.58 bcfd, up 0.29 bcfd from June

* Gross gas output still running 4.3 percent above year-ago

* New Mexico production saw biggest gain, up 2.6 percent (Adds byline, details, background, updates futures prices)

By Joe Silha

NEW YORK, Sept 28 (Reuters) - Gross natural gas production in July in the lower 48 U.S. states climbed slightly from downwardly revised June output, data from the U.S. Energy Information Administration showed on Friday.

Lower 48 "wet" gas output in July totaled 72.58 billion cubic feet per day, about 0.4 percent above revised June output of 72.29 bcf daily, the EIA said in its Monthly Natural Gas Gross Production Report.

Lower 48 refers to gas production in the United States, excluding Alaska and Hawaii.

The EIA's previous estimate for June was 72.37 bcf per day.

Gross gas production is still running about 3 bcf per day, or 4.3 percent, above the same year-ago month.

New Mexico production saw the biggest monthly increase, rising 2.6 percent from June due to well maintenance completions and some new wells coming on line.

Offshore Gulf of Mexico output also grew by 1.8 percent as production resumed after Tropical Storm Debby.

"Other States" production, which counts several shale plays including Marcellus, continued to edge higher, up 0.4 percent.

Output in Wyoming decreased by 1.1 percent to 6.1 bcfd.

Gas futures on the New York Mercantile Exchange, which were down 3.3 cents at $3.264 per mmBtu just before the EIA data was released at 12 noon EDT (1600 GMT), edged up about a penny after the report.

For complete report: link.reuters.com/dyb84m

OUTPUT STUBBORNLY HIGH

Gross gas output, which has declined in three of the last six monthly reports, is still not far below the record high of 72.74 bcf per day hit in January.

Traders were waiting for the next Baker Hughes drilling rig report on Friday. Drilling for natural gas has been in a nearly steady decline for the last 11 months, with the gas-directed rig count recently posting a 13-year low.

But so far, production shows few, if any, signs of slowing.

(Rig graphic: r.reuters.com/dyb62s )

While dry gas drilling has become largely uneconomical at current prices, gas produced from more-profitable shale oil and shale gas liquids wells has kept output stubbornly high.

The EIA expects marketed gas production in 2012 to hit a record for a second straight year, climbing 4 percent from 2011 levels to 68.86 bcf per day.

Gross withdrawals, according to EIA, are converted to marketed natural gas production by subtracting gas used for repressuring, quantities vented and flared, and nonhydrocarbon gases removed in treating or processing operations. (Editing by Jim Marshall)