Natural gas storage operators put a net 100 Bcf into Lower 48 inventories in the week to May 17, above the five-year-average injection of 88 Bcf, the U.S. Energy Information Administration reported.

The build, which came in below an injection forecast of 103 Bcf by an S&P Global Platts analyst survey, brought total working gas supply in the Lower 48 to 1,753 Bcf, or 137 Bcf above the year-ago level and 274 Bcf below the five-year average.

By region:

* In the East, inventories rose 23 Bcf on the week at 353 Bcf, 19% more than a year earlier.

* In the Midwest, storage levels were up 28 Bcf at 364 Bcf, 28% above a year earlier.

* In the Mountain region, inventories climbed 7 Bcf at 89 Bcf, 16% under a year ago.

* In the Pacific region, stockpiles were up 12 Bcf at 186 Bcf, 12% under the year-ago level.

* In the South Central region, storage levels were up 31 Bcf at 762 Bcf, 6% more than the year before.

Of that total, 249 Bcf of gas was in salt cavern facilities and 513 Bcf was in non-salt-cavern facilities. Working gas stocks rose 4% in salt cavern facilities from the previous week and gained 4.5% in non-salt-cavern facilities.

S&P Global Platts and S&P Global Market Intelligence are owned by S&P Global Inc.