The agency made the argument in a letter sent to officials in Utah, who are considering whether or not to release the data to the Salt Lake Tribune. Back in May, Tribune reporter Nate Carlisle asked for local records relating to the data center, but when he got his files a few months later, the water usage data was redacted.

The situation shows just how important the new data center will be to the agency’s operations, including its widely discussed efforts to eavesdrop on internet communication. If it revealed how much water it’s using in Bluffdale, the agency believes, outsiders could get a good idea of the scope of NSA surveillance.

“By computing the water usage rate, one could ultimately determine the computing power and capabilities of the Utah Data Center,” wrote the NSA’s associate director for policy and records, David Sherman, in an undated letter filed with Bluffdale in response to the Tribune’s public records request. “Armed with this information, one could then deduce how much intelligence NSA is collecting and maintaining.”