Utilities are privy to information about energy use from data centers in their region; they use that information to forecast growth. But data centers will often shop around to different utilities, which, experts say, causes utilities to double-count projects and forecast “phantom” growth—data centers that will never be built in their region. The CEO of Vistra, a retail electricity company, said during its first quarter earnings call last year that utilities may be inflating electricity demand anywhere from three to five times beyond what is actually needed.

In December, EIA Administrator Tristan Abbey said at a roundtable that he expects the EIA “is going to be an essential player in providing objective data and analysis to policymakers” with respect to data centers. The agency announced on Wednesday that it would be conducting a voluntary pilot program to collect energy consumption information from nearly 200 companies operating data centers in Texas, Washington, and Virginia, which will cover “energy sources, electricity consumption, site characteristics, server metrics, and cooling systems.”

While the senators praise the EIA pilot program, their letter includes several questions about how the agency plans to move forward with more data collection, such as whether or not the energy surveys will be mandatory and whether or not the EIA will collect information on behind-the-meter power. This information will be especially crucial, the senators say, to make sure that Big Tech companies that signed the agreement at the White House earlier this month pledging that consumers won’t bear the costs of data center electricity use will stick to their promises.

“Without this data, policymakers, utility companies, and local communities are operating in the dark,” the senators write.

The EIA mandates that other industries, including oil and gas and manufacturing, provide regular data to the agency; Hawley and Warren assert that the EIA should be able to collect similar information from data centers under the same provision. The provision is broad enough, Peskoe says, that it could absolutely be interpreted to encompass data centers.

The letter comes amid widespread concern in Washington and around the country over data center development. On Wednesday, Senator Bernie Sanders introduced a bill that would introduce a national moratorium on data center construction and development until AI safety laws were passed. The same day, Democratic Senator Dick Durbin introduced a bill to mandate data centers disclose their energy and water use. And state legislatures have brought forth hundreds of data center bills, with at least a dozen states considering a moratorium on construction altogether.

This story originally appeared on wired.com.