Trump’s Pick for Interior Dept. Continued Lobbying After Officially Vowing to Stop, New Files Indicate

It includes a bill for $2,432.68 for Mr. Bernhardt’s travel and $25,000 “for professional services rendered” in February 2017. Ms. Vander Voort described the invoice as “inappropriately labeled by the billing department.”

Mr. Bernhardt’s activities, if they constituted lobbying, could violate federal laws requiring lobbyists to disclose their activities, according to four independent authorities on the rules.

The action described by the documents “raises ethical questions,” said Virginia Canter, the chief ethics counsel for Citizens for Responsibility and Ethics in Washington, a watchdog group. “He obviously was engaged in some sort of federal lobbying activity on behalf of Westlands even after he de-registered as a lobbyist.”

The documents include an email dated December 2016 from John Watts, an aide to Senator Dianne Feinstein, a California Democrat who works closely on the state’s water policy issues, to Mr. Bernhardt and Thomas Birmingham, the Westlands general manager. The subject line is “Memo: Endangered Species Act consistency of California water language.” It addresses two issues, endangered species and water rights, on which Mr. Bernhard had lobbied for Westlands.

A spokesman for Senator Feinstein did not respond to a request for comment.

Another email, dated April 19, from Johnny Amaral, the former deputy general manager of Westlands, asked Mr. Bernhardt if he could make it to a “team breakfast” the following Wednesday, April 25. Bernhardt responded, “Yes.” Three days later, Mr. Trump nominated Mr. Bernhardt to be deputy secretary of the Interior Department.

Mr. Amaral now works for another California water district, the Friant Water Authority. An email to Friant requesting comment from Mr. Amaral was not returned.

Ethics experts said the documents shed light on the close relationship Mr. Bernhardt maintained with his former lobbying client.