U.S. Rep. Don Young failed for 25 years to disclose his inherited one-third interest in a family farm in California that netted him at least $250,000 when he sold it last year.

In a letter to the House clerk in May, Young, a Republican, admitted his failure to disclose his interest and said it was accidental.

But his ownership of the land was no mystery to him: In 1993 and in 2001, Young and several family members signed oil and gas leases for the property.

Young, 83, reported income from the 1993 oil and gas leases on his financial disclosures at the time and valued the leases at no more than $15,000. He said he received $1,001 to $2,500 in annual rental income before the leases lapsed in the late 1990s.

Even after he belatedly disclosed his ownership in the farm in May, Young has never reported the 2001 lease to Kansas-based Slawson Exploration Co. Public records in Sutter County, California, show that Young signed it seven months after finishing a six-year stint as chair of the House Committee on Resources, which had oversight of legislation affecting oil and gas on public land.

Young was traveling in rural Alaska and unavailable for an interview for this story, said his spokesman, Matt Shuckerow.

After being asked about the 2001 lease, Shuckerow said the agreement paid Young $4,100 over a three-year period. That income was reflected on Young's tax filings, Shuckerow said, though not on his public congressional disclosure.

Young's 2001 financial disclosure had asked him to disclose assets worth more than $1,000 at the end of the year, and those that generated more than $200 in income.

Shuckerow said in an emailed response to questions that Young would be correcting his disclosures to "update this oversight."

The 2001 lease, between Slawson Exploration, Young and five members of Young's family, gave Slawson exclusive rights to look for oil and gas on the farm. But it did not specify whether or how much the Youngs would be paid, according to a copy filed with the Sutter County Clerk-Recorder office.

Slawson is one of the biggest privately owned oil companies in the United States, and it helped pioneer development of the Bakken field in North Dakota. Its executives have donated tens of thousands of dollars to Republican candidates.

The company didn't respond to a request for comment about its lease of the Youngs' land, which appeared to be one of dozens signed by Slawson in Sutter County, according to public records.

Shuckerow said Young inherited his share of the farm, in his birthplace of Meridian, California, after the death of Young's mother in 1990. Young's older brother, Russell, "solely managed and operated the property as his primary farming business" until he died in 2014, Shuckerow said.

The farm's subsequent sale led to Young's discovery that he should have disclosed his previous ownership of the land, Shuckerow said.

The letter Young sent to the House clerk in May said he inherited his share of the farm on March 3, 1995, and he asked that his financial disclosures for the last two decades be updated.

The farm, Young wrote in his letter, "produces crops of walnuts, beans and grains. I do not generate any income from this property."

"I assure you this omission was unintentional and I hope that this update now fulfills my obligation to amend prior year filings," Young wrote.

Asked why Young's signature had appeared on the 1993 oil and gas leases if he hadn't inherited his share of the farm until 1995, Shuckerow said Young's letter to the House clerk had "misidentified" the date of his inheritance and would be updated.

Financial disclosure requirements have bedeviled Alaska's congressional officials for years. A jury found former Republican U.S. Sen. Ted Stevens guilty in 2008 of seven counts of lying on his disclosures, though the Justice Department later dropped those charges when it admitted it failed to turn over evidence to Stevens' defense team.

And Young's failure to report his ownership stake in the farm wasn't his first omission from his own financial disclosures. In 2014, the House Ethics Committee said Young had broken congressional rules by failing to report nearly $60,000 in gifts between 2001 and 2013, including flights on private planes and hunting trips.

The committee issued a letter of rebuke to Young, who apologized and issued a statement saying he'd taken steps "to ensure that these types of oversights do not happen again."

"It is through these actions that I show my colleagues and Alaskans that I fully respect the House Rules and will continue to comply with them now and in the future," said Young's 2014 statement, two years before he disclosed his ownership in the farm.

California property records show the Youngs' Meridian property was sold for $1.5 million in early 2015 by Young and four family members to Young's relative Troy and Troy's wife, Susan Young. Troy Young was among the farm's original owners; he and Susan Young didn't respond to a phone message last week.

Don Young's most recent financial disclosure said his share of the farm was sold for between $250,001 and $500,000. Elected officials are only required to disclose a range for their income.

Young is seeking his 23rd term in Congress this fall.

Alaska voters re-elected him in 2014 less than six months after his ethics rebuke, with Young winning 51 percent of the vote to Democratic opponent Forrest Dunbar's 41 percent.