Oregon State Treasurer Ted Wheeler is asking the U.S. Treasury to help weed growers get bank accounts.

Wheeler is sending a letter today to U.S. Treasury Secretary Jacob Lew, asking the feds to assure banks that they will not face legal risk if they offer checking accounts to marijuana growers, processors and retailers.

"I am concerned by the lack of access to banking services by legal, state-regulated marijuana businesses," Wheeler writes. "The hazards of a growing, cash-only industry are becoming all too real for Oregon.  I respectfully call on the Treasury Department to issue new guidance that will result in banking access for Oregon marijuana businesses."

Only one Oregon bank, Gresham-based MBank, has offered checking accounts to weed businesses, but it canceled those accounts in April.

MBank CEO Jef Baker told WW in April that MBank, which has $165 million in assets, was "not big enough" to deal with government regulations created by handling weed money. He described the decision as being "the cost, but not in dollars."

Wheeler cites the WW story in his letter. He says banks currently must conduct costly investigations into whether their clients are selling pot to minors or transporting it across state lines.

"The net effect," Wheeler writes, "is a de facto requirement that financial institutions police potential customers and willingly accept liability for any illegal activity by that customer even where it is unreasonable for the institution to know of that activity." 

Wheeler tells the feds banks need more certainty about what the rules are for banking with marijuana businesses.

"Banks need assurances that accepting legal marijuana customers will not put their charters in jeopardy, diminish access to federal deposit insurance, or otherwise imperil relationships with federal banking regulators," Wheeler writes. "The more certainty you can give banks and credit unions, the less states and communities will experience the high costs of an all-cash business."