Sacramento, Calif. — Any private U.S. bank that is insured by the federal government is forbidden by law from knowingly handling money from cannabis businesses. That leaves people in the rapidly growing industry with few options when it comes to dealing with business basics like payroll, taxes, and finances.

That is a particular problem in California, the country’s biggest market for marijuana. Every year, the state produces 14 million to 16 million tons of pot and consumes 1.5 million to 2 million tons. Along with Massachusetts and Nevada, California voters in November made marijuana legal for recreational use. Recreational marijuana will be regulated alongside medical marijuana beginning on January 1, 2018.

A recent study by the UC-Davis Agricultural Issues Center estimated that sales of recreational marijuana in California could top $5 billion annually. But because cannabis is illegal under federal law, marijuana businesses must continue to operate as cash-only enterprises and may not tap credit and debt products the way ordinary companies do. That’s a risky proposition that also limits growth.

Customers “have to pay us in cash,” a Sacramento area cannabis cultivator, who asked to be identified only as “Morales,” told CBS News.

Full Report on CBSMoney