Only if you lived in a cave could you avoid news about California's dire financial situation. The governor and legislators still disagree about what to do, but all of the proposals aimed at closing the state's $42 billion budget gap are painful and politically unpopular. One obvious way to take a big chunk out of the deficit - without closing schools or putting the sick and elderly out on the streets - hasn't even been discussed. Tax marijuana.

New sin taxes are likely going to be part of the solution to our financial woes. Gov. Arnold Schwarzenegger proposed a nickel-per-drink alcohol tax increase last year. More recently, Assemblyman Tom Torlakson, D-Antioch, introduced legislation to tack on an additional $2.10 per pack in cigarette taxes. Yet marijuana, California's largest cash crop, is completely untaxed.

The marijuana crop is valued at $13.8 billion annually - nearly double the value of our vegetable and grape crops combined. Our state is the nation's top marijuana producer. Indeed, the average annual value of our marijuana crop is more than the combined value of wheat and cotton produced in the entire United States.

According to government surveys, 14.5 million Americans use marijuana at least monthly but both the producers and consumers of this crop escape paying any taxes whatsoever on it. While precise figures are impossible given the illicit nature of the market, it is reasonable to suggest that California could easily collect at least $1.5 billion and maybe as much as $4 billion annually in additional tax revenue, if we took marijuana out of the criminal underground and taxed and regulated it, similar to how handle beer, wine and tobacco.

Marijuana prohibition costs us in other ways as well.

Last year, the state's Campaign Against Marijuana Planting (CAMP) eradicated 2.9 million marijuana plants. CAMP and similar efforts have never made the slightest dent in the availability of marijuana, but they do involve many thousands of person-hours of effort and the use of helicopters and other expensive equipment - all at taxpayers' expense.

It gets worse. Some 70 percent of the plants CAMP seized were on public lands - often remote corners of national forests, parks and other wilderness areas. These clandestine gardens pose a threat to our environment as well as the safety of hikers and other visitors to our parks. Regulating marijuana would remove incentives to grow these secret farms on public land and save millions in eradication and environmental clean-up costs. After all, there's a reason we never hear of criminal gangs planting illicit vineyards in our national forests.

California's taxpayers are also paying law enforcement officers to arrest marijuana consumers. According to FBI statistics, California arrested 74,119 people on marijuana charges in 2007 - nearly 80 percent of those were for simple possession. Chasing down people for using this plant costs us real money and isn't proving an effective strategy for curbing its use.

Every lost revenue source or misplaced expenditure is another deep cut into public safety, schools, and other essential services. It's time to tax and regulate the state's largest cash crop.