A perfect storm of environmental and economic factors could be gathering to nudge Congress to end the ethanol mandate.

In recent years, even staunch environmentalists have been admitting that the ethanol mandate does not make sense. While the corn-based alcohol does burn more cleanly than gasoline, its total environmental impact, including fueling tractors to grow, harvest and process the alternative fuel, makes it more harmful in overall greenhouse gas production than gasoline.

An often-repeated rationale for the creation of the ethanol mandate was energy security. Promoters talked about making the United State energy self-sufficient by using fuel made from corn grown in the Midwest. But the recent surge in domestic oil and natural gas production from hydraulic fracturing, coupled with a global glut of oil, has led to low energy prices. The rapid jump in oil and gas production from fracking has made the United States energy independent; justification for the ethanol mandate is gone.

It’s also been widely known that the ethanol mandate doesn’t make environment or economic sense. The cost of the mandate has been estimated at about $10 billion a year, which is how much extra motorists pay when filling their gas tanks with ethanol-enhanced fuel. And because ethanol contains less energy per gallon than gasoline, motorists buy more gallons at the pump than if they were using straight gasoline.

Another knock on ethanol is that it has diverted some corn production away from food and that diversion has raised food prices in the U.S. and around the world.

If those reasons were not enough to end the ethanol mandate, there is the unprecedented depletion of the Ogallala Aquifer, a massive underground source of water spanning eight Great Plains states. Irrigation of corn grown for ethanol is a big reason the aquafer’s level is dropping.

The ethanol mandate is tied to federal subsidies for corn production. Higher corn prices, created in part by the artificial market for mandated ethanol, have driven many farmers to grow more corn or switch to corn from wheat. Corn is a relatively thirsty crop, so in areas with not enough rainfall, farmers must irrigate their massive corn fields.

Ending the ethanol mandate would reduce corn acreage and that would cut irrigation in dry regions, saving precious water.

Finally, the obvious need for increased spending on roads and bridges in the United States supports ending the ethanol mandate. Despite the federal gas tax being unchanged since 1993, politicians in Washington are not inclined to raise taxes, even taxes that support pay for maintenance of roads and bridges.

Ending the ethanol mandate would save motorists $10 billion a year, which would offset an overdue increase in the federal gasoline tax.

In Congress, there have been recent efforts to end the ethanol subsidy. Pennsylvania’s Sen. Pat Toomey joined with Jeff Flake, R-Ariz. and Dianne Feinstein, D-Calif. in backing a Senate bill to end the ethanol mandate.

In the House, a similar bill has emerged with co-sponsor Rep. Bob Goodlatte, R-Va., saying Congress should “stop this boondoggle.”

And that’s what the ethanol mandate is — a boondoggle. It benefits big Midwestern corn growers and ethanol producers at the expense of every American motorist.

Ending the ethanol mandate will hurt some large-scale farming operations that expanded corn production to capture government-backed profits. But ending the mandate will help far more people than it hurts.

Ending the mandate will save drivers $10 billion a year and it will help the environment. Ending the mandate also will save precious water being drained from the Ogallala Aquafer and it will not undo America’s energy independence.

Ending the mandate should be a no-brainer. It would be, except for the political power of the farm lobby and the influence of Iowa as the first primary state where few presidential candidates have the courage to propose ending it.