Senior Regional Correspondent

It’s easy to see why farmers in the fast-growing outer suburbs of Charles County are furious over Maryland Gov. Martin O’Malley’s battle against development sprawl. It’s all about the money.

An acre of farmland typically fetches $4,500 to $5,000 if it’s going to grow corn, wheat or vegetables. But the county farm bureau says the same property, if sold to a developer to build homes or businesses, is valued at up to $200,000 an acre.

The difference helps explain why Charles landowners and developers are taking drastic steps to try to get around a 2012 “smart growth” law, championed by O’Malley (D), that is designed to rein in uncontrolled construction.

The effort has triggered a struggle that is attracting statewide attention and made Charles a major battleground in the contest over how Maryland’s outer suburbs will grow in coming decades.

The real estate interests have won the early rounds. But the state administration, conservationists and local residents weary of congestion are fighting back hard.

I understand the Charles farmers’ annoyance at missing a big payday, but that doesn’t mean they’re in the right. The rest of the public has a compelling interest in slowing the replacement of fields and other open spaces by spread-out subdivisions.

O’Malley’s “smart growth” approach aims at concentrating growth in relatively small, targeted areas. In Charles’s case, that would be Waldorf and La Plata.

That strategy is designed to protect the environment and hold down the cost of public services such as roads and schools. It also aims to preserve farmland in the county, especially west and south of La Plata.

“What we have indeed in Charles is a test case for will we actually plan for a strong, vibrant future for all of Maryland, or are we going to just plan for developers to make a buck,” said Dru Schmidt-Perkins, president of 1000 Friends of Maryland, a smart-growth advocacy group.

O’Malley’s main achievement in this arena was pushing through the “septic law” of 2012. It sharply restricted new construction on lots that required septic systems for waste disposal.

That was important partly because septic systems are more damaging to the environment than sewer systems, which ultimately put less pollution into the Chesapeake Bay watershed.

The septic law was a huge disappointment to landowners in rural and outer-suburban areas. It meant that fewer could cash in, because most had property too isolated to be connected to sewer lines.

“It’s basically the government taking value away from your property,” said David Hancock Jr., president of the Charles County Farm Bureau.

Hancock reaffirmed a comment he made in October at a heavily attended public meeting on the issue: “The biggest enemy the farmers have right now is Martin O’Malley. He’s killing us.”

So the Charles real estate interests tried to dodge the law by radically redrawing the county’s comprehensive plan, or long-range zoning document.

They have tentatively pushed through a plan that would reduce the share of county land planned or zoned for resource conservation from 82 percent to 8 percent. That would open the way for a big increase in land on which development could take place using septic systems — law or no law.

It would give also Charles the dubious distinction of having by far the lowest share of protected land in Maryland. Montgomery County has the lowest fraction, at 33 percent, and Prince George’s County is at 39 percent, according to state figures.

That didn’t sit well with the O’Malley administration. In an unprecedented move, 13 state Cabinet secretaries and agency heads wrote a joint letter in September denouncing the plan as contrary to state policies and the 2012 law.

The letter threatened to withhold millions of dollars of state funds from Charles for transportation, economic development and other projects if the plan is approved.

The state’s criticisms were reinforced by the October public meeting, where opponents of the plan outnumbered supporters by about 3 to 1.

Now the Board of Charles County Commissioners has set up a working group — evenly divided between three supporters and three opponents of the plan — to try to draft a compromise.

It seems that one possibility could be to significantly increase the amount of protected land while expanding programs that pay farmers to leave their holdings undeveloped.

Frankly, though, there’s little common ground. In the end, I expect, the farmers and developers will have to accept that the need to protect the environment and the public’s quality of life has cost them a windfall.

I discuss local issues Friday at 8:50 a.m. on WAMU (88.5 FM). For previous columns, go to washingtonpost.