"Of the 431 lots that could be lost ... most of them are in for grandfathering," McLaughlin said at last week's council work session.

In addition to the grandfathering, McLaughlin said the law allows property owners to sell their development rights through the county's density exchange program.

Fox, who represents the rural west, said taking away the development rights of those 61 properties would affect their underlying values, which most owners use as collateral when borrowing money to operate their farms.

"Those underlying property values are what allows them to borrow for their equipment or their seed," Fox said.

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'Can't afford to lose it'

Hall said coming up with an appropriate grandfathering process was one of the more complex and contentious aspects of the bill, but he believes the law sets the bar at an appropriate level, given the various steps and time involved.

To qualify for grandfathering, Howard property owners must have applied for soil percolation testing with the county Health Department by July 1. Applying for percolation testing, which would determine if their land could accommodate a septic system, costs property owners $506 per lot for up to 10 lots or $512 per lot for 11 or more lots.

After passing the soil percolation test, the property owner must then submit a preliminary subdivision plan to the county within 18 months. Paying for design and engineering of the plans is expected to cost thousands more dollars.

The county must approve the plan by Oct. 1, 2016, for the property to be grandfathered.

Once the plan is approved, a public road must be put in for the property to be legally recorded as a subdivision.

Council members fear the grandfathering process is so costly that property owners will have no choice but to partner with developers and build homes on the land.

If his land ends up in Tier IV, as is proposed, Cissel, who is in debt and has already had to borrow money to pay for the percolation applications, said he sees no other option.

"We can't afford to lose it," he said. "We've got to develop it."

'Much weaker'

The septic bill has been a priority of O'Malley's in the past two General Assembly sessions.

Though weaker than the 2011 proposal that failed, the Sustainable Growth and Agricultural Preservation Act of 2012 was still not palatable to most state lawmakers until it was heavily amended in the last few weeks of the General Assembly session.

The amendment that brought several lawmakers on board eliminated the provision giving the state final approval of tiers. Another amendment added the grandfathering provision.

Del. Liz Bobo, of Columbia, was a co-sponsor of the O'Malley's septic bill when it was introduced in the House, but after all the amendments she became the only one of Howard's eight Democrat delegates and senators to vote against it.

"It's much weaker than it was put in, and I think that was a big mistake," she said. "We made it much easier (for developments to be built on septic systems) and we made many more properties eligible for grandfathering."

Septic systems, Bobo said, "are a huge issue with the (Chesapeake) Bay."