A proposed Planning and Zoning Commission amendment that would impose new regulations governing the coverage allowed on residential properties in Westport again provoked spirited debate at a public hearing Thursday night.

The meeting continued debate of the proposal that began at a Sept. 30 hearing. Under Text Amendment 621, the changes would include a new requirement for residential properties in the town's one- and two-acre zoning districts to adhere to a building coverage limit of 15 percent of the property's total counted area.

The amendment would also reclassify swimming pools as part of total coverage and fully count tennis courts toward total structural coverage. Swimming pools are currently counted as building coverage, while only half the area of tennis courts is presently counted toward total coverage on a property. Additionally, decks would be reclassified from building coverage to total coverage, and would receive a coverage discount if they were made out of water-permeable materials.

Turnout at Thursday's hearing was substantially lower than for the previous week's meeting on the amendment. Members of the public nevertheless expressed both strong support and opposition to 621.

"Changing the coverage requirements takes away value from property," said Lois Schine, a Representative Town Meeting member from District 8.

Some attendees also questioned the powers that the P&Z has to regulate residential development.

"Government should not dictate where, who, why or the size of any house we choose to live in," said Gerald Romano, a real estate agent.

But Michele Lamothe countered that "only through amendments to our existing regulations can we protect our environment and our streetscapes."

If the proposed amendment is enacted, the P&Z Department estimates that the building coverage on about 300 additional lots in Westport would be classified as nonconforming. The P&Z currently counts about 1,450 lots as not conforming to existing building coverage regulations.

Current Westport zoning regulations do not mandate an automatic penalty for a nonconforming use on a property. However, if a property owner wants to further develop the property, he or she must either receive a variance from the Zoning Board of Appeals or eliminate existing coverage to compensate for the new development.

P&Z Director Larry Bradley told the Westport News that no single factor prompted the P&Z to consider the amendment. Instead, he said that drainage problems and other long-standing environmental concerns in Westport are driving the proposed changes.

"If you want to fix a drainage problem, you have to deal with runoff, permeability and water quality," he said. "Looking at coverage is one of the things we need to do to achieve this goal."

Bradley also addressed some residents' concerns that the amendment was unduly influenced by a 2007 town survey that indicated that a limit on house sizes was the No. 1 quality-of-life issue for respondents. The results of the survey were considered in formulating the proposal, but Bradley pointed out the survey represented just "one element" of the P&Z's rationale for proposing the amendment.

The P&Z will hold another public hearing on the proposed amendment on residential property coverage regulations at 7 p.m. Thursday in Town Hall.