RIDGEFIELD — Stormwater regulations meant to strengthen protection for water resources and the environment — but likely to increase development costs for some property owners — have taken effect following final approval by the Planning and Zoning Commission.

“Although I completely agree it’s necessary, it’s going to cause some hardship for some people. It’s not an inexpensive proposition,” Commission member Joe Fossi said in July, when new rules were sent to a Sept. 1 public hearing.

A longtime Planning and Zoning Commission member, Fossi served on a subcommittee that spent two years developing the draft regulations.

The rules would govern the way storm runoff is handled — limited, captured, cleaned up, reduced and redirected — in development projects. They were approved by the commission following a public hearing at its Sept 1 meeting.

Assistant planner Karen Martin described the effect of the new regulations, which targets projects that will increase a property’s “impervious coverage” — rooftops and paved driveway and parking areas.

“Prior to the initiation of any activity or development that will increase the impervious coverage of any property within the Town of Ridgefield, the owner/agent of the premises shall submit to the Land Use Office, Planning and Zoning Department, a Class A-2 survey prepared by a Connecticut licensed surveyor stating the existing impervious coverage for said premises, and the proposed increase in impervious coverage. Impervious coverage shall be calculated in square feet,” the regulation reads.

If the calculations show the impervious coverage will be increased, the comprehensive package of regulations — Stormwater Management Requirements, Section 7.15 — must be followed for the project.