As new or extensively remodeled homes go up on properties along Portola Valley's three major creeks -- Los Trancos, Corte Madera and Sausal -- the wild corridors along the banks should become increasingly well defined after recent action by the Town Council.
The council unanimously approved a resolution establishing minimum but flexible creek setbacks for new construction of 30 feet, 45 feet and 55 feet for parcels that are, respectively, less than one acre, between one and 2.5 acres, and greater than 2.5 acres in size.
(Councilman Richard Merk recused himself from the decision because he lives along a creek.)
The rules are the product of several years of consideration by the town's Planning Commission and members of the public, and reflect the town's longstanding interest in healthy creeks.
The goals, as stated in the Nov. 14 resolution, include keeping new buildings safe from bank failure and flooding, allowing room for creek bank maintenance, and allowing natural plant and animal life to thrive.
"As these homes turn over, as they are replaced, the goal is to maintain a reasonable wildlife corridor," Commissioner Ann Wengert told the council and an audience of about 20.
The setbacks allow property owners to add gentle slopes to the banks, if necessary, to slow the creeks down, added Commissioner Linda Elkind. "Some of our creek banks have slipped and been eroded 5 to 15 feet since the late 1990s," she said. "You can't get (the energy out of the creek) if you don't have a buffer."
Before voting, Councilman Ed Davis was brief while lifting his hands in prayer: "It's been 10 years," he said. "Thank you."
"The balance of this has been exquisitely done," added Councilman Steve Toben.
Flexibility built in
The new regulations allow a homeowner a choice of where to start counting the feet of the setback: the ordinary high water level or the top of the bank -- a location that can be debatable if the creek bank is complex, said Town Planner George Mader.
Structures such as buildings and decks that are already inside a setback may be rebuilt to their original dimensions on the same spot if damaged by an involuntary calamity such as a flood or fire, and if the town planning staff agree with the involuntary nature of the calamity.
The same rule applies if a remodel affects less than 50 percent of the floor area (or the surface area of an impervious surface such as a driveway).
The Planning Commission can adjust these setbacks as needed to "achieve better consistency" with the purposes of the town's zoning code.
"There's a lot of giving here, I think, so that people can hopefully live within these regulations," Mr. Mader said.
New construction or a major remodel would trigger the new setbacks. Also affected are existing fences inside the setbacks, as well as non-native vegetation, grading, bridges, and trails and paths.
The resolution also specifies that all new subdivisions will use setbacks of at least 55 feet and possibly more if the area includes sensitive habitats, floodplains and eroding banks.
Given that the creeks can be cantankerous in the winter and are owned in common by residents who often aren't familiar with the ways and means of the government agencies that oversee even small waterways, creek-side dwellers Bob Bond and Bud Eisberg suggested that the town take the next step and provide some guidance for protecting creeks.
The council seemed to like this idea. Handouts already exist at Town Hall, planning staff said. Mr. Toben, with the endorsement of Mayor Ted Driscoll, suggested that the town consider facilitating a late spring creek walk every year so that neighbors might approach the maintenance problem as a group and share their "collective wisdom."