A. The overall purpose of this chapter is to improve the quality of creek bank protection measures used on town creeks, discourage practices that pose a risk to property improvements and neighboring properties, and protect the unique scenic qualities and habitat values of the creek environment that sustain wildlife by furnishing habitation, freshwater and migration corridors. It is envisioned that this chapter will benefit creekside property owners, residents of the town and region, and the overall environmental quality of the creeks and adjacent habitats. The measures are intended to help ensure that, over time, changes within creek setbacks will help restore the creeks and creeksides to a healthy natural environment.

B.

The specific purposes of the setbacks are:

1.

To keep new buildings out of range of potential creekbank failure and flooding.

2.

To provide for the review of modifications or replacements of existing structures and impervious surface areas within creek setbacks in order to prevent further encroachment, and to encourage decreasing existing encroachments when modifications or replacements take place.

3.

To restrict new structures in creek setbacks to those deemed necessary for creekbank stabilization projects, utility crossings, roads and driveways.

4.

To retain adequate space adjacent to creek banks for access and work space to replace failing bank protections; to remove obstructions that pose a risk of flooding; and to facilitate bank protection projects utilizing state-of-the art practices, such as grading to achieve more stable bank angles and biotechnical or bioengineered designs.

5.

To retain adequate space adjacent to creekbanks to allow wildlife movement and migration.

6.

To protect creekside vegetation that stabilizes the soil and reduces flow velocities, erosion, sedimentation and creekbank failure.

7.

To protect creekside vegetation as wildlife habitat for those species (song birds, waterfowl, mammals, reptiles, fish, amphibians) dependent on creeks and their flanking native vegetation.

8.

To protect water quality and creekside vegetation for shading and cooling of creek water to provide an environment supportive of trout, other fish, amphibians and invertebrates.

9.

To implement the policies of the general plan that designate creek corridors as sensitive areas providing important aquatic and terrestrial wildlife habitat and that require all new subdivisions and site development proposals to contain setback areas sufficient to buffer wildlife inhabiting the creek corridor from the impact of development.

(Ord. 2007-369 § 1, 2007)

The following creeks are subject to the creek setback provisions in this chapter: Los Trancos Creek, Corte Madera Creek and Sausal Creek.

(Ord. 2007-369 § 1, 2007)

A. For building permits and site development permits, setbacks may be measured from either the top of creek bank or ordinary high water mark (see definitions under Sections 18.59.040 and 18.59.050 below) at the option of the property owner:

1.

Parcels less than one acre in size - Thirty feet from top of bank, or thirty-five feet from ordinary high water mark.

2.

Parcels of one acre to two and one-half acres—Forty-five feet from top of bank or fifty feet from ordinary high water mark.

3.

Parcels of two and one-half acres or more—Fifty-five feet from top of bank or sixty feet from ordinary high water mark.

B.

For planned unit developments, setbacks may be modified by the planning commission to achieve better consistency with the purposes of this chapter as part of the planned unit development process to increase safety as well as protect the natural environment.

C.

For new subdivisions, parcels shall have a minimum creek setback of fifty-five feet from the top of creek bank, but this setback may be required to be enlarged as part of the subdivision process to increase safety as well as protect the natural environment. Sensitive habitats, floodplains, and eroding creek banks should be included within the setback area.

D.

Persons proposing development along creeks should consult Section 18.32, F-P (Floodplain) Combining District Regulations, contained in the zoning regulations as these provisions affect development in the floodplains along creeks.

(Ord. 2007-369 § 1, 2007)

The "top of creek bank" is where the creek channel sides intercept adjoining higher ground. In cases where the top of creek bank is difficult to discern, the top of creek bank shall be based on a physical inspection by the town geologist or his designee in concert with the property owner.

(Ord. 2007-369 § 1, 2007)

The "ordinary high water mark" is a line on a creek bank that reflects the normal high water mark experienced over time. In the town, the OHWM is usually about three to four feet above the normal base water flow. The town geologist or his designee will assist a property owner in identifying the OHWM consistent with the Army Corps of Engineers standards.

(Ord. 2007-369 § 1, 2007)

Existing buildings, decks, driveways, impervious surfaces, and other structures that are within a required creek setback may be maintained and repaired as necessary to keep them useable or improve their condition or quality pursuant to any required building/site development permit. Fences are addressed in Section 18.59.090 below.

(Ord. 2007-369 § 1, 2007)

Existing buildings, decks, driveways, impervious surfaces, and other structures that are within a required creek setback may be reconstructed or replaced as provided for in items A. and B. below, provided that in no case shall such construction increase the extent of the encroachment into the setback area. The extent of encroachment takes into account both the total square footage of structures within the setback and their proximity to the creek. Since flexibility in design is desirable for property owners and provides opportunities to reduce impacts on the creek, new construction is not limited to the footprint or location of the preexisting structure but may be relocated in order to provide a design more consistent with the purposes of Section 18.59.010. Such relocations cannot, however, increase the extent of encroachment in the setback. The building permit and/or a site development permit may require measures that are reasonably related to the project in order to prevent creek bank failure and erosion and to mitigate adverse effects on the creek environment. Property owners are encouraged to decrease existing encroachments in creek setbacks when construction or replacement takes place.

A.

Reconstruction and replacement following involuntary damage. Existing buildings, decks, driveways, impervious surfaces, and other structures that are within a required creek setback may be reconstructed or replaced when necessitated by involuntary damage. For purposes of this chapter, involuntary damage is defined as damage by fire, flood, explosion, wind, earthquake, war, riot, or wood destroying pests or other calamity or force majeure. Involuntary damage necessitating reconstruction or replacement shall be confirmed by the town. Reconstruction or replacement beyond that necessitated by involuntary damage shall be treated in accordance with subsection B. below. Fences are addressed in Section 18.59.090 below.

B.

Reconstruction and replacement following voluntary demolition. Existing buildings, decks, driveways, impervious surfaces, and other structures that are within a required creek setback may be reconstructed or replaced following voluntary demolition when such demolition affects less than fifty percent of the floor area of a building, deck, other structure or less than fifty percent of the surface area of a driveway or other impervious surface. If voluntary demolition affects fifty percent or more of the total floor or total surface area, such replacement or reconstruction shall conform to the required creek setback unless there is no alternate site that is completely or partially outside of the required creek setback. Fences are addressed in Section 18.59.090 below.

(Ord. 2007-369 § 1, 2007)

New, expanded or repaired creek bank stabilization projects are permitted within the creek setback pursuant to a building permit and/or site development permit. Such projects shall be designed to state-of-the-art practices. Designs using the most up-to-date techniques for protecting banks by employing environmentally sound solutions such as revegetation, bioengineered and biotechnical methods are encouraged. Projects shall minimize the risk of causing physical damage to upstream, downstream or opposing properties. Physical damage includes flooding, creek bank erosion, or creek bank failure. Stabilization projects are to be designed to provide long-term protection and at the same time be consistent with the purposes of Section 18.59.010.

(Ord. 2007-369 § 1, 2007)

Existing fences below the top of bank may not be repaired, reconstructed or replaced other than as an approved creek bank stabilization measure as provided for in Section 18.59.080. Existing fences above the top of bank may be repaired, reconstructed or replaced when in conformance with Chapter 18.43 of the Zoning Ordinance. New fences shall conform to Chapter 18.43 of the Zoning Ordinance. (See Section 18.04.155 for definition of "fence.")

(Ord. 2007-369 § 1, 2007)

Removal of existing non-native vegetation in creek setbacks is encouraged, and new creek stabilizing vegetation is to be selected from the town's list of riparian vegetation, or vegetation shown to be a native species of this watershed. Owners are encouraged to select from the town's list of riparian vegetation, or vegetation shown to be native species of this watershed, for all plantings in the creek setback area.

(Ord. 2007-369 § 1, 2007)

Grading up to five cubic yards and installation of impervious surfaces up to two percent of the setback area are permitted. These limits may be exceeded when consistent with the provisions of this chapter and approved by the planning staff, provided they do not reach the threshold for which a site development permit is required.

(Ord. 2007-369 § 1, 2007)

Road, bridge, and utility crossings are permitted in creek setbacks pursuant to a building/site development permit and shall be designed to minimize adverse impacts on the creek channel, adjoining banks and flooding potential. Footings for support of such crossings must be located outside of the creek channel.

(Ord. 2007-369 § 1, 2007)

Trails and paths are permitted subject to the provisions of the site development ordinance and must be designed to minimize adverse impacts on the natural environment.

(Ord. 2007-369 § 1, 2007)

Discharging or dumping pollutants into a creek, such as yard wastes, animal wastes, chemically treated water, and other pollutants are prohibited by Chapter 8.28 of this Code, Storm Water Management and Discharge Control, regulations mandated by the Federal Clean Water Act.

(Ord. 2007-369 § 1, 2007)