Planning commission narrowly approves Del Casa creek-setback variance after debate over precedent and habitat

The Mill Valley Planning Commission on Feb. 25 approved a variance to allow a modest second-floor addition at 81 Del Casa Drive that increases habitable area within the 30-foot Warner Canyon Creek setback. The vote was 3–2 after a lengthy staff presentation, public comment and close deliberation over environmental sensitivity and precedent.

Senior Planner Daisy Allen summarized the application and staff’s analysis. Allen said the house, built in 1948, sits largely within the city’s creek setback and that previous variances and nonconforming setbacks already apply to the parcel. The revised project removes a lower deck, a bay-window fireplace and several other earlier-sought features, does not expand the building footprint and does not propose new foundation work. Allen said the project’s updated landscape plan replaces nonnative plants with native riparian species, adds bioswales for on-site runoff control and removes a second-story deck. She told the commission that because of those design changes — and because the site has unusually limited buildable area due to the creek routing and FEMA floodplain history — staff found the variance findings could be made, and staff recommended approval subject to conditions.

Applicant Adrienne Fodder Hans said the owners had substantially redesigned the proposal since an earlier denial and had engaged creek and habitat specialists and Streamkeepers, a local…