101-Permanente Creek information packet.pdf
Permanente CreekFlood Protection Project Informationfrom Santa Clara Valley
Water District
The Permanente Creek Flood Protection Project (Project) is being developed to provide flood
protection to the residents, businesses, and major transportation corridors in the cities of
Mountain View and Los Altos, and includes opportunities for community enhancements such as
development of trails, parks, athletic fields, environmental protection of riparian habitat, and
removal of concrete from portions of the creek. The Project is now in design phase.
Over the past seven years, the District has been engaged in a comprehensive alternatives
analysis for the Project. Twenty-six conceptual alternatives were identified and analyzed.
Twelve feasible alternatives were analyzed in much greater detail, following the District Board of
Directors’ Natural Flood Protection criteria. The best-rated alternative was identified by District
staff as the recommended alternative and accepted by the District’s Board in September 2008.
The draft environmental impact report (EIR) for the project was circulated for public review and
comment in 2009; and the final EIR was certified by the District Board on June 17, 2010.
Project Background
Historical Flooding and Response
The Permanente Creek watershed has had a history of recurring floods which have adversely
impacted the safety and economic stability of residents and businesses in Mountain View.
Flooding occurred in 1862, 1911, 1940, 1950, 1952, 1955, 1958, 1963, 1968, 1983, 1995,and
1998. In December 1955, the so-called “Christmas Storm” inundated approximately 770 acres
in the lower reaches of Permanente Creek. Homes, businesses and agricultural lands in
Mountain View sustained losses, bridges and culverts in Mountain View were extensively
damaged,and 100 people had to beevacuated from their homes for several weeks.
In response to thatflooding, structural channel improvements were constructed from 1959
through the 1960’sby the Santa Clara County Flood Control and Water Conservation District.
While these improvements have reduced flooding in the ensuing years, they do not provide
protection up to the one-percent flood event, which is the flood that has aone in one hundred
chance of occurring in any one year.It is currently estimated that a one-percent flood would
inundate 3,170 parcels, including 2,740 parcels in Mountain Viewand 430parcels in Los Altos.
It is estimated that a one-percentflood event would cause approximately $48million (1999
dollars) in damages for a single event.
In November 2000, the voters of Santa Clara Valley approved the “Clean, Safe Creeksand
Natural Flood Protection” measure (CSC Measure). One of the nine flood protection measures
included in theCSC Measure is the Permanente Creek project. The CSC Measure would
provide $27.4million (1999 dollars) in construction fundingto increase the stream’s ability to
convey the one-percent flow north of El Camino Real.Approximately 1,664 parcels, including
1,378 homes, 160 businesses, and four schools and institutions, all located in Mountain View,
would be protected.The CSC Measure was supported by 67% of the voters.
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Flood Protection Project Goal and Objectives
The Project is currently at the beginning ofthe designphase. The specific goalof the Project is:
Provide flood protection from the one-percent event for the portion of the floodplain north
of El Camino Real by 2016for $38 million.
Community Outreach Efforts
The outreach effort was aimed at solicitinginput on Project elements.Outreach efforts
included:
1.Permanente Creek Task Force: a committee of volunteer Mountain View, Los Altos, and
(recently) Cupertino residents and City of Mountain View and Los Altos staff was set up
in 2003 to assist the Project team in Project planning. The Task Force has received
detailed information and analysis during the planning of the Project and has provided
evaluation of the problem definition, Project elements, conceptual plans, and feasible
alternatives.
2.Public meetings:Meetings have been held in January 2002, March 2003, March and
November 2004, and May 2007. These meetings were held on Project planning
milestones such as problem definition, conceptualalternatives, and feasible alternatives.
The May 2007 meetings were Project scoping meetings and discussed the likely feasible
alternatives.In October 2009, a public hearing was held for the Draft EIR. This was
followed by another public meeting in June of 2010 for the Final EIR. In March 2009, the
District made a presentation to the Cupertino Rancho San Antonio community that
focused on the project impacts to that specific neighborhood. Similar meetings were
held in April 2009 for the Blach School and McKelvey Park neighborhoods.As the
design phase has gotten started, these community meetings have begun to be held
again in September 2010.
3.Mountain View City Council:In November 2004, the District presented the conceptual
alternatives to the Council. At that time, the Council expressed interest in a follow-up
study session. Inthe follow-upFebruary 2006presentation, the District requested that
the Council consider incorporationofan objective forflood protection in the master
planning of Cuesta Park Annex. The Council indicated that it could be an objective but
not a primary objective. OnJanuary 16, 2007,the District presented an update on the
Project to the City Council.On February 26, 2008, the District presented another update
to the City Council, describing the feasible alternatives and the staff recommended
alternative. On December 9, 2008, the City Council culminated the master planning
process forCuesta Park Annex with a decision to approveflood detention in the northern
portion of the Annex.
4.Los Altos City Council: In November 2004, the District presented the conceptual
alternatives to the City Council. The Council expressed interest in follow up study
sessions. In March, 2007 the District provided a presentation to the Council which listed
the feasible alternatives. In April, 2008 the District provided another presentation on the
project, describing the recommended alternative.
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5.Cupertino City Council:In March, 2007 the District provided a presentation on the
feasible alternatives to the Council. In September, 2008 the District provided another
presentation on the project, describing the recommended alternative.
6.Santa Clara County Board of Supervisors:In March, 2007 the District provided a
presentation to the Board on the project’s feasible alternatives. There have been follow-
up meetings with Supervisor Kniss and her staff over the past two years.There were
also presentations in 2009 to the County Parks Commission and in 2010 to the County
HLUET Commission.
7.Los Altos School Board:There have been several meetings held with the School
Superintendent and Blach School Principal and staff over the past two years. In April
2009, the District provided a presentation on the project and the recommended
alternative.
8.Executive Committee: An executive committee composed of the city managers of
Mountain View, Los Altos, and Cupertino, an assistant executive representing the
County of Santa Clara (County), theCounty Parks manager, and the District CEO was
set up in 2007;sixmeetingshave been heldthus far. The meetings are opportunities to
share information and coordinate activities to achieve Project goals in a manner
beneficial to all interested parties.
9.Other interested Parties: Throughout the planning process, the District has reached out
to community groups to engage and to solicit feedback. Letters inviting groups to
participate in one-on-one meetings with Project staff were sent out in 2006 and 2007. To
date, presentations have been made to the following groups:
Save Open Space
Mountain View Chamber of Commerce
Stevens and Permanente Creek Watersheds Council
Committee for Green Foothills
Gate of Heaven Cemetery
10.Environmental Resource Agencies:The latest such meeting was in July 2006, where
the ten feasible alternatives were discussed. The resource agencies unanimously
indicated that they would not favor alternatives that included construction of a dam in the
upper watershed, due to concerns overthe significant environmental impacts.Resource
agency comments on the Notice of Preparation (May 2007) underlined their concern
regarding the impacts of a dam in the upper watershed.
The Approved Project
The approved project (see Figure 1)utilizes a system of flood detention areas located
strategically around the watershed to maximize flood protection benefits at an acceptable cost.
The major project elements are:
Flood detention areas located at Rancho San Antonio County Park, Blach Junior High
School, Cuesta Park Annex, and McKelvey Park.
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Floodwalls downstream of Highway 101
Channel improvement for some concrete lined portions of Permanente Creek and Hale
Creek
New diversion structure at the Permanente Diversion to Stevens Creek
Once this alternative is in place, 2220 parcels in Mountain View and 250 parcels in Los Altos will
be protected from floods ranging up to the one-percent event.
Next Steps
The next step for the Project is to develop a detailed design for the proposed project. The
current schedule is:
Conduct community outreach for each flood detention site to develop conceptual design
in 2010
Achieve acceptance of conceptual designs by each property owner in early 2011
Finish plans and specification 2012
Begin construction in 2012-2013
Construction completed 2015-2016
Once schematic designs are selected and approved, detailed design of each site can
commence. At the same time, memoranda of understanding could be developed to determine
long term maintenance and operation responsibilitieswith each of the site owners. The final
designs and final right-of-way agreements would be subject to site owner and District Board
approval.
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Figure 1 –Recommended Alternative
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Figure 2 –Current Conceptual Rancho San AntonioPlan
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