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Upper Yosemite Creek Daylighting Project

Project URL link
Sponsoring Agency San Francisco Public Utilities Commission
Subregions ('West Bay',)
Counties San Francisco
Watershed Tributary
Public or private land? ()
Location (lat/lon) 37.723353, -122.413308
Start Date 12/03/2012
End Date 11/24/2019
Location Description The project is located in the Yosemite watershed, on the southeastern side of San Francisco. Green infrastruture components will be placed within and around MacLaren Park. The properties surrounding the project site are zoned as residential housing with one unit per lot and the surrounding neighborhood is considered a socio-economically disadvantaged community.

This project will utilize green infrastructure to improve stormwater management in the historic Upper Yosemite Creek area of San Francisco. The main goals of the project are stormwater volume reduction and peak flow attenuation. Bioretention structures and creek daylighting are some of the techniques that will be used to reach these goals. This project will contribute to development of performance, maintenance and design standards for future green infrastructure projects.

Drinking Water Supply
Water Quality Improvement
Water Reuse/Recycling
Stormwater Improvements
Groundwater Benefits
Habitat Protection and Restoration
Flood Protection
Water Reuse/Recycling: Project will assess reuse of stormwater for irrigation; Stormwater Improvements: on-site management of stormwater run-off with green infrastructure improvements; Groundwater Benefits: treated stormwater which ultimately recharges groundwater; Infiltration: the project area has soil types conducive for stormwater infiltration (>0.5 in/hr); Habitat Protection and Restoration: restoration of historic creek and landscaping will include native plants which provides potential habitat for local species; Flood Protection: green infrastructure elements are designed to reduce surface flows and provide additional protection against flooding; Related to a Disadvantaged Community: project is placed in a disadvantaged community (Portola Valley Neighborhood).

Part 2 - Detail

The Upper Yosemite Creek Daylighting project will daylight the headwaters of the historic Yosemite Creek to manage stormwater runoff from 110 acres of McLaren Park. This San Francisco Public Utilities Commission (SFPUC) project will feature storage and infiltration facilities, as well as a creek channel to convey stormwater and alleviate localized flooding issues. This is the first creek daylighting project initiated by the City, and it has the added benefit of reintroducing natural habitat and providing opportunities for community learning and beautification.

Currently, stormwater from the area drains into Yosemite Marsh and McNab Lake. When the water levels in Yosemite Marsh and McNab Lake reach the outlet elevations, water spills into the combined sewer system. San Francisco’s combined sewer system collects, transports, and treats both wastewater and stormwater.   During severe wet weather events, the combined sewer system can become overwhelmed, sometimes causing combined sewer discharges (CSD) at permitted CSD outfalls in the Pacific Ocean and the San Francisco Bay.

The Yosemite Creek Daylighting project is one of eight Early Implementation Projects (EIPs) that the SFPUC is planning to construct as part of its Sewer System Improvement Program (SSIP). The common goal of the EIPs is to demonstrate the use of performance-based green infrastructure technologies to remove stormwater from the combined sewer system and attenuate peak flows. However, the Upper Yosemite Creek Daylighting Project is unique in that it is the only EIP featuring creek daylighting. The information and expertise gained will be used to support the future of green infrastructure within the City of San Francisco.

The proposed scope for the Yosemite Creek Daylighting project includes a creek channel that will flow along the northern edge of McLaren Park from Yosemite Marsh, the southern edge of the soccer field, and the northern, eastern and southern edges of the softball fields. Overflow structures will be modified at Yosemite Marsh and McNab Lake to divert excess water to the new creek channel. To control flow velocity and increase habitat space, bioretention facilities will be incorporated at various points along the creek. Subsurface stormwater storage tanks will be installed at the northwestern edge of the softball fields. These subsurface tanks will be used to store stormwater and manage flow volumes heading for the combined sewer system. In addition, opportunities to reuse captured stormwater to irrigate the soccer field or the creek channel are being investigated.

The project team has been working closely with the SF Recreation and Parks Department to integrate the creek into existing park uses. The project area is surrounded by a socio-economically disadvantaged community called Portola Valley. During the planning phase of this project, public workshops and multiple small community group meetings were held to solicit public input and feedback. Two online surveys were provided for additional public feedback on the project. Public input has been used to refine the scope and aesthetic of the project. The project will feature an outdoor classroom to provide opportunities to learn about San Francisco's historic creeks and the benefits of natural systems to treat and manage stormwater. The proposed scope incorporates design features to create habitat and biodiversity, increase education and public involvement regarding water resource management, promote neighborhood greening, and enhance interagency project synergies. Additional agencies that the Project Team worked with to refine and gain project approvals are the San Francisco Municipal Transportation Agency, San Francisco Fire Department, and the San Francisco Department of Public Works.

Impervious surfaces such as buildings, streets, and parking lots cover most of San Francisco, preventing rainfall infiltration. Over time creeks were buried and connected to the combined sewers, and wetlands were infilled. Instead of percolating into soils, runoff now travels over impervious surfaces, mobilizes pollutants and washes them into the sewer system or receiving water bodies. During heavy rain events, stormwater runoff can contribute to localized flooding, combined sewer discharges and the degradation of surface water quality. Moreover, the decrease in infiltration resulting from paved surfaces contributes to groundwater depletion. While water quality protection is the fundamental driver behind stormwater management, well-designed stormwater controls (i.e., green infrastructure) offer many direct and ancillary benefits. Some of the direct benefits include reducing and delaying the volumes and peak flows of stormwater reaching the sewer system.  Volume reduction and peak flow desynchronization can help reduce the number of stormwater overflows, decrease flooding and protect water quality. Green infrastructure projects have the potential to improve the capacity and efficiency of San Francisco's treatment facilities. Some of the ancillary benefits include enhancement of community spaces, street beautification, and improved conditions for bicyclists and pedestrians.  Green infrastructure also protects and creates more livable habitat for native wildlife and provides an opportunity to integrate stormwater management into the redevelopment of historic sites. Yosemite Creek Daylighting is one of eight Early Implementation Projects that will be placed throughout San Francisco to provide the basis for performance, maintenance and design standards for future city-wide green infrastructure initiatives. 

These early implementation projects are critical to gain public support for the SSIP Green Infrastructure Program, inform the cost/benefit as utility assets, and meet the goals for the City and County of San Francisco to revitalize public streets, create green jobs and improve wildlife habitat.

Previous studies conducted by the SFPUC identified needs for flood and stormwater management in the Yosemite watershed. This project will decrease localized flooding and increase groundwater infiltration by capturing stormwater runoff and directing it to a new unlined creek channel, bioretention facilities, and subsurface storage tanks. In addition to watershed needs, the project considered synergy opportunities and social and environmental factors. Proposed enhancements to McLaren Park include improved drainage of athletic fields and construction of a new pedestrian path that would provide safer access the park. The project will feature an outdoor classroom to provide opportunities to learn about San Francisco's historic creeks and the benefits of treating and managing stormwater with natural systems. The headwater reach of the historic Yosemite creek will be restored and bioretention facilities will create potential habitat using native plant species. Subsurface storage tanks will be installed to retain excess stormwater, and potential reuse for irrigation of McLaren Park athletic fields or the creek channel will be investigated.

The green infrastructure technologies included in the current scope of the preferred project alternative can manage stormwater from approximately 110 acres of McLaren Park. The creek channel and inline bioretention areas are estimated to remove approximately 1 million gallons of stormwater per year from the combined sewer system (in a typical rainfall year). The underground storage facility is estimated to remove approximately 6.5 million gallons of stormwater per year. The reduction in peak flow resulting from a “Level of Service” storm (1.3 inches in three hours) is estimated to be approximately 1.2 million gallons per event. These are initial estimates based on unit green infrastructure performance metrics developed using numerous citywide Sewer System Master Plan and SSIP modeling analyses conducted using the City and County of San Francisco Hydrologic and Hydraulic model10. These values will be refined through project-specific modeling during conceptual engineering and design. Based on this preliminary estimate of annual stormwater volume removed and the estimated annualized life cycle cost, the costs of the Yosemite Creek Daylighting Project is approximately $0.114 per gallon of stormwater removed.

As one of SFPUC’s Early Implementation Projects, information obtained from this project will be used to develop plans for future installations of green infrastructure.

Increases Water Supply Reliability
Advances/ Expands Conjunctive Management of Multiple Water Supply Sources
Increases Water Use and/or Reuse Efficiency
Provides Additional Water Supply
Promotes Water Quality Protection
Reduces Water Demand
Advances/Expands Water Recycling
Promotes Urban Runoff Reuse
Addresses Sea Level Rise
Addresses other Anticipated Climate Change Impact (e.g. through water management system modifications)
Improves Flood Control (e.g. through wetlands restoration, management, protection)
Promotes Habitat Protection
Establishes Migration Corridors
Re-establishes River-Floodplain Hydrologic Continuity
Re-introduces Anadromous Fish Populations to Upper Watersheds
Enhances and Protects Upper Watershed Forests and Meadow Systems
Other (Please Describe)
Increases Water Use Efficiency or Promotes Energy-Efficient Water Demand Reduction
Improves Water System Energy Efficiency
Advances/Expands Water Recycling
Promotes Urban Runoff Reuse
Promotes Use of Renewable Energy Sources
Contributes to Carbon Sequestration (e.g. through vegetation growth)
Other (Please Describe)
(low) - (high)
Drought Preparedness
Use and Reuse Water More Efficiently
Climate Change Response Actions (Adaptation to Climate Change, Reduction of Greenhouse Gas Emissions, Reduce Energy Consumption)
Expand Environmental Stewardship
Practice Integrated Flood Management
Protect Surface and Groundwater Quality
Improve Tribal Water and Natural Resources
Ensure Equitable Distribution of Benefits
Reduce Reliance on the Bay-Delta
Reduce Water Demand
Improved Operational Efficiency and Transfers
Increase Water Supply
Improve Water Quality
Improve Flood Management
Practice Resources Stewardship
Other Strategies (Please Describe)
Groundwater Management Plan
Urban Water Management Plan
Water Meter Requirements
Groundwater Monitoring Requirements
AB 1420 Compliance
BMP Compliance
CEQA Compliance
Water supply reliability, water conservation and water use efficiency
Stormwater capture, storage, clean-up, treatment, and management
Removal of invasive non-native species, the creation and enhancement of wetlands, and the acquisition, protection, and restoration of open space and watershed lands
Non-point source pollution reduction, management and monitoring
Groundwater recharge and management projects
Contaminant and salt removal through reclamation, desalting, and other treatment technologies and conveyance of reclaimed water for distribution to users
Water banking, exchange, reclamation and improvement of water quality
Planning and implementation of multipurpose flood management programs
Watershed protection and management
Drinking water treatment and distribution
Ecosystem and fisheries restoration and protection
Reduced Reliance on the Bay-Delta
Projects that directly address a critical water quality or supply issue in a DAC
Urban water suppliers implementing certain BMPs as on page 17 of Guidelines
Be designed to manage stormwater runoff to reduce flood damage (PRC §5096.827)
Be consistent with the applicable Regional Water Quality Control Plans (Basin Plans) (PRC §5096.827)
Not be a part of the State Plan of Flood Control (SPFC) (PRC §5096.827)

Project team

Part 3 - Benefits