Preferred project: A federal-state-local partnership
This project continues a partnership with the U.S. Army Corps of Engineers (USACE) and the State of California to plan, design and construct improvements along 13.9 miles of channel. The project extends from Buena Vista Avenue to Llagas Road and includes West Little Llagas Creek in downtown Morgan Hill. The federally authorized preferred project protects the urban area of Morgan Hill from a 1% flood (100-year event) and reduces the frequency of flooding in surrounding areas. Construction includes channel modifications and replacement of road crossings. Valley Water continues to work with Congress to aggressively pursue federal funds to bring this project to full fruition.
Local-funding-only project
Construct flood protection improvements along Llagas Creek from Buena Vista Avenue to Highway 101 in San Martin (Reaches 4 and 5), Monterey Road to Watsonville Road in Morgan Hill (Reach 7a), approximately W. Dunne Avenue to W. Main Avenue (a portion of Reach 8), and onsite compensatory mitigation at Lake Silveira.
Valley Water begins construction of the final phase
Valley Water began construction on Phase 2B, the final phase of the Upper Llagas Creek Flood Protection Project, in September 2024. This phase includes improvements on approximately eight (8) miles of Upper Llagas Creek, from US 101 upstream to Llagas Road. Phase 2B is scheduled for completion in spring 2027. Once completed, approximately 1,100 homes, 500 businesses, and over 1,300 acres of agricultural land will be protected from the 100-year flood. The Phase 2B mailer is available with details about the work scheduled for each of the four reaches where construction will occur.
Hale Avenue Temporary Closure April 14 through October 2025
Progress continues on the Upper Llagas Creek Flood Protection Project. Starting on April 14, 2025, a section of Hale Ave. will be temporarily closed, and crews will resume the construction of twin box culverts beneath Hale Avenue, starting from the Morgan Hill Shopping Center and moving towards Wright Avenue. A box culvert is similar to a square-shaped underground tunnel. The two 10-foot wide by 9-foot high culverts will replace West Little Llagas Creek along the eastern side of Hale Avenue to convey a 100-year storm, which has a 1% chance of occurring once a year.
Crews will work from 7:00 a.m. to 8:00 p.m. Monday through Friday and 9:00 a.m. to 6:00 p.m. on Saturdays. Hale Avenue will remain closed through October 2025. The map on the right provides detour information.
Access to the Morgan Hill Shopping Center remains open on Main Avenue, but access from Hale Avenue is only open from the first driveway near the donut shop. The entrance to the Park Plaza Professional Center will be on Crest Avenue.
A curb, gutter, and sound wall will also be constructed on the east side of Hale Avenue, and the existing overhead utility lines along the west side of Hale Avenue will be relocated underground. Valley Water’s contractor will also re-construct the west side sidewalk.
Cosmo Ave, Edes St, Spring Ave, and Trail Entrance Closures (end of April 2025)
Beginning at the end of April 2025 and continuing through fall 2025, Valley Water will construct new box culverts where West Little Llagas Creek crosses under Cosmo Avenue, Edes Street and Spring Avenue. This work requires the temporary full closure of Spring and Cosmo avenues; and a one-lane closure of Edes Street. For public safety, the three trail entrances to West Little Llagas Creek Trail on the above-mentioned roads will also be closed.
Construction activity at Edes Street is scheduled from late April through mid-September 2025. Work at Cosmo Avenue is scheduled from early May through mid-July 2025, while work at Spring Avenue is scheduled from mid-July through mid-October 2025.
Click here to view the project mailer with additional details and maps of the street and trail detours.
Crews will work weekdays from 7:00 a.m. to 8:00 p.m. and Saturdays from 9:00 a.m. to 6:00 p.m. when needed. The streets will not reopen until the construction for that section is completed. The anticipated start and end dates for these closures may shift due to unforeseen work conditions.
Spring Ave Temporary Closure (week of April 14, 2025)
Construction crews will be working on a new sewer line to prepare for Valley Water’s installation of box culverts on West Little Llagas Creek, where it crosses under Spring Ave. to Monterey Rd. The work hours will be from Monday through Friday, 7:00 a.m. to 5:00 p.m., with completion anticipated within 12 days. At the end of each workday, the lane will be reopened. While work is occurring, turns to and from Monterey Rd. will be limited to the following:
Phase 1: Five days to complete
Drivers can turn right onto Monterey from Spring Ave. Drivers must use W. Dunne Ave or Cosmo Ave. to access northbound Monterey Rd. Left turns from Monterey Rd. to Spring will not be allowed. Drivers must use Ciolino Ave. or Cosmo Ave. to reach Spring Ave.
Phase 2: Seven days to complete
Drivers can turn left onto Spring Ave from Monterey Rd. Right turns from Spring Ave. to Monterey Rd. will not be allowed, and drivers will need to use Ciolino Ave. or Cosmo Ave. to access southbound Monterey Rd.
Valley Water will work on additional efforts along Spring Ave. starting in mid-July 2025, which will require the closure of both lanes on Spring Ave. at West Little Llagas Creek and the adjoining trail. Once details are confirmed, additional notice will be provided.
Here is a social media post explaining the work and a postcard with details about the work.
Project Information
The project is being constructed in several phases, each with specific sections (referred to as reaches on the map) where the proposed improvements will occur. Phase 1 was completed in April 2022, including creating a new wetland habitat at Lake Silveira and planting more than 45,000 native plants along the widened and deepened channel. In August 2024, Valley Water completed Phase 2A of the project, including constructing a 2,300-foot-long tunnel underneath downtown Morgan Hill. The final phase of the project, Phase 2B, is now under construction and expected to be completed in 2027.
The Phase 2B mailer is available with details about the work scheduled for each of the four reaches where construction will occur.
Phase 1: Complete
Phase 1 of the Upper Llagas Creek Flood Protection Project was completed ahead of schedule in April 2022. Phase 1 project work included 4.4 miles of channel excavation, construction of the on-site compensatory mitigation at Lake Silveira wetlands, Masten Avenue Bridge concrete underpinning, Monterey Road Bridge concrete lining with a low flow channel for fish passage, installation of rock slope protection, storm drain outfall modifications, removal of concrete rubble, debris, and legacy trash, destruction of monitoring wells, installation of bat boxes, installation of permanent fencing and gates, removal of 12.5 acres of invasive blackberry bushes at Lake Silveira, planting of approximately 45,000 new, native plants on approximately 50 acres of Valley Water project property, and restoration of 2,000 linear feet of Llagas Creek adjacent to Lake Silveira The three-year native plant establishment and maintenance period is anticipated to be completed in April 2025.
Valley Water created a video of the completed wetlands and Llagas Creek restoration work. A story on this work is also available on the Valley Water News blog.
In the 1970s, Lake Silveira was an active quarry, and presumably, as a result of those operations, there was a significant amount of abandoned concrete rubble dispersed on and adjacent to Llagas Creek. Valley Water removed the rubble and created new wetlands. The wetland habitat at Lake Silveira included creating islands, constructing habitat features, constructing side-weir inlet and outlet structures, and planting thousands of native wetland and riparian plants that will become habitat for birds, frogs, turtles, and other wildlife. The Land Trust of Santa Clara Valley is Valley Water’s long-term land management partner of the Lake Silveira wetlands.
During the 2020 and 2021 in-channel construction seasons, approximately 600,000 cubic yards (CY) of soil was excavated and removed from Upper Llagas Creek from Reaches 4, 5, 7A, and a portion of Reach 6 to increase the capacity of the creek channel during storm events. Rock slope protection was placed at existing bridge abutments for erosion and scour protection. Approximately 75,000 CY of nutrient-rich topsoil was placed along the creek banks to help support the dozens of acres of newly planted native riparian vegetation. Instream complexities, such as coarse woody debris and rootwad-log structures, were installed along the creek bottom throughout Phase 1 to serve as future habitat for native wildlife.
Valley Water entered into a cost-sharing agreement with the City of Morgan Hill in October 2020 to construct a public trail within Reach 7A. Valley Water completed the paved trail on behalf of the city. The city completed the construction of new pedestrian crosswalks at Middle Avenue and Watsonville Avenue. The project is an example of Valley Water’s commitment to restoring wildlife habitat and providing open space for public use.
Phase 2A: Complete
Phase 2A construction began in June 2021 in a portion of Reach 8 in downtown Morgan Hill. Phase 2A included approximately 2,300 linear feet of a horseshoe-shaped underground tunnel 14 x 12 feet and approximately 1,600 linear feet of 10 ft x 9 ft twin reinforced concrete box culverts upstream and downstream of the tunnel to carry high water flows. Low flows will remain within the existing creek that traverses through downtown Morgan Hill. The Phase 2A construction contract Notice of Completion was accepted by the Valley Water Board of Directors on January 28, 2025.
Valley Water entered into a cost-sharing agreement with the City of Morgan Hill in April 2021 to construct an approximate 600-foot portion of the City’s Hale Avenue Extension Project, including a fully signalized intersection at West Main Avenue as part of Phase 2A. Valley Water utilized the City property as a staging area to construct the necessary flood protection improvements. Phase 2A is an example of the cooperation and commitment of Valley Water and the City to save public funds while minimizing impacts to the community.
Phase 2B: in construction through spring 2027
Phase 2B construction consists of approximately 1,900 linear feet of twin reinforced concrete box culverts (10 ft x 9 ft), creek modifications and excavation by widening and deepening, installation and modification of culverts at various street crossings, construction of an inlet basin weir split-flow structure to divert high creek flows, and support of existing bridges by underpinning. Valley Water will construct improvements on approximately eight (8) miles of Upper Llagas Creek, from US 101 upstream to Llagas Road. Construction will include creek widening and deepening, bridge/culvert construction, traffic control, utility coordination and relocation, construction of maintenance roads, and habitat enhancements. Construction is expected to be completed in spring 2027.
After the project's completion in spring 2027, a three-year post-construction mitigation native plant revegetation period will follow.
Valley Water and Boy Scout Troop 730
In May 2023, Morgan Hill Boy Scout Troop 730 constructed a bat roost adjacent to Lake Silveira. The construction was the culmination of many days of planning and preparation for the bat roost. Approximately 15 troop and community members helped at various stages of the project.
Volunteers and troops design the bat roost.
Volunteers help with the roost.
The bat roost is done and installed. THANK YOU!
For more information:
- Stephen M. Ferranti, P.E., (408) 630-2677
- Jose Villarreal, (408) 630-2879
- Sign up to receive project updates via email.
- Use "Access Valley Water" to submit questions, complaints or compliments.
Pursuant to the California Environmental Quality Act, Valley Water, as the lead agency for the Project, has prepared a Final Environmental Impact Report (FEIR) to evaluate environmental impacts of the proposed Project
- Final Environmental Impact Report
- Draft Environmental Impact Report, May 19, 2014
Additional reports related to the Project can be found by clicking on the link below:
- Geotechnical Report (2006)
- Part 1
- Part 2 - Site Characterization Report (2012)
- Reach 4 and 5 Limited Phase II ESA (2003)
- Reach 4, 5, 6, and 7B – Phase I ESA Vol 1 (2003)
- Reach 4, 5, 6, and 7B – Phase I ESA Vol 2 (2003)
- Part 1
- Part 2 - Reach 5 and 6 – Phase I ESA (2002)
- Reach 8 – Phase I ESA (2003)
- Reach 14 – Phase I ESA(2005)
September Pre-construction Public Meeting
Valley Water held a pre-construction meeting on September 3, 2024, to update the community on the anticipated construction impacts and measures Valley Water will take to mitigate and reduce these disturbances. A question-and-answer session followed the presentation. Below is a recording of the meeting and a copy of the presentation slides.
FY22-36 Key Performance Indicator for the Safe, Clean Water Program
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Preferred project with federal and local funding: Plan, design and construct flood protection improvements along 13.9 miles of Upper Llagas Creek from Buena Vista Avenue to Llagas Road to provide flood protection to 1,100 homes, 500 businesses, and 1,300 agricultural acres, while improving stream habitat.
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With local funding only: Construct flood protection improvements along Llagas Creek from Buena Vista Avenue to Highway 101 in San Martin (Reaches 4 and 5 (portion)), Monterey Road to Watsonville Road in Morgan Hill (Reach 7a), approximately W. Dunne Avenue to W. Main Avenue (portion of Reach 8), and onsite compensatory mitigation at Lake Silveira.
Benefits
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Provides 1% flood capacity for four (4) miles along West Little Llagas Creek within downtown Morgan Hill, protecting approximately 1,100 homes and 500 businesses
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Provides 10% (10-year event) flood protection to approximately 1,300 agricultural acres in Morgan Hill, Gilroy and San Martin
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Locally funded project provides improved flood protection for a limited number of homes and businesses in Morgan Hill
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Improves stream habitat and fisheries
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Creates additional wetlands
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Improves stream water quality
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Identifies opportunities to integrate recreation improvements with the City of Morgan Hill and others as appropriate
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Addresses climate change as the project is designed to increase flow capacity, thereby reducing flood risks from storm events projected to become more frequent and intense due to climate change. Additionally, Valley Water considered the implications of sea level rise (SLR) and determined that the project is outside SLR impact reach
Geographic Area of Benefit
Morgan Hill, San Martin and Gilroy
Flooding History
The area sustained damage in 1937, 1955, 1958, 1962, 1963, 1969, 1982, 1986, 1996, 1997, 1998, 2002, 2004, 2008, 2009, and 2011. In 2009, many businesses and residences in downtown Morgan Hill were flooded under 1 foot of water.
Project Background
The Upper Llagas Creek Flood Protection Project was initially part of the voter-approved Clean, Safe Creeks and Natural Flood Protection Plan (CSC Plan) that came into effect in Fiscal Year 2001-2002 (FY02).
The project entailed providing 1% flood protection for approximately 4.5 miles of the channel in the urban area of Morgan Hill; the remaining 9.4 miles of the channel within the rural areas would have approximately 10% level of flood protection.
Due to very little federal funding for the project, in 2009, the Valley Water Board and the City of Morgan Hill decided to proceed with the project using only local funding while still working with the U.S. Army Corps of Engineers to secure federal funding. The City of Morgan Hill agreed to contribute up to $3 million towards the project design. As part of the CSC Plan, planning and 65% project design was completed. Upon certification of the Environmental Impact Report in June 2014, VW began acquisition of more than 100 parcels required for construction.
Voters Approve 2012 Safe, Clean Water Program
In November 2012, voters approved the 15-year Safe, Clean Water and Natural Flood Protection Program (2012 Program), which replaced the CSC Plan. The project was carried forward into the 2012 Program with two key performance indicators (KPIs). The preferred project with federal and local funding entailed providing flood protection to 1,100 homes, 500 businesses, and 1,300 agricultural acres while improving stream habitat. The local-funding only project focused on providing 100-year flood protection for Reach 7 only (up to W. Dunne Avenue in Morgan Hill).
In 2020, the Valley Board modified the local-funding-only KPI #2 to “Construct flood protection improvements along Llagas Creek from Buena Vista Avenue to Highway 101 in San Martin (Reaches 4 and 5 (portion), Monterey Road to Watsonville Road in Morgan Hill (Reach 7a), approximately W. Dunne Avenue to W. Main Avenue (portion of Reach 8), and onsite compensatory mitigation at Lake Silveira.”
The modification increased the length of the locally funded project from approximately 2.9 miles to 4.9 miles in addition to constructing the onsite compensatory mitigation. Besides getting the most out of the available local dollars, this approach kept the project moving forward, shortening the construction window without inducing flooding downstream. This modification maximized the potential for external funding opportunities and also reflected improved collaboration with regulatory permitting agencies that require early mitigation for the project impacts. Details about the modification can be found at https://www.valleywater.org/sites/default/files/SCW_FY19%20ModificationsWithAttachments.pdf.
As part of the 2012 Program, Valley Water began Phase 1 construction in FY20 and Phase 2A in FY21.
Voters Approve the Renewed Safe, Clean Water Program
In November 2020, voters approved the renewed Safe, Clean Water and Natural Flood Protection Program (Safe, Clean Water Program), replacing the 2012 Program. The project has continued in the renewed Safe, Clean Water Program.
About the Safe, Clean Water and Natural Flood Protection Program
In November 2020, voters in Santa Clara County overwhelmingly approved Measure S, a renewal of Valley Water’s Safe, Clean Water and Natural Flood Protection Program.
The program was first passed by voters in 2000 as the Clean, Safe Creeks and Natural Flood Protection Plan, then again in 2012 as the Safe, Clean Water and Natural Flood Protection Program. The renewal of the Safe, Clean Water Program will continue to provide approximately $47 million annually for local projects that deliver safe, clean water, natural flood protection, and environmental stewardship to all the communities we serve in Santa Clara County.
While evaluating ways to improve the 2012 program, Valley Water gathered feedback from more than 21,000 community members. That helped Valley Water create the six priorities for the renewed Safe, Clean Water Program, which are:
Priority A: Ensure a Safe, Reliable Water Supply
Priority B: Reduce Toxins, Hazards and Contaminants in our Waterways
Priority C: Protect our Water Supply and Dams from Earthquakes and Other Natural Disasters
Priority D: Restore Wildlife Habitat and Provide Open Space
Priority E: Provide Flood Protection to Homes, Businesses, Schools, Streets and Highways
Priority F: Support Public Health and Public Safety for Our Community
Each year, Valley Water prepares a report providing a progress update for each of these program priorities, along with fiscal year accomplishments.
To ensure transparency and accountability to the voters, the ballot measure also created an Independent Monitoring Committee, appointed by the Santa Clara Valley Water District Board of Directors. The Independent Monitoring Committee annually reviews the program’s progress to ensure the outcomes are achieved in a cost-efficient manner and reports its findings to the Board. Additionally, the IMC also reviews each proposed 5-year implementation plan prior to its submittal for Board approval.
In addition, the program requires three independent audits.
