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B1: Impaired Water Bodies Improvement*

About This Project

This project helps Valley Water meet surface water quality standards and reduces pollutants in streams, groundwater, lakes and reservoirs. Efforts are carried out in compliance with the Regional Water Quality Control Board (RWQCB) Total Maximum Daily Loads (TMDLs) standards as they continue to evolve (TMDLs are the maximum amount of a pollutant that a water body can receive and still safely meet water quality standards). Under this project, Valley Water employs treatment systems in reservoirs to reduce methylmercury formation, and helps create realistic plans and expectations for reducing contaminant loads by engaging in the regulatory development process with the RWQCB for new and emerging contaminants.


*This project was voter approved as part of the Safe, Clean Water and Natural Flood Protection Program.

Calero Reservoir Oxygenation System
On Target
Start FY 2014 / Finish FY 2028
Safe, Clean Water Fund ($27.4 million)
News and UpdatesNews and Updates
Reports and DocumentsReports and Documents
Environmental and Community BenefitsEnvironmental and Community Benefits
History and BackgroundHistory and Background
News & Updates

The project is on schedule and within budget.

KPI #1: Treatment Systems in Reservoirs and Mercury Studies

  • The oxygenation systems were deployed between May and June. The Almaden Reservoir system and the Calero Reservoir system had electric or mechanical failures in late June and early July, respectively. Repairs to the Almaden Reservoir system were completed and the system was restarted in mid-September. Repairs to the Calero Reservoir system are still underway.

  • Valley Water performs twice-monthly water quality monitoring at Almaden, Guadalupe, Calero, and Stevens Creek reservoirs, and Almaden Lake when the reservoirs and lake are stratified (monthly the rest of the year). Monitoring was suspended in April 2020 due to the COVID-19 pandemic. Regular monitoring resumed from October to Mid-December, at which point it was again suspended in keeping with the Statewide stay at home order.

  • Valley Water submitted a biennial report to the San Francisco Bay Regional Water Quality Control Board (RWQCB) in March 2020. The report is posted here.

  • Valley Water staff worked with colleagues from RWQCB and UC Merced to author a technical manuscript on the effectiveness of the oxygenation system in reducing fish tissue mercury. The manuscript was recently published in the journal Environmental Pollution, available here.

  • Valley Water coordinated with project partners (County of Santa Clara, Midpeninsula Regional Open Space District, and Guadalupe Rubbish Disposal Company) and the RWQCB to plan the second 5-year phase of the Coordinated Monitoring Program for the Guadalupe River Watershed Mercury TMDL project. For more information on the TMDL project, please see here. On January 23, 2018, the Valley Water Board of Directors approved a cost share agreement ( The partners selected Tetra Tech to perform the required monitoring. The RWQCB approved the sampling plan developed for the Coordinated Monitoring Program in October 2018 (see letter posted under documents). The consultants performed two monitoring events during storm flows during the 2019-2020 wet season. A progress report was submitted to the RWQCB in March 2020 and can be found here.  An annual report was submitted in June 2020 and can be found here.

  • In partnership with USGS, Valley Water sampled water in May and August of 2019 to study methylmercury production in the water columns of four reservoirs. USGS is preparing a data release and technical report to be published by April 2021.

  • To better understand the effects of the oxygenation system on Stevens Creek Reservoir discharge and downstream dissolved oxygen, turbidity, and temperature, Valley Water is conducting a one-year study starting in June 2020.  Results of the study will help staff optimize operation of the oxygenation system to maximize overall benefits. The study plan can be found here.

  • Valley Water staff gave presentations on reservoir oxygenation and mercury remediation at the North American Lake Management Society annual conference (November 2020), the California Lake Management Society annual conference (October 2020), the California Aquatic Bioassessment Workgroup (October 2020), the Delta Tributaries Mercury Council (September 2020), and at the Waste Management Symposium (March 2020). A recorded presentation covering reservoir oxygenation systems is available here.

  • Valley Water collected suspended particulate matter and zooplankton from Almaden, Calero, Guadalupe, and Stevens Creek reservoirs in October 2020. These samples will be analyzed for stable isotopes of nitrogen and carbon, total mercury, and methylmercury as part of Valley Water’s reservoir mercury bioaccumulation study.


KPI #2 Prioritization Plan

  • Valley Water developed the Prioritization and Implementation of Pollution Prevention and Reduction Activities Plan to Address Impaired Water Bodies in Santa Clara County in January 2015 and updated it in June 2017 with revised analysis of impaired water bodies. The plan is currently being revised. 


KPI #3: Pollution prevention activities

  • Pollution Prevention Activity #1: Accumulation Point Mapping and Removal (Guadalupe River)
    Valley Water and City of San José staff conducted visual trash assessments of Guadalupe Rive in October 2020. Trash accumulations are being prioritized for cleanup in spring 2021. 

  • Pollution Prevention Activity #2: Discourage the re-establishment of encampments along Guadalupe River and Coyote Creek
    In May 2019, Valley Water signed an agreement with the San José Police Department (SJPD) to fund a pilot program for SJPD to conduct patrols targeting criminal activities along local waterways. That agreement was extended in January 2020. Valley Water also funds a California Department of Fish and Wildlife warden position. Patrols are suspended during the COVID-19 pandemic.

  • Pollution Prevention Activity #3: Coyote Creek Trash Mapping and Removal
    Valley Water and City of San Jose staff began visual trash assessments along Coyote Creekin October 2020. Remaining assessments were suspended in December 2020 due to the COVID-19 pandemic. Trash accumulations are being prioritized for cleanup in spring 2021.  See the Coyote and Guadalupe Creek Trash Accumulation Point GIS map here.

  • Pollution Prevention Activity #4: Angler Survey 
    Valley Water completed the Santa Clara County Reservoir Angler Survey at mercury-impaired reservoirs and lakes to assist with future outreach and signage. Valley Water completed a final report which is posted here.

  • Pollution Prevention Activity #5: Homelessness Best Practices
    Valley Water previously collaborated with the City of San José to provide homeless residents with trash bags to contain their waste, primarily along Coyote Creek and Guadalupe River. The City previously distributed transparent blue trash bags to its creek cleanup partners, Downtown Streets Team, and homeless service providers to encourage homeless people to bag their trash. Homeless people used the bags and left them along trails and sidewalks for pickup by various city departments, creek partners, and Downtown Streets Team. In 2019, Valley Water began assisting the City with this effort, including purchasing 2,500 bags for distribution and conducting two bag pickup events. Trash bag pickups by Valley Water under this effort are no longer active. Bag pickup and distribution needs are now being serviced through the City of San Jose’s Beautify SJ initiative as part of their response to the COVID-19 pandemic. Staff is researching additional options for homelessness best practices to support clean waterways.

  • Pollution Prevention Activity #6: Reservoir Greenhouse Gas Emission Study
    Valley Water entered a collaborative agreement with University of California, Davis to study greenhouse gas emissions from the surfaces of Chesbro, Stevens Creek, and Uvas Reservoirs. During this year-long study, researchers will quantify the seasonal and spatial variation of reservoir greenhouse gas fluxes. This information will be incorporated Valley Water’s Climate Change Action Plan to help achieve carbon neutrality. Findings may also be used to improve global climate models.

Updated February 2021

For more information:



Example of a trash accumulation point on Coyote Creek between Highway 880 and E. Brokaw Road (January 29, 2018). 



Photos from Guadalupe Trash Raft Clean-Up (September 13, 2017). 







Reports & Documents

Mercury studies

District studies

Coordinated monitoring program

Pollution prevention activities

Environmental & Community Benefits

Key Performance Indicators for the Safe, Clean Water Program 

  1. Operate and maintain existing treatment systems in 4 reservoirs to remediate regulated contaminants, including mercury.

  2. Prepare plan for the prioritization of pollution prevention and reduction activities.

  3. Implement priority pollution prevention and reduction activities identified in the plan in 10 creeks.


  • Reduces contamination in creeks and reservoirs

  • Improves water quality, including water going to drinking water treatment plants

  • Reduces methylmercury in reservoirs to prevent its entry into the food web

  • Improves ecosystem health by reducing mercury contamination in fish and other biota. 

  • Supports regulatory compliance of TMDL standards affecting Valley Water operations

Geographic Area of Benefit 


History & Background

About the Safe, Clean Water and Natural Flood Protection Program

In November 2012 the voters of Santa Clara County overwhelmingly approved Measure B, the Safe, Clean Water and Natural Flood Protection Program, as a countywide special parcel tax for 15 years with a sunset date of June 30, 2028. This Program replaced the Clean, Safe Creeks and Natural Flood Protection Plan, which voters approved in November 2000.

The Safe, Clean Water Program was developed with input from more than 16,000 residents and stakeholders and was created to match the community’s needs and values. The voters of Santa Clara County identified five priorities:

Priority A: Ensure a Safe, Reliable Water Supply

Priority B: Reduce Toxins, Hazards and Contaminants in our Waterways

Priority C: Protect our Water Supply from Earthquakes and Natural Disasters

Priority D: Restore Wildlife Habitat and Provide Open Space

Priority E: Provide Flood Protection to Homes, Businesses, Schools and Highways

Other: Six projects from the Clean, Safe, Creeks Plan have been carried forward into the Safe, Clean Water Program.  

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.

In addition, the Program requires three independent audits, the first of which was conducted in FY 2017.

View the Safe, Clean Water Program’s annual reports, annual IMC audit reports, and independent audits, including a staff response, on the Valley Water website.