|The Guadalupe River Watershed supports many beneficial uses, such as drinking water supply, sport fishing, and habitat for wildlife and endangered species. Santa Clara County has issued a fish consumption advisory for mercury contamination. Mercury concentrations in fish tissue that exceed the U.S. EPA human health mercury fish criterion (0.3 mg/kg), have been measured at numerous creeks and reservoirs in the Guadalupe River Watershed. Elevated mercury concentrations in fish tissue may also pose a threat to wildlife, such as birds, amphibians, and mammals.
The Guadalupe River Watershed Mercury TMDL examined this water quality problem and provided a watershed-wide mercury management strategy. The main source of mercury in the Watershed is the New Almaden Mining District, the largest-producing mercury mine in North America. Other sources include atmospheric deposition from global and local sources, soil erosion from areas not known to contain mines, urban stormwater runoff, seepage from landfills, and Central Valley Project water inputs to Calero Reservoir. In addition to being the primary regulatory means of achieving water quality goals in the watershed, the Guadalupe River Watershed Mercury TMDL will simultaneously reduce the amount of mercury in the Bay in accordance with the San Francisco Bay Mercury TMDL's proposed requirements.
June 2013 TMDL Implementation Update
Mercury mine sites: As planned, we started implementation at the top of the watershed by requiring mine site owners to evaluate and report on the potential for mining waste to erode from their properties. These reports are posted below. The following erosion control work is underway:
- In June, the Board adopted Site Cleanup Requirements Order No. R2-2013-0024 for Guadalupe Mine, owned by the Guadalupe Rubbish Disposal Company. The SCRs require GRDC to complete appropriate mercury mining waste cleanup and stabilization measures, focused on erosion control, by December 31, 2015.
- The Santa Clara County Department of Parks and Recreation and the Midpeninsula Regional Open Space District have grant-funded mine cleanup projects underway Staff will continue to work with them on these projects.
- County Parks completed 60% design plans to reduce erosion of mercury mining wastes at Senador Mine. This project is funded by U.S. EPA’s San Francisco Bay Water Quality Improvement Fund. The project will restore a headcut and other targeted features in a creek channel, remediate several small calcine piles (piles of roasted mercury ores), and reduce erosion of mercury mining wastes. Nearly 300 pounds of mercury will be removed or stabilized. Construction is expected to be completed in the 2014 dry season.
- County Parks completed 25% design plans to remediate calcine-paved roads in Almaden Quicksilver County Park. Approximately 4 miles of historic mine roads were paved with calcines, and are one of the last areas of eroding calcines in the Park. Pending County Parks’ evaluation of grant opportunities, and decisions about the role of the Department of Toxic Substances Control, the Water Board may need to issue Site Cleanup Requirements. Construction is expected to be completed in the 2014 dry season.
- Under a Natural Resource Damages Assessment legal settlement unrelated to the TMDL, County Parks is developing designs to restore creeks adjacent to the Hacienda Furnace Yard, by far the largest mercury ore processing facility at New Almaden. This would remove calcines from about 500 feet of creek bed, and restore these stretches of creeks. More information on the New Almaden Mine CERCLA Site is available at: http://www.dfg.ca.gov/ospr/NRDA/new-almaden-mine.aspx.
- The Midpeninsula Regional Open Space District completed designs and released construction bid documents to remediate an eroding slope of mercury mining waste at Hicks Flat. The project is funded by a Water Board and U.S. EPA Clean Water Act Section 319(h) grant. Construction is expected to be completed in the 2013 dry season.
- Reports from mine site owners are available here:
Guadalupe Rubbish Disposal Company
Santa Clara County Department of Parks and Recreation
Midpeninsula Regional Open Space District
The Santa Clara Valley Water District continued its voluntary methylmercury production and control studies, which it initiated in 2005. Solar-powered circulators were effective in suppressing methylmercury production at Lake Almaden, but not in the Almaden or Guadalupe reservoirs. Recently, the District installed oxygenation systems in Calero and Guadalupe Reservoirs, and they are continuing to study how this affects methylmercury levels.
More information is available in their December 2011 biennial report (Their next report is due December 2013).
The four entities discussed above have established a coordinated monitoring program, led by Santa Clara County Parks. Monitoring data gathered thus far is inconclusive regarding changes in mercury concentrations. Prey fish were monitored at five locations in 2011 and 2012, and there was no statistically significant difference in prey fish mercury concentrations between these years. A cursory analysis of prey fish monitoring data shows that fish mercury concentrations were lower in reservoirs in 2011, as compared to 2004 (see comparison plot), but higher in Lake Almaden and creek sites (see comparison plot). The program submitted two interim reports, the January 2012 and January 2013 annual data reports. Mercury loads to San Francisco Bay are scheduled to be monitored in the 2014-2015 wet season, and prey fish monitoring is scheduled for 2016.
U.S. EPA gives final approval to TMDL and Water Quality Objectives for Mercury in the Guadalupe River Watershed
On June 1, 2010, the U.S. Environmental Protection Agency approved the Basin Plan amendment adopted by the Regional Water Board in October 2008. These actions establish New Water Quality Objectives and Total Maximum Daily Loads (TMDLs) and an Implementation Plan for mercury in waters of the Guadalupe River Watershed. The amendment is now part of the Water Quality Control Plan for the San Francisco Bay Basin (Basin Plan), the master planning document for water quality in the Bay Area.
Previously, the State Office of Administrative Law (OAL) approved the amendment on February 24, 2010, the State Water Board approved the amendment on November 17, 2009, and the Regional Water Board adopted the amendment on October 8, 2008.
Materials from Sept. 11, 2008 meeting with Alamitos Creek property owners
Questions and Answers about the Guadalupe River Watershed Mercury TMDL
Streambank Repair Guidance Manual for the Private Landowner (Santa Clara Valley Water District publication)
Final Conceptual Model Report, May 22, 2005 (Tetra Tech, Inc.)
Due to the size of the original PDF document (47.98 MB), we have made both the full document and each separate chapter available below for download. All these PDF files were created using Adobe Version 6. If you do not have this version (or higher), you will not be able to view the files.
Full Document (47.98 MB)
Individual Files (smaller-size documents):
Cover Page, Table of Contents, and Executive Summary (1.4 MB)
Chapter 1. Introduction (233 K)
Chapter 2. Watershed Characterization (15 MB)
Chapter 3. Data Summary (2.3 MB)
Chapter 4. Estimated Mercury Loads (4.3 MB)
Chapter 5. Conceptual Model of Mercury (5.9 MB)
Chapter 6. Summary (203 K)
Chapter 7. References (233 K)
Derivation of Numeric Wildlife Targets for Methylmercury in the Development of a Total Maximum Daily Load for the the Guadalupe River Watershed (USFWS 2005) (2.3 MB)
Reservoir Sediment Sampling, April 2005 (Tetra Tech, Inc., 203 KB)
Draft Project Plan, June 2004 (407 KB)
Preliminary Project Definition, August 2004 (45 KB)
Santa Clara Valley Water District (home page)
For extensive Guadalupe River Watershed information, scroll to the bottom of the page and click on "Healthy Creeks and Ecosystems", from the list on the left, first click on "Watersheds," then click on "Guadalupe."
CalFed (Bay-Delta Authority) Mercury Project
See especially the document "Mercury Strategy for the Bay Delta Ecosystem"
San Francisco Bay Mercury TMDL