HomeMy WebLinkAbout02.17.26 Board Correspondence - FW_ Gridley 1,2,3-TCP, Electronic Transmittal, Central Valley Water Board, Redding Office.ATTENTION: This message originated from outside Butte County. Please exercise judgment before opening
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From:Clerk of the Board
To:Clerk of the Board; Connelly, Bill; Cook, Holly; Cook, Robin; Durfee, Peter; Jessee, Meegan; Kimmelshue, Tod;
Kitts, Melissa; Krater, Sharleen; Lee, Lewis; Little, Melissa; Pickett, Andy; Ritter, Tami; Stephens, Brad J.;
Sweeney, Kathleen; Teeter, Doug; Zepeda, Elizabeth
Cc:Loeser, Kamie; Nuzum, Danielle; Soderstrom, Monica; Mutony, Heather
Subject:Board Correspondence - FW: Gridley 1,2,3-TCP, Electronic Transmittal, Central Valley Water Board, Redding
Office
Date:Tuesday, February 17, 2026 9:12:56 AM
Attachments:image001.png
Gridley_RPT for BCEH 20251204.ces.bb.pdf
Please see Board Correspondence -
From: WB-RB5R-CentralValleyRedding <CentralValleyRedding@waterboards.ca.gov>
Sent: Tuesday, February 17, 2026 8:51 AM
To: Flower, Chris@Waterboards <Chris.Flower@waterboards.ca.gov>; Tabor,
Rebecca@Waterboards <Rebecca.Tabor@Waterboards.ca.gov>; Rezvani, Ali@Waterboards
<Ali.Rezvani@waterboards.ca.gov>; Clerk of the Board <clerkoftheboard@buttecounty.net>;
McSpadden, Elaine <EMcspadden@buttecounty.net>
Cc: Bergmann, William R.@Waterboards <William.Bergmann@Waterboards.ca.gov>; Snyder,
Clint@Waterboards <Clint.Snyder@waterboards.ca.gov>
Subject: Gridley 1,2,3-TCP, Electronic Transmittal, Central Valley Water Board, Redding Office
Good morning,
Please find the attached Sampling Results letter dated 17 February 2026. A hard copy was
sent to the addressee separately. Should those receiving this correspondence have any
questions, please contact Bill Bergmann at William.Bergmann@Waterboards.ca.gov, or
(530)224-4852.
Thank you,
Ciera Collins
Staff Services Analyst
R5 CENTRAL VALLEY - REDDING
Regional Water Quality Control Boards
364 Knollcrest Drive, #205, Redding CA 96002
Website: www.waterboards.ca.gov
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Central Valley Regional Water Quality Control Board
17 February 2026
Elaine McSpadden
Environmental Health Division Director
Butte County Environmental Health
202 Mira Loma Drive
Oroville, CA 95965
SAMPLING RESULTS, DOMESTIC WATER WELLS IN THE VICINITY OF
MANZANITA SCHOOL, EAST GRIDLEY, BUTTE COUNTY
Central Valley Regional Water Quality Control Board (Central Valley Water Board) staff
recently collected samples from numerous domestic wells in the vicinity of the
Manzanita School in Gridley, Butte County. Samples were collected in coordination with
respective homeowners as part of an ongoing investigation to identify sources of 1,2,3 -
trichloropropane (TCP) detected in the Manzanita School supply well in 2018. Staff
have prepared and sent each homeowner information relevant to concentrations, or lack
thereof, of TCP in their well. This letter serves to notify Butte County Department of
Environmental Health of the collective sampling results.
BACKGROUND
In December 2017, the State Water Resources Control Board’s Division of Drinking
Water (DDW) adopted the maximum contamination level (MCL) for TCP of 5 parts per
trillion (ppt). The regulation required that public water systems statewide begin sampling
for TCP to assess compliance with the MCL.
The Manzanita Elementary School (School), located near the intersection of
East Evans Reimer Road and Larkin Road, has a public water supply system used to
serve approximately 300 students and staff. An initial water sample collected from the
school's well on 28 February 2018 indicated the presence of TCP at a concentration of
49.1 ppt. The well was re-sampled on 21 March 2018 and indicated TCP at a
concentration of 54.6 ppt. On 26 April 2018, the Butte County Department of
Public Health distributed a public notification describing the detection of TCP in the
School well. On 26 April 2018, Butte County Environmental Health Department
(BCEHD) issued a Compliance Order for Noncompliance to the Manzanita School
District for exceedances of the 1,2,3-TCP MCL per California Code of Regulations, Title
22, Section 64444. The School District has and continues to work with BCEHD and
DDW, to address concentrations of TCP detected in the School's well. Bottled drinking
Elaine McSpadden - 2 - 17 February 2026
Butte County Environmental Health Division
water is currently provided to the school occupants. A map showing the location of the
School and the surrounding area is attached as Figure 1.
CENTRAL VALLEY WATER BOARD’S INVESTIGATION
In late June 2018, Central Valley Water Board staff initiated an investigation into the
potential source and extent of TCP in the vicinity of the Manzanita School. Initial efforts
included sample collection from School's well and nine other private wells located near
the School. The purpose of this sampling was to assess potential threats or impacts to
nearby domestic supply wells, and to determine whether additional actions (e.g.
wellhead treatment) were required to protect public health. Two of the nine wells
sampled exceeded the State's MCL for TCP; one of which was obtained from the
School well.
The State Water Board maintains a public web-based database, Drinking Water Watch.
The database allows users to search for public water wells and obtain associated
chemical concentration data. This system indicates that TCP was detected in a nearby
restaurant supply well (Water System CA0400169) on 20 January 2020 and
28 January 2021 at concentrations of 25 ppt and 34 ppt, respectively.
Given the concentrations in the School and restaurant supply wells it was necessary to
expand the investigation to better delineate the extent of TCP in area groundwater. On
9 October 2025, 15 October 2025, and 16 October 2025 Central Valley Water Board
staff expanded the investigation by sampling fourteen domestic wells and three
groundwater monitoring wells near Manzanita School and the Restaurant.
Table 1 summarizes the initial results from sampling in 2018 and the latest
October 2025 sampling results. The 2025 laboratory analytical report is included as
Appendix A. Four of the wells sampled exceeded the State MCL of 5 ppt for TCP.
Additionally, eight supply wells had estimated ("J-flagged") results which indicates that
the result was below the method reporting limit (MRL) but above the method detection
limit (MDL). Generally, results that are below the MRL are estimated and so low that
they are difficult for lab equipment to quantify. Samples from the remaining wells did
not have detectable concentrations of TCP and are reported as "not detected" or "ND".
Elaine McSpadden - 3 - 17 February 2026
Butte County Environmental Health Division
TABLE 1, 1,2,3-Trichloropropane (TCP) Groundwater Analytical Results
Domestic Well Sampling, E. Gridley, Butte County
Sample Location Sample Date
1,2,3-TCP
(ppt) Flag
Method
Reporting
Limit (ppt)
Minimum
Detection
Limit (ppt)
606 Center Ave 10/16/25 ND 5 1.0
607 Center Ave 6/26/18 ND 5 1.2
607 Center Ave 10/16/25 ND 5 1.0
628 Center Ave 6/26/18 1.4 J 5 1.2
646 Center Ave 6/26/18 1.8 J 5 1.2
646 Center Ave 10/15/25 1.4 J 5 1.0
655 Center Ave 6/26/18 7.9 5 1.2
622 Center Ave 10/16/25 1.7 J 5 1.0
663 Center Ave 10/16/25 1.0 J 5 1.0
627 E. Evans Reimer Rd (School) 6/26/18 39 5 1.2
661 E. Evans Reimer Rd Well #1 6/26/18 ND 5 1.2
661 E. Evans Reimer Rd Well #1 10/09/25 1.7 J 5 1.0
665 E. Evans Reimer Rd 6/26/18 ND 5 1.2
665 E. Evans Reimer Rd. 10/09/25 1.6 J 5 1.0
665 E. Evans Reimer Rd MW-1 10/09/25 ND 5 1.0
665 E. Evans Reimer Rd MW-2 10/09/25 ND 5 1.0
665 E. Evans Reimer Rd MW-3 10/09/25 ND 5 1.0
718 E Evans Reimer Rd 10/16/25 3.9 J 5 1.0
1073 Gilstrap Ave 10/15/25 ND 5 1.0
867 Hwy 99 10/15/25 ND 5 1.0
783 Larkin Rd 6/26/18 ND 5 1.2
935 Larkin Rd 6/26/18 ND 5 1.2
2021 Larkin Rd 10/16/25 ND 5 1.0
537 Meyers Ave 10/15/25 ND 5 1.0
524 Meyers Ave 10/15/25 5.6 5 1.0
187 Turner Ave 10/15/25 93 5 1.0
Trip Blank 6/26/18 ND 5 1.2
Bold = exceeds MCL of 5 ppt
ND – Concentration is less than the laboratory method reporting limit.
J - Estimated concentration falls between the minimum detection limit and the method
reporting limit.
Elaine McSpadden - 4 - 17 February 2026
Butte County Environmental Health Division
NOTIFICATION
Central Valley Water Board staff (Staff) received the laboratory results report on
29 October 2025. On 30 October 2025, Central Valley Water Board staff phoned the
Assistant Clerk of the Butte County Board of Supervisors and the Director of the Butte
County Environmental Health Division notifying them that 1,2,3-TCP was detected in the
two domestic wells listed above.
Central Valley Water Board staff also phoned the two owners whose wells had
1,2,3-TCP concentrations greater than the MCL. On 22 January 2026, Staff issued
written notifications of results to the owners of all the sampled wells. To maintain
confidentiality, the notifications to domestic well owners were issued separately.
RECOMMENDATIONS
Central Valley Water Board staff recommend that the domestic wells where TCP was
detected above the MRL and the six domestic wells with J-flagged detections be
re-sampled to verify results. We further recommend expanding the investigation area to
better understand potential sources and extent of TCP in groundwater. Central Valley
Water Board staff will schedule a meeting with the Butte County Department of
Public Health, and Butte County Department of Environmental Health to identify
appropriate means to further collaborate on this investigation.
Please contact Bill Bergmann, Engineering Geologist, at (530) 224-4852, or
William.Bergmann@waterboards.ca.gov should you have any questions.
Clint E. Snyder, P.G.
Assistant Executive Officer
WB: cc
cc electronically:
Chris Flower, Central Valley Water Board, Rancho Cordova
Rebecca Tabor, Division of Drinking Water, Redding
Ali Rezvani, Valley District Section I, Division of Drinking Water, Redding
Melissa Kitts, Butte County Board of Supervisors, Oroville
Elaine McSpadden - 5 - 17 February 2026
Butte County Environmental Health Division
FIGURE 1. Vicinity of Manzanita Elementary School, Gridley, Butte County