THE COMMONWEALTH OF MASSACHUSETTS
WATER RESOURCES COMMISSION
100 C A M B R I D G E S T R E E T , B O S T O N MA 02114
REPORT OF THE FINDINGS, JUSTIFICATIONS AND DECISION
OF THE WATER RESOURCES COMMISSION
Town of Foxborough
Witch Pond Wells
2022 Amendment to the September 3, 2001
Interbasin Transfer Act Approval
Pursuant to M.G.L. Chapter 21 § 8C
DECISION
On November 10, 2022, by a unanimous roll call vote of the ten (10) voting members present at
a public meeting, the Water Resources Commission (WRC), as described in this document,
approved a limited number of Foxborough’s requests to reduce monitoring and also approved
additional Conditions to address concerns regarding existing impacts, potential new impacts
from increased pumping, and Foxborough’s compliance with Conditions outlined in past
Decisions of the WRC. This vote was taken after review of the facts provided by the applicant,
analysis of the associated data, and consideration of comments received concerning this
proposal.
BACKGROUND
On September 13, 2001, the WRC approved, with conditions, the Town of Foxborough’s request
for an Interbasin Transfer for two proposed wells adjacent to Witch Pond (the Pond or SG-1), in
the Ten Mile River basin. Wells 14 and 15 (the Wells) are shown on the site map below (Figure
1). The transfer was approved for a daily maximum of 1.44 million gallons per day (MGD) with
water level thresholds that trigger reduced or no pumping. The area where these Wells are
located is an Atlantic white cedar swamp (the Swamp), which provides habitat for the then-state-
listed spotted turtle and the rare Hessel’s hairstreak butterfly. The thresholds were designed to
protect the wetlands habitat and the nectar sources for the Hessel’s hairstreak butterfly. Since the
establishment of the thresholds, the area has been further identified as habitat for the blue-spotted
salamander which is a state-listed species of special concern.
The Interbasin Transfer Act (ITA) was triggered because the wastewater generated from these
Wells would be discharged to the Mansfield-Foxborough-Norton Regional Wastewater Facility
in the Town of Norton, in the Taunton River basin. The 2001 WRC Decision (the Decision) that
approved the transfer outlined conditions (the Conditions) including the requirement for a
monitoring program to verify the hydrologic conditions at Witch Pond, and the establishment of
threshold water table levels to control the impacts of pumping on nearby surface water resources.
The Decision also required that when the reduced-pumping thresholds are approached, pumping
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Figure 1. Site map
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will be reduced and that when the no-pumping thresholds are reached, pumping will cease until
the water table recovers. Hydrologic monitoring requirements included a one-year baseline
monitoring period prior to the use of the Wells and on-going monitoring for the operational life
of the Wells. In addition, a wetland vegetation monitoring plan was required to verify that
invasive species are not increasing and that the nectar sources utilized by the Hessel’s hairstreak
butterfly are not impacted by pumping. The Conditions also required one-time and on-going
water conservation activities.
During the initial approval process, the WRC recommended additional pump tests to quantify the
complex hydrogeologic relationships at the site, specifically, the hydrologic connection between
the Swamp and the underlying aquifer, but Foxborough did not complete such tests.
The first monitoring plan was approved in 2007 with baseline monitoring through 2009.
Foxborough constructed the Witch Pond water treatment facility (the WTF) with 1.44 MGD
capacity. MassDEP under the Water Management Act (WMA) approved each Well for an
annual average daily withdrawal of 0.48 MGD and the two Wells for a total of 0.96 MGD.
MassDEP’s Drinking Water Program (DWP) approved a maximum daily pump rate of 0.48
MGD each and 0.72 MGD total. These rates are summarized in Table 1 below.
Table 1. Summary of Flows for Wells 14 and 15
Total Flow
Description
(MGD)
ITA maximum daily 1.44
DEP WMA annual average daily at 0.48 MGD each, 0.96 MGD total 0.96
DEP DWP maximum daily at 0.48 MGD each, 0.72 MGD total 0.72
2015-2020 combined average annual daily at Wells 14 and 15 0.47
In 2013, the WRC approved an amendment to the Conditions outlined in the 2001 Decision. The
Amendment was initiated because of a hydraulic response to pumping occurring in the wetland
peat (0.6-foot decline since baseline) that could lead to permanent compaction if continued and a
shift in wetland plant species to plants which tolerate a drier regime. The Amendment required
Foxborough to alter its monitoring plan to provide reduced and no pumping thresholds at one
additional site (F-7PD, a deep peat monitoring location). However, on July 17, 2013, MassDEP
issued a formal Emergency Declaration allowing Foxborough to use the Witch Pond Wells even
if thresholds are triggered while treatment plants were completed elsewhere for alternative water
supply sources. Operations under an Emergency Declaration are specifically exempt from the
ITA and any conditions imposed as a result. However, the 2013 Amendment incorporated
language from the Emergency Declaration as follows for conditions when an Emergency
Declaration is in place and Witch Pond wells are still proposed to be used.
Foxborough must:
• Exhaust options to purchase water from other surrounding communities via the existing
emergency connections;
• Maximize pumpage from Foxborough’s other sources which are currently in operation;
• Impose tighter restrictions on outdoor water use, up to a total ban on any outdoor water
use. A total outdoor water ban will be implemented when Witch Pond wells are used and
the thresholds are exceeded.
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This introduced an important new requirement of a total outdoor water ban when Witch Pond
wells are used under an Emergency Declaration and thresholds are surpassed. Although this was
not followed during the 2013-2014 Emergency Declaration, it was followed during the
subsequent 2016 and 2020 Emergency Declarations.
The Emergency Declaration in 2013 was extended to March 17, 2014 to allow for the completion
and startup of the Oak Street water treatment plant. The allowed pumping resulted in extensive
periods spent below the thresholds established to protect the ecosystem.
In February 2016, the WRC approved Foxborough’s September 2015 request to eliminate
monitoring and groundwater thresholds for site F-4A. The purpose of site F-4A was to monitor
conditions in a replicated wetland that was intended to replace the Swamp area lost due to
construction of the WTF. However, it was demonstrated that the replicated wetland was not
functioning as an Atlantic white cedar swamp. Foxborough was required to update its monitoring
plan to reflect the additional 2013 threshold requirements, the elimination of the monitoring site
in the replicated wetland, and the previous monitoring requirements that remained in effect. The
2016 monitoring plan is the latest and is in effect.
In July 2020, Foxborough submitted a 48-hour pump test report as part of a permit application to
MassDEP to replace Well 14. The replacement well, Well 14R, has the same well construction
(e.g., total depth of 40 feet, screened at the bottom 10 feet) and accesses the same
hydrostratigraphic unit as Well 14. Therefore, Well 14R should draw from the same location in
the aquifer. According to the pump test report, the pumping rate was selected to evaluate whether
Well 14R can replace the combined capacity of Well 14 and 15. The pump test showed that Well
14R can replace both Wells 14 and 15 with a proposed approvable yield of 1.56 MGD. On
January 7, 2021, MassDEP DWP approved Well 14R for a maximum daily withdrawal of 0.48
MGD because the rate of a replacement well cannot exceed that of the well being replaced. On
March 12, 2021, MassDEP approved the decommissioning of Well 14. The maximum daily
withdrawal for Wells 14R and 15 remains at 0.72 MGD. To increase pumping at Well 14R
beyond the limits specified in Table 1, Foxborough would need to apply for a New Source
Approval from the DWP and an amendment for its WMA permit and likely for its ITA Decision
based on a change in conditions. MassDEP WMA Program also expects to reduce the annual
average daily allocation volume during either the amendment process or as part of the permit
renewal in the Ten Mile basin. The reduction is to reflect the fact that the annual allocation
volume should not reflect the maximum daily approval rate for the well.
According to Foxborough, the practical limit from Well 14 and 15 for annual average daily yield
has been approximately 0.49 MGD due to reduced yields at both Wells. This is approximately
half the permitted volume and is reflected in the 6-year annual average daily pumping rate of
0.47 MGD (Table 2). With Well 14R, Foxborough can double its recent historical withdrawals
from Well 14 from a recent average annual daily pumping rate of 0.24 MGD to 0.48 MGD. The
new potential total withdrawals from the two Wells may increase from 0.47 MGD to 0.72 MGD
(Well 15 at 0.23 MGD plus Well 14R at 0.48 MGD). Therefore, the total average annual
pumping at Witch Pond may increase by 51%.
Historically, Foxborough’s reduced and no pumping thresholds have been triggered multiple
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Table 2. Pumping from 2015 through 2020
Annual Average Daily Maximum Day
Year Withdrawal (MGD) (MGD)*
Well Well Well Well
Total
14 15 14 15
2015 0.18 0.20 0.38 0.43 0.48
2016 0.27 0.21 0.48 0.47 0.44
2017 0.31 0.31 0.63 0.43 0.50
2018 0.20 0.30 0.49 0.27 0.42
2019 0.25 0.17 0.42 0.38 0.34
2020 0.23 0.18 0.41 0.33 0.27
Average 0.24 0.23 0.47
Maximum 0.31 0.31 * 0.47 0.50
* Since maximum pumping days rarely occur on the same day, total
maximum day is not calculated. Total values may not be the exact sum
of individual values due to rounding.
times. The triggers that occurred from January 2011 through December 2020 are summarized in
Table 3 by site and are highlighted in gray. The triggered thresholds include periods of
Emergency Declarations. Foxborough requested and MassDEP granted Emergency Declarations
three times out of the past eight years - 2013 with an extension to 2014, 2016 ending in early
2017 1 and 2020. During an Emergency Declaration, Foxborough may continue to pump even if
the ITA thresholds are triggered. Triggers during Emergency Declarations are summarized in
Table 4.
During the concurrent events of the 2016 drought and 2016 Emergency Declaration, thresholds
were triggered 64% of the time during the 5-month period of August through December. Water
levels dropped 1.26 feet below the peat surface whereas triggers were set to keep water within 1
foot of the wetland hollow surface as recommended by experts on Atlantic white cedar swamps.
Of this period, August, September and October are the natural dry periods which were
exacerbated by the drought and by continued pumping beyond the protective thresholds. Such
extended dry conditions favor invasive species and can affect native species’ and the Swamp
ecosystem’s health.
A similar situation occurred during the 2020 drought with an Emergency Declaration that
coincided with the drought. This time water levels reached historical lows and water levels
dropped 2 feet below the peat surface. The dry conditions lasted 6 months from June through
November with water levels below the no pumping thresholds 57% of the time. Due to the
Emergency Declaration, the wells were not shut off until September 29th when the new treatment
facility on Chestnut Street was activated. Water levels at some sites took over 2 months to
recover above the thresholds and the Pond took over a year until October 2021 to recover to
above its no pumping threshold. Despite the heavy rains in July 2021, the expected recovery of
1
On January 5, 2017, Foxborough requested to end the 2016 Emergency Declaration. For the rest of the document,
2017 is not considered as a year with an Emergency Declaration.
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Table 3. Summary of Triggered Thresholds from January 2011 through December 2020
Hours spent* below reduced or no pumping threshold,
Threshold January 2011 through December 2020
Sites
Total Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
F1AS 0 0 0 0 0 0 0 0 0 0 0 0 0
F1APD 690 0 0 0 0 0 0 18 0 576 96 0 0
F1AD 0 0 0 0 0 0 0 0 0 0 0 0 0
F2S 2,484 0 0 0 0 0 0 0 324 1,440 720 0 0
F2AD 0 0 0 0 0 0 0 0 0 0 0 0 0
F7D 72 0 0 0 0 0 0 0 0 0 66 0 6
SG1 8,448 0 0 0 0 0 186 96 1,950 3,102 2,238 876 0
F7PD 4,026 0 0 0 0 0 0 0 456 2,052 1,146 372 0
Table 4. Triggered Thresholds During Years of Emergency Declarations
Hours spent* below either reduced or no pumping threshold
Year Comments
Total F1AS F1APD F1AD F2S F2AD F7D SG1 F7PD
Declaration 7/17/13-3/17/14 until new treatment
2013/
600 0 0 0 0 0 0 600 0 plant completed for alternative water supply
2014 sources. Triggers in October & November 2013.
Declaration 9/20/16-1/5/17. June was start of the
2016 2,274 0 90 0 1,422 0 72 2,022 2,268 2016 Drought. Triggers August through December.
Declaration 7/2/20 to 10/8/20. June was start of the
2020 2,496 0 552 0 948 0 0 2,496 846 2020 Drought. Triggers June through November.
*Tables are in hours because levels are measured every 6 hours. Therefore, 24 hours spent below a threshold is not necessarily on a
single calendar day as the measurements could have been collected on multiple days.
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water levels did not occur for multiple months indicating that the peat may have been
permanently compacted. This impact was part of the concern in 2010 and 2011 that resulted in
the 2013 Amendment. Future monitoring and surveys will show whether this has occurred.
Since the 2013 Amendment, four years – 2015, 2017, 2018 and 2019 – did not have Emergency
Declarations and in two of those years reduced pumping and no pumping thresholds for the
Swamp were triggered for significant periods of time. In 2015, thresholds were triggered on
roughly half of the days in a 3-month period. In 2019, thresholds were triggered on 65% of the
days in a 4-month period as shown in Table 5. This may indicate that the thresholds are not
protective enough because once they are triggered, they remain triggered for an extended period.
It may be that thresholds are triggered during the naturally dry period and, therefore, take a long
time to recover. More protective measures may be needed to initiate earlier reduced pumping
year-round or at least during the naturally dry period. For example, reduced pumping thresholds
may need to be set at higher elevations so that they trigger earlier, prevent the no pumping
threshold from being reached, and ensure that the levels can recover more readily. In addition,
the term reduced pumping may need to be defined at a lower withdrawal rate than in the 2007
monitoring plan.
Table 5. Time Spent Beyond Thresholds
Percent of time spent
Count of months
beyond thresholds
Year with triggers at Other relevant conditions
during months with
one or more sites
triggers
2013