HomeMy WebLinkAbout2016.06.21_Madaket Harbor WQWATER QUALITY
SUMMARY
2010 THROUGH 2015
MADAKETHARBOR
WATERSHED
Is This Polluting the Water?
The landfill is located adjacent to Long Pond, with groundwa-
ter flowing towards the Pond. The MEP states that 24% of
the nutrient pollution in the Watershed is coming from this
location. In 2015, tests showed lower Total Nitrogen levels
at Station 6, with variable results from one year to another at
Station 5 on Long Pond (see map on reverse). Other testing
showed lower values as well, but none were low enough to
meet water quality standards set in the TMDL.
What is happening at the landfill that could account for this?
The landfill is currently being reduced by mining-removing
any valuable fill dirt left behind after all of the organic pro-
cesses have completed their natural cycle. The leftover
plastic, metal, etc. is being reprocessed and reclaimed. The
landfill will be reduced to about 15 acres and will be con-
tained in new lined cells constructed to todays standards-no
leaching.We will continue with the mining operation and
continue to monitor this area closely to determine the impact
the mining may or may not have on the water quality in this
area.
WHAT ABOUT THE LANDFILL?
Board of Selectmen
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Department of Public Works
Board of Health
Natural Resources Department
Planning and Land Use
“Long Pond’s Bay Health scores for both stations (5 & 6) in the
4 years of monitoring (2010, 2012, 2013, 2014) clearly indicate
poor nutrient related water quality. Town’s management of the
Landfill, which should reduce the nitrogen load from this source
is temporally consistent with improvements in the water quality
Index for Long Pond and the lower TN levels. While continued
monitoring will determine the level of improvement, it does
appear that a reduction in N loading may be occurring with
beneficial effects. “
Water Quality Monitoring and Assessment of theNantucket Island-Wide Estuaries and Salt PondsUpdate 2015
Visit us on the Web!
http://www.nantucket-ma.gov/719/Sewer
COMMENT / QUESTION CORNER
Comments and/or questions for the
Wastewater Plan Update can be sent to:
Sewerproject@nantucket-ma.gov
Answers and/or comments will appear in future communications and/oraddressed at Board of Selectmen meetings.
16 Broad Street
TOWN OF NANTUCKET
Phone: 508-228-7255
Fax: 508-228-7272
NOTE: All figures are from the MEP Reports and subsequent Technical Memos.
Watershed Land Use
The Madaket Harbor and Long Pond Estuarine System
Report, November 2010 (MEP),identified the largest Water-
shed land use as open space and roads taking up 55 per-
cent. The second largest use is residential, of which all use
on-site wastewater systems that leach nutrients into the
ground. The MEP study determined that the largest contrib-
utor of nitrogen pollution is 58 percent from wastewater.
Other locally controllable nutrient contributors are the landfill
at 24%, storm water at 10% and fertilizer at 8%.
The MEP completed analyses to determine how the Town
could reduce the nutrient loading. These “scenarios” of
what if we did this or what if we did that, looked at potential
solutions to reduce the nutrient pollution to meet water
quality standards set by the Clean Water Act. What if the
Town removed the landfill totally from the Watershed, would
that reduce the nutrient pollution enough to meet water
quality standards? The scenario results showed no, not by
itself, so we needed additional reductions. What if we elimi-
nated all on-site wastewater? Yes, that meets the water
quality standards. This makes sense as wastewater is the
largest polluter that, we, as a Town, can control. Would
Innovative/Alternative (I/A) Septic Systems meet the water
quality standard? The answer is no, as these systems
typically remove about 50% of the nitrogen and we need to
remove 100% to meet the TMDL.
Besides the nitrogen pollution, the Madaket/Warrens Land-
ing Needs Areas were shown in the CWMP to not be long-
term sustainable with septic systems due to the severity of
the soils (fast percing) and high groundwater-all pose not
only technical issues with meeting state and local regula-
tions, but public health as well. The Board of Health moni-
tors these.
Madaket Harbor Watershed
The Madaket Harbor Watershed consists of six sub-watersheds
as shown in the figure above from the The Madaket Harbor and
Long Pond Estuarine System Report, November 2010 (MEP).
Madaket Harbor is one of the largest enclosed bays in southeast-
ern Massachusetts, with the major basin supporting relatively high
water quality capable of supporting high quality ecological habi-
tats, such as eelgrass beds. The sub-watersheds of Nos. 1-4 in
the above figure, however, are not supporting good water quality
based on the ongoing Annual Water Quality Sampling Program
the Town manages through the Natural Resources Department.
The main reason for this is that the larger, open Madaket Harbor
(including sub-watersheds 0, 5 & 6) are open to the ocean and
receive a continual flushing of fresh water with the tides. The
other sub-watersheds are more closed and do not receive the
clean, fresh waters from the ocean. Long Pond is a brackish
water (salty with fresh water) that due to its brackish category,
does not get breached to the open ocean as is done to improve
the water quality in Hummock Pond and Sesachacha Pond. The
MEP detailed the nitrogen polluters that the Town is capable of
controlling, while also evaluating ways in which the Town can
reduce the pollution to meet federal and state water quality stand-
ards set in the Clean Water Act. The Environmental Protection
Agency (EPA), in coordination with the Massachusetts Depart-
ment of Environmental Protection (MassDEP), issued mandates,
Total Maximum Daily Loads (TMDL) to ensure Nantucket acts to
reduce the nutrient pollution to the waters.
Sampling History
Madaket Harbor Watershed is sampled in the outer Harbor,
Hither Creek and Long Pond as shown in the figure below.
The water quality standard per the TMDL is set at Station 1 in
the middle of Hither Creek.
The sampling typically takes place from May through Octo-
ber, with multiple samples taken at each location through the
period. Tests are done to determine salinity, Total Nitrogen,
ammonium, orthophosphate and chlorophyll-a and pheophyt-
in-a (how much oxygen is in the water to support aquatic life).
These tell us if the water is salt or fresh or a combination
(brackish as in Long Pond), how much light is able to pene-
trate the water, how clear the water is, how nutrient enriched
the water is and where it is impacted.
Samples are collected by the Natural Resources Department
(NRD) and all work is coordinated with and processed by the
University of Massachusetts School of Marine Science and
Technology (SMAST). SMAST has worked analyzing water
quality in Nantucket from 2010-present, with the exception of
2012 when the Town used another entity. SMAST historical-
ly coordinated data with the Town’s Marine Department be-
fore the NRD, which had many years of sampling to evaluate.
The sampling information in this brochure has been decades
in the making. For those who would like more detailed infor-
mation,The Madaket Harbor and Long Pond Estuarine Sys-
tem Report, November 2010 (MEP) can be accessed in its
entirety on the NRD website at:
http://www.nantucket-ma.gov/132/Water-Quality-Initiative
Wastewater is the largest polluter of nitrogen in the Watershed