| Blackstone River TMDL Water Quality |
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Project Title: |
Quantification and Analysis of In-Stream Nutrient and Trace Element
Transport in the Massachusetts Segment of the Blackstone River
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Start Date: |
2006 |
End Date: |
2009 |
Location: |
Blackstone River |
Funding Source: |
Massachusetts Department of Environmental Protection and USGS Cooperative Water Program |
Contact: |
Robert Breault |
Team: |
Robert Breault, Marcus Waldron, Kirk Smith, Gerry Girouard, Kimberly Campo, Andrew Waite |
Problem |
Excessive nutrient and trace metal levels have been identified
as the causes of poor water quality in the Blackstone River and
Narragansett Bay (Wright and others, 2001). Reductions are
needed in both point- and non-point-source loadings to reduce
the amounts of nutrients and trace metals released to the river
and estuary. This is part of a comprehensive multi-state
(Massachusetts and Rhode Island) effort to achieve
contaminant-load reductions to restore water quality in both
the Blackstone River and Narragansett Bay.
Nitrogen loading from point- and non-point-sources, including
stormwater, treated wastewater, bottom sediment, and
combined sewage from numerous POTWs and combined sewer
overflows (CSOs) is of particular concern in the Blackstone
River Drainage Area. For example, excessive nitrogen levels
have been identified as the trigger for algal blooms and
dissolved oxygen deficits observed in Narragansett Bay.
In-stream losses of nitrogen (nitrogen attenuation) may reduce
the impact of (far) upstream sources relative to downstream
sources. However, the location and extent of nitrogen
attenuation along the river are unknown. Precise
measurements of nitrogen attenuation are needed to partition
permissible nitrogen loadings among sources and develop
strategies for nitrogen removal in the MA section of the river.
Available nitrogen models (for example, SPARROW) use
nitrogen attenuation rates which may not be applicable to the
Blackstone River, because such rates vary dramati Problem
cally among rivers and streams. Therefore, field measurements to assess
site-specific rates for the Blackstone River are needed.
Scouring of riverbanks and bottom-sediment deposits may be
substantial non-point sources of nutrients and trace elements
to the river. Flow fluctuations due to precipitation, runoff, and
hydropower operations may increase bank scouring and
resuspension of bottom sediment. Resuspended material with
associated contamination moves into the water column and is
transported and redeposited downstream. Currently, there is no
quantitative information on the amounts of contaminated
sediment moving through the system or the hydrologic factors
that determine whether a given impoundment acts as a source,
sink, or both for contaminated sediment.
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Objectives |
| Measure bi-weekly, monthly, seasonal, and annual loads of
nutrients and trace metals contributed to the RI portion of the
Blackstone River Basin by the MA portion;
Assess the potential for resuspension and transport of
previously deposited, nutrient- and metal-enriched bottom
sediment; and, determine the potential for nitrogen attenuation by means
of mass balance in the Massachusetts portion of the river
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Approach |
Objective 1:
Nutrient and trace-metal loading from the MA segment of the
Blackstone River to the RI segment will be measured for one
year (May 2007 –May 2008). Loads during low (base) and high
(storm and controlled releases) flows will be measured
separately during this period. Water-quality samples for
chemical analysis will be collected using a newly developed
automated sampling device.
Conditions exist that preclude situating the USGS
streamflow-monitoring station exactly at the MA-RI State Line.
Consequently, parts of the Massachusetts portion of the
mainstem will not be gaged or sampled. Existing nitrogen
models will be evaluated for nutrient loading from these areas.
Objective 2:
The resuspension and transport of previously deposited,
nutrient- and metal-enriched bottom sediment from two MA
impoundments, Rice City Pond and Rockdale Pond will be
assessed by continuously measuring stage, turbidity, or
Chlorophyll.
Instantaneous measurements of streamflow, turbidity,
Chlorophyll, and element and suspended-sediment
concentrations will also be made. Equations that relate
element and suspended-sediment concentrations to turbidity
will be developed and used to estimate continuous loads from
continuous turbidity and stage measurements. Next, a
mass-balance approach will be used to determine whether or
not contaminated bottom sediment are resuspended and
transported at a range of flow conditions.
Objective 3:
The mass of nitrogen discharged to the Blackstone River by the
Upper Blackstone Water Pollution Abatement District
(UBWPAD) that is attenuated within the Massachusetts portion
of the river will be estimated by means of a mass balance
approach. Nitrogen loads will be measured during base flow
and storms separately at streamflow and water-quality
monitoring stations located throughout the MA portion of the
Blackstone River. Streamflow will be measured continuously for
eight months (May—December, 2007). Water samples for
chemical analysis will be collected over a 14-day period during
each month using an automated sampling device.
Other nitrogen sources to the Blackstone River include POTW’s,
tributaries, and non-point sources. Nitrogen concentration data
for POTW discharges will be obtained from direct
measurement. For the wastewater treatment plants at Millbury
(UBWPAD), Grafton, Northbridge, and Uxbridge; daily samples
of wastewater effluent collected by the treatment plant
operators will be composited into a bi-monthly (14 day)
samples that will be analyzed for nutrients and
suspended-sediment concentration. Discharge will be obtained
from treatment plant operators. Other loads must be estimated
using existing water-quality models.
Calculations of in-stream nitrogen mass flux entering and
exiting each reach will indicate when and where nitrogen
removal processes are significant.
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References |
Linsley, R.K., Kohler, M.A. and Paulus, J.L.H. Hydrology for
Engineers (3rd ed.), McGraw-Hill, New. York, 1982 508pp.
Wilde, F.D., Radtke, D.B., Gibs, Jacob, and Iwatsubo, R.T., 1999,
Collection of Water Samples, in National field manual for the
collection of water-quality data: U.S. Geological Survey
Techniques of Water-Resources Investigations, book 9, chap.
A4.
Wright, R.M., Nolan, P.M., Pincumbe, D., Hartman, E., and
Viator, O.J., 2001, Blackstone River Initiative: water quality
analysis of the Blackstone River under wet and dry weather
conditions: University of Rhode Island, Kingston, RI., variously
paged.
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U.S. Department of the Interior |
U.S. Geological Survey