NRWPP Appendix (PDF)

APPENDIX A 
 
Acronyms and Abbreviations 
 

 
APPENDIX A 
 
Acronyms and Abbreviations 
 
 
 
‰ – parts per thousand 
ACOE – US Army Corps of Engineers 
AqP – Aquifer & Primary Recharge Protection Zone 
AqS – Secondary Recharge Protection Zone 
BMP – Best Management Practice 
BOD – Biological Oxygen Demand 
BWPLR – Bureau of Water Protection and Land Reuse 
CAD – Computer-aided Design 
CALM – Connecticut Consolidated Assessment and Listing Methodology 
CAM – Coastal Boundary Overlay District 
CHN – Percent Carbon and Nitrogen 
CLEAR – Center for Land Use Education and Research 
CN – Curve Number 
CNP – Coastal Nonpoint Source Pollution Control Program 
ConnDOT – Connecticut Department of Transportation 
CPI – Conservation Priority Index 
CPUE – Catch per unit effort 
CTDEP – Connecticut Department of Environmental Protection 
CTDOAG – Connecticut Department of Agriculture 
CWP – Center for Watershed Protection 
CZARA – Coastal Zone Act Reauthorization Amendments 
CT DA/BA – Connecticut Department of Agriculture, Bureau of Agriculture 
DEIS – Draft Environmental Impact Statement 
DEM – Digital Elevation Model 
DNC – Dominion Nuclear Connecticut 
DOM – Dissolved Organic Matter 
DPW – Department of Public Works 
CTDPUC – Connecticut Department of Public Utility Control 
 
A - 1 

 
E&S – Erosion and Sediment Control 
EFC – Environmental Finance Center 
EMC – Event Mean Concentration 
ERT – Environmental Review Team 
ESRI – Environmental Systems Research Institute 
FEMA – Federal Emergency Management Agency 
FTE – Full Time Employee 
GIS – Geographic Information System 
HSG – Hydrologic Soil Groups 
I/E – Information and Education 
IS – Impervious Surface 
ISSC – Interstate Shellfish Sanitation Conference 
LEDPA – Least Environmentally Damaging Preferred Alternative 
MEL – Millstone Environmental Laboratory 
MGD – Million gallons per day 
MPO – Metropolitan Planning Organization 
MS4 – Municipal Separate Storm Sewer System 
MSD – Marine Sanitation Device 
NAS – National Academy of Sciences 
NDA – No Discharge Area 
NDZ – No Discharge Zone 
NEMO (UCONN) – Nonpoint Education for Municipal Officials 
NFWF – National Fish and Wildlife Foundation 
NH4
+ – Ammonium 
NHD – National Hydrography Database 
NO2 – Nitrite 
NO3 – Nitrate 
NOAA – National Oceanographic and Atmospheric Association 
NPDES – National Pollutant Discharge Elimination System 
NPS – Nonpoint Source 
NSSP – National Shellfishing Sanitation Program 
NSSP-MO – National Shellfish Sanitation Program Model Ordinance 
 
A - 2 

 
OCRM – NOAA’s Office of Ocean and Coastal Resource Management 
OLISP – Office of Long Island Sound Programs 
PAR – Photosynthetically active radiation 
PO4
- – Phosphates 
POCD – Plan of Conservation and Development 
PRD – Planned Residential Development 
RBV – Rivers by Volunteers 
RPI – Restoration Priority Index 
SAFTEA-LU – The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy 
for Users 
SAV – Submerged Aquatic Vegetation 
SCCOG – Southeastern Connecticut Council of Governments 
SDD – Special Development District 
SE – Standard Error 
SMPI – Stormwater Management Priority Index 
SNET – Southern New England Telephone 
SSURGO – Soil Survey Geographic Database 
STICS – Spatial Trends in Coastal Socioeconomics 
SWMM – Stormwater Management Model 
SWMPP – Stormwater Management Program Plan 
TKN – Total Kjeldhal Nitrogen 
TM – Tidal Marsh 
TMDL – Total Maximum Daily Load 
TN – Total Nitrogen 
TP – Total Phosphorous 
TPL – Trust for Public Land 
TSS – Total Suspended Solids 
UCONN – University of Connecticut 
UID – Unidentified 
USDA NRCS – US Department of Agriculture, Natural Resources Conservation Service 
USDOT – US Department of Transportation 
USEPA – US Environmental Protection Agency 
 
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USFWS – US Fish and Wildlife Service 
USGS – United States Geological Survey 
WELSCO – Waterford-East Lyme Shellfish Commission 
WQ – Water Quality 
WQS – Water Quality Standards 
WVA – Watershed Vulnerability Assessment 
YOY – Young of the year 
 
 
A - 4 

 
APPENDIX B 
 
Terms and Definitions 
 

 
APPENDIX B 
 
Terms and Definitions 
 
 
 
Antidegradation policy – A policy or legal principal stating that activities degrading a 
waterbody’s quality will not be allowed.  
 
Aquatic Life Support – The waterbody provides suitable habitat for protection and 
propagation of desirable fish, shellfish,and other aquatic organisms. 
 
Designated uses – See ‘Use Classification” 
 
Indicator bacteria – Some waterborne bacteria, viruses and protozoa can cause human 
illnesses, ranging from typhoid and dysentery to minor skin diseases.  These pathogens may 
enter waters through a number of routes, including inadequately treated sewage, storm water 
drains, septic systems, runoff from livestock pens and sewage dumped overboard from 
recreational boats.  Because it is impossible to test waters for every possible disease causing 
organism, regulatory agencies usually measure fecal coliforms (like Escherichia coli or “e. coli”) 
as indicator bacteria (which are found in great numbers in the stomachs of warm blooded 
animals).  The presence of indicator bacteria suggests that the waterbody may be contaminated 
with untreated sewage and that other, more dangerous organisms may also be present.  Bacterial 
criteria are frequently used to determine if waters are safe for contact recreation or shellfish 
harvesting. 
 
National Shellfish Sanitation Program (NSSP) – The NSSP requires annual 
assessments of shellfish growing areas to ensure that the growing areas are properly classified.  
These ‘Shellfishing Area Classifications’ are different from the water quality classifications 
mentioned above and are designated specifically for shellfish growing areas.  More information 
is available from the Guide for the Control of Molluscan Shellfish 2003.  U. S. Department of 
Health and Human Services Public Health Service, Food and Drug Administration, Center for 
Food Safety and Nutrition, Washington D.C. (http://www.cfsan.fda.gov/~ear/nss2-toc.html).  
 
 
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Primary Contact Recreation (Swimming) – People can swim in the waterbody without 
risk of adverse human health effects (such as catching waterborne diseases from raw sewage 
contamination). 
 
Shellfish Grow Area Classifications – A shellfish growing area is any area which 
supports, or could support, the growth and/or propagation of molluscan shellstock (live clams, 
oysters, mussels and scallops in their shell).  All shellfish growing areas are classified in 
accordance with the Interstate Shellfish Sanitation Conference (ISSC) National Shellfish 
Sanitation Program Model Ordinance (NSSP-MO).  These classifications established to 
minimize health risks and may restrict the taking and use of shellfish from some areas.  No fresh 
water areas have been classified for the harvesting of shellfish (CT DOAG). 
 
Shellfishing / Shellfish Harvesting – The waterbody supports a population of shellfish 
free from toxicants and pathogens that could pose a human health risk to consumers.  
 
Tier – Waters are assigned to one of five tiers for the 303(d) List.  Tier 2 signifies that it 
has been determined that the impairment is caused by a pollutant stressor (e.g., chemical, clean 
sediment and/or temperature), a surrogate indicator (e.g., indicator bacteria) or can be attributed 
to a source that contributes multiple pollutants to a waterbody such that implementing a TMDL 
for one or more pollutants can be reasonably expected to result in attainment of uses.  Where 
more than one pollutant is associated with the impairment, the waterbody or waterbody segment 
will remain in this category until TMDLs for all pollutants have been completed and approved 
by USEPA.  Further investigative monitoring, if necessary, will be scheduled to confirm causes.  
Follow-up monitoring will be scheduled to determine if the standard is attained following TMDL 
implementation.  Tier 3 – The waterbody or waterbody segment does not support a use based on 
biological, or other information, and the cause is unknown.  It is uncertain whether the 
impairment is caused by a pollutant.  Additional monitoring will be scheduled to identify the 
cause of the impairment.  If the additional monitoring determines the cause of the impairment to 
be a pollutant(s), CTDEP will complete a TMDL(s) for the pollutant(s).  If the additional 
monitoring determines the impairment is not caused by a pollutant, the waterbody or waterbody 
segment will be moved to Tier 5. 
 
 
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TMDL (Total Maximum Daily Load) – “A TMDL is a watershed plan that focuses 
resources on reducing loads of known pollutants.  TMDLs provide the framework to restore 
impaired waters by establishing the maximum amount of a pollutant that a waterbody can 
assimilate without adverse impact to aquatic life, recreation, or other public uses.  The TMDL is 
then divided up between all potential sources of that pollutant.  TMDLs are often expressed by 
the mathematical equation: 
 
TMDL = Point Sources + Nonpoint Sources + Background + Margin of Safety. 
 
The end result of the TMDL process is a Water Quality management Plan with 
quantitative goals to reduce pollutant loadings to the impaired waterbody.  TMDLs are 
implemented under the existing authorities of CT DEP and may include both regulatory and 
voluntary actions as part of a larger Water Quality Management Plan.” CTDEP, 2004b 
 
Use classification – Classifications are assigned to surface and groundwater in all areas 
of the state.  These assignments are based on both the use, or potential use, of such waters as well 
as on their known., or presumed, quality.  Generally, the classification describes the actual 
activities that the waterbody is expected to support (e.g. swimming, fishing, habitat for fish and 
wildlife).  The individual water quality classifications are described in more detail at CTDEP’s 
website: http://dep.state.ct.us/wtr/wq/wqsinfo.htm. 
 
Use Support Category – “In making water quality assessments, each designated use of a 
waterbody or waterbody segment is assigned a level of support (e.g., full support, partial 
support), which characterizes the degree to which the water is suitable for that use.” CTDEP, 
2004c. 
 
Water Quality Impairments – Describes the state of pollution of a waterbody with 
relation to the negative impacts it has on the use of that waterbody.  
 
Water quality standards (WQS) – Standards that set an “overall policy” for 
management of Connecticut's surface and groundwaters in accordance with the directives 
provided by Section 22a-426 of the Connecticut General Statutes and Section 303 of the Federal 
 
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Clean Water Act.  These standards are made up of three components: designated uses, water 
quality or pollution criteria/thresholds, and a policy of antidegradation.  
 
Water quality or pollution criteria – Criteria or limits on the levels of biological, 
chemical and physical characteristics of water. 
 
 
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APPENDIX C 
 
SA Criteria from Connecticut Water Quality Standards 
 

 
 
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APPENDIX C 
SA Criteria from Connecticut Water Quality Standards 
 
CLASS SA CRITERIA 
Parameter 
 
Criteria 
Aesthetics 
 
Uniformly excellent. 
 
Dissolved oxygen  
Not less than 6.0 mg/L at any time in the nearshore water of Long 
Island Sound, including harbors, embayments and estuarine tributaries. 
 
Not less than 6.0 mg/L at any time in the offshore waters of Long 
Island Sound, above the seasonal pycnocline and throughout the Sound when no 
pycnocline is established. 
 
Not less than 3.5 mg/L for offshore waters within and below the 
seasonal pycnocline. Cumulative periods of dissolved oxygen in the 3.5 
– 4.8 mg/L range shall not exceed exposure parameters. 
 
Sludge deposits solid  
None other than of natural origin. 
refuse-floating 
solids-oils and 
grease-scum 
 
Color 
 
 
None other than of natural origin. 
 
Suspended 
 
None other than of natural origin. 
and settleable solids 
 
Silt or sand deposits 
None other than of natural origin except as may result from normal 
agricultural, road maintenance, construction activity, dredging activity 
or the discharge of dredged or fill materials provided all reasonable 
controls or Best Management Practices are used in such activities and 
all designated uses are protected and maintained. 
 
Turbidity  
 
None other than of natural origin except as may result from normal 
agricultural, road maintenance, or construction activity, dredging 
activity or discharge of dredged or fill materials provided all 
reasonable controls and Best Management Practices are used to control 
turbidity and none exceeding levels necessary to protect and maintain 
all designated uses. 
 
Indicator bacteria  
NEXT PAGE 
 
Taste and odor   
As naturally occurs. 
 
pH  
 
 
6.8 – 8.5 
 
Allowable 
 
There shall be no changes from natural conditions that would impair 
temperature increase 
any existing or designated uses assigned to this Class and, in no case 
exceed 83 degrees F, or in any case raise the temperature of the 
receiving water more than 4 degrees F. During the period including 
July, August, and September, the temperature of the receiving water 
shall not be raised more that 1.5 degrees F unless it can be shown that 
spawning and growth of indigenous organisms will not be significantly 
affected. 
 
Chemical  
 
None in concentrations or combinations which would be harmful to 
constituents 
 
designated uses. Refer to Standards numbers 10, 11, 12,13, 17, and 19. 

 
WATER QUALITY CRITERIA FOR BACTERIAL INDICATORS OF SANITARY QUALITY 
SEE ALSO STANDARDS # 23 AND 25 
DESIGNATED USE 
 
 
CLASS  
INDICATOR 
 
CRITERIA 
Freshwater 
Drinking Water Supply (1) 
Existing / Proposed  
 
 
AA  
 
Total coliform  
 
Monthly Moving Average less than 100/100ml 
Single Sample Maximum 500/100ml 
Potential  
 
 
 
A 
 
 ----  
 
 
-------- 
Recreation (2)(3) 
Designated Swimming (4)  
 
AA, A, B  
Escherichia coli   
Geometric Mean less than 126/100ml 
Single Sample Maximum 235/100ml 
Non-designated Swimming (5)  
 
AA, A, B  
Escherichia coli   
Geometric Mean less than 126/100ml 
Single Sample Maximum 410/100ml 
All Other Recreational Uses  
 
AA, A, B  
Escherichia coli   
Geometric Mean less than 126/100ml 
Single Sample Maximum 576/100ml 
Saltwater 
Shellfishing 
Direct Consumption  
 
 
SA  
 
Fecal coliform  
 
Geometric Mean less than 14/100ml 
90% of Samples less than 43/100ml 
Commercial Harvesting   
 
SB  
 
Fecal coliform  
 
Geometric Mean less than 88/100ml 
90% of Samples less than 260/100ml 
Recreation 
Designated Swimming (4)  
 
SA, SB   
Enterococci  
 
Geometric Mean less than 35/100ml 
Single Sample Maximum 104/100ml 
All Other Recreational Uses  
 
SA, SB   
Enterococci  
 
Geometric Mean less than 35/100ml 
Single Sample Maximum 500/100ml 
Table Notes:  
(1) Criteria applies only at the drinking water supply intake structure. 
 
(2) Criteria for the protection of recreational uses in Class B waters do not apply when disinfection of sewage treatment plant effluents is not 
 
 
required consistent with Standard 23. 
(3) See Standard # 25. 
(4) Procedures for monitoring and closure of bathing areas by State and Local Health Authorities are specified in: Guidelines for Monitoring 
Bathing Waters and Closure Protocol, adopted jointly by the Department of Environmental Protection and the Department of Public Health, May 1989, 
revised June 1992. 
(5) Includes areas otherwise suitable for swimming but which have not been designated by State or Local authorities as bathing areas, waters 
which support tubing, water skiing, or other recreational activities where full body contact is likely. 
Guidelines for Use of Indicator Bacteria Criteria 
Water Quality Classifications are reviewed approximately every three years at which time all available water quality monitoring data is considered along with other relevant 
information. Relevant information includes but is not limited to federal guidance concerning the scientific basis for deriving the criteria and the potential health risks associated 
with excursions above the criteria, recommended implementation procedures, and the results of sanitary surveys or other investigations into sources of indicator bacteria in the 
watershed. Public input is also solicited and considered in determining the existing water quality conditions and water quality goals. Nevertheless, the Water Quality 
Classification may not be an accurate representation of current water quality conditions at any particular site. For this reason, the Water Quality Classification should not be 
considered as a certification of quality by the State or an approval to engage in certain activities such as swimming or shellfish harvest 
 
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APPENDIX D 
 
Methodology: 2004 Land Cover, Build-Out, Impervious Surfaces 
 

 
APPENDIX D 
 
Methodology: 2004 Land Cover, Build-Out, Impervious Surfaces 
 
 
 
The purpose of this component of the project was to develop an updated land cover data 
set for the watershed using existing information from CLEAR for the years 1985, 1990, 1995 
and 2002 and updating them to be current as of 2004.  The second component of this task 
includes the development of a point data layer of possible building centers resulting from 
hypothetical buildout scenarios.  Finally, an analysis to develop a methodology to estimate the 
increase in impervious surfaces that could occur within the Niantic River Watershed under full 
buildout conditions was created and implemented. 
 
Appendix D.1 – 2004 Land Cover Development 
 
Updated land cover data were developed for the purpose of conducting a watershed-scale 
assessment of land cover changes over the past two decades.  Using ArcGIS version 9.1 at the 
ArcView licensing level along with two plug-in tools developed by ET Spatial Technologies, 
existing land cover data sets were updated to be current as of April 2004.  The ET Spatial 
Technology tools, ET GeoTools and ET GeoWizards, provide enhanced editing functionality and 
data processing in the ArcView environment.  More information about these tools can be found 
at http://www.ian-ko.com/. 
 
Computer-aided design (CAD) drawings of the edge of forested area was converted to a 
GIS format for the towns of East Lyme (1995), Montville (approximately 1995) and Waterford 
(1995).  For Salem, this information was digitized from April 2004 aerial photographs.  The 
information for the four towns was conflated to a single data layer and used as a base for the land 
cover, designating forested and non-forested areas.  The forested areas for Montville, Salem and 
Waterford were modified to reflect changes occurring up through the ConnDOT/CTDEP April 
2004 black and white aerial photography and for East Lyme using Southern New England 
Telephone (SNET) (SBC/AT&T) 2004 color aerial photography.   
 
 
 
D - 1 

 
The aerial photography was used to portion the non-forested polygons into Anderson 
(1976) Level 1 and Level 2 cover types (Figure C1).  Where the Level 3 cover type was easily 
distinguishable it was defined, though this attribute is incomplete for the data set.  A moderate 
amount of field checking was done during the spring of 2006.  The field checks were done by 
visual aerial survey supplemented by photographs taken during the aerial flights.  The final land 
cover data set has an accuracy determined to be to the level discernable with the SNET and 
CTDEP/ConnDOT 2004 aerial photography, which was produced with a six-inch pixel 
resolution. 
 
Appendix D.2 – Buildout Analysis 
 
Scenario360, a software product developed by the Orton Family Foundation that runs as 
an extension to ArcGIS, was used to perform the buildout analysis.  A buildout is an estimate of 
how much development can occur on buildable land based on current zoning densities.  
Buildable land can be defined as land that does not have any user-defined constraints and that is 
not already built to its maximum allowed density.  For this analysis, we used the following data 
sets, many of which underwent some modification to make them suitable for the analysis.  
 
From the municipalities: 
• 
Zoning 
• 
Parcels 
• 
Roads 
• 
Building footprints (except for Salem) 
• 
Proposed Route 11 ROW (provided by East Lyme) 
 
Developed or provided by UCONN 
• 
Interpreted detailed land cover 
• 
2004 digital B&W 0.8’ resolution orthoimagery 
• 
2004 digital color 0.5m resolution orthoimagery (did not include Salem) 
• 
Buildings point layer with one point / residential parcel (created by heads-
up digitizing using the building footprints and orthoimagery as a guide) 
• 
Water features – lakes, ponds, streams 
 
D - 2 

 
• 
Wetland soils 
 
The buildout analysis was parcel-zoning based.  Zoning designations were used to 
determine future residential building densities for existing parcels.  The analysis also determines 
the portion of each parcel that is buildable land.  The user-defined assumptions for this analysis 
were: 
 
1. 
No construction can take place on protected open space; 
2. 
No construction can take place on water bodies, streams, wetlands or within 100’ 
of these resources; 
3. 
No construction can take place on the proposed Route 11 corridor; 
4. 
No construction can take place on parcels already developed unless the parcel 
exceeds the minimum lot size for the zone it is in; 
5. 
Only one building can be built on flag lots regardless of their size; 
6. 
Only one building can be built on lots without road frontage. 
 
Additionally, based on input from local officials, a number of specific parcels were 
assigned unique zone classes that were used to define future building densities.  For example, in 
East Lyme there are several special use zones.  One is being developed as a high density housing 
complex and the other as a golf course with homes.  The zone designations for these properties 
were changed from SU (special use) to SU-600 and SU-110 where the numeric portion of the 
class refers to the number of houses or dwelling units that will be allowed.  In other cases where 
specific numbers of dwelling units will be permitted, the zoning was changed to DU-1, DU-25, 
etc. where DU is dwelling units and the numeric portion of the class is the permitted number of 
units.  A complete list of all general zone designations used in the buildout is included in the 
Buildout Report in Appendix D4. 
 
After removing the constrained areas described above, the buildout tool of Scenario360 
determined the number of existing residential buildings per parcel and then calculated the 
number of new buildings that could be added, based on the buildable area and permitted zoning 
densities.  For this analysis, a dataset of existing buildings was created so every developed 
residential parcel had one building point feature.  The dataset was based on building footprints 
 
D - 3 

 
provided by the towns and augmented by a visual inspection of the 2004 orthoimagery, used to 
add residential buildings not included in the town datasets.  A spatial buildout was then run that 
randomly placed “new” residential buildings in the buildable areas.  It should be noted that this is 
not a site planning analysis and that the placement of “new” buildings provides a general picture 
of future development.  Absent from the buildout was the creation of new roads. 
 
 
D - 4 

East Lyme
Waterford
Montville
Salem
Lake
Konomoc
Bogue Brook
Reservoir
Barnes
Reservoir
Fairy
Lake
Darrow
Pond
Niantic
Bay
2004 Land Cover Classes
Anderson Level 2 Classifications
Artificial Lakes & Reservoirs
Bare Exposed Rock, Rock Slides
Brushland/Shrubland
Coastal Wetlands
Commercial & Services
Coniferous Forestland
Cropland & Pastureland
Deciduous Forestland
Extractive Mining
Industrial
Interior Wetlands
Natural Lakes
Orchard, Vineyards, Nurseries & Horticultural Area
Other Agriculture
Other Urban or Built-up
Recreational Land
Residential
Transitional Areas
Transportation, Communication & Utilities
Undifferentiated Barren Land
Town
0
4,000
8,000
2,000
Scale In Feet
Land cover classes developed by the University of Connecticut Center for Land Use Education and Research, June 2006.
D.1-1
DEPT. OF ENVIRONTMENTAL PROTECTION
HARTFORD, CONNECTICUT
NIANTIC RIVER WATERSHED
MANAGEMENT PLAN
2004 ANDERSON LEVEL 2
LAND COVER CLASSIFICATION
AS SHOWN
1314-001
uconn lc.mxd
SEK
09-07-2006
Scale:
Project No:
Filename:
Drawn By:
Date Drawn:
3 5  P r a t t  S t . ,  S u it e  2 0 1
Es s e x,  C o n n e c ti c u t   0 6 4 2 6
Te l ep h o n e:  ( 8 6 0 )  7 6 7 - 5 0 6 9
Fa x :  ( 8 6 0 )  7 6 7 - 5 0 9 7
w w w . K l ei n s c h m i d t U S A . c o m

 
Appendix D.3 – Impervious Surface Analysis 
 
Results from the buildout analysis were used to estimate additional impervious surface 
(IS) created as a result of the hypothetical buildout.  In residential zones, this is based on the 
number of “new” residential buildings where each building adds a certain square footage of 
additional impervious area.  A summary of the methods used to generate these estimates can be 
found in Appendix D.5.  The area is based on the following parameters: 
 
• 
Footprint of house 
2,000 
• 
Outbuildings  
   260 
• 
Associated road 
2,636 
• 
Driveway 
 
1,440 
• 
Total IS per house 
6,336 
 
For non-residential areas, it was estimated that 55% of the buildable area will be covered 
with impervious surfaces at buildout.  This is based on impervious surface research conducted by 
William Sleavin (1999) as part of his Master’s Thesis research at UCONN where the percent 
area of impervious surfaces in commercial and industrial zones in Woodbridge and West 
Hartford, Connecticut was calculated.  This was reviewed with town staff in East Lyme, 
Montville and Waterford and it was agreed that this would be a reasonable estimate for future 
imperviousness in these zones.  
 
A dataset of non-residential parcels was created from the parcel-zoning.  Each non-
residential parcel was overlaid on the 2004 orthoimagery and visually inspected.  An estimated 
current percent impervious surface value was added as an attribute to each parcel in the data 
layer and was used to calculate the current area of impervious surface for the parcel. 
 
 
D - 6 

 
To calculate how much additional impervious surface may be built on each non-
residential parcel, the buildable area of the parcel was calculated as part of the buildout analysis.  
If the current percent impervious surface area of the parcel was less than 55%, then additional 
impervious surfaces could be added to the parcel.  The calculation to determine this amount was: 
 
(IS%BO - IS%C) * Buildable Area (sq. feet) = Additional IS (sq. feet), where 
IS%BO  = 55% 
IS%C = current estimated % impervious 
 
 
Appendix D.4 – Buildout Report 
 
 
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Appendix D.5 – Methods Used to Generate IS Estimates and IS Summary 
 
 
Methods to develop components used in the impervious surface estimates 
 
Statistics for buildings classified as residences in residential Land Cover polygons 
 
 
 
From this analysis, the average size of existing houses is ~ 1,600 square feet. For 
buildout analysis purposes, the average size for new homes was increased to 2,000 square 
feet since houses today tend to be significantly larger than older homes. 
 
Statistics for outbuildings in residential Land Cover polygons 
 
 
 
Not all homes have outbuildings.  Therefore, an average outbuilding area was calculated 
as the sum of all outbuildings divided by the number of residential homes. 
 
900,734 / 3,482 = 259 square feet 
 
 
D - 17 

 
This average amount, rounded to 260, will be added to all new homes created through the 
buildout analysis. 
 
Area of road associated with existing residential homes 
 
 
 
The average square foot area of road associated with each house was calculated by calculating 
the area of roads in residential land cover polygons (Anderson Level II code = 1100, 1976) and 
then dividing by the number of houses. Since the buildout analysis does not create new roads, we 
needed an average road square footage per house value in order to estimate IS from new roads. 
 
8,792,170 / 3,335 = 2,636 square feet 
 
Area of driveways associated with each home 
 
The impervious surface area associated with residential driveways and parking is highly variable 
and depends on the lot configuration and distance of the house to the road.  Planimetric data for 
the towns in the study area did not include driveways for all residential structures nor were the 
planimatric data, which were in a CAD format, easily converted to a GIS format.  Therefore, 
CommunityViz was used to calculate the straight-line distance from residential homes to the 
closest road in the watershed and the average house-to-road distance was determined. 
 
 
D - 18 

 
 
 
Note: there are more houses in this analysis than in the analysis to calculate average house 
footprint.  This is because no planimetric data exist for Salem and houses in the other towns had 
been built since the last town GIS data updates.  Point locations of existing houses were created 
based on the 2004 aerial orthoimagery and were included in the driveway calculations. 
 
The area of each driveway is calculated to be the average driveway length (~130’) times an 
average width of 8 feet and a turn/parking area of 400 square feet. 
 
(130 * 8) + 400 = 1,440 square feet 
 
Summary – residential areas 
 
Average square foot areas of impervious surfaces associated with existing houses is calculated as 
follows: 
 
Footprint of house 
1,600 
Outbuildings 
   260 
Driveway 
1,440 
Total IS per house  3,300 
 
~ 4,150 houses existed within the watershed based on 2004 orthoimagery. 
 
The area of existing house related IS was calculated as 4,150 houses * 3,300 sq. feet per house = 
13,695,000 square feet (~ 314 acres) 
 
Average square foot areas of impervious surfaces associated with new houses is calculated as 
follows: 
 
Footprint of house 
2,000 
Outbuildings 
   260 
Associated road 
2,636 
Driveway 
1,440 
Total IS per house 
6,336 
 
 
D - 19 

 
The buildout tool calculated that an additional 2,855 houses could be built under full buildout 
conditions based on current zoning. 
 
The area of buildout house related IS was calculated as 2,855 houses * 6,336 square feet per 
house = 18,089,280 square feet (~ 415 acres) 
 
Roads 
 
The area of existing roads in the watershed is 15,115,257 square feet (~ 347 acres).  This  
value was used to calculate existing IS. 
 
 
 
Impervious surfaces for non-residential areas 
 
The current percent IS area for parcels with a general zone designation of commercial, industrial, 
business and government was estimated by visually inspecting parcels overlaid on the 2004 
orthoimagery and adding the estimated value to the attribute table.  Parcels with structures were 
assigned a minimum value of 5% to a maximum value of 100%.  The area of each parcel was 
then multiplied by the percent IS to calculate the square footage of IS and statistics were run to 
calculate the total IS for these parcels. 
 
 
D - 20 

 
 
 
Estimated total existing IS = 10,565,842 square feet (~ 243 acres) 
 
Impervious surfaces for non-residential areas at buildout 
 
To estimate future impervious 
surface area for parcels zoned for 
business, commercial, industrial and 
government uses and for the area of 
Camp Rell, it was decided that 
approximately 55% of the buildable 
land within these zones would be 
covered with IS at buildout. The 
total buildable non-residential area 
was calculated after running the 
buildout analysis and the constraint 
areas had been removed. These are 
the shaded areas in the 
example screen capture. For each 
buildable area polygon, an estimate 
was made of the current percent IS. 
This is the number shown in each 
shaded polygon. For all polygons 
where the current IS percent was less 
than 55, the following calculation was run: 
 
(55% - current IS %) * buildable area = increase in IS area at buildout 
 
 
D - 21 

 
 
 
Area of additional IS, in buildable areas at buildout = 18,425,817 square feet (~ 423 acres) 
 
 
D - 22 

 
 
D - 23 

 
 
D - 24 

 
 
D - 25 

 
 
 
D - 26 

 
APPENDIX E 
 
Methodology: Watershed Vulnerability Assessment 
 

 
APPENDIX E 
 
Methodology: Watershed Vulnerability Assessment 
 
 
 
Appendix E.1 – Data Acquisition and Treatment 
 
The primary data set required for this effort was the 2004 land cover data produced by 
UCONN (Appendix D).  Other important data sets were the USDA NRCS Soil Survey 
Geographic (SSURGO) Database, USGS elevation and USGS National Hydrography Dataset 
(NHD), aquifer protection areas and municipal and DEP lands.  An abbreviated metadata listing 
is included as Table E.1-1 to provide additional details. 
 
Using these data sets, additional inputs for the model were created, totaling eight in all.  
The USGS 10-meter digital elevation model (DEM) was used to produce a percent slope layer 
for the watershed.  The DEM was also used to create a flow accumulation grid.  The Flow 
Accumulation matrix holds values of accumulated flow as the accumulated weight of all cells 
flowing into each down slope cell in the output raster (ESRI, 2005).   
 
The SSURGO data was used for two input layers into the model: permeability and depth 
to water table.  Both of these parameters are included with the data from NRCS, no additional 
computations were necessary. 
 
Though ideally a comprehensive layer of protected lands would be available to use as a 
definitive input, one was not available for this effort.  In place of that, several layers were 
combined and features extracted to produce a preserved lands input layer.  The DEP property, 
municipal property and the DEP aquifer protection areas were merged to produce a single layer 
then the schools, cemeteries, golf courses, boat ramps, marinas and the Waterford Speed Bowl 
were removed.  The remaining categories of land included preserved open space, State forests, 
and trust lands, for example.  One layer noticeably not obtainable was the surface water 
protection areas within the watershed. 
 
 
E - 1 

 
Multiple ring buffers were created around the water bodies and streams in the NHD at 50 
and 100 feet.  The final data input that was developed was a forest-water-roads layer.  This input 
provides a distinctive layer of forested areas that are within 200 feet of both roads and water  (de 
la Crétaz et al., 2003). 
 
E - 2 

 
Table E.1-1.  Watershed Vulnerability Assessment Abbreviated Metadata Listing 
 
Feature 
 
 
 
 
 
Data Type
Projection
Date 
Source
Comment
 
 
 
 
 
 
Slope 
Raster Dataset 
Connecticut State Plane, NAD 1983, feet 
1999 
USGS Eros Data Center 
Slope grid calculated from the USGS 10-meter digital 
elevation model. 
Flow accumulation 
Raster Dataset 
Connecticut State Plane, NAD 1983, feet 
1999 
USGS Eros Data Center 
Flow accumulation calculated from the slope grid. 
Soil permeability 
Personal Geodagtabase Feature Class 
Connecticut State Plane, NAD 1983, feet 
7/15/2005 
USGS NRCS SSURGO 
 
Soil depth to water table 
Personal Geodagtabase Feature Class 
Connecticut State Plane, NAD 1983, feet 
7/15/2005 
USGS NRCS SSURGO 
 
Preserved lands 
Personal Geodagtabase Feature Class 
Connecticut State Plane, NAD 1983, feet 
2004 & 1997 
CT DEP GIS Data Downloads 
DEP Property layer and Municipal and Private Open 
Space Property layer were merged to produce a single 
layer.  The following categories were removed to 
produce the protected lands layer: cemeteries, schools 
and the Waterford Speedbowl. 
Forest-water-roads 
Personal Geodagtabase Feature Class 
Connecticut State Plane, NAD 1983, feet 
2004 & 2000 
UCONN, USGS NHD & CT 
DEP Data Downloads 
Forested areas were extracted from the land cover 
layer.  The NHD was buffered at 200' and used to clip 
the forested layer, producing a layer of forested areas 
within 200' of water.  Finally the roads were buffered 
at 200' and used to clip the forest/water layer 
producing forested areas within both 200' of water and 
roads. 
Distance to water 
Personal Geodagtabase Feature Class 
Connecticut State Plane, NAD 1983, feet 
2004 
USGS NHD 
This layer is a multiple ring buffer around water 
features at distances of 50' and 100'. 
Land cover 
Personal Geodagtabase Feature Class 
Connecticut State Plane, NAD 1983, feet 
2004 
UCONN CLEAR 
This layer is described in detail in Appendix D. 
 
 
E - 3 

 
Appendix E.2 – Data Model Development 
 
The vulnerability assessment model was developed in the ESRI ArcGIS version 9.1 suite 
of software.  Using the Spatial Analyst extension to the package, a ModelBuilder model was 
developed from the input layers.  The process used within the model was developed by the 
University of Massachusetts and the U.S. Forest Service Watershed Exchange and Technology 
Partnership in cooperation with the Massachusetts Department of Conservation and Recreation 
(de la Crétaz et al., 2003) and only modified due to recent updates in the software and to include 
additional data inputs that were not used, or only discussed, in the Partnership’s methods. 
 
Classifying the data inputs added to the Niantic River Watershed model was specific to 
the watershed and required some research of soil types, slopes and land covers.  Though the 
detailed process is not summarize here, it is important to outline the rankings of data inputs used.  
These are listed in Table E.2-1 and described below. 
 
Development restrictions set by the towns listed the gentlest ‘no-build’ slope at 20%, i.e., 
the other towns that were reviewed allowed a steeper slope on which development can occur.  
This gentlest slope was used as the cutoff for the highest priority ranking.  Flow accumulation 
can be a measure of areas of concentrated flow (ESRI, 2005) with high values likely representing 
overland flow.  In this study, flow accumulation is used as an indicator of high erosion potential, 
possibly due to scour rather than highly erodible soil types.  Priority rankings were assigned on 
the likelihood of accumulation developing into overland flow. 
 
The rankings for soil permeability were assigned using the SSURGO data set from the 
NRCS.  Each soil type is assigned a vertical saturated hydraulic conductivity class, in this case it 
was important to use the “representative value” from the data set as this is a highly variable 
characteristic of soils.  The vertical, saturated hydraulic conductivity classes from the NRCS Soil 
Survey Manual along with the Niantic River Watershed priority rankings for each class are listed 
in Table E.2-2 (USDA NRCS, 1993). 
 
 
E - 4 

 
Table E.2-1. Input Layer Priority Rankings 
Rank 
Input Layer 
3 (High Rank) 
2 (Intermediate Rank) 
1 (Low Rank) 
0 (No Rank) 
Slope (%) 
>20 - 150 
>10 - 20 
0 - 10 
none 
Flow 
Accumulation 
1801 - 676,860 
1351 - 1800 
0 - 1350 
none 
Soil 
Permeability 
>100 
>1 - 100 
>0 - 1 
0 
Soil Depth to 
Water Table 
D 
B, C 
A 
All others 
Preserved Lands 
All 
none 
none 
none 
Forest-Water-
Roads 
All 
none 
none 
none 
Distance to 
Water (ft) 
0 - 50 
>50 - 100 
none 
>100 
Land Cover 
  
Conservation 
Priority Index 
Deciduous forestland, 
Plantation, 
Old field, 
Deciduous brush/shrubland,
Saline marshes, 
Interior wetlands, 
Deciduous wooded 
wetlands 
none 
none 
All others 
Restoration 
Priority Index 
Cropland & pastureland, 
Horse farms 
Inactive cropland, 
Orchards, vineyards, 
nurseries & horticultural 
areas 
none 
All others 
Stormwater 
Management 
Priority Index 
High density residential, 
Commercial & services, 
Education institutions, 
Health institutions, 
Military installations, 
Industrial, 
Power generation, 
Transportation, 
communication & utilities,
Limited access highways, 
Railroad facilities, 
Power facilities, 
Water treatment facilities, 
Sewage treatment facilities 
Low & medium density 
residential, 
Other urban or built-up 
Rural residential, 
Golf courses, 
Picnic & camping parks, 
Marinas & boat launches, 
Community recreation 
areas, 
Open areas in parks 
All others 
 
 
E - 5 

 
Table E.2-2. Vertical Saturated Hydraulic Conductivity Classes and Priority Rankings 
Ksat Class (µm/s)  
Ranking
Very High (> 100) 
3 
High (>10 – 100) 
2 
Moderately High (>1 – 10) 
2 
Moderately Low (0.1 -1) 
1 
Low (>0.01 - 0.1) 
1 
Very Low (< 0.01) 
1 
 
 
The depth to water table rankings ideally would be derived from the distance from the top 
of the soil to the upper boundary of the moisture layer, which is also in the SSURGO data set.  
These values were not available in the data for this region of Connecticut.  Therefore, the natural 
drainage classes (USDA NRCS, 1993) were applied to the hydrologic soil groups to rank the 
soils generally corresponding to appropriate depth to water table values.  The “excessively 
drained” through “very poorly drained” natural drainage classes provide a strong indication of 
where in the soil profile the free water occurs. 
 
Due to the nature of preserved lands and their direct correspondence to the ability to be 
used for conservation activities, all currently preserved and trust lands were assigned high 
rankings for the Conservation Priority Index.  These lands were not used in the two remaining 
priority indices.  Similar to preserved lands, the Forest-Water-Roads input has a high ranking for 
the Conservation Priority Index.  These forested areas that are within 200 feet of both roads and 
water lend support to the idea of creating buffers around water bodies.  This is a specialized 
buffer that identifies the forested areas within a safe distance from both water bodies and roads 
and ideally would act as a filter for pollutants between the roads and the water. 
 
As mentioned previously, the idea of creating buffers around water bodies allows the 
surrounding areas to add a safeguard to the surface water.  High rankings were applied to the 
smaller 50-foot buffer and intermediate values to the larger 100-foot buffer.  All areas outside of 
this range were not assigned a ranking.  This particular range was defined as it has been deemed 
appropriate in other coastal studies for the use of nutrient removal (Palone and Todd, 1997). 
 
 
 
E - 6 

 
The land cover data layer was classified for each of the three priority indices using the 
guidance document developed by the University of Massachusetts (de la Crétaz et al., 2003).  
Each of the land cover types were assigned to one of the three indices, generally following the 
idea that undeveloped lands would be placed in the Conservation Priority Index; agricultural 
lands would be placed in the Restoration Priority Index; and all other developed lands, such as 
residential, commercial and industrial, would be placed in the Stormwater Management Priority 
Index.  All of the lands in the CPI were assigned high rankings.  The agricultural lands that run 
active animal operations and cropland applying fertilizers and pesticides to the soils were 
assigned high rankings in the RPI with inactive cropland and cropland applying spray fertilizers 
and pesticides given intermediate rankings.  The SMPI land cover types were assigned rankings 
based on the use intensity of the development.  That is, high density residential, industrial and 
commercial land cover types were assigned high rankings, while low and medium density 
residential and other built-up land cover types were assigned intermediate rankings.  The low 
rankings in the SMPI were rural residential areas and managed recreation areas such as golf 
courses, marinas and community parks. 
 
Each of the input layers held a one-to-one ranking with each other, with the exception of 
the two derivatives of the soils layer, which were assigned a weight of 0.5.  The weighted input 
layers were overlain and their ranking values added on a cell by cell basis.  The model produced 
three output matrices with each cell containing the calculated sum of the rankings for all input 
layers. 
 
E - 7 

 
APPENDIX F 
 
Methodology: Stormwater Modeling (SWMM Model) 
 

 
APPENDIX F 
 
Methodology: Stormwater Modeling (SWMM Model) 
 
 
 
Appendix F.1 – Methodology 
 
Appendix F.1.1 – Pollutant Loading Approach 
 
Pollutant loadings from a watershed are obtained when rainfall actually becomes runoff 
and is not lost due to infiltration.  Runoff passes over yards, forests, parking lots and all other 
land covers and can ‘pick up’ pollutants along the flow path.  Every type of land cover 
contributes some degree of pollutants, but the type of pollutant and the concentration will vary.  
The first assumption is how the concentration of pollutants is accounted for within the runoff.  
Some methods allow for a buildup of pollutant loads over time, followed by a wash-off.  The 
first one-inch (1”) of rain after a dry spell will produce a higher pollutant load concentration than 
the following one inch of rain during the same storm.  Analysis using this method requires a 
detailed study of active land management practices such as potential buildup ratios over time, or 
street sweeping schedules. 
 
Another method is called the Event Mean Concentration (EMC) approach, which uses a 
constant loading of a pollutant per volume of calculated runoff.  This was the approach utilized 
for the analysis of the Niantic River Watershed.  This method allows for even analysis of 
potential pollutant loadings without biasing loadings from variable methods of street 
maintenance or pollution enforcement between towns or locations.   
 
Variables for EMCs for the studied land covers were obtained from various published 
sources and have been referenced.  Using these variables is a generalization of loadings from 
certain land covers and is assumed to be homogenous across the watershed, which may not 
always be the case.  In some instances, published values for certain land covers are not readily 
available, so the most similar type of cover or land use (i.e. animals, excess fertilizers, parking 
areas, etc.) was used to determine the EMC loading rates (Table F.2.1-1). 
 
 
F - 1 

 
The following key pollutants were studied within the SWMM model: 
 
• 
Total Suspended Solids (TSS) 
• 
Total Kjeldahl Nitrogen (TKN) 
• 
Total Nitrogen as NO2 & NO3 (TN) 
• 
Total Phosphorous (TP) 
• 
Biological Oxygen Demand (BOD) 
 
 
F - 2 

 
Table F.1.1-1.  Land Use and Event Mean Concentration Pollutant Loading Rates1, 2, 3, 4,5 
Value
TSS
(mg/l)
BOD
(mg/l)
Total P
(mg/l)
NO3-NO2
(mg/l)
TKN
(mg/l)
Residential
1100
54.5
11.5
0.26
0.53
1.47
Residential (High Density)
1110
100
36
0.5
0.84
1.49
Residential (Rural)
1140
42
11.5
0.4
0.34
1.48
Commercial & Services
1200
55.5
23
0.32
0.26
1.1
Educational Institutions
1207
67
7.8
0.26
0.56
1.3
Health Institutions
1208
67
7.8
0.26
0.56
1.3
Military Installations
1211
67
7.8
0.26
0.56
1.3
Industrial
1300
60.5
14
0.28
0.3
1
Power Generation
1330
55.5
23
0.32
0.26
1.1
Transportation, Communication & Utilities
1400
1
0.5
0.01
0.4
0.2
Limited Access Highways
1410
50.3
5.6
0.34
0.1
2.72
Railroad Facilities
1420
50
0.5
0.1
0.01
0.1
Power Facilities
1460
1
0.5
0.01
0.4
0.2
Water Treatment Facilities
1470
67
7.8
0.26
0.56
1.3
Sewage Treatment Facilities
1480
60.5
14
0.28
0.3
1
Other Transportation, Communication & Utilities
1490
50
0.5
0.1
0.01
0.1
Other Urban or Built-up
1700
11.1
1.45
0.05
0.25
1
Cemeteries
1710
3
4
0.03
0.4
0.2
Open Areas
1740
3
4
0.03
0.4
0.2
Golf Courses
1801
202
10
1.07
1.02
6.85
Picnic & Camping Parks
1802
3
4
0.03
0.4
0.2
Marina & Boat Launches
1803
60.5
14
0.28
0.3
1
Community Recreation Areas
1804
3
4
0.03
0.4
0.2
Open Areas in Parks
1809
3
4
0.03
0.4
0.2
Cropland & Pastureland
2100
55.3
3.8
0.344
1.6
1.7
Harvested Cropland
2110
107
4
0.562
0.5
1.7
Pastureland
2120
151
5.1
2.14
1.3
3.46
Inactive Cropland
2130
5
0.5
0.01
0.4
0.2
Orchards, Vineyards, Nurseries & Horticultural Areas
2200
16.3
2.55
0.14
0.5
1.25
Nurseries
2230
16.3
2.55
0.14
0.5
1.25
Horse Farm
2430
151
7
2.14
1.3
3.46
Deciduous (>50% Crown Closure)
4120
487
0.1
0.15
0.17
0.61
Plantation
4230
3
4
0.03
0.4
0.2
Old Field (<25% Brush Covered)
4410
1
0.5
0.01
0.4
0.2
Deciduous Brush/Shrubland (>25% Brush with Decid Species >75%)
4420
80
4
0.25
0.1
1.37
Natural Lakes
5200
3.1
1.6
0.11
0.25
1.0
Artificial Lakes & Reservoirs
5300
3.1
1.6
0.11
0.25
1.0
Artificial Lakes
5310
3.1
1.6
0.11
0.25
1.0
Saline Marshes
6110
15
5
0.05
0.25
1.0
Interior Wetlands
6200
10.2
5
0.19
0.6
1.0
Deciduous Wooded Wetlands
6210
487
0.1
0.15
0.17
0.61
Exposed Rock
7220
5
0.05
0.1
0.01
0.1
Extractive Mining
7300
3491
0.1
0.43
0.21
1.08
Stone Quarries
7310
3491
0.1
0.43
0.21
1.08
Sand & Gravel Pits (Borrow Pits)
7320
3491
0.1
0.43
0.21
1.08
Transitional Areas
7500
1453
0.1
0.28
1
5.69
Single Unit Residential Under Construction
7510
1453
0.1
0.28
1
5.69
Transportation/Communication/Utilities Under Construction
7550
1453
0.1
0.28
1
5.69
Undifferentiated Barren Land
7600
11.1
1.45
0.05
0.25
1
 
1  Harper (1998) 
2  Schueler (1996) 
3  USEPA (2005d) 
4  Line (2002) 
5  Lin (2004) 
 
 
F - 3 

 
Appendix F.1.2 – Model Approach 
 
In order to assemble and analyze the vast collection of data, the USEPA Storm Water 
Management Model v.5 .008 (SWMM5) was utilized.  SWMM “is a dynamic rainfall-runoff 
simulation model used for single event or long-term (continuous) simulation of runoff quantity 
and quality from primarily urban areas.  The runoff component of SWMM operates on a 
collection of subcatchment areas that receive precipitation and generate runoff and pollutant 
loads.  The routing portion of SWMM transports this runoff through a system of pipes, channels, 
storage/treatment devices, pumps, and regulators.  SWMM tracks the quantity and quality of 
runoff generated within each subcatchment, and the flow rate, flow depth, and quality of water in 
each pipe and channel during a si