Unfed
Environmental Protection
Agency
Office of Wafer
4304
EPA822-B-00-014
December 2000
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EPA 822-B-00-014
AMBIENT WATER QUALITY CRITERIA RECOMMENDATIONS
INFORMATION SUPPORTING THE DEVELOPMENT OF STATE AND TRIBAL
NUTRIENT CRITERIA
FOR
LAKES AND RESERVOIRS IN NUTRIENT ECOREGION XIII
Southern Florida Coastal Plain
and authorized Tribes -within the Ecoregion
U.S. ENVIRONMENTAL PROTECTION AGENCY.
OFFICE OF WATER
OFFICE OF SCIENCE AND TECHNOLOGY
HEALTH AND ECOLOGICAL CRITERIA DIVISION
WASHINGTON, D.C.
DECEMBER 2000
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FOREWORD
This document presents EPA's nutrient criteria for Lakes and Reservoirs in Nutrient
Ecoregion XIII. These criteria provide EPA's recommendations to States and authorized Tribes
for use in establishing their water quality standards consistent with section 303(c) of CWA.-
Under section 303(c) of the CWA, States and authorized Tribes have the primary responsibility
for adopting water quality standards as State or Tribal law or regulation. The standards must
contain scientifically defensible water quality criteria that are protective of designated uses.
EPA's recommended section 304(a) criteria are hot laws or regulations — they are guidance that
States and Tribes may use as a starting point for the criteria for their water quality standards.
The term "water quality criteria" is used in two sections of the Clean Water Act, Section
304(a)(l) and Section 303(c)(2). The term has a different impact in each section. In Section 304,
the term represents a scientific assessment of ecological and human health effects that EPA
recommends to States and authorized Tribes for establishing water quality standards that
ultimately provide a basis for controlling discharges or releases of pollutants or related
parameters. Ambient water quality criteria associated with specific waterbody uses when
adopted as State or Tribal water quality standards under Section 303 define the level of a
pollutant (or, in the case of nutrients, a condition) necessary to protect designated uses in ambient
waters.. Quantified water quality criteria contained within State or Tribal water quality standards
are essential to a water quality-based approach to pollution control. Whether expressed as
numeric criteria or quantified translations of narrative criteria within State or Tribal water quality
standards, quantified criteria serve as a critical basis for assessing attainment of designated uses
and measuring progress toward meeting the water quality goals of the Clean Water Act.
EPA is developing section 304(a) water quality criteria for nutrients because States and
Tribes consistently identify excessive levels of nutrients as a major reason why as much as half
of the surface waters surveyed in this country do not meet water quality objectives, such as full
support of aquatic life. EPA expects to develop nutrient criteria that cover four major types of
waterbodies — lakes and reservoirs, rivers and streams, estuarine and coastal areas, and wetlands
- across fourteen major ecoregions of the United States. EPA's section 304(a) criteria are
intended to provide for the protection and propagation of aquatic life and recreation. To support
the development of nutrient criteria, EPA is publishing Technical Guidance Manuals that
describe a process for assessing nutrient conditions in the four waterbody types.
EPA's section 304(a) water quality criteria for nutrients provide numeric water quality
criteria, as well as procedures by which to translate narrative criteria within State or Tribal water
quality standards. In the case of nutrients, EPA section 304(a) criteria establish values for causal
variables (e.g., total nitrogen and total phosphorus) and response variables (e.g., turbidity and
chlorophyll a). EPA believes that State and Tribal water quality standards need to include
quantified endpoints for causal and response variables to provide sufficient protection of uses
and to maintain downstream uses. These quantified endpoints will most often be expressed as
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numeric water quality criteria or as procedures to translate a State or Tribal narrative criterion
into a quantified endpoint.
EPA will work with States and authorized Tribes as they adopt water quality criteria-for
nutrients into their water quality standards. EPA recognizes that States and authorized Tribes
require flexibility in adopting numeric nutrient criteria into State and Tribal water quality
standards. States and authorized Tribes have several options available to them. EPA
recommends the following approaches, in order of preference:
(1) Wherever possible, develop nutrient criteria that fully reflect localized conditions and
protect specific designated uses using the process described in EPA's Technical Guidance
Manuals for nutrient criteria development. Such criteria may be expressed either as
numeric criteria or as procedures to translate a State or Tribal narrative criterion into a
quantified endpoint in State or Tribal water quality standards.
(2) Adopt EPA's section 304(a) water quality criteria for nutrients, either as numeric
criteria or as procedures to translate a State or Tribal narrative nutrient criterion into a
quantified endpoint.
(3) Develop nutrient criteria protective of designated uses using other scientifically
defensible methods and appropriate water quality data.
Geoffrey H./irubbsf Director
Office of Scfience and Technology
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DISCLAIMER
This document provides technical guidance and recommendations to States, authorized
Tribes, and other authorized jurisdictions to develop water quality criteria and water quality
standards under the Clean Water Act (CWA) to protect against the adverse effects of nutrient
overenrichment. Under the CWA, States and authorized Tribes are to establish water quality
criteria to protect designated uses. State and Tribal decision-makers retain the discretion to adopt
approaches on a case-by-case basis that differ from this guidance when appropriate and
scientifically defensible. While this document contains EPA's scientific recommendations
regarding ambient concentrations of nutrients that protect aquatic resource quality, it does not.
substitute for the CWA or EPA regulations; nor is it a regulation itself. Thus it cannot impose
legally binding requirements on EPA, States, authorized Tribes, or the regulated community, and
it might not apply to a particular situation or circumstance. EPA may change this guidance in the
future.
IV
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EXECUTIVE SUMMARY
Nutrient Program Goals
EPA developed the National Strategy for the Development of Regional Nutrient Criteria
(National Strategy) in June 1998. The strategy presents EPA's intentions to develop technical
guidance manuals for four types of waters (lakes and reservoirs, rivers and streams, estuaries and
coastal waters, and wetlands) and produce section 304(a) criteria for specific nutrient ecoregions
by the end of 2000. In addition, the Agency formed Regional Technical Assistance Groups
(RTAGs) which include State and Tribal representatives working to develop more refined and
more localized nutrient criteria based on approaches described in the waterbody guidance ,
manuals. This document presents EPA's current recommended criteria for total phosphorus, total
nitrogen, chlorophyll a, and turbidity for lakes and reservoirs in Nutrient Ecoregion XIII
(Southern Florida Coastal Plain) which were derived using the procedures described in the Lakes
and Reservoirs Nutrient Criteria Technical Guidance Manual (U.S. EPA, 2000a).
EPA's ecoregional nutrient criteria are intended to address cultural eutrophication— the
adverse effects of excess nutrient inputs. The criteria are empirically derived to represent
conditions of surface waters that are minimally impacted by human activities and protective of
aquatic life and recreational uses. The information contained in this document represent starting
points for States and Tribes to develop (with assistance from EPA) more refined nutrient criteria.
In developing these criteria recommendations, EPA followed a process which included,
to the extent they were readily available, the following elements critical to criterion derivation:
• Historical and recent nutrient data in Nutrient Ecoregion XIII
Nutrient Data from Legacy STORET (from 1990-1998) were used to assess historical and
recent nutrient conditions and develop reference conditions in Ecoregion XIII
• Reference sites/reference conditions in Nutrient Ecoregion XIII
Reference sites/reference conditions in Nutrient Ecoregion XIII were based on the lake
population distribution approach using a representative sample of all lakes within the
Ecoregion (see Nutrient Criteria Technical Guidance Manual-Lakes and Reservoirs, April
2000, EPA-822-BOO-001. States and Tribes are urged to determine their own reference
sites for lakes and reservoirs within the ecoregion at different geographic scales and to
compare them to EPA's reference conditions.
• Models employed for prediction or validation
EPA did not identify any specific models used in the ecoregion to develop nutrient :
criteria. States and Tribes are encouraged to identify and apply appropriate models to
support nutrient criteria development.
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• RTAG expert review and consensus
EPA recommends that when States and Tribes prepare their nutrient criteria, they obtain .
the expert review and consent of the RTAG.
• Downstream effects of criteria
EPA encourages the RTAG to assess the potential effects of the proposed criteria on
downstream water quality and uses.
In addition, EPA followed specific QA/QC procedures during data collection and
analysis: All data were reviewed for duplications. All data are from ambient waters that were
not located directly outside a permitted discharger. The following States indicated that their data
were sampled and analyzed using either Standard methods or EPA approved methods: Florida
The following tables contain a summary of Aggregate and level HI ecoregion values for TN, TP,
water column chl a, and turbidity:
BASED ON 25th PERCENTILE ONLY
Nutrient Parameters
Total phosphorus (/ig/L)
Total nitrogen (mg/L)
Chlorophyll a (,ug/L) (Trichromatic method)
Secchi depth (meters)
Aggregate Nutrient Ecoregion XIII
Reference Conditions (same as
subecoregion 76)
17.5
1.27
12.35
0.79
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NOTICE OF DOCUMENT AVAILABILITY
This document is available electronically to the public through the INTERNET at:
(http://www.epa.gov/OST/standards/nutrient.html). Requests for hard copies of the document
should be made to EPA's National Service Center for Environmental Publications (NSCEP),
11029 Kenwood Road, Cincinnati, OH 45242 or (513) 489-8190 or toll free (800) 490-9198.
Please refer to EPA document number EPA-822-B-00-014.
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ACKNOWLEDGMENTS
The authors thankfully acknowledge the contributions of the following State and Federal
reviewers: The State of Florida, EPA Region 4; the Tribes within the Ecoregion; EPA
Headquarters personnel from the Office of Wetlands, Oceans and Watersheds, Office of
Wastewater Management, Office of General Counsel, Office of Research and Development, and
the Office of Science and Technology. EPA also acknowledges the external peer review efforts
of Eugene Welch (University of Washington), Robert Carlson (Kent State University), Steve
Heiskary (Minnesota Pollution Control Agency), Greg Denton and Sherry Wang (Tennessee
Department of Environment and Conservation), and Gerhard Kuhn (U.S. Geological Survey).
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LISTS OF TABLES AND FIGURES
Figures
Figure 1
Figure 2
Figures
Figure 4a
Figure 4b
Tables
Table 1
Table 2
Table 3a
Aggregate Ecoregion XIII 7
Aggregate Ecoregion XIH with level III ecoregions shown 8
Sampling locations within each level III ecoregion .'.. 11
Illustration of data reduction process for lake data 18
Illustration of reference condition calculation 19
Lake and reservoir records for Aggregate Ecoregion - Southern
Florida Coastal Plain .12
Reference conditions for Aggregate Ecoregion XIII lakes ..... 14
Reference conditions for level III ecoregion lakes 15
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TABLE OF CONTENTS
Foreword ii
Disclaimer iv
Executive Summary v
Notice of Document Availability vii
Acknowledgments viii
List of Tables and Figures ix
Table of Contents x
1.0 Introduction 1
2.0 Best Use of this Information 4
3.0 Area Covered by This Document (waterbody type and ecoregion) 6
3.1 Description of Aggregate Ecoregion - Southern Florida Coastal Plain 6
3.2 Geographical Boundaries of Aggregate Ecoregion XIII 7
3.3 Level m Ecoregions within Aggregate Ecoregion XIII 7
4.0 Data Review for Lakes and Reservoirs in Aggregate Ecoregion XIII 9
4.1 Data Sources 9
4.2 Historical Data from Aggregate Ecoregion Xin (TP, TN, Chi a, Turbidity) 9
4.3 QA/QC of Data Sources 9
4.4 Data for All Lakes/Reservoirs within Aggregate Ecoregion XIII 10
4.5 Statistical Analysis of Data 13
4.6 Classification of Lake/Reservoir Type 17
4.7. Summary of Data Reduction Methods 17
5.0 Reference Sites and Conditions in Aggregate Ecoregion XIII 20
6.0 Models Used to Predict or Verify Response Parameters : 20
7.0 Framework for Refining Recommended Nutrient Criteria for Lakes and Reservoirs in
Aggregate Ecoregion XIII 20
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7.1 Example Worksheet for Developing Aggregate Ecoregion and Subecoregion Nutrient
Criteria 21
7.2 Tables of Refined Nutrient Water Quality Criteria for Aggregate Ecoregion XIII and
Level III Subecoregions 22
7.3 Setting Seasonal Criteria ,. 22
7.4 When Data/Reference Conditions Are Lacking 22
7.5 Site-Specific Criteria Development 22
8.0 Literature Cited , 23
9.0 Appendices 23
XI
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1.0 INTRODUCTION
Background
Nutrients are essential to the health and diversity of our surface waters. However, in
excessive amounts, nutrients cause hypereutrophication, which results in overgrowth of plant life
and decline of the biological community. Excessive nutrients can also result in potential human
health risks, such as the growth of harmful algal blooms - most recently manifested in the
Pfiesteria outbreaks of the Gulf and East Coasts. Chronic nutrient overenrichment of a waterbody
can lead to the following consequences: low dissolved oxygen, fish kills, algal blooms,
overabundance of macrophytes, likely increased sediment accumulation rates, and species shifts
of both flora and fauna.
Historically, National Water Quality Inventories have repeatedly shown that nutrients are a major
cause of ambient water quality use impairments. EPA's 1996 National Water Quality Inventory
report identifies excessive nutrients as the leading cause of impairment in lakes and the second
leading cause of impairment in rivers (behind siltation). In addition, nutrients were the second
leading cause of impairments reported by the States in their 1998 lists of impaired waters. Where
use impairment is documented, nutrients contribute roughly 25-50% of the impairment nationally.
The Clean Water Act establishes a national goal to achieve, wherever attainable, water quality
which provides for the protection and propagation offish, shellfish, and wildlife and recreation in
and on the water. In adopting water quality standards, States and Tribes designate uses for their
waters in consideration of the Clean Water Act goals, and establish water quality criteria that
contain sufficient parameters to protect those uses. To date, EPA has not published information
and recommendations under section 304(a) for nutrients to assist States and Tribes in establishing
numeric nutrient criteria to protect uses when adopting water quality standards.
In 1995, EPA gathered a set of national experts and asked the experts how to best deal with the
national nutrient problem. The experts recommended that the Agency not develop single criteria
values for phosphorus or nitrogen applicable to all water bodies and regions of the country.
Rather, the experts recommended that EPA put a premium on regionalization, develop guidance
(assessment tools and control measures) for specific waterbodies and ecological regions across the
country, and use reference conditions (conditions that reflect pristine or minimally impacted
waters) as a basis for developing nutrient criteria.
With these suggestions as starting points, EPA developed the National Strategy for the
Development of Regional Nutrient Criteria (National Strategy), published in June 1998. This
strategy presented EPA's intentions to develop technical guidance manuals for four types of
waters (lakes and reservoirs, rivers and streams, estuaries and coastal waters, and wetlands) and,
thereafter, to publish section 304(a) criteria recommendations for specific nutrient ecoregions.
Technical guidance manuals for lakes/reservoirs and rivers/streams were published in April 2000
and July 2000, respectively. The technical guidance manual for estuaries/coastal waters will be
published in spring 2000 and the draft wetlands technical guidance manual will be published by
December 2001. Each manual presents EPA's recommended approach for developing nutrient
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criteria values for a specific waterbody type. In addition, EPA is committed to working with
States and Tribes to develop more refined and more localized nutrient criteria based on
approaches described in the waterbody guidance manuals and this document.
Overview of the Nutrient Criteria Development Process
For each Nutrient Ecoregion, EPA developed a set of recommendations for two causal variables
(total nitrogen and total phosphorus) and two early indicator response variables (chlorophyll a and
some measure of turbidity). Other indicators such as dissolved oxygen and macrophyte growth or
speciation, and other fauna and flora changes are also deemed useful. However, the first four are
considered to be the best suited for protecting designated uses.
The technical guidance manuals describe a process for developing nutrient criteria that involves
consideration of five factors. The first of these is the Regional Technical Assistance Group
(RTAG), which is a body of qualified regional specialists able to objectively evaluate all of the
available evidence and select the value(s) appropriate to nutrient control in the water bodies of
concern. These specialists may come from such disciplines as limnology, biology, natural
resources management- especially water resource management, chemistry, and ecology. The
RTAG evaluates and recommends appropriate classification techniques for criteria determination,
usually physical within an ecoregional construct.
The second factor is the historical information available to establish a perspective of the resource
base. This is usually data and anecdotal information available within the past ten-twenty five
years. This information gives evidence about the background and enrichment trend of the
resource.
The third factor is the present reference condition. A selection of reference sites chosen to
represent the least culturally impacted waters of the class existing at the present time. The data
from these sites is combined and a value from the distribution of these observations is selected to
represent the reference condition, or best attainable, most natural condition of the resource base at
this time.
A fourth factor often employed is theoretical or empirical models of the historical and reference
condition data to better understand the condition of the resource.
The RTAG comprehensively evaluates the other three elements to propose a candidate criterion
(initially one each for TP, TN, chl a, and some measure of turbidity).
The last and final element of the criteria development process is the assessment by the RTAG of
the likely downstream effects of the criterion. Will there be a negative, positive, or neutral effect
on the downstream waterbody? If the RTAG judges that a negative effect is likely, then the
proposed State/Tribal water quality criteria should be revised to ameliorate the potential for any
adverse downstream effects.
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While States and authorized Tribes would not necessarily need to incorporate all five elements
into their water quality criteria setting process (e.g., modeling may be significant in only some
instances), the best assurance of a representative and effective criterion for nutrient management
decision making is the balanced incorporation of all five elements, or at least all elements except
modeling.
Because some parts of the country have naturally higher soil and parent material enrichment, and
different precipitation regimes, the application of the criterion development process has to be
adjusted by region. Therefore, an ecoregional approach was chosen to develop nutrient criteria
appropriate to each of the different geographical and climatological areas of the country. Initially,
the continental U.S. was divided into 14 separate ecoregions of similar geographical
characteristics. Ecoregions are defined as regions of relative homogeneity in ecological systems;
they depict areas within which the mosaic of ecosystem components (biotic and abiotic as well as
terrestrial and aquatic) is different than adjacent areas in a holistic sense. Geographic phenomena
such as soils, vegetation, climate, geology, land cover, and physiology that are associated with
spatial differences in the quantity and quality of ecosystem components are relatively similar
within each ecoregion.
The Nutrient ecoregions are aggregates of U.S. EPA's hierarchal level IE ecoregions. As such,
they are more generalized and less defined than level III ecoregions. EPA determined that setting
ecoregional criteria for the large scale aggregates is not without its drawbacks - variability is high
due to the lumping of many waterbody classes, seasons, and years worth of multipurpose data
over a large geographic area. For these reasons, the Agency recommends that States and Tribes
develop nutrient criteria at the level III ecoregional scale and at the waterbody class scale where
those data are readily available. Data analyses and recommendations on both the large aggregate
ecoregion scale as well as more refined scales (level III ecoregions and waterbody classes), where
data were available to make such assessments, are presented for comparison purposes and
completeness of analysis.
Relationship of Nutrient Criteria to Biological Criteria
Biological criteria are quantitative expressions of the desired condition of the aquatic community.
Such criteria can be based on an aggregation of data from sites that represent the least-impacted
and attainable condition for a particular waterbody type in an ecoregion, subecoregion, or
watershed. EPA's nutrient criteria recommendations and biological criteria recommendations
have many similarities in the basic approach to their development and data requirements. Both
are empirically derived from statistical analysis of field collected data and expert evaluation of
current reference conditions and historical information. Both utilize direct measurements from
the environment to integrate the effects of complex processes that vary according to type and
location of waterbody. The resulting criteria recommendations, in both cases, are efficient and
holistic indicators of water quality necessary to protect uses.
States and authorized Tribes can develop and apply nutrient criteria and biological criteria in
tandem, with each providing important and useful information to interpret both the nutrient
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enrichment levels and the biological condition of sampled water-bodies. For example, using the
same reference sites for both types of criteria can lead to efficiencies in both sample design and
data analysis. In one effort, environmental managers can obtain information to support
assessment of biological and nutrient condition, either through evaluating existing data sets or
through designing and conducting a common sampling program. The traditional biological
criteria variables of benthic invertebrate and fish sampling can be readily incorporated to
supplement a nutrient assessment. To demonstrate the effectiveness of this tandem approach,
EPA has initiated pilot projects in both freshwater and marine environments to investigate the
relationship between nutrient overenrichment and apparent declines in diversity indices of benthic
invertebrates and fish.
2.0 BEST USE OF THIS INFORMATION
EPA recommendations published under section 304(a) of the CWA serve several purposes,
including providing guidance to States and Tribes in adopting water quality standards for
nutrients that ultimately provide a basis for controlling discharges or releases of pollutants. The
recommendations also provide guidance to EPA when promulgating Federal water quality
standards under section 303(c) when such action is necessary. Other uses include identification of
overenrichment problems, management planning, project evaluation, and determination of status
and trends of water resources.
State water quality inventories and listings of impaired waters consistently rank nutrient
overenrichment as a top contributor to use impairments. EPA's water quality standards
regulations at 40 CFR §131.1 l(a) require States and Tribes to adopt criteria that contain sufficient
parameters and constituents to protect the designated uses of their waters. In addition, States and
Tribes need quantifiable targets for nutrients in their standards to assess attainment of uses,
develop water quality-based permit limits and source control plans, and establish targets for total
maximum daily loads (TMDLs).
EPA expects States and Tribes to address nutrient overenrichment in their water quality standards,
and to build on existing State and Tribal initiated efforts where possible. States and Tribes can
address nutrient overenrichment through establishment of numerical criteria or through use of new
or existing narrative criteria statements (e.g., free from excess nutrients that cause or contribute to
undesirable or nuisance aquatic life or produce adverse physiological response in humans,
animals, or plants). In the case of narrative criteria, EPA expects that States and Tribes establish
procedures to quantitatively translate these statements for both assessment and source control
purposes.
The intent of developing ecoregional nutrient criteria is to represent conditions of surface waters
that are minimally impacted by human activities and thus protect against the adverse effects of
nutrient overenrichment from cultural eutrophication. EPA's recommended process for
developing such criteria includes physical classification of waterbodies, determination of current
reference conditions, evaluation of historical data and other information (such as published
literature), use of models to simulate physical and ecological processes or determine empirical
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relationships among causal and response variables (if necessary), expert judgement, and
evaluation of downstream effects. To the extent allowed by the information available, EPA has
used elements of this process to produce the information contained in this document. The values
for both causal (total nitrogen, total phosphorus) and biological and physical response
(chlorophyll a, turbidity) variables represent a set of starting points for States and Tribes to use in
establishing their own criteria in standards to protect uses.
In its water quality standards regulations, EPA recommends that States and Tribes establish
numerical criteria based on section 304(a) guidance, section 304(a) guidance modified to reflect
site-specific conditions, or other scientifically defensible methods. For many pollutants, such as
toxic chemicals, EPA expects that section 304(a) guidance will provide an appropriate level of
protection without further modification in most cases. EPA has also published methods for
modifying 304(a) criteria on a site-specific basis, such as the water effect ratio, where site-specific
conditions warrant modification to achieve the intended level of protection. For nutrients,
however, EPA expects that, in most cases, it will be necessary for States and authorized Tribes to
identify with greater precision the nutrient levels that protect aquatic life and recreational uses.
This can be achieved through development of criteria modified to reflect conditions at a smaller
geographic scale than an ecoregion such as a subecoregion, the State or Tribe level, or specific
class of waterbodies. Criteria refinement can occur by grouping data or performing data analyses
at these smaller geographic scales. Refinement can also occur through further consideration of
other elements of criteria development, such as published literature or models.
The values presented in this document generally represent nutrient levels that protect against the
adverse effects of nutrient overenrichment and are based on information available to the Agency
at the time of this publication. However, States and Tribes should critically evaluate this
information in light of the specific designated uses that need to be protected. For example, more
sensitive uses may require more stringent values as criteria to ensure adequate protection. On the
other hand, overly stringent levels of protection against the adverse effects of cultural
eutrophication may actually fall below levels that represent the natural load of nutrients for certain
waterbodies. In cases such as these, the level of nutrients specified may not be sufficient to
support a productive fishery. In the criteria derivation process, it is important to distinguish
between the natural load associated with a specific waterbody and current reference conditions,
using historical data and expert judgement. These elements of the nutrient criteria derivation
process are best addressed by States and Tribes with access to information and local expertise.
Therefore, EPA strongly encourages States and Tribes to use the information contained in this
document and to develop more refined criteria according to the methods described in EPA's
technical guidance manuals for specific waterbody types.
To assist in the process of further refinement of nutrient criteria, EPA has established ten
Regional Technical Advisory Groups (experts from EPA Regional Offices and States/Tribes). In
the process of refining criteria, States and authorized Tribes need to provide documentation of
data and analyses, along with a defensible rationale, for any new or revised nutrient criteria they
submit to EPA for review and approval. As part of EPA's review of State and Tribal standards,
EPA intends to seek assurance from the RTAG that proposed criteria are sufficient to protect uses.
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In the process of using the information and recommendations contained in this document, as well
as additional information, to develop numerical criteria or procedures to translate narrative
criteria, EPA encourages States and Tribes to:
• Address both chemical causal variables and early indicator response variables. Causal
variables are necessary to provide sufficient protection of uses before impairment occurs
and to maintain downstream uses. Early response variables are necessary to provide
warning signs of possible impairment and to integrate the effects of variable and
potentially unmeasured nutrient loads.
• Include variables that can be measured to determine if standards are met, and variables
that can be related to the ultimate sources of excess nutrients.
• Identify appropriate periods of duration (i.e., how long) and frequency (i.e., how often) of
occurrence in addition to magnitude (i.e., how much). EPA does not recommend
identifying nutrient concentrations that must be met at all times, rather a seasonal or
annual averaging period (e.g., based on weekly measurements) is considered appropriate.
However, these seasonal or annual central tendency measures should apply each season or
each year, except under the most extraordinary of conditions (e.g., a 100 year flood).
3.0 AREA COVERED BY THIS DOCUMENT
The following sections provide a general description of the aggregate ecoregion and its
geographical boundaries. Descriptions of the level III ecoregions contained within the
aggregate ecoregion are also provided.
3.1 Description of Aggregate Ecoregion XIII - Southern Florida Coastal Plain
The Southern Florida Coastal Plain is nearly level and subtropical to tropical. It is
characterized by wildlife-rich fresh water marshes, wet prairies, sloughs, swamps, and coastal
wetlands; only about 10% is used as cropland. Canals, ditches, and broad, poorly-defined stream
channels are common. Lakes are generally rare but one large, shallow, regulated lake is found in
the region, Lake Okeechobee; it links the waters of the Kissimmee Basin to the Everglades.
Elevations are low and range from sea level to less than 50 feet; only hummocks, limestone
ridges, beach ridges, and dunes relieve the flatness of the region. Poorly- and very poorly-
drained, organic soils, peat, and muck are common and overlie carbonate-rich bedrock. Most of
the Southern Florida Coastal Plain (XIE) has been set aside as parks, game refuges, water
conservation areas, and Indian reservations. However, extensive areas have also been urbanized
or drained for agriculture, resulting in the widespread alteration of hydrological and biological
systems, depletion of peat deposits, and reduction of regional water quality. Streams draining
developed areas have higher nutrient concentrations than those flowing through undeveloped
areas. Lake Okeechobee is one of the largest lakes in the United States and has been significantly
impacted by agricultural runoff. Cattle and dairy farms have contributed a large amount of
phosphorus to the lake and the Everglades Agricultural Area has pumped nitrogen-rich water into
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the lake to control flooding. During the 1970s, lake concentrations of phosphorus and nitrogen
more than doubled and bottom sediments accumulated a massive quantity of phosphorus. By the
mid-1980s, large algal blooms had occurred. State and federal government has since intervened
and both nitrogen and phosphorus inputs have been greatly reduced.
3.2 Geographic Boundaries of Aggregate Ecoregion XIII
Aggregate Nutrient Ecoregion 13
A
Figure 1. Aggregate Ecoregion XIII.
Ecoregion XIII is small compared to the other ecoregions; encompassing only the southern
quarter of Florida.
3.3 Level III Ecoregions Within Aggregate Ecoregion XIII
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Aggregate Nutrient Ecoregion 13
Ecoregion ID
D 76
Figure 2. Ecoregion XIII with level III ecoregions shown
76. SOUTHERN FLORIDA COASTAL PLAIN
The frost free climate of the Southern Florida Coastal Plain makes it distinct from other
ecoregions in the conterminous United States. This region is characterized by flat plains with wet
soils, marshland and swamp land cover with everglades and palmetto prairie vegetation types.
Although portions of this region are in parks, game refuges, and Indian reservations, a large part
of the region has undergone extensive hydrological and biological alteration.
Suggested Ecoregional subdivisions or adjustments
EPA recommends that the RTAG evaluate the adequacy of EPA nutrient ecoregional and
subecoregional boundaries and refine them as needed to reflect local conditions.
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4.0 DATA REVIEW FOR LAKES AND RESERVOIRS IN AGGREGATE
ECOREGIONXIII
The following section describes the nutrient data EPA has collected and analyzed for this
Ecoregion, including an assessment of data quantity and quality. The data tables present the data
for each causal parameter— total phosphorus and total nitrogen (both reported and calculated from
TKN and nitrite/nitrate), and the primary response variables— some measure of turbidity and
chlorophyll a. These are the parameters which EPA considers essential to nutrient assessment
because the first two are the main causative agents of enrichment and the two response variables
are the early indicators of system enrichment for most of the surface waters. (See Chapter 5 of the
Lakes and Reservoirs Nutrient Criteria Guidance Manual (U.S. EPA, 2000a) for a complete
discussion on choosing causal and response variables.)
4.1 Data Sources
Data sets from Legacy STORET were used to assess nutrient conditions from 1990 to
1999. EPA recommends that the RTAGs identify additional data sources that can be used to
supplement the data sets listed above. In addition, the RTAGs may utilize published literature
values to support quantitative and qualitative analyses.
4.2 Historical Data from Aggregate Ecoregion XIII (TP, TN, Chlor a and Secchi Depth)
EPA recommends that States/Tribes assess long-term trends observed over the past 50
years. This information may be obtained from scientific literature or documentation of historical
trends. To gain additional perspective on more recent trends, it is recommended that States and
Tribes assess nutrient trends over the last 10 years (e.g., what do seasonal trends indicate?)
4.3 QA/QC of data sources
An initial quality screen of data was conducted using the rules presented in Appendix C.
Data remaining after screening for duplications and other QA measures (.e.g., poor or unreported
analytical records, sampling errors or omissions, stations associated with outfalls, storm water
sewers, hazardous waste sites) were used in the statistical analyses.
The State of Florida was contacted regarding the quality of their data. The State of Florida
provided information on the methods used to sample and analyze their waters. In all cases, the
State indicated a Standard method or an approved EPA method was used. :
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4.4 Data for all Lakes/Reservoirs within Aggregate Ecoregion XIII
The map in Figure 2 shows the location of the sampling stations within each sub
ecoregion. Table 1 presents all data records for all parameters for Aggregate Ecoregion XIII and
subecoregions within the Aggregate Ecoregion.
10
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Aggregate Nutrient Eeoregion 13
Lake and Reservoir Stations
Fonda
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Level til Ecoregions
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Stations
60
FigureS Map of sampling locations within each level III ecoregion
11
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Table 1. Lake records for Aggregate Ecoregion XIII - Southern Florida Coastal
Plain
# of lakes
# of Lake Stations
Key Nutrient Parameters (listed
below)
- # of records for Secchi depth
- # of records for Chlorophyll a
(all methods)
- # of records for Total Kjeldahl
Nitrogen (TKN)
- # of records for Nitrate +
Nitrite (NO2+NO3)
- # of records for Total Nitrogen
(TN)
- # of records for Total
Phosphorus (TP)
Total # of records for key
nutrient parameters
Aggregate
Ecoregion
Xffl
16
88
4302
4004
8895
8776
4536
9097
39,610
Sub
ecoR 76
16
88
4302
4004
8895
8776
4536
9097
39,610
12
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Definitions usedto complete Table I:,.
I, # of records refers to the total count of observations for that
parameter over the entire.decade (1990-1999) for that particular
aggregate or subecoregiort These are counts' for all seasons over
that decade.
2. # of lake stations refers to "the total number of lake and
reservoir stations within the aggregate or subecoregion-from
which nutrient'data were collected. 'Since lakes andTeservoirs
can cross ecoregional boundaries, jt is important to note that only
those portions of alake or reservoir (and>!data associated with
those stations) that exist within the ecoregion are included within
this table,
4.5 Statistical Analysis of Data
EPA's Technical Guidance Manual for Developing Nutrient Criteria for Lakes and
Reservoirs describes two ways of establishing a reference condition. One method is to choose the
upper 25th percentile (75th percentile) of a reference population of lakes. This is the preferred
method to establish a reference condition. The 75th percentile was chosen by EPA since it is
likely associated with minimally impacted conditions, will be protective of designated uses, and
provides management flexibility. When reference lakes are not identified, the second method is to
determine the lower 25th percentile of the population of all lakes within a region. The 25th
percentile of the entire population was chosen by EPA to represent a surrogate for an actual
reference population. Data analyses to date indicate that the lower 25th percentile from an entire
population roughly approximates the 75th percentile for a reference population. See case studies
for Minnesota lakes in the Lakes and Reservoirs Nutrient Criteria Technical Guidance Document
(U.S. EPA, 2000a) and the case study for Tennessee streams in the Rivers and Streams Nutrient
Criteria Technical Guidance Document (U.S. EPA, 2000b), and the letter from Tennessee
Department of Environment and Conservation to Geoffrey Grubbs [TNDEC, 2000]). New York
State has also presented evidence that the 25th percentile and the 75 percentile compare well based
on user perceptions of water resources (NYSDEC., 2000)
The following tables 2 and 3 a, present the potential reference conditions for both the
aggregate ecoregion and the subecoregions using both methods. However, the reference lake
column is left blank because EPA does not have reference data and anticipates that States will
provide information on reference lakes. Appendix A provides a complete presentation of all
descriptive statistics for both the aggregate ecoregion and the level III subecoregion.
13
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Table 2.
Reference conditions for aggregate ecoregion XIII lakes.
Parameter
TKN (mg/L)
N02 + NO3(mg/L)
TN (mg/L) - calculated
TN (mg/L) -reported
TP(«g/L)
Sccchi (meters)
Chlorophyll a (ug/L) - F
Chlorophyll a (ug/L) - S
Chlorophyll a (wg/L) - T
No. of
Lakes
N~
10
10 •
NA
7
10
9
Iz
Iz
9
Reported values
Min
1.14
0.002
1.14
1.15
10
0.418
6.6
3.35
7.65
Max
2.89
0.11
3.00
3.04
108
1.19
6.6
3.35
29.1
25th Percentiles based on all
seasons data for the Decade
P25* all seasons +
1.30-
0.01
1.31
1.27
17.5
0.79
6.6
3.35
12.35
Reference Lakes **
P75 all seasons
P25r
P75:
**
F
S
T
NA
25* percentile of all data
75* percentile of all data
as determined by the Regional Technical Assistance Groups (RTAGs)
Median for all seasons' 25th percentiles. E.g. this value was calculated from four seasons' 25lh
percentiles. If the seasonal 25* percentile (P2S) IP values are - spring lOwg/L, summer
ISug/L, fall l2ug/L, and winter 5ag/L, the median value of all seasons P25 will be 11 «g/L. *
N = largest value reported for a decade / Season.
TN calculated is based on the sum of TKN + KO2+NO3>
TN reported is actual TN value reported in the database for one sample.
Chlorophyll a measured by Fluorometric method with acid correction.
Chlorophyll a measured by Spectrophotometric method with acid correction.
Chlorophyll a be measured by Trichromatic method,
Not Applicable
Table 3 a presents the potential reference conditions for lakes and reservoirs in the Level
HI subecoregions within the Aggregate Ecoregion. The footnotes for Table 2 apply to table 3a.
14
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Table 3a. Reference conditions for Subecoregion 76 ecoregion XIII lakes.
Parameter
TKN (mg/L)
NO2 + NO3(mg/L)
TN (mg/L) - calculated
TN (mg/L) - reported
TP («g/L)
Secchi (meters)
Chlorophyll a («g/L) - F
Chlorophyll a (ag/L) - S
Chlorophyll a («g/L) - T
No. of
Lakes
N~
10
10
NA
7
10
9
1 z
Iz
9
Reported values
Min
1.14
0.002
1.14
1.15
10
0.418
6.6
3.35
7.65
Max
2.89
0.11
3.00
3.04
108
1.19
6.6
3.35
29.1
25th Percentiles based on all
seasons data for the Decade
P25* all seasons +
1.30
0.01
1.31
1.27
17.5
0.79
6.6
3.35
12.35
Reference Lakes
. **
P75 all seasons
15
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Definitions used in filling Tables 2 and 3 - Reference Condition-tables
1. Number of Lakes in Table 2 refers to the largest number of lakes and reservoirs for
which data existed for a given season within an aggregate nutrient ecoregion.
2. Number of Lakes in Table 3 refers to the number of lakes and reservoirs for which
data existed for the summer months since summer is generally when the greatest
amount of nutrient sampling is conducted. If another season greatly predominates,
notification is made (s=spring, f=fall, w=winter).
3. Medians. All values (min, max, and 25th percentiles) included in the table are based
on waterbody medians. All data for a particular parameter within a lake for the decade
were reduced to one median for that lake. This prevents over-representation of
individual waterbodies with a great deal of data versus those with fewer data points
within the statistical analysis. :,
4. 25"1 percentile for all seasons is calculated by taking the median of the 4 seasonal
25th percentiles. If a season is missing, the median .was calculated with 3 seasons of
data. If less than 3 seasons were used to derive the median, the entry is flagged (z).
5. A 25th percentile for a season is best derived with-data from a minimum of 4 -
lakes/season. However, this table provides 25
-------
N/A is placed in this box.
3. TN reported: This is the median based on reported values for TN from the database.
4. Chlorophyll a: Medians based on all methods are reported, however, the acid corrected
medians are preferred to the uncorrected medians. In developing a reference condition from a
particular method, it is recommended that the method with the most observations be used.
Fluorometric and Spectrophotometric are preferred over all other methods. However, when no
data exist for Fluorometric and Spectrophotometric methods, Trichromatic values may be used.
Data from the variance techniques are not interchangeable.
5. Periphyton: Where periphyton data exist, record them separately For periphyton-dominated
streams, a measure of periphyton chlorophyll is a more appropriate response variable than
planktonic chlorophyll a. See Table 4, p. 101 of the Rivers and Streams Nutrient Technical
Guidance Manual (U. S. EPA, 2000b) for values of periphyton and planktonic chlorophyll a
related to eutrophy in streams.
6. Secchi depth: The 75th percentile is reported for Secchi depth since this is the only variable for
which the value of the parameter increases with greater clarity. (For lakes and reservoirs only.)
7. Turbidity units: All turbidity units from all methods are reported. FTUs and NTUs are
preferred over JCUs. If FTUs and NTUs do not exist, use JCUs. These units are not
interchangeable. Turbidity is chosen as a response variable in streams since it can be an indicator
of increasing algal biomass due to nutrient enrichment. See pages 32 -33 of the Rivers and
Streams Nutrient Technical Guidance Manual for a discussion of turbidity and correlations with
algal growth.
8. Lack of data: A dash (-) represents missing, inadequate, or inconclusive data. A zero (0) is
reported if the reported median for a parameter is 0 or if the component value is below detection.
4.6. Classification of Lake/Reservoir Type
It is anticipated that assessing the data by lake type will further reduce the variability in the data analysis.
There was no readily available classification data in the National datasets used to develop these criteria to
make this assessment for this ecoregion and set of subecoregions, but it is strongly encouraged that this
assessment be made before a State or Tribe develops a final criterion.
4.7. Summary of Data Reduction Methods
All descriptive statistics were calculated using the medians for each lake within ecoregion
XIII, for which data existed. For example, if one lake had 300 observations for phosphorus over
17
-------
the decade or one year's time, one median resulted. Each median from each lake was then used in
calculating the percentiles for phosphorus for the aggregate nutrient ecoregion/subecoregion (level
HI ecoregion) by season and year (Figure 4a & b).
Observations for All Lakes/Reservoirs
Ecoregion
Winter
Rainy Lake Median
Fish Reservoir Median
Swan Lake Median
Moon Lake...
Timber...
Spring
Data Reduced
to
Median Value
for each
Lake/Reservoir
by
Season
Summer
Fall
Rainy Lake Median
Fish Reservoir Median
Swan Lake Median
Moon Lake ...
Timber...
Rainy Lake Median
Fish Reservoir Median
Swan Lake Median
Moon Lake ...
Timber...
Rainy Lake Median
Fish Reservoir Median
Swan Lake Median
Moon Lake ...
Timber...
Figure 4a. Illustration of data reduction process for lake data.
18
-------
25th
Winter
25%
Select 25th Percentile
from Distribution
of Median
Values
25%
Spring
Summer
25%
Fall
TP 1
TN IP
TKN f
NO2+NO3 •*
Calculate Median
Value of the
25th Percentiles
for the Four Seasons
Itj
Half values ^Jf!
Below Median ^~
25%
1 1
125% 25%
Season A Season B
75%
JgL. Half values
•"""^ Above Median
1 1
25% 25%
Season C Season D
Median = Reference Condition for the Ecoregion
Figure 4b. Illustration of reference condition calculation.
19
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5.0 REFERENCE SITES AND CONDITIONS IN AGGREGATE ECOREGION XIII
Reference conditions represent the natural, least impacted conditions or what is considered
to be the most attainable conditions. This section compares the different reference conditions
determined from the two methods and establishes which reference condition is most appropriate.
A priori determination of reference sites. The preferred method for establishing reference
condition is to choose the upper percentile of an a priori population of reference lakes. States and
Tribes are encouraged to identify reference conditions based on this method.
Statistical determination of reference conditions (25th percentile of entire database.^ See Tables 2
and 3a-f in section 4.0.
RTAG discussion and rationale for selection of reference sites and conditions in Ecoregion VI.
The RTAG should compare the results derived from the two methods described above and present
a rationale for the final selection of reference sites.
6.0 MODELS USED TO PREDICT OR VERIFY RESPONSE PARAMETERS
The RTAG is encouraged to identify and apply relevant models to support nutrient criteria
development. The following are three scenarios under which models may be used to derive
criteria or support criteria development.
• Models for predicting correlations between causal and response variables
• Models used to verify reference conditions based on percentiles
• Regression models used to predict reference conditions in impacted areas
7.0 FRAMEWORK FOR REFINING RECOMMENDED NUTRIENT CRITERIA FOR
LAKES AND RESERVOIRS IN AGGREGATE ECOREGION XIII
Information on each of the following six weight of evidence factors is important to refine
the criteria presented in this document. All elements should be addressed in developing criteria,
as is expressed in our nutrient criteria technical guidance manuals. It is our expectation that EPA
Regions, States, and Tribes (as RTAGs) will consider these elements as States/Tribes develop
their criteria. This section should be viewed as a work sheet (sections are left blank for this
20
-------
purpose) to assist in the refinement of nutrient criteria. If many of these elements are ultimately
unaddressed, EPA may rely on the proposed reference conditions presented in Tables 3 a and other
literature and information readily available to the HQ nutrient team to develop nutrient water
quality recommendations for this ecoregion.
7.1 Example Worksheet for Developing Aggregate Ecoregion and Subecoregion Nutrient
Criteria
Literature sources
Historical data and trends
• Reference condition
Models
RTAG expert review and consensus
Downstream effects
21
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7.2 Tables of Refined Nutrient Water Quality Criteria for Aggregate Ecoregion XIII and
Level III Subecoregions for TP, TN, Chi a, Turbidity (where sufficient data exist)
Aggregate Ecoregion XIII- Southern
Florida Coastal Plain
Total Phosphorus C"g/L)
Total Nitrogen (mg/L)
Chlorophyll a (/"g/L or mg/m2)
Secchi depth (meters)
Other (Index; other parameter such as DO)
Proposed Criterion
7.3 Setting Seasonal Criteria
The criteria presented in this document are based in part on medians of all the 25th
percentile seasonal data (decadal), and as such are reflective of all seasons and not one particular
season or year. It is recommended that States and Tribes monitor in all seasons to best assess
compliance with the resulting criterion. States/Tribes may choose to develop criteria which
reflect each particular season or a given year when there is significant variability between
seasons/years or designated uses that are specifically tied to one or more seasons of the year (e.g.,
recreation, fishing). Using the tables in Appendix A and B, one can set reference conditions
based on a particular season or year and then develop a criterion based on each individual season.
Obviously, this option is season-specific and would also require increased monitoring within each
season to assess compliance.
7.4 When Data/Reference Conditions are Lacking
When data are unavailable to develop a reference condition for a particular parameter(s)
within a subecoregion, EPA recommends one of three options: 1. Use data from a similar
neighboring subecoregion. E.g., If data are few or nonexistent for the northern cascades, consider
using the data and reference condition developed for the cascades; or 2. Use the 25th perecentiles
for the Aggregate ecoregion or 3. Consider using the lowest of the yearly medians for that
parameter calculated for all the subecoregions within the Aggregate Ecoregion.
7.5 Site-specific Criteria Development
Criteria may be refined in a number of ways. The best way to refine criteria is to follow
22
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the critical elements of criteria development as well as to refer to the Lakes and Reservoirs
technical guidance manual (U. S. EPA, 2000a).
The Lakes and Reservoirs Nutrient Criteria Technical Guidance Manual presents sections
on each of the following factors to consider in setting criteria
- refinements to ecoregions (Chapter 3)
- classification of waterbodies (Chapter 3)
- setting seasonal criteria to reflect major seasonal climate differences (Chapter 7)
- accounting for significant or cyclical rainfall events - high flow/low flow conditions (Chapter
•7)
setting criteria for reservoirs only (The technical guidance manual recommends that data be
separated for lakes and reservoirs and treated independently if possible because of differing
physical conditions that occur in lakes and reservoirs. In this document all data from both
reservoirs and lakes were considered together since STORET does not allow for the
differentiation of data except by waterbody name.)
8.0 LITERATURE CITED
NYSDEC (New York State Department of Environment and Conservation). 2000.
Memorandum from Scott Kishbaugh to Jay Bloomfield, September 26, 2000, regarding
reference lakes for nutrient criteria.
TNDEC (Tennessee Department of Environment and Conservation). 2000. Letter to
Geoff Grubbs, October 5, 2000, containing comments on draft nutrient criteria
recommendations.
U.S. EPA. 2000a. Nutrient Criteria Technical Guidance Manual: Lakes and Reservoirs,
U.S. Environmental Protection Agency, Washington, DC. EPA-822-BOO-001.
U.S. EPA. 2000b. Nutrient Criteria Technical Guidance Manual: Rivers and Streams,
U.S. Environmental Protection Agency, Washington, DC. EPA-822-BOO-002.
9.0 APPENDICES
A. Descriptive Statistics Data Tables for Aggregate Ecoregion
B. Descriptive Statistics Data Tables for Level HI Subecoregions within Aggregate Ecoregion
C. Quality Control/Quality Assurance Rules
23
-------
-------
APPENDIX A
Descriptive Statistics Data Tables for Aggregate Ecoregion
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-------
APPENDIX C
Quality Control/Quality Assurance Rules
-------
-------
INDUS
CORPORATION
Know! edge-Based Sol lit ions
Support for the Compilation and Analysis of
National Nutrient Data
15 Nutrient Ecoregion/Waterbody Type Summary
Chapters .'
Prepared for:
Robert Cantiili
Environmental Protection Agency
OW/OST/HECD
Prepared by:
INDUS Corporation
1953 Gallows Road
Vienna, Virginia 22182
Contract Number:
Task Number:
Subtask Number:
68-C-99-226
04
4
August 8, 2000
-------
-------
15 Nutrient Ecoregion/Waterbody Type Summary Chapters, Contract # 68-C-99-226, TO# 04
CONTENTS
August 8, 2000
1.0 BACKGROUND 1
1.1 Purpose 1
1.2 References - - - - 1
2.0 QA/QC PROCEDURES - 2
2.1 National Data Sets • 3
2.2 State Data 3
2.3 Laboratory Methods • 4
2.4 Waterbody Name 4
2.5 Ecoregion Data • 5
3.0 STATISTICAL ANALYSIS REPORTS .... 5
3.1 Data Source Reports • 6
3.2 Remark Code Reports • 7
3.3 Median of Each Waterbody 7
3.4 Descriptive Statistic Reports 7
3.5 Regression Models :.... 8
4.0 TIME PERIOD - • • • : .... 8
5.0 DATA SOURCES AND PARAMETERS FOR THE AGGREGATE NUTRIENT
ECOREGIONS • 9
5.1 Lakes and Reservoirs 9
5.1.1 Aggregate Nutrient Ecoregion 2 9
5.1.2 Aggregate Nutrient Ecoregion 6 • • *0
5.1.3 Aggregate Nutrient Ecoregion 7 10
5.1.4 Aggregate Nutrient Ecoregion 8 : :...!!
5.1.5 Aggregate Nutrient Ecoregion 9 12
5.1.6 Aggregate Nutrient Ecoregion 11 12
5.1.7 Aggregate Nutrient Ecoregion 12 -• 1... 13
5.1.8 Aggregate Nutrient Ecoregion 13 13
5.2 Rivers and Streams 14
5.2.1 Aggregate Nutrient Ecoregion 2 14
5.2.2 Aggregate Nutrient Ecoregion 3 15
5.2.3 Aggregate Nutrient Ecoregion 6 , !6
5.2.4 Aggregate Nutrient Ecoregion 7 16
5.2.5 Aggregate Nutrient Ecoregion 9 *7
5.2.6 Aggregate Nutrient Ecoregion 11 18
5.2.7 Aggregate Nutrient Ecoregion 12 • 19
11
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15 Nutnnu Ecoregion/Waterbody Type Summary Chapters. Contract # 68-C-99-226. TO# 04
5.2.8 Aggregate Nutrient Ecoregion 14
August 8,2000
20
APPENDIX A
APPENDIX B
APPENDIX C
Process Used to QA/QA the Legacy STORE! Nutrient Data Set
Process for Adding Aggregate Nutrient Ecoregions and Level HI
Ecoregions
Glossary
111
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15 Nutneni Ecoreaion/Waterbody Type Summary Chapters. Contract # 68-C-99-226, TO# 04
— * f.
1.0 BACKGROUND
August 8. 2000
The Nutrient Criteria Program has initiated development of a national Nutrient Criteria Database
application that will be used to store and analyze nutrient data. The ultimate use of these data
will be to derive ecoregion- and waterbody-specific nutrient criteria ranges. EPA converted
STOrage and RETrieval (STORET) legacy data, National Stream Quality Accounting Network
(NASQAN) data, National Water-Quality Assessment (NAWQA) data, and other relevant
nutrient data from universities and States/Tribes into the database. The data imported into the
Nutrient Criteria Database will be used to develop national nutrient criteria ranges.
1.1 Purpose
The purpose of this deliverable is to provide EPA with information regarding the data used to
create the statistical reports which will be used to derive ecoregion- and waterbody-specific
nutrient criteria ranges for Level HI ecoregions. There are fourteen aggregate nutrient
ecoregions. Each aggregate nutrient ecoregion is divided into smaller ecoregions referred to as
Level m ecoregions. EPA will determine criteria ranges for the waterbody types and Level m
ecoregions within the following aggregate nutrient ecoregions:
• Lakes and Reservoirs
Aggregate Nutrient ecoregions: 2,6,7, 8, 9, 11, 12,13
• Rivers and Streams ,
Aggregate Nutrient ecoregions: 2, 3, 6, 7, 9, 11, 12, 14
1.2 References
This section lists documents that contain baselines, standards, guidelines, policies, and references
that apply to the data analysis. Listed editions were valid at the time of publication. All
documents are subject to revision, but these specific editions govern the concepts described in
this document. . •
Nutrient Criteria Technical Guidance Manual: Lakes and Reservoirs (Draft).- EPA, Office of
Water, EPA 822-D-99-001, April 1999.
Nutrient Criteria Technical Guidance Manual: Rivers and Streams (Draft). EPA. Office of
Water. EPA 822-D-99-003, September 1999.
Guidance for Data Quality Assessment: Practical Methods for Data Analysis. EPA, Office of
Research and Development, EPA QA/G-9, January 1998.
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15 Nutrient Ecorcgion/Waterbody Type Summary Chapters, Contract # 68-C-99-226. TO# 04
2.0 QA/QC PROCEDURES
August 8, 2000
In order to develop nutrient criteria, EPA needed to obtain nutrient data from the states. EPA
requested nutrient data from the states and forwarded the data sets to INDUS via e-mail and/or
US mail. In addition, EPA tasked INDUS to convert data from three national data sets. EPA
provided INDUS with a Legacy STORET extraction to convert into the database. The United
States Geologic Survey (USGS) sent INDUS a CD-ROM with NASQAN data to convert.
INDUS downloaded NAWQA files from the USGS Web site to convert the data. In total,
INDUS converted and imported the following national and state data sets into the Nutrient
Criteria Database:
Legacy STORET
NAWQA
NASQAN
• Region 1
• Region 2 - Lake Champlain Monitoring Project
• Region 2 - NYSDEC Finger Lakes Monitoring Program
• Region 2 - NY Citizens Lake Assessment Program
• Region 2 - Lake Classification and Inventory Survey
Region 2 - NYCDEP (1990-1998)
Region 2 - NYCDEP (Storm Event data)
• Region 2 - New Jersey Nutrient Data (Tidal Waters)
• Region 5
• Regions.
• Region 3 - Nitrite Data
• Region 3 - Choptank River files
• Region 4 - Tennessee Valley Authority
• Region 7 - Central Plains Center for BioAssessment (CPCB)
Region 7 - REMAP
• Region 2 - Delaware River Basin Commission (1990-1998)
Region 3 - PA Lake Data
• Region 3 - University of Delaware
Region 10
• University of Auburn
As part of the conversion process, INDUS performed a number of Quality Assurance/Quality
Control (QA/QC) steps to ensure that the data was properly converted into the Nutrient Criteria
Database. Section 2 explains the steps performed by INDUS to convert the data.
_
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15 Nument Ecoregiom Waterbody Type Summary Chapters. Contract # 68-C-99-226, TO# 04
2.1 National Data Sets
August 8.2000
INDUS converted three national data sets into the Nutrient Criteria Database: Legacy STORET
data, NASQAN data, and NAWQA data. A previous EPA contractor performed the extraction of
Legacy STORET data and documented the QA/QC procedures used on the data. This
documentation is included in Appendix A. INDUS performed minimal QA/QC on the Legacy
STORET data set because the previous contractor completed the steps outlined in Appendix A.
INDUS and EPA also agreed to convert the NAWQA and NASQAN data sets with minimal
QA/QC on the assumption that the source agency, the USGS, QA/QC'd the data.
For each of the three national data sets, INDUS ran queries to determine if 1) samples existed
without results and 2) if stations existed without samples. Per Task Order Project Officer
(TOPO) direction, these records were deleted from the system. For analysis purposes, EPA
determined that there was no need to keep station records with no samples and sample records
with no results. INDUS also confirmed that each data set contained no duplicate records.
In addition, INDUS deleted all composite results from the Legacy STORET data. Per TOPO
direction, jl was decided that composite sample results would not be used in the statistical
analysis. "?' ' ' *• *-=...,:**-.- . ... . • ^cs?;.^- • •- ' :
2.2 State Data
Each state data set was delivered in a unique format. Many of the data sets were delivered to
INDUS without corresponding documentation. INDUS analyzed each state data set in order to
determine which parameters should be converted for analysis. INDUS obtained a master ,
parameter table from EPA and converted the parameters in the state data sets according to those
that were present in the EPA parameter table. INDUS converted all of the data elements in the
state data sets that mapped directly to the Nutrient Criteria Database; data elements that did not,
map to the Nutrient Criteria Database were not converted. In some cases, state data elements that
did not directly map into the Oracle database were inserted into a comment field within the
database. Also. INDUS maintained an internal record of which state data elements were inserted
into the comment field.
As part of the data clean-up efforts, INDUS determined whether or not there were any duplicate
records in the state data sets and deleted the duplicate records. INDUS checked the waterbody,
station and sample entities for duplicate records. In addition, INDUS deleted station records
with no samples and sample records with no results. INDUS also deleted waterbody records that
were not associated with a station. In each case, INDUS maintained an internal record of how
many records were deleted.-
If INDUS encountered referential integrity errors, such as samples that referred to stations that
did not exist, or if INDUS was unsure of whether a record was a duplicate, INDUS contacted the
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15 Nutrient Ecoregion/Waterfaody Type Summary Chapters. Contract 2 68-C-99-226. TO* 04 Auaus: 8 7000
agency directly via e-mail or phone to resolve any issues that arose. INDUS saved an electronic
copy of each e-mail correspondence with the states to ensure that a record of the decision was
maintained. INDUS also contacted each agency to determine which laboratory methods were
used for each parameter.
Finally, INDUS examined the remark codes of each result record in the state data sets. INDUS
mapped the remark codes to the STORET remark codes listed in Table 2 of Appendix A. If any
of the state result records were associated with remark codes marked as "Delete" in Table 2 of
Appendix A, the result records were not converted into the database.
2.3 Laboratory Methods
Many of the state data sets did not contain laboratory method information. In addition,
laboratory method information was not available for the three national data sets. In order to
determine missing laboratory method information, EPA tasked another contractor to contact the
data owners to obtain the laboratory method. In some cases, the data owners responded and the
laboratory methods were added to the database.
2.4 Waterbody Name and Class Information
A large percentage of the data did not have waterbody-specific information. The only waterbody
information contained in the three national data sets was the waterbody name, which was
embedded in the station 'location description' field. Most of the state data sets contained
waterbody name information; however, much of the data was duplicated throughout the data sets.
Therefore, the waterbody information was cleaned manually. For the three national data sets, the
'location description' field was extracted from the station table and moved to a temporary table.
The 'location description' field was sorted alphabetically. Unique waterbodies were grouped
together based on name similarity and whether or not the waterbodies fell within the same
county, state, and waterbody type. Finally, the 'location description' field was edited to include
only waterbody name information, not descriptive information. For example, 110 MILE CREEK
AT POMONA DAM OUTFLOW, KS PO-2 was edited to 110 MILE CREEK. Also, if 100
MILE CREEK was listed ten times in New York, but in four different counties, four 100 MILE
CREEK waterbody records were created.
Similar steps were taken to eliminate duplicate waterbody records in the state data sets. If a
number of records had similar waterbody names and fell within the same state, county, and
waterbody type, the records were grouped to create a unique waterbody record.
Most of the waterbody data-did not contain depth, surface area, and volume measurements. EPA
needed this information to classify waterbody types. EPA attempted to obtain waterbody class
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15 Nutrient Ecorcgiorv Waterbody Type Summary Chapters, Contract * 68-C-99-226. TO# 04 August 8.2000
information from the states. EPA sent waterbody files to the regional coordinators and requested
that certain class information be completed by each state. The state response was poor; therefore,
EPA was not able to perform statistical analysis for the waterbody types by class.
2.5 Ecoregion Data
Aggregate nutrient ecoregions and Level in ecoregions were added to the database using the
station latitude and longitude coordinates. If a station was lacking latitude and longitude
coordinates or county information, the data were not included in the statistical analysis.
Appendix B lists the steps taken to add the two ecoregion types (aggregate and Level IE) to the
Nutrient Criteria Database. The ecoregion names were pulled from aggregate nutrient ecoregion
and Level HI ecoregion Geographical Information System (GIS) coverages. In summary, the
station latitude and longitude coordinates were used to determine the ecoregion under the •
following circumstances:
The latitude and longitude coordinates fell within the county/state listed in the station
table.
The county data was missing.
The county centroid was used to determine the ecoregions under the following circumstances:
The latitude and longitude coordinates were missing, but the state/county information was
available.
The latitude and longitude coordinates fell outside the county/state listed in the station
table. The county information was assumed to be correct; therefore, the county centroid
was used.
If the latitude and longitude coordinates fell outside the continental US county coverage file
(i.e., the point fell in the ocean or Mexico/Canada), the nearest ecoregion was assigned to the
station.
3.0 STATISTICAL ANALYSIS REPORTS
Aggregate nutrient ecoregion tables were created by extracting all observations for a specific
aggregate nutrient ecoregion from the nutrient criteria database. Then, the data were reduced to
create tables containing only the yearly median values. To create these tables, the median value
for each waterbody was calculated using all observations for each waterbody by Level IE
ecoregion, year, and season. Tables of decade median values were created from the yearly
median tables by calculating the median for each waterbody by L^vel III ecoregion by decade and
season.
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15 Nutnent Ecorcgion/Waierbody Type Summary Chapters, Contract # 68-C-99-226, TO* 04
August 8,2000
The Data Source and the Remark Code reports were created using all observations (ail reported
values). All the other reports were created from either the yearly median tables or the decade
median tables. In other words, the descriptive statistics and regressions were run using the
median values for each waterbody and not the individual reported values.
Statistical analyses were performed under the assumption that this data set is a random sampled
If this'assumption cannot be verified, the observations may or may not be valid. Values below
the Pl and 99th percentile were removed from the Legacy STORE! database prior to the creation
of the national database. Also, data were treated according the Legacy STORET remark codes in
Appendix A.
The following contains a list of each report and the purpose for creating each report:
• Data Source—Created to provide a count of the amount of data and to identify the
source(s).
• Remark Codes—Created to pro vide a description of the data.
• Median of Each Waterbody by Year—This was an intermediate step performed to obtain
a median value for each lake to be used in the yearly descriptive statistics reports and the
regression models.
• Median of Each Waterbody by Decade—This was an intermediate step performed to
obtain a median value for each lake to be used in the decade descriptive statistics.
• Descriptive Statistics—Created to provide EPA with the desired statistics for setting
criteria levels.
• Regression Models—Created to examine the relationships between biological and
nutrient variables.
Note: Separate reports were created for each season.
»
3.1 Data Source Reports
Data source reports were presented in the following forlha'ts:
• The number and percentage of data from each data source were summarized in tables for
each aggregate nutrient ecoregion by season and waterbody type.
• The number and percentage of data from each data source were summarized in tables for
each Level III ecoregion by season and waterbody type.
The 'Frequency' represent? the number of data values from a specific data source for each
parameter by data source. The 'Row Pet' represents the percentage of data from a specific data
source for each parameter.
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15 Nutrient Ecoregion/Waterbody Type Summary Chapters. Contract # 68-C-99-226, TO# 04 August 8. 2000
3.2 Remark Code Reports
Remark code reports were presented in the following formats:
• The number and percentage of data associated with a particular remark code for each
parameter were summarized in-tables by Level HI ecoregion by decade and season.
• The number and percentage of data associated with a particular remark code for each
parameter were summarized in tables by Level HI ecoregion by year and season.
The 'Frequency' represents the number of data values corresponding to the remark code in the
column. The 'Row Pet' represents the percentage of data that was associated with the remark
code in that row.
In the database, remark codes that were entered by the states were mapped to Legacy STORET
remark codes. Prior to the analysis, the data were treated according to these remark codes. For
example, if the remark code was 'K,' then the reported value was divided by two. Appendix A
contains a complete list of Legacy STORET remark codes.
Note: For the reports, a remark code of 'Z' indicates that no remark codes were recorded. It does
not correspond to Legacy STORET code'Z.'
3.3 Median of Each Waterbody
To reduce the data and to ensure heavily sampled waterbodies or years were not over represented
in the analysis, median value tables (described above) were created. The yearly median tables
and decade median tables were delivered to the EPA in electronic format as csv (comma
separated value or comma delimited) files. •
3.4 Descriptive Statistic Reports
The number of waterbodies, median, mean, minimum, maximum, 5th, 25th , 75th , 95th percentiles,
standard deviation, standard error, and coefficient of variation were calculated. The tables
(described above) containing the decade median values for each waterbody for each parameter
were used to create descriptive statistics reports for:
Level III ecoregions by decade and season
Aggregate nutrient ecoregions by decade and season
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15 Nutrient Ecoregion/Waterfaody Type Summary Chapters. Contract # 68-C-99-226, TO# 04
August 8. 2000
In addition, the tables containing the yearly median values for each waterbody for each parameter
were used to create descriptive statistics reports for:
• Level HI ecoregions by year and season
3.5 Regression Models
Simple linear regressions using the least squares method were performed to examine the
relationships between biological and nutrient variables in lakes and reservoirs, and rivers and
streams. Regressions were performed using the yearly median tables. Chlorophyll(s) in
micrograms per liter (ug/L), secchi in meters (m), dissolved oxygen in milligrams per liter
(mg/L), turbidity, and pH were the biological variables in these models. When there was little or
no data for chlorophyll, then pH or dissolved oxygen was substituted for chlorophyll. .Secchi'
data were used in the lake and reservoir models, and turbidity data were used in the river and
stream models. The nutrient variables in these models include: total phosphorus in ug/L, total
nitrogen in mg/L, total kjeldahl nitrogen in mg/L, and nitrate and nitrite in mg/L. Regressions
were also run for total nitrogen and total'phosphorus for ecoregions where both these variables
were measured.
•»
Note: At the time of creation of this document only regressions for aggregate nutrient ecoregion 7
for lakes and reservoirs were delivered to the EPA. Regressions for the remaining aggregate
nutrient ecoregions will be delivered in August 2000.
4.0 TIME PERIOD
Data collected from January 1990 to December 1999 were used in the statistical analysis reports.
To capture seasonal differences, the data were classified as follows:
• Aggregate nutrient ecoregions: 6, 7, and 8
- Spring: April to May
- Summer: June to August
- Fall: September to October
- Winter: November to March
• Aggregate nutrient ecoregions: 1, 2, 9, 10, 11, 12, and 13
Spring: - March to May
- Summer: June 'to August
Fall: September to November
Winter: December to February
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August 8.2000
5.0 DATA SOURCES AND PARAMETERS FOR THE AGGREGATE NUTRIENT
ECOREGIONS
This section provides information for the nutrient aggregate ecoregions that were analyzed by
waterbody type. Each section lists the data sources for the aggregate nutrient ecoregion
including: 1) the data sources, 2) the parameters included in the analysis, and 3) the Level HI
ecoregions within the aggregate nutrient ecoregions.
Note: For analysis purposes, the following parameters were combined to form Phosphorous,
Dissolved Inorganic (DIP):
Phosphorus, Dissolved Inorganic (DIP)
Phosphorus, Dissolved (DP)
Phosphorus, Dissolved Reactive (DRP)
Orthophosphate, dissolved, mg/L as P
Orthophosphate (OPO4_PO4)
5.1 Lakes and Reservoirs
5.1.1 Aggregate Nutrient Ecoregion 2
Data Sources:
Legacy STORET
EPA Region 10
Parameter:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Phosphorous. Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg71-)
Nitrogen, Total Kjeldahl (TKN) ' (mg/L)
Phosphorus. Total (TP) (ug/L)
Phosphorus. Total Reactive (ug/L)
SECCHI ~ - (m>
PH
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Level IIT ecoregions:
1, 2, 4, 5, 9, 11, 15, 16, 17, 19, 21, 23, 41, 77, 78
5.1.2 Aggregate Nutrient Ecoregion 6
Data Sources:
Legacy STORE!
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP) (ug/L)
SECCHI (m)
Level III ecoregions:
46,47,48, 54, 55, 57
5.1.3 Aggregate Nutrient Ecoregion 7
Data Sources:
LCMPD
Legacy STORET
NYCDEP
EPA Region 1
Parameters:
Chlorophyll A, Fluorometric Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric. Uncorrected (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Phosphorous. Dissolved Inorganic (DIP) (ug'L)
August 8.2000
10
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Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Orthophosphate, Total as P (ug/L)
Phosphorus, Total (TP) (ug/L)
SECCHI (m)
Level HI ecoregions:
51,52,53,56,60,61,83
5.1.4 Aggregate Nutrient Ecoregion 8
Data sources:
LCMPD
Legacy STORET
NYCDEP
NYCDEC
EPA Region 1
EPA Region 3
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A. Phytoplankton, Spectrophotometric, Uncorrected (ug/L)
Chlorophyll A, Trichromatic, Uncorrected . (ug/L)
Chlorophylls ' (ug/L)
Chlorophyll C ' . (u§/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP)
SECCHI (m)
Level III ecoregions:
49, 50, 58, 62. 82
August 8, 2000
11
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5.1.5 Aggregate Nutrient Ecoregion 9
Data sources:
Auburn University
Legacy STORET
EPA Region 4
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Pheophytin (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate. (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP) (ug/L)
SECCHI (m)
Level HE ecoregions:
29, 33, 35, 37, 40, 45, 64, 65..71, 72, 74
5.1.6 Aggregate Nutrient Ecoregion 11
Data sources:
Auburn University
Legacy STORET
NYSDEC
EPA Region 3
EPA Region 4
Parameters:
Chlorophyll A. Fluorometric, Corrected (ug/L)
Chlorophyll A. Pheophytin (ug/'L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
August 8. 2000
12
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Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected
Chlorophyll A, Trichromatic, Uncorrected
Phosphorous, Dissolved Inorganic (DIP)
Dissolved Oxygen (DO)
Nitrite and Nitrate, (NO2+NO3)
Nitrogen, Total (TN)
Nitrogen, Total Kjeldahl (TKN)
Phosphorus, Total (TP)
SECCHI
Level ffl ecoregions:
36,38, 39, 66, 67, 68,69, 70
5.1.7 Aggregate Nutrient Ecoregion 12
Data sources:
Legacy STORET
August 8. 2000
(ug/L)
(ug/L)
(ug/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(ug/L)
(m)
Parameters:
Chlorophyll A, Phytoplankton, Spectrophotometric Acid
Chlorophyll A, Trichromatic, Uncorrected
Dissolved Oxygen (DO)
Nitrite and Nitrate, (NO2+NO3)
Nitrogen, Total (TN)
Nitrogen, Total Kjeldahl (TKN)
Phosphorus, Total (TP)
SECCHI
Level IE ecoregions:
75
5.1.8 Aggregate Nutrient Ecoregion 13
Data sources:
Legacy STORET
(ug/L)
(ug/L)
(mg/L)
(mg/L.)
(mg/L)
(mg/L)
(ug/L)
(m)
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Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug^)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP) (ug/L)
SECCHI (m)
Level HI ecoregions:
76
5.2 Rivers and Streams
5.2.1 Aggregate Nutrient Ecoregion 2
Data sources:
Legacy STORET
NASQAN
NAWQA
EPA Region 10
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, chromotographic- fluorometric (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Chlorophyll B, Phytoplankton, chromotographic- fluorometric (ug/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Phosphorus. Orthophosphate, Total as P (ug/L)
Phosphorus, Total (TP) Reactive (ug/L)
Nitrogen, Total (TN) " (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP) (ug/L)
August 8, 2000
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Turbidity (FTU)
Turbidity (JCU)
Turbidity (NTU)
Level HI ecoregions:
1, 2, 4, 5, 8, 9, 11, 15, 16, 17, 19, 21, 23, 41, 77, 78
5.2.2 Aggregate Nutrient Ecoregion 3
Data sources:
Legacy STORET
NASQAN
NAWQA
EPA Region 10
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, chromotographic- fluorometric (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Chlorophyll B, Phytoplankton, chromotographic- fluorometric (ug/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) ' (mg/L)
Nitrogen, Total (TN) ' (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/'L)
Phosphorus, Total (TP) (ug/L)
Turbidity ' .
Turbidity
Turbidity (NTU)
Level III ecoregions:
6, 10, 12, 13, 14. 18. 20, 22, 24, 79, 80, 81
August 8. 2000
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5.2.3 Aggregate Nutrient Ecoregion 6
Data sources:
Legacy STORET
NASQAN
NAWQA
EPA Region 5
EPA Region 7
Parameters:
Chlorophyll A, Fluorometric, Corrected
Chlorophyll A, Phytoplankton, Spectrophotometric Acid
Chlorophyll A, Phytoplankton, chromotographic- fluorometric
Chlorophyll A, Trichromatic, Uncorrected
Chlorophyll B, Phytoplankton, chromotographic- fluorometric
Phosphorous, Dissolved Inorganic (DIP)
Dissolved Oxygen (DO)
Nitrite and Nitrate, (NO2+NO3)
Nitrogen, Total (TN)
Nitrogen, Total Kjeldahl (TKN)
Organic, Phosphorus
Phosphorus, Total (TP)
Phosphorus, Orthophosphate, Total as P
Turbidity
Turbidity
Turbidity
Level HI ecoregions:
46,47,48, 54, 55, 57
5.2.4 Aggregate Nutrient Ecoregion 7
Data sources:
LCMPD
Legacy STORET
NASQAN
NAWQA
NYCDEP
August 8. 2000
(ug/L)
(ug/L)
(ug/L)
(ug/L)
(ug/L)
(ug/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(ug/L)
(ug/L)
(ug/L)
(FTU)
(JCU)
(MTU)
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Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected (ug/L)
Chlorophyll A, Phytoplankton, chromotographic- fluorometric (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Chlorophyll B, Phytoplankton, chromotographic- fluorometric (ug/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) . (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Organic, Phosphorus (ug/L)
Phosphorus, Orthophosphate, Total as P (ug/L)
Phosphorus, Total (TP) (ug/L)
Turbidity . (FTU)
Turbidity (JCU)
Turbidity (MTU)
Level HI ecoregions:
51,52,53,56,60,61,83
5.2.5 Aggregate Nutrient Ecoregion 9
Data sources:
Auburn University
Legacy STORET
NASQAN
NAWQA
EPA Region 3
EPA Region 5
EPA Region 7
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/'L)
Chlorophyll A, Phytoplankton, chromotographic- fluorometric (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected (ug/L)
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Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Chlorophyll B, Phytoplankton, chromotographic- fluorometric (ug/'L)
Chlorophyll B, Phytoplankton, Spectrophotometric (ug/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Organic, Phosphorus (ug/L)
Phosphorus, Orthophosphate, Total as P (ug/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP) (ug/L)
Turbidity (FTU)
Turbidity ' (JCU)
Turbidity' (NTU)
Level HI ecoregions:
29, 33, 35, 37, 40, 45, 64, 65, 71, 72, 74
5.2.6 Aggregate Nutrient Ecoregion 11
Data sources:
Auburn University
Legacy STORET
NASQAN
NAWQA
EPA Region 3
EPA Region 5
EPA Region 7
Parameters:
Chlorophyll A, Fluorometric, Corrected (ug/'L)
Chlorophyll A, Phytoplankton, chromotographic- fluorometric (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Chlorophyll B, Phytoplankton, chromotographic- fluorometric (ug/L)
Phosphorous, Dissolved Inorganic (DIP) (ug/L)
Dissolved Oxygen (DO) (mg/L)
Organic, Phosphorus (ug/L)
August 8.2000
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Phosphorus, Orthophosphate, Total as P (ug/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/L)
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Total (TP) (ug/L)
Turbidity - (FTU)
Turbidity (JCU)
Turbidity (NTU)
Level HI ecoregions:
36, 38, 39, 66, 67, 68, 69, 70
5.2.7 Aggregate Nutrient Ecoregion 12
/
Data sources:
Legacy STORET
•NASQAN
NAWQA
Parameters:
Chlorophyll A, Phytoplankton, Spectrophotometric Acid (ug/L)
Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected (ug/L)
Chlorophyll A, Trichromatic, Uncorrected (ug/L)
Chlorophyll B, Phytoplankton, Spectrophotometric (ug/L)
Phosphorous. Dissolved Inorganic (DIP) " (ug/L)
Dissolved Oxygen (DO) (mg/L)
Nitrite and Nitrate, (NO2+NO3) (mg/L)
Nitrogen, Total (TN) (mg/D
Nitrogen, Total Kjeldahl (TKN) (mg/L)
Phosphorus, Orthophosphate, Total as P (ug/L)
Phosphorus, Total (TP) (U§/L)
Turbidity . (FTU>
Turbidity (NTU)
Level III ecoregions:
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5.2.8 Aggregate Nutrient Ecoregion 14
Data sources:
Legacy STORET
NASQAN
NAWQA
NYCDEP
EPA Region 1
EPA Region 3
Parameters:
Chlorophyll A, Fluorometric, Corrected
Chlorophyll A, Phytoplankton, Spectrophotometric Acid
Chlorophyll A, Phytoplankton, Spectrophotometric, Uncorrected
Chlorophyll A, Trichromatic, Uncorrected
Phosphorous, Dissolved Inorganic (DIP)
Dissolved Oxygen (DO)
Nitrite and Nitrate, (NO2+NO3)
Phosphorus, Orthophosphate, Total as P
Nitrogen, Total Kjeldahl (TKN)
Nitrogen, Total (TN)
Phosphorus, Total (TP)
Turbidity
Turbidity
Turbidity
August 8, 2000
Level
ecoregions:
(ug/L)
(ug/L)
(ug/L)
(ug/L)
(ug/L)
(mg/L)
(mg/L)
(ug/L)
(mg/L)
(mg/L)
(ug/L)
(FTU)
(JCU) '
(NTU)
59, 63, 84
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APPENDIX A
Process Used to QA/QA the Legacy STORET Nutrient Data Set
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STORET water quality parameters and Station and Sample data items were retrieved
from USEPA's mainframe computer. Table 1 lists all retrieved parameters and data
items. :
TABLE 1: PARAMETERS AND DATA ITEMS RETRIEVED FROM STORET
Parameters Retrieved
(STORET Parameter Code)
TN-mg/1(600) '
TKN - mg/1 (625)
Total Ammonia (NH3+NH4) - mg/1 (6 1 0)
Total N02-rNO3 - mg/1 (630)
Total Nitrite - mg/1 (615)
Total Nitrate - mg/1 (620)
Organic N - mg/L (605)
TP - mg/1 (665)
Chlor a - ug/'L (spectrophotometric method,
32211)
Chlor a - ug/L (fluorometric method corrected.
32209)
Chlor a - ug/L (trichromatic method corrected,
32210)
Secchi Transp. - inches (77)
Secchi Transp. - meters (78)
+Turbidiry JCUs (70)
-Turbidity FTUs (76)
•^Turbidity NTUs field (82078)
^Turbidity NTUs lab (82079)
-DO - mg/L (300)
* Water Temperature (degrees C, 10/degrees F,'
11)
Station Data Items Included
(STORET Item Name)
Station Type (TYPE)
Agency Code (AGENCY)
Station No. (STATION)
Latitude - std. decimal degrees
(LATSTD)
Longitude - std. decimal degrees
(LONGSTD)
Station Location (LOCNAME)
County Name (CONAME)
State Name (STNAME)
Ecoregion Name - Level III
(ECONAME)
Ecoregion Code -Level III
(ECOREG)
Station Elevation (ELEV)
Hydrologic Unit Code
(CATUNIT)
RJF1 Segment and Mile
(RCHMIL)
RF1 ON/OFF tag (ONOFF)
Sample Data Items
Included
(STORET Item Name)
Sample Date (DATE)
Sample Time (TIME)
Sample Depth (DEPTH)
Composite Sample Code
(SAMPMETH)
>
* If data record available at a station included data only for this or other such marked parameters, data record was
deleted from data set.
The following set of retrieval rules were applied to the retrieval process:
• Data were retrieved for waterbodies specified only as 'lake', 'stream', 'reservoir',
or 'estuary' under "Station Type" parameter. Any stations specified as 'well,'
'spring,' or 'outfall' were eliminated from the retrieved data set.
• Data were retrieved for station types described as 'ambient' (e.g., no pipe or facility
discharge data) under the "Station Type" parameter.
• Data were retrieved that were designated as 'water' samples only. This includes
'bottom' and 'vertically integrated' water samples.
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• Data were retrieved that were designated as either 'grab' samples and 'composite'
samples (mean result only).
• No limits were specified for sample depths.
• Data were retrieved for all fifty states, Puerto Rico, and the District of Columbia.
• The time period specified for data retrieval was January 1990 to September 1998.
• No data marked as "Retired Data" (i.e., data from a generally unknown source) were
retrieved.
• Data marked as "National Urban Runoff data" (i.e., data associated with sampling
conducted after storm events to assess nonpoint source pollutants) were included in
the retrieval. Such data are part of STORET's 'Archived' data.
• Intensive survey data (i.e., data collected as part of specific studies) were retrieved.
2. Any values falling below the 1st percentile and any values falling above the 99th
percentile were transformed into 'missing' values (i.e., values were effectively removed
from the data set, but were not permanently eliminated).
3. Based on the STORET 'Remark Code' associated with each retrieved data point,.the
following rules were applied (Table 2):
TABLE 2: STORET REMARK CODE RULES
*
STORET Remark Code
blank - Data not remarked.
A-
B-
C-
D-
E-
F-
G-
Value reported is the mean of two or more determinations.
Results based upon colony counts outside the acceptable ranges.
Calculated. Value stored was not measured directly, but was
calculated from other data available.
Field measurement.
Extra sample taken in compositing_process.
In the case of species. F indicates female sex.
Value reported is the maximum of two or more determinations.
Keep or Delete Data Point
Keep
Keep
Delete
Keep
Keep
Delete
Delete
Delete
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TABLE 2: STORET REMARK CODE RULES
H-
I-
J-
K-
L-
M-
X-
o-
p-
Q-
R-
S-
T-
U-
V-
W-
X-
Y-
7 ',-
Value based on field kit determination; results may not be accurate.
The value reported is less than the practical quantification limit and
greater than or equal to the method detection limit.
Estimated. Value shown is not a result of analytical measurement.
Off-scale low. Actual value not known, but known to be less than
value shown.
Off-scale high. Actual value not known, but known to be greater
than value shown.
Presence of material verified, but not quantified. Indicates a
positive detection, at a level too low to permit accurate
quantification.
Presumptive evidence of presence of material.
Sample for, but analysis lost. Accompanying value is not
meaningful for analysis.
Too numerous to count.
Sample held beyond normal holding time.
Significant rain in the past 48 hours.
Laboratory test.
Value reported is less than the criteria of detection.
Material was analyzed for, but not detected. Value stored is the
limit of detection for the process in use.
Indicates the analyte was detected in both the sample and associated
method blank.
Value observed is less than the lowest value reportable under
remark "T."
Value is quasi vertically-integrated sample.
Laboratory analysis from unpreserved sample. Data may not be
accurate.
Too manv colonies were present to count.
Delete
Keep, but used one-half the
reported value as the new value.
Delete
Keep, but used one-half the reported
value as the new value.
Keep
Keep, but used one half the reported
value as the new value.
Delete
Delete
Delete
Delete
Delete
Keep
Keep, but replaced reported value with
0.
• Keep, but replaced reported value with ,
0.
Delete
Keep, but replaced reported value with
.0. :
No data point with this remark code in
data set.
Delete
Delete
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TABLE 2: STORET REMARK CODE RULES
If a parameter (excluding water temperature) value was less than or equal to zero and no remark code was present,
the value was transformed into a missing value.
Rationale - Parameter concentrations should never be zero without a proper explanation. A method detection limit
should at least be listed.
4. Station records were eliminated from the data set if any of the following descriptors were
present within the "Station Type" parameter:
> MONITR - Source monitoring site, which monitors a known problem or to detect
a specific problem.
*• HAZARD - Site of hazardous or toxic wastes or substances.
*• ANPOOL - Anchialine pool, underground pools with subsurface connections to
watertable and ocean.
> DOWN - Downstream (i.e., within a potentially polluted area) from a facility
which has a potential to pollute.
> IMPDMT - Impoundment. Includes waste pits, treatment lagoons, and settling
and evaporation ponds.
»• STMSWR - Storm water sewer.
> LNDFL - Landfill.
> CMBMI - Combined municipal and industrial facilities.
* CMBSRC - Combined source (intake and outfall).
Rationale - these descriptors potentially indicate a station location that at which an
ambient water sample would not be obtained (i.e., such sampling locations are potentially
biased) or the sample location is not located within one of the designated water body types
(i.e, ANPOOL).
5. Station records were eliminated from data set' if the station location did not fall within any
established cataloging unit boundaries based on their latitude and longitude.
6. Using nutrient ecoregion GIS coverage provided by USEPA. all station locations with
latitude and longitude coordinates were tagged with a nutrient ecoregion identifier
(nutrient region identifiers are values 1-14) and the associated nutrient ecoregion name.
Because no nutrient ecoregions exist for Alaska, Hawaii, and Puerto Rico, stations located
in these states were tagged with "dummy" nutrient ecoregion numbers (20 = Alaska, 21 =
Hawaii, 22 = Puerto Rico).
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Using information provided by TV A, 59 station locations that were marked as 'stream'
locations under the "Station Type" parameter were changed to 'reservoir' locations.
8. The nutrient data retrieved from STORET were assessed for the presence of duplicate data
records. The duplicate data identification process consisted of three steps: 1) identification
of records that matched exactly in terms of each variable retrieved; 2) identification of
records that matched exactly in terms of each variable retrieved except for their station
identification numbers; and 3) identification of records that matched exactly in terms of
each variable retrieved except for their collecting agency codes. The data duplication
assessment procedures were conducted using SAS programs.
Prior to initiating the data duplication assessment process, the STORET nutrient data set
contained:
41,210 station records
924,420 sample records
Identification of exactly matching records
All data records were sorted to identify those records that matched exactly. For two
records to match exactly, all variables retrieved had to be the same. For example,
they had to have the same water quality parameters, parameter results and associated
remark codes, and have the same station data item and sample data item information.
Exactly matching records were considered to be exact duplicates, and one duplicate
record of each identified matching set were eliminated from the nutrient data set. A
total of 924 sample records identified as duplicates by this process were eliminated
from the data set.
Identification of matching records with the exception of station identification number
All data records were sorted to identify those records that matched exactly except for
their station identification number (i.e., they had the same water quality parameters,
parameter results and associated remark codes, and the same station and sample data
item information with the exception of station identification number). Although the
station identification numbers were different, the latitude and longitude for the
stations were the same indicating a duplication of station data due to the existence of
two station identification numbers for the same station. For each set of matching
records, one of the station identification numbers was randomly selected and its
associated data were eliminated from the data set. A total of 686 sample records
were eliminated from the data set through this process.
Identification of matching records with the exception of collecting asencv codes
All data records were sorted to identify those records that matched exactly except for
their collecting agency codes (i.e., they had the same water quality parameters,
parameter results and associated remark codes, and the same station and sample data
item information with the exception of agency code). The presence of two matching
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data records each with a different agency code attached to it suggested that one
agency had utilized data collected by the other agency and had entered the data
into STORET without realizing that it already had been placed in STORE! by the
other agency. No matching records with greater than two different agency codes
were identified. For determining which record to delete from the data set, the
following rules were developed:
>• If one of the matching records had a USGS agency code, the USGS record
was retained and the other record was deleted.
*• Higher level agency monitoring program data were retained. For example,
federal program data (indicated by a "1" at the beginning of the STORET
agency code) were retained against state (indicated by a "2") and local
(indicated by values higher than 2) program data.
»• If two matching records had the same level agency code, the record from the
agency with the greater number of overall observations (potentially indicating
the data set as the source data set) was retained.
A total of 2,915 sample records were eliminated through this proce:v.
As a result of the duplicate data identification process, a total of 4,525 sample records and
36 individual station records were removed from the STORET nutrient data set. The
resulting nutrient data set contains the following:
41,174 station records
919,895 sample records
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APPENDIX B
Process for Adding Aggregate Nutrient Ecoregions and Level m Ecoregions
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Steps for assigning Level HI ecoregions and aggregate nutrient ecoregion codes and names to the
Nutrient Criteria Database (performed using ESRI's ARCView v 3.2 and its GeoProcessing
Wizard). This process is performed twice; once for the Level IH ecoregions and once for the
aggregate nutrient ecoregions:
Add the station .dbf data table, with latitude and longitude data, to project by 'Add Event
Theme1 .
Convert to the shapefile format
Create 'stcojoin' field, populate the 'stcojoin' field with the following formula:
'County.LCase+State.LCase'
Add field 'stco_flag' to the station shapefile
Spatially j oin the station data with the county shapefile (cntys Jned.shp)
Select 'stcojoin' (station shapefile) field = 'stco Join2' (county shapefile) field
Calculate "stco_flag = 0 for selected features
Step through all blank stco_flag records, assign the appropriate stco_flags, see list on the
following page
Select all stco_flags = 4 or 7, switch selection
Calculate ctyfips (station) to cntyfips (county)
Stop editing and save edits, remove all joins ;
Add in 2 new fields 'x-coordl1 and 'y-coordl' into station table
Select all stco_flags = 1,2, and 6
Link county coverage with station coverage
Populate 'x-coordl' and 'y-coordl' with 'x-coord' and 'y-coord1 from county coverage
Select all stco_flags =1,2, and 6, export to new .dbf file ;
Add new .dbf file as event theme
Convert to shapefile format
Add the following fields to both tables (original station and station!26 shapefiles):
'eco_omer', 'name_omer', 'dis_aggr*, 'code_aggr1, Iname_aggr1
Spatially join station!26 and eco-omer coverage
Populate the 'eco_omer' field with the 'eco' value
Repeat the previous step using the nearest method (line coverage) to determine ecoregion
assignment for the line coverage, if some records are blank
Spatially join the ecoregion line coverage to station coverage, link the
LPoly# (from the spatially joined table) to Poly# (of the ecoregion polygon
coverage)
Populate the Eco fields with the appropriate information.
Follow the same steps to the Rpolytf .
Remove all table joins
Link the useco-om table with station!26 table and populate 'name-omer1 field
Spatially join station aggr coverage and populate the rest of the fields. Follow the same
procedures as outlined above !
Remove all joins
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Make sure the new Eco field added into the station 126 shapefile are different than the
ones in the original station shapefile
Join station!26 and station coverage by station-id
Populate all the Eco fields in the original station coverage
Remove all joins
Save table
Make sure that all ctyfips records are populated; the county shapefile may have to be
joined to populate the records, if the stco_flag = 4
Create 2 new fields, 'NewCounty1 and 'NewState'
Populate these new fields with a spatial join to the county coverage
Select by feature (ecoregion shapefile) all of the records in the station shapefile
Switch selection (to get records outside of the ecoregion shapefile)
If any of the selected records have stco_flag = 0 (they are outside the ecoregion
shapefile boundary), calculate them to stco_flag = 3
stco_flags (state/county flags in order of importance)
0 The state and county values from the data set matched the state and county values
from the spatial join.
(Ecoregions were assigned based on the latitude/longitude coordinates.)
1 The state and county values from the data set did not match the state and county
values from the spatial join, but the point was inside the county coverage
boundary.
(Ecoregions were assigned based on the county centroid.)
2 The state and county values from the data set did not match the state and county
values from the spatial join because the point was outside the county coverage
boundary; therefore, there was nothing to compare to the point (i.e., the point
falls in the ocean/Canada/Mexico). This occurred for some coastal samples.
(Ecoregions were assigned based on the county centroid.)
3 The state and county values from the data set matched the state and county from
the spatial join, but the point was outside the ecoregion boundary.
(Ecoregions were assigned to the closest ecoregion to the point,)
(No ecoregions were assigned to AK, HI, PR, BC, and GU.)
4 Latitude/longitude coordinates were provided, but there was no'county
information.
(Ecoregions were assigned based on the latitude/longitude coordinates.)
5 The state and county values from the data set did not match the state and county
values from the spatial join due to spelling or naming convention errors.
The matches were performed manually.
(Ecoregions were assigned based on the latitude/longitude coordinates.)
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No latitude/longitude coordinates were provided, only state and county
information was available.
(Ecoregions were assigned based on the county centroid.) --
No latitude/longitude coordinates were provided, only state information was
available; therefore, no matches were possible.
(Ecoregions were not assigned. Data is not included in the analysis.)
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APPENDIX C
Glossary
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Coefficient of Variation—Equal to the standard deviation divided by the mean multiplied by 100.
Maximum—The highest value.
Mean—The arithmetic average.
Median—The 50th percentile or middle value. Half of the values are above the median, and half
of the values are below the median.
Minimum-—The lowest value.
Standard Deviation—Equal to the square root of the variance with the variance defined as the
sum of the squared deviations divided by the sample size minus one.
Standard Error— Standard error of the mean is equal to the standard deviation divided by the
square root of the sample size.
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