National Rivers and Streams Assessment 2023/24 Site Evaluation Guidelines Version 2.0


United States Environmental Protection Agency
Office of Water
Washington, DC
EPA-841-B-2 2-005

National Rivers and Streams Assessment

2023/24

Site Evaluation
Guidelines

Version 2.0

SEPA

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NOTICE

The intention of the National Rivers and Streams Assessment 2023/24 is to provide a comprehensive
"State of Flowing Waters" assessment for rivers and streams across the United States. The complete
documentation of overall project management, design, methods, quality assurance, and standards is
contained in four companion documents, including:

National Rivers and Streams Assessment 2023/24:

National Rivers and Streams Assessment 2023/24:
006

National Rivers and Streams Assessment 2023/24:
22-007

Quality Assurance Project Plan EPA-841-B-22-004
Site Evaluation Guidelines EPA-841-B-22-005
Wadeable Field Operations Manual EPA-841-B-22-

Non-Wadeable Field Operations Manual EPA-841-B-

National Rivers and Streams Assessment 2023/24: Laboratory Operations Manual EPA-841-B-22-008

This document (Site Evaluation Guidelines [SEG]) contains an overview of the processes involved in
locating a sampling site, evaluating the site, and selecting appropriate alternate sites when necessary,
and is based on the guidelines developed and followed in the Western Environmental Monitoring and
Assessment Program (Peck et al. 2003) and the National Rivers and Streams Assessment 2008/09,
2013/14 and 2018/19. Methods described in this document are to be used specifically in work relating
to the NRSA 2023/24. Mention of trade names or commercial products in this document does not
constitute endorsement or recommendation for use. More detail of the project overview and of specific
methods for field sampling, sample handling, and sample processing can be found in the appropriate
companion document.

The suggested citation for this document is:

USEPA. 2022. National Rivers and Streams Assessment 2023-2024: Site Evaluation Guidelines. EPA-841-
B-22-005. U.S. Environmental Protection Agency, Office of Water, Washington, DC.

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TABLE OF CONTENTS

NOTICE 2

TABLE OF CONTENTS	3

LIST OF FIGURES	4

LIST OF TABLES	4

1	INTRODUCTION	5

2	SURVEY DESIGN	6

2.1	Target Population	6

2.2	Sample Frame	6

2.3	Survey Design	6

2.4	Resample Sites	9

2.5	New Sample Sites	9

3	LOCATING THE INDEX SITE ON MAPS	9

4	OBTAINING PERMISSION TO ACCESS CANDIDATE SITE	9

5	SITE VERIFICATION	11

5.1	Site Verification Procedures	11

5.2	Sampleable Categories	11

5.3	Non-Sampleable Categories	12

5.3.1	Non-Sampleable (permanent condition; stream/river becomes non-target)	12

5.3.2	Non-Sampleable (temporary condition; stream/river can be revisited)	13

5.4	No Access to Site Categories	13

5.5	Target, Excessive Effort Required	14

5.6	Tidal Sites	14

5.7	Blackwater Sites	14

5.8	Run-of-the-River Reservoirs	14

6	SELECTING ALTERNATE SITES	15

6.1	Site Sampling Categories	15

6.2	Sampling Sites from Previous Surveys	15

6.3	Example of Site Replacement Process	18

6.4	State Designs	19

7	LITERATURE CITED	19

3

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LIST OF FIGURES

Figure 1.1. Site Evaluation Process	5

Figure 4.1. Example Permission Cover Letter	10

Figure 6.1 NRSA 2023/24 Site Replacement Plan	17

Figure 6.2 Example of Replacement of Revisit Site in Rivers Reach Category	18

LIST OF TABLES

Table 5.1Sampleable Categories	12

Table 5.2 Non-Sampleable Categories (permanent condition)	12

Table 5.3 Non-Sampleable Categories (temporary condition)	13

Table 5.4 No Access to Site Categories	13

Table 6.1 Alternative Site Replacement Instructions	16

4

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1 INTRODUCTION

This document is provided to clarify all of the steps involved in the process of locating and evaluating a
sampling site for the National Rivers and Streams Assessment (NRSA) 2023/24. There are five steps
involved in this process (Figure 1.1):

•	Locate the index site ("X-Site") on a topographic map

•	Verify that the "X-Site" is aligned with an actual channel segment using geospatial data
programs

•	Obtain permission to access the site

•	Verify that the site is sampleable

•	Sample the site OR replace with an alternate site

Step 1

Locate index site
("X -site") on map

Step 2

Step 3

Step 4

Step 5

Conduct desktop recon--
verify that X -site is aligned
with an actual stream segment

No „



>	~

Reject site

Select
alternate site

Reject site

Select
alternate site

Sample
site

Figure 1.1. Site Evaluation Process

Field crews must assemble a dossier containing important locational and access information for each
site they are scheduled to visit. The dossier must contain the appropriate maps, contact information,
copies of permission letters (if applicable), and access instructions. Before a site visit, each field crew
should confirm access to the waterbody if possible. The landowner(s) listed in the dossier should be

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contacted to confirm permission to sample and to identify any revisions to the information in the
dossier.

2 SURVEY DESIGN

2.1 Target Population

The target populations consist of all streams and rivers within the 48 contiguous states that have flowing
water during the study index period excluding portions of tidal rivers up to head of salt (defined as < 0.5
ppt for this study). The study index period extends from the beginning of June to the end of September
and is generally characterized by base flow conditions. Run-of-the-river ponds and pools are included
while reservoirs with greater than seven-day residence time are excluded. A complete definition of the
target population is given in the Field Operations Manuals.

2.2 Sample Frame

The sampling frame was derived from and is a subset of the National Hydrography Dataset (NHD)
product NHDPIus HR. The NHDPIus HR (https://doi.org/10.3133/fs20203033) is a geospatial dataset
depicting the flow of water across the Nation's landscapes and through the stream network. The
NHDPIus HR is built using the NHD High Resolution data at 1:24,000 scale or more detailed, the IO-
meter 3D Elevation Program data, and the nationally complete Watershed Boundary Dataset (Moore
et.al. 2019). Since this is a better representation of streams and rivers in the contiguous United States,
NRSA 2023/24 will use it as the source for its sampling frame with the intent to use it for at least the
next 10-15 years. Note that NHDPIus HR is not restricted to a single map scale, e.g., 1:24K. While
NHDPIus HR also includes attributes for Strahler order and Strahler calculator, they are based on the
available map scale, which means their definition depends on the map scale. NHDPIus HR also includes
an attribute for mean annual flow for each reach. Mean annual flow estimates are based on a model
described in the NHDPIus HR User Guide. Attributes from NHD-Plus HR and additional attributes added
to the sample frame that are used in the survey design are:

• Strahler order

• Ecological Reporting Region: Nine aggregated Omernik ecoregions that are used for reporting.

• Omernik and North American ecoregions Levels I, II, III, and IV.

2.3 Survey Design

The NRSA 2023/24 survey design consists of two separate designs to address the dual objectives of (1)
estimating current status and (2) estimating change in status for all flowing waters:

• Resample design applied to NRSA 2018/19 sites

• New site design for NRSA 2023/24

There are 11 panels which are separated into three tabs of the Site Evaluation Spreadsheet. These tabs
represent the panel uses within the three reach categories in the NRSA 2023/24 design: Rivers (RV),
Large Streams (LS), and Small Streams (SS). Each of the following panels are defined as "Base" sites and
"Oversample" replacement sites.

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Note, the FT suffix in some of the base River sites refers to whole fish for "Fish Tissue" samples. EPA
does not currently plan on collecting this data though the suffix has been left in should EPA obtain
funding for the collection of whole fish for fish tissue analysis purposes. The evaluation process is the
same regardless of the FT suffix. Examples of the replacement process can be found in Section 6.

Panel use codes are assigned to each site to describe the type of site and contain the components listed
below and a detailed description of each panel is also provided.

1. A prefix indicating the survey design

a. NRS23_18 - Resample sites from NRSA 2018/19

b. NRS23_23 - New sites for NRSA 2023/24

2. Panel type

a. RVT2 - A revisit site designated to be sampled twice during the same index period

b. Base - Sites designated to be sampled once during the NRSA 2023/24 survey

c. Over - Sites to be used as replacements for dropped sites

3. Size category

a. RV - River

b. LS - Large stream

c. SS - Small stream

i. Note, unlike NRSA 2018/19, crews will not have to determine replacement of
sites based on Strahler Order or Ecoregion for NRSA 2023/24. Replacement sites
will only be based on panel type, year and reach categories (RV, SS or LS).

4. Fish tissue designator

a. _FT is appended to the panels code for those sites that have been designated for

potential whole fish tissue sampling in the event this sample is added to NRSA 2023/24.
Currently, this sample not be part of NRSA 2023/24 sampling process. Please disregard
unless receive instruction from NRSA Lead regarding sampling for whole fish tissue
samples at a later date.

Small Streams

• NRS23_18RVT2SS - only one of these for each state and it is the first resample site in this reach
category in Site ID order. Note that it is very possible that this site may have not been sampled
in 2018/19. It will be evaluated again in 2023/24 to determine if it can be sampled, and if not, it
is then replaced by the first NRS23_18BaseSS site. This is referred to as a "revisit site" as it will
be evaluated and sampled twice, with at least two weeks in between each visit.

• NRS23_18BaseSS - all the remaining sites required for each state in this reach category from
2018/19. If it cannot be sampled in 2023/24, then it will be replaced by the next available
NRS23_180verSS site. If no NRS23_180verSS sites are available, then the site is replaced by the
next available NRS23_230verSS site.

• NRS23_180verSS - remaining SS sample sites evaluated in 2018/19 listed in their sitelD order.

• NRS23_23BaseSS - SS new sites selected for 2023/24 listed in their sitelD order. If it cannot be
sampled in 2023/24, then it will be replaced by the next available NRS23_230verSS site

• NRS23_230verSS - SS new over sample sites selected for 2023/24 listed in their sitelD order.

Large Streams

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• NRS23_18RVT2LS - only one of these for each state and it is the first resample site in this reach
category in sitelD order. Note that it is very possible that this site may have not been sampled in
2018/19. It will be evaluated again in 2023/24 to determine if it can be sampled, and if not, it is
then replaced by the first NRS23_18BaseLS site. This is referred to as a "revisit site" as it will be
evaluated and sampled twice, with at least two weeks in between each visit.

• NRS23_18BaseLS- all the remaining sites required for each state in this reach category from
2018/19. If it cannot be sampled in 2023/24, then it will be replaced by the next available
NRS23_180verLS site. If no NRS23_180verLS sites are available, then the site is replaced by the
next available NRS23_230verLS site.

• NRS23_180verLS - remaining LS sample sites evaluated in 2018/19 listed in their sitelD order.

• NRS23_23BaseLS - LS new sites selected for 2023/24 listed in their sitelD order. If it cannot be
sampled in 2023/24, then it will be replaced by the next available NRS23_230verLS site

• NRS23_230verLS - LS new over sample sites selected for 2023/24 listed in their sitelD order.

Rivers - Note, please ignore the _FT designation as we do not plan on collecting whole fish samples
for fish tissue analysis at this time.

• NRS23_18RVT2RV_FT - two of these for each state and it is the first two resample sites in this
reach category in sitelD order. Note that it is very possible that these sites may have not been
sampled in 2018/19. It will be evaluated again in 2023/24 to determine if it can be sampled and
if not then replaced by the first NRS23_18BaseRV site. This is referred to as a "revisit site" as it
will be evaluated and sampled twice, with at least two weeks in between each visit. Note
regarding the _FT distinction, currently we will not be collecting whole fish for fish tissue
contaminant analysis. Please treat these sites as a regular revisit site (NRS23_18RVT2RV) unless
instructed differently by the NRSA Lead.

• NRS23_18BaseRV_FT- Sampled once in 2023/24. If it cannot be sampled in 2023/24, then it will
be replaced by the next available NRS23_18BaseRV or NRS23_180verRV site if no
NRS23_18BaseRV site is available. Note regarding the _FT distinction, currently we will not be
collecting whole fish for fish tissue contaminant analysis. Please treat these sites as a regular
NRS23_18BaseRV site unless instructed by the NRSA Lead.

• NRS23_18BaseRV- all the remaining sites required for each state in this reach category from
2018/19. If it cannot be sampled in 2023/24, then it will be replaced by the next available
NRS23_180verRV site. If no NRS23_180verRV sites are available, then the site is replaced by the
next available NRS23_230verRV site.

• NRS23_180verRV - remaining RV sample sites evaluated in 2018/19 listed in their sitelD order.

• NRS23_23BaseRV_FT- RV new sites selected for 2023/24 listed in their sitelD order. If it cannot
be sampled, then it will be replaced by the next available NRS23_180verRV site. Note regarding
the _FT distinction, currently, we will not be collecting whole fish for fish tissue contaminant
analysis. Please treat these sites as a regular NRS23_23BaseRV site unless instructed by the
NRSA Lead.

• NRS23_23BaseRV- RV new sites selected for 2023/24 listed in their sitelD order. If it cannot be
sampled in 2023/24, then it will be replaced by the next available NRS23_230verRV site.

• NRS23_230verRV - RV new over sample sites selected for 2023/24 listed in their sitelD order.

The survey design is explicitly stratified by state. The unequal probability categories are specific to
survey design used for NRSA 2018/19 and NRSA 2023/24. Note, all Base sites/revisit sites must be
evaluated regardless of whether they are sampled. Base/revisit sites that are found to be target and
sampleable must be sampled, those found to be non-target or unsampleable are replaced.

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2.4 Resample Sites

The Resample survey design is a subsample of the NRSA 2023/24 sites that were target and evaluated in
NRSA 18/19. These sites all begin with the NRS23_18 prefix. The major objective for this design is
change estimation. This results in 790 resample base sites which are part of the 2023/24 design.
Allocation of sites to NARS aggregated ecoregions is proportional to the number sampled in the prior
surveys.

2.5 New Sample Sites

The NRSA 2023/24 survey design includes 1028 new sites which have not been included in previous
NRSA surveys. Allocation of number of sites to states is proportional to stream length and is stratified by
state. Unequal probability categories are 27 combinations of NARS nine aggregated ecoregions and
three waterbody reach categories (SS - small streams, LS - large streams, and RV - Rivers). A minimum
of 20 sites was guaranteed in each state and the maximum number of sites was set at 75 for an
individual state.

3 LOCATING THE INDEX SITE ON MAPS

Stream sampling points were chosen from the "blue line" stream network represented on 1:100,000
scale USGS maps, following a systematic random site selection process developed for NRSA 2023/24.
Each point is referred to as the "index site" or "X-Site". The "X-Site" is the mid-point of the segment to
be sampled. The latitude/longitude of the "X-Site" was listed on a regional sampling site spreadsheet
that was distributed electronically to the field crews and EPA Regional Coordinators.

The line work for US EPA's NHDPIus (NHDPIus HR) is based on 1:100,000-scale Digital Line Graphs and,
therefore, will not match exactly with the 1: 24,000-scale maps. Use the NHDPIus HR line to locate
important features such as confluences or bends in the channel to assist in placing the "X-Site"
accordingly on the 1:24,000-scale (or 7.5") map. All NHDPIus HR lines are shown even though many are
not channel traces. Line segments for lakes, inundated areas, wetlands, and occasionally, even map
boundaries are shown as NHDPIus HR line work. State, 2023/24 site ID, panel use, waterbody reach
category, Strahler order, ecoregion, coordinates, and 2018/19 Site ID and evaluation status are also
included in the Site Evaluation Spreadsheet. All information, including the longitude/latitude, refers to
the location of the "X-Site". Note, the 2018/19 Site ID and evaluation status are given for reference
material only. Crews should evaluate all sites as if they have not been evaluated before as things can
change in the five years between surveys.

If you have any questions about the site maps or how to use them, please contact Richard Mitchell (202-
566-0644, mitchell.richard@epa.gov). If you have questions regarding the Site Evaluation Spreadsheets,
please contact Danielle Grunzke (202-566-2876, grunzke.danielle@epa.gov).

4 OBTAINING PERMISSION TO ACCESS CANDIDATE SITE

Each field crew is responsible for obtaining permission for their sampling crew to access their sampling
sites. Obtaining permission prior to the sampling day is often important to minimize loss of time on the
part of the field crew. An in-person visit is an effective way to establish contact with landowner(s). Past
surveys have found that landowners are more likely to grant permission if they meet with a study
representative than if their only contact is through a phone call or letter. If a personal visit cannot be
made, a phone call is considered the best alternative. A local representative may be more effective in

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securing permission, so it is important to request assistance at this level if you are not local to the area.
If attempts to reach the landowner(s) through an in-person visit or telephone call are unsuccessful, a
letter should be mailed (see Figure 4.1 for an example) with a fact sheet on the survey (Appendix A) and
a permission slip for the landowner(s) to return (Appendix B). Included in this package should be a
return-addressed and postage-paid envelope with a specific date by which the permission slip should be
returned. A signed permission slip is important to use as documentation on the day of sampling. Some
crews will choose to deal with access issues on the day of the sampling event. This method is usually
adequate if a desk-top reconnaissance shows that the area around the site includes enough public land
to gain access to the waterway. If the site is in an area that is largely privately owned land, waiting until
the day of sampling could pose unnecessary delays and access issues that should have been resolved
prior to the scheduled sampling day.

Landowner information can often be obtained from the county tax assessor office. Tax assessor maps
will display landowner boundaries, addresses and, oftentimes, phone numbers. This information enables
the crew to contact landowners before the sampling day, and identifies which landowner owns which
portions of the stream or riverbanks. The provision of county maps for the field crews will help clarify
access to the targeted sampling reach.

(Date)

Dear Landowner:

The US Environmental Protection Agency, in cooperation with state agencies, is
conducting an environmental assessment of rivers and streams across the United States. A
computer was used to randomly select these streams. A total of approximately 1,800
sampling sites in rivers and streams were selected for sampling in 2023 and 2024. Water
quality chemistry, aquatic life, and habitat will be evaluated at each site. The findings of the
study will not be used for enforcement or regulatory purposes.

We are contacting you prior to the site visit to obtain permission (form enclosed) to
access the sampling site. We have enclosed a copy of a topographic map(s) with the site(s)
identified by an "X" at the specific point on the stream to be sampled. We realize that
working on your property is a privilege and we will respect your rights and wishes at all times.

Please return the completed Access Permission Form in the enclosed envelope by
(date). If you have any questions concerning this request, please contact me (phone
number). We are looking forward to hearing from you.

Sincerely,

(Name)

NRSA 2023/24 Crew Leader

Figure 4.1. Example Permission Cover Letter

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5 SITE VERIFICATION

While traveling from a base location to a site, record a detailed description of the route taken on the
Verification Form in the NRSA field app. This information will allow others to find the site again if it is
selected for a repeat visit in the future. Upon reaching the "X-Site" for a stream or river channel, confirm
its location and that the crew is at the correct location. Record the information on the Verification Form
in the NRSA field app. Complete a Verification Form for each site visited with the intent to sample
(regardless of whether it is sampled), following the procedures described below.

5.1 Site Verification Procedures

1. Find the site location in the field corresponding to the "X-Site" coordinates and the "X" marked
on the map ("X-Site") prepared for each site. Record the routes taken and other directions on
the Verification Form so that others can visit the same location in the future.

2. Use a GPS receiver to confirm the latitude and longitude of the "X-Site" with the coordinates for
the site. Make sure the GPS unit is set to reference the NAD 83 geospatial data set. Record these
coordinates in decimal degrees on the Verification Form. Be sure to use the negative (-) sign for
all longitudes.

3. Use all available means to ensure that you are at the correct location as marked on the map
including: 1:24,000 USGS map, topographic landmarks, county road maps, local contacts, etc.

4. Scan the channel upstream and downstream from the "X-Site", determine whether the site is
sampleable using the guidelines provided below, and mark the appropriate box in the
Verification Form.

5. Do not sample non-target or "Non-sampleable Permanent", "Non-sampleable Temporary", or
"No Access" sites. If the site is not sampleable for the above reasons, select the "NO" bubble
next to the "Did you sample this site?" section of the Verification Form, otherwise select "YES".

5.2 Sampleable Categories

The Site Evaluation Spreadsheet prompts evaluators to assess and record each site's target status and
sampleability in columns P-R. The available drop-down selections in columns Q and R are dependent
upon the selections made in the previous column(s). If a subsequent change is made to the selections in
columns Q or R, be sure to review and/or change the selections made in the previous column(s) to avoid
incongruent answers. The columns are:

1. Column P: Ql. Is the site sampleable? (Yes or No). Select the proper answer to indicate whether
the site is sampleable or not. Table 5.1 showcases the dropdown options which will appear in
Column Q if the evaluation selects "Yes" in Column P. Selecting "No" in column P changes the
available drop-down options in the next column to correspond to non-sampleable categories.

2. Column Q: Q2. For sampleable sites, select the method by which the site will be or was sampled.
For non-sampleable sites, choose the best category for why the site is not sampleable and enter
a sub-category explanation in Q3. Tables 5.2, 5.3, and 5.4 showcase the dropdown options
which will appear in Column R should the evaluator answer "No" in Column P. The headings of
the Tables are the dropdowns which appear in Column Q.

3. Column R: Q3. Non-Sampleable Sub-Category. If the site is not sampleable, select the
appropriate sub-category which is based on the previous column's selection. An entry in this

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column is only required if "No" was selected for Ql. Leave this column blank if the site is
sampleable.

Table 5.1 Sampleable Categories

Category

Description

Dry Channel

A discernible stream channel is present but there is no water anywhere within a 150-
m reach centered on the "X-Site". If determined at the time of the sampling visit,
record as "Dry-Visited"; if site was determined to be dry (or otherwise non-perennial)
from another source and/or field verified before the actual sampling visit, record as
"Dry-Not Visited."

Wetland

(No definable stream channel) there is standing water present, but no definable
stream channel. In cases of wetlands surrounding a recognizable stream channel,
define the site as sampleable but restrict sampling to the stream channel.

Map Error

No evidence that a water body or stream channel was ever present at the coordinates
provided for the "X-Site".

Impounded

The stream is submerged under a lake or pond due to man-made or natural (e.g.,

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Stream

beaver dam) impoundments. If the impounded stream, however, is still wadeable,
record the stream as "Altered" and sample.

Tidal

The site in question occurs near a coast and is below the head of salt. If the site has a
salinity of greater than 0.5 parts per thousand.

Other

The site is non-target for reasons other than those above. Examples include
underground pipelines or a non-target canal. A sampling site must meet both of the
following criteria to be classified as a non-target canal:

•	The channel is constructed where no natural channel has ever existed.

•	The sole purpose/usage of the reach is to transfer water. There are no other uses
of the waterbody by humans (e.g., fishing, swimming, boating).

Be sure to record additional information in column S of the site evaluation
spreadsheet if "Other" is chosen as the reason for dropping a site.

5.3.2 Non-Sampleable (temporary condition; stream/river can be revisited)
Table 5.3 Non-Sampleable Categories (temporary condition)

Category

Description 1

Not

Boatable

Unable to reach a site with a boat. Site should be rescheduled for another visit during
the same 2-year survey cycle.

Not

Wadeable

Unable to reach a site without a boat. Site should be rescheduled for another visit
during the same 2-year survey cycle.

Other

The site could not be sampled on that particular day but is a target site. Examples
include a recent precipitation event that has caused unrepresentative conditions or
the crew assessing the site does not perform both protocols and cannot complete the
methods necessary for said site. Site should be rescheduled for another visit during
the same 2-year survey cycle.

5.4 No Access to Site Categories
Table 5.4 No Access to Site Categories

Category

Description

Access

Permission

Denied

You are denied access to the site by the landowners.

Permanently
Inaccessible

Site is unlikely to be sampled by anyone due to physical barriers that prevent access
to the site (e.g., cliffs).

Temporarily
Inaccessible

Site cannot be reached at the present time due to barriers that may not be present at
some future date (e.g., forest fire, high water, road temporarily closed, unsafe
weather conditions). Site may be sampled at a later date, however if deemed
necessary, can be replaced.

Other

Site may not be sampled for other unforeseen reasons. This could include excessive

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effort required by crews to sample site defined below. Please explain in the
comments section of the Site Evaluation Spreadsheet.

The primary distinction between "Sampleable" and "Non-Sampleable" rivers or streams is based on the
presence of a defined channel and water content. If the site is determined to be non-sampleable or
inaccessible, no further sampling activities are conducted. The site must then be replaced by an
alternate site.

5.5 Target, Excessive Effort Required

Some remote rivers and streams may be physically accessible, but the effort required to reach them is
prohibitive because an extreme effort (in terms of time and/or cost) would be required to sample them.
This would represent very few, if any sites, and should not be used for sites which are merely
inconvenient to sample. Please assign these sites a response of No Access- Other and describe the
excessive effort constraint (i.e., the time or cost that would be needed) in the COMMENTS column of the
Site Evaluation Spreadsheet. You will then need to select and evaluate a replacement site. Crews may be
contacted for further detail if they use this response.

5.6 Tidal Sites

The NRSA design contains sites that are above the head of salt, including tidal sites. Consult the NOAA
head of salt maps for reconnaissance information about these sites in relation to the head of salt. Mark
if sites are tidally influenced on the Site Verification Form in the app and on Column T of the Site
Evaluation Spreadsheet.

However, sites are considered non-target if they are below the head of salt. In addition to looking at
the NOAA maps, crews must evaluate tidal sites salinity levels in the field. Sites that are tidal and exceed
the salinity threshold of > 0.5 ppt are considered non-target and should not be sampled. They should be
replaced following the site replacement procedures.

5.7 Blackwater Sites

For the NRSA 2023/24, we are looking to evaluate how many target sites are considered "blackwater"
sites by the field sampling crews and local experts. If the site you are sampling is a blackwater site,
please mark that on the field Verification Form in the app and sample the site. This is for data analysis
purposes only and is not a factor for whether a site should be dropped or not, though you should also
mark it in Column U on the Site Evaluation Spreadsheet.

5.8 Run-of-the-River Reservoirs

Large streams and rivers with run-of-the-river reservoirs on them are considered target for the NRSA
2023/24. The determination if a site with a dam is a run of the river or a reservoir is based on the
residency time of the water. Sites with less than seven-day residence time are considered TARGET for
the NRSA. Sites with greater than seven-day residence time are considered NON-TARGET for the
NRSA.

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6 SELECTING ALTERNATE SITES

The sampling site lists for the NRSA 2023/24 are organized by state and replacement is done within the
state. Each Site Evaluation Spreadsheet contains a list of all primary sites (panel=base) which also
includes revisit (RVT2) sites, and alternate (panel=oversample) sites in the state. The sites are listed on
the Site Evaluation Spreadsheet in the order in which they were randomly selected. All primary (base
and revisit) sites must be evaluated for potential sampling and must be sampled unless they are
determined to be non-target, non-sampleable, or not accessible. If a primary site is rejected, then it
will be replaced by an alternate site within the same state, panel year (if possible), and reach (size)
category. Table 6.1 describes the order in which sites are replaced.

6.1 Site Sampling Categories

There are 11 sampling panels within three waterbody reach categories for the NRSA 2023/24 (Section
2.3). Sites are designated as "base sites" which must be evaluated and "oversample sites" which will be
evaluated in a given order based on the base site within the panel they are replacing. If a base site is
deemed non-target or non-sampleable during the reconnaissance process or in the field, a site from the
replacement site list must be selected. The replacement site must be done within the same state and
waterbody reach category.

The replacement site must be the next available site in site ID order. Table 6.1 discusses the logical
order in which sites are replaced and Figure 6.1 shows the order in a flowchart for each reach category.
Note, within the Site Evaluation Spreadsheet, each panel use and their replacement sites have been
separated by a black line. Should you run out of replacement sites for those panels, please proceed to
utilizing the first available NRS23_23 Oversample site at the bottom portion of each reach category tab.

6.2 Sampling Sites from Previous Surveys

If a primary site is rejected because it is non-target, non-sampleable, or not accessible, then it will be
replaced by an alternate site within the same state, reach category (small stream, large stream, or river),
and, whenever possible, the same year category. Should there be a need to select an alternative site
from the revisit sites, specific instructions can be found in flowcharts described in Figure 6.1.

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Table 6.1 Alternative Site Replacement Instructions

Type of

Original Site

Primary Oversample

Replacement Site If No Oversample Site is Available

Sites





Replacement Site



Revisit

NRS23_

18RVT2SS

NRS23_18BaseSS

NRS23_18RVT2SS - > NRS23_18BaseSS -> NRS23_180verSS -> NRS23_230verSS

Sites from

NRS23_

18RVT2LS

NRS23_18BaseLS

NRS23_18RVT2LS - > NRS23_18BaseLS -> NRS23_180verLS -> NRS23_230verLS

2018/19

NRS23_

18RVT2RV

NRS23_18BaseRV

NRS23_18RVT2RV - > NRS23_18BaseRV -> NRS23_180verRV -> NRS23_230verRV

(Revisit sites









were







*lf a site supposed to be sampled in 2023/24 after being sampled in 2018/19 but cannot be sampled, please

evaluated in







replace with first BASE site on list within the respective Rivers/ Streams tabs. This replacement must be

2018/19 and







sampled TWICE. The base site that was used must be replaced with an available oversample site to

will be







compensate for the shift in sites. Strahler Category and Ecoregion do not matter in the selection of oversample

evaluated







sites.

again









2023/24.









Sites with









RVT2 will be









sampled









twice)









Resample

NRS23_

_18BaseSS

NRS23_180verSS

N RS23_18BaseSS -> NRS23_180verSS -> NRS23_230verSS

Sites from

NRS23_

_18BaseLS

NRS23_180verLS

NRS23_18BaseLS -> NRS23_180verLS -> NRS23_230verLS

2018/19

NRS23_

_18BaseRV

NRS23_180verRV

NRS23_18BaseRV -> NRS23_180verRV -> NRS23_230verRV

(Sites that









are







*lf a base site supposed to be sampled in 2023/24 after being sampled in 2018/19 but cannot be sampled,

evaluated in







please replace with first available oversample site

both









2018/19 and









2023/24, but









sampled









once)









New sites

NRS23_

_23BaseSS

NRS23_230verSS

NRS23_23BaseSS -> NRS23_230verSS

only

NRS23_

_23BaseLS

NRS23_230verLS

NRS23_23BaseLS -> NRS23_230verLS

sampled

NRS23_

_23BaseRV

NRS23_230verRV

NRS23_23BaseRV -> NRS23_230verRV

in 2023/24







*lf a base site new in 2023/24 cannot be sampled, please replace with first available oversample site







16

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RIVERS

LARGE STREAMS

NR523 13IWT2LS

* See Footnote

r

NRS23_

.IBBaseLS



>

NRS23

ISOverLS







5





f	^	1

. No more ISOver sites I
^ 1

















NRS23.

.23 Base LS





NRS23

_230verLS



1-







SMALL STREAMS

*When re placing a Revisit (RVT2) site with a Base Site, Redesignate the appropriate Base site as a
Revisit site AND re place t hs d rapped Base site with an ap p rap riate aversam p Is site

Figure 6.1 NRSA 2023/24 Site Replacement Plan. Darker shaded colors are the revisit sites (sites to be sampled twice), lighter shaded sites are regular base
sites and cells without shading are oversample sites. Each of these colors refers to reach category tabs within the Site Evaluation Spreadsheet.

17

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6.3 Example of Site Replacement Process

Figure 6.2 describes the replacement process of a revisit site within the river's reach category evaluated
in NRSA 2023/24, If the revisit base site (NRS23_18RVT2RV_FT) in question, NRS23_NJ_10005, is non-
target or otherwise unsampleable, it needs to be replaced by the first available NRS23_18BaseRV site
regardless of FT suffix (NRS23_NJ_10007) and will be evaluated and sampled twice. All base sites must
be conserved. Therefore, if a site is dropped and replaced with another base site, which is the case for
all revisit sites, the replacement base site must also be replaced.

In this case, the base site which will replace the revisit site (NRS23_NJ_10007) is used as Revisit site
replacement and is also replaced with first available NRS23_180ver oversample site (NRS23_NJ_10032).
If all oversample sites are used and more are needed, crews should select the first available
NRS23_230ver site from that reach category (on the same tab in the Site Evaluation Spreadsheet as the
original dropped site). Sites may not be used as a replacement for multiple sites. Evaluators will mark if a
site was used as a replacement for another base site in Column V of the Site Evaluation Spreadsheet (Yes
or No). If the site was used as a replacement and was sampled, please include the Site ID of the dropped
site in Column W.



State

2023-24 Site ID

Panel Use

Water body
Category

Strahler Order

Ecoregion

NRSA provided
Coordinates Latitude /
Longitude

2018-19 Site
10

2018-19 Evaluation
Status

Waterbody Name

r









V5











V











NJ





RV

6

Northern Appalac

40.8333482

-74.982711



Target_Sampied

Pequest River

V8

NJ

INRS23 NJ 10009

NRS23 ISBaseRV

RV

71Southern Appalacl|

40.85885

-74.119

NRS18 NJ 11

Target Sampled

Passaic River



NJ

I NRS23_NJ_10032

INRS23_lSOverRV

RV

8 Coastal Plains

40.0154233

-75.033912

I NRS18_NJ_11



Delaware River





10 I



111

NJ

NRS23 NJ 10016

NRS23 23BaseRV FT

RV

8

Coastal Plains

39.6572591

-75.54324





Delaware River

12 i

NJ

NRS23 NJ 10017

NRS23 23BaseRV FT

RV

6

Coastal Plains

39.6184954

-74.603724





Mullica River

13]

NJ

NRS23_NJ_10018

NRS23_23BaseRV_FT

RV

8

Southern Appalacl

40489117

-74 433518





Raritan River

14

NJ

NRS23_NJ_10019

NRS23_23BaseRV

RV

5

Northern Appalacl

40.7332083

-74.830764





South Branch Raritan River

15

NJ

NRS23_NJ_10020

NRS23_23BaseRV

RV

6

Coastal Plains

39.2456273

-75.006188





Maurice River

16

NJ

NRS23_NJ_10063

NRS23_230verRV

RV

5

Southern Appalacl

41.0775123

-74.19519





Ramapo River

17

NJ

NRS23_NJ_10064

NRS23_230verRV

RV

8

Northern Appalacl

40.9763861

-73.89809





Hudson River

18

NJ

NRS23_NJ_10065

NRS23_230verRV

RV

7

Coastal Plains

40.199931

-74.761264





Delaware River

19

NJ

NRS23_NJ_10066

NRS23_230verRV

RV

8

Coastal Plains

38.9386609

-75.096007





Delaware River

20

NJ

NRS23_NJ_10067

NRS23_230verRV

RV

7

Southern Appalacl

40.8538-161

-74.325523





Passaic River

21

NJ

NRS23_NJ_10068

NRS23_230verRV

RV

8

Southern Appalacl

40.7878362

-73.991956





Hudson River

22

NJ

NRS23_NJ_10069

NRS23_230verRV

RV

7

Northern Appalacl

40.6178677

-75.20121





Delaware River

23 '

NJ

NRS23_NJ_10070

NRS23 230verRV

RV

8

Coastal Plains

39.2923818

-75.36974





Delaware River

Figure 6.2 Example of Replacement of Revisit Site in Rivers Reach Category

New base sites which start with a Panel Use of "NRS23_23Base" are replaced with the "NRS23_230ver"
sites within that reach category. Oversample sites must be evaluated in order and sites may not be
skipped. Using the lower half of the image in Figure 6.2, if NRS23_NJ_10016 must be dropped, the
evaluator would first evaluate site NRS23_NJ_10063 as a potential replacement for that base site and
sample that site if target and permission has been granted. If NRS23_NJ_10063 is also dropped,
evaluators must assess the next Oversample site on the list and continue doing so until all dropped sites
have been replaced. All sites must be evaluated in order. If all oversample sites are used from the new
NRS23_23 Panel Use within that reach category, evaluators must contact EPA for additional oversample
sites.

Note, crews can disregard the FT suffix in the panels. The design includes sites which are meant for Fish
Tissue collection. Currently, EPA does not plan on collecting Fish Tissue samples, but have kept the FT in
the design in case the opportunity presents itself later.

18

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6.4 State Designs

Eight states have state-specific survey designs: Arizona, Indiana, Kansas, New Hampshire, Oklahoma,
Texas, Virginia, and Wisconsin. These designs are described in the design document. In addition, a state
may implement a state-level survey using the national design for their state. The above survey design
describes the national survey design and sets the required number of sites that must be sampled within
each state. If a state implements a state-level design, the NRSA 2023/24 design sites must be sampled as
part of the state-wide design. It is critical that the site replacement process be followed and that the
state communicate to the NRSA 2023/24 coordinator whether only the required NRSA 2023/24 sites will
collect all the NRSA indicators or if all state-level sites will collect all the NRSA indicators. This
information is required by the NRSA staff to know what sites evaluated should be included in the weight
adjustment after field implementation.

Site Evaluation Point of Contact: Richard Mitchell (202-566-0644)
7 LITERATURE CITED

Environmental Monitoring and Assessment Program -Surface Waters: Western Pilot Study Field
Operations Manual for Wadeable Streams. EPA 841-B-17-003a. U.S. Environmental Protection
Agency, Washington, D.C.

EPA841-B-04-006. U.S. Environmental Protection Agency, Washington D.C.

EPA841-B-07-006. U.S. Environmental Protection Agency, Washington D.C. Attachment 1.

Peck, D.V., J.M. Lazorchak, and D.J. Klemm (editors). Unpublished draft.

U.S. EPA. 2004. Wadeable Streams Assessment: Site Evaluations Guidelines.

U.S. EPA. 2017. National Rivers and Streams Assessment: Site Evaluations Guidelines.

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