June 2025
EPA-843-B-25001
United States
Environmental Protection
lAgency
Streamflow Duration Assessment
Methods for the Northeast and
Southeast of the United States
OERD
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Streamflow Duration Assessment Methods for
the Northeast and Southeast of the United
States
Version 2.0
June 2025
Prepared by Amy James1, Ken M. Fritz2, Brian Topping3, Rachel Fertik Edgerton3, Kristina Nicholas4,
Raphael Mazor5 and Tracie-Lynn Nadeau6.
1 Ecosystem Planning and Restoration. Raleigh, NC
2 U.S. Environmental Protection Agency—Office of Research and Development. Cincinnati, OH
3 U.S. Environmental Protection Agency—Office of Wetlands, Oceans, and Watersheds. Washington,
D.C.
4 Oak Ridge Institute of Science and Education (ORISE) Fellow at U.S. Environmental Protection
Agency—Office of Wetlands, Oceans, and Watersheds. Washington, D.C.
5 Southern California Coastal Water Research Project. Costa Mesa, CA
6 U.S. Environmental Protection Agency—Region 10. Portland, OR (retired)
The following members of the National Steering Committee, and the Regional Steering Committee for
the Northeast and Southeast, provided input and technical review:
National
Tunis McElwain
U.S. Army Corps of Engineers
Headquarters, Regulatory Program
Washington, DC
Gabrielle David
U.S. Army Corps of Engineers
Engineer Research and Development Center
Hanover, NH
Matt Wilson
U.S. Army Corps of Engineers
Headquarters, Regulatory Program
Washington, DC
Rose Kwok
U.S. Environmental Protection Agency
Office of Wetlands, Oceans and Watersheds
Washington, DC
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Regional
Erica Sachs, Raymond Putnam, and
Stephanie Tougas
U.S. Environmental Protection Agency
Region 1
Boston, MA
Marco Finocchiaro and Stephanie Andreescu
U.S. Environmental Protection Agency
Region 2
New York, NY
Nancy Rodriguez
U.S. Environmental Protection Agency
Region 2
San Juan, PR
Christine Mazzarella and Natalie Motley
U.S. Environmental Protection Agency
Region 3
Philadelphia, PA
Greg Pond and Kelly Krock
U.S. Environmental Protection Agency
Region 3
Wheeling, WV
Eric Somerville, Kacy Sable, and
Cynthia Van der Wiele
U.S. Environmental Protection Agency
Region 4
Athens, GA
Melanie Burdickand Nicki DeWeese
U.S. Environmental Protection Agency
Region 5
Chicago, IL
Chad LaMontagne and Kamren Metzger
U.S. Army Corps of Engineers
Regulatory Branch
St. Louis District
Mike Moxey
U.S. Army Corps of Engineers
Regulatory Division
Mobile District
Jeanne Richardson, Tucker Smith, Silvia
Gazzera, and Laura Herrmann
U.S. Army Corps of Engineers
Regulatory Branch
Norfolk District
Taylor Bell and Erin Davis
U.S. Army Corps of Engineers
Regulatory Division
New England District
Alyssa Barkley, Alani Taylor and Alex Veto
U.S. Army Corps of Engineers
Regulatory Branch
Pittsburgh District
Bryton Hixson
U.S. Army Corps of Engineers
Regulatory Branch
Vicksburg District
Tyler Crumbley
U.S. Army Corps of Engineers
Regulatory Division
Wilmington District
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Raul Gutierrez and Chelsey Sherwood
U.S. Environmental Protection Agency
Region 6
Dallas, TX
Blain McNabb, Jeanette Schaeffer, and
Gabriel DuPree
U.S. Environmental Protection Agency
Region 7
Lenexa, KS
Aric Payne, Mark G. Mcintosh, and
Eric Sinclair
U.S. Army Corps of Engineers
Regulatory Division
Nashville District
Jeremy Kinney
U.S. Army Corps of Engineers
Regulatory Division
Charleston District
Elizabeth Shelton and Joseph Shelnutt
U.S. Army Corps of Engineers
Regulatory Division
Fort Worth District
Sabrina Miller
U.S. Army Corps of Engineers
Regulatory Branch
Detroit District
Robert Hoffmann and Michael Ware
U.S. Army Corps of Engineers
Regulatory Branch
Tulsa District
Mark Pattillo, Kara Vick, and Shawn Patrick
Hillen
U.S. Army Corps of Engineers
Regulatory Division
Galveston District
Damon McDermott
U.S. Army Corps of Engineers
Regulatory Branch
Memphis District
Wes Barnett, Brian Bridgewater, and Justin
Elkins
U.S. Army Corps of Engineers
Regulatory Division
Huntington District
Matthew Hynson
U.S. Army Corps of Engineers
Regulatory Branch
Baltimore District
Pablo Bacon
U.S. Army Corps of Engineers
Regulatory Division
Little Rock District
Andy Dangler
U.S. Army Corps of Engineers
North Atlantic Division
Ryan Langer
U.S. Army Corps of Engineers
Regulatory Branch
Kansas City District
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Andrew Blackburn
U.S. Army Corps of Engineers
Regulatory Branch
Chicago District
Justin Hammonds, Nathan Driggers,
and Adam White
U.S. Army Corps of Engineers
Regulatory Branch
Savannah District
Rosita Miranda
U. S. Army Corps of Engineers
Regulatory Division
New York District
Jon Barmore
U.S. Army Corps of Engineers
Regulatory Division
New Orleans District
Russel Retherford and Sam Werner
U.S. Army Corps of Engineers
Regulatory Division
Louisville District
Suggested citation:
James, A., Fritz, K.M., Topping, B., Fertik Edgerton, R., Nicholas, K., Mazor, R., and Nadeau, T.-L. 2025.
Streamflow Duration Assessment Methods for the Northeast and Southeast of the United States.
Version 2.0. Document No. EPA-843-B-25001.
Photographs courtesy of the U.S. Environmental Protection Agency unless otherwise noted.
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Acknowledgments
We thank Abel Santana, Robert Butler, Duy Nguyen, Kristine Gesulga, Kenneth McCune, Adriana
LeCompte-Santiago, Will Saulnier, and Anne Holt for assistance with data management and web
application development. We thank Megan Annis, Jackson Bates, Joe Bertherman, Emma Duguay,
Brian Emlaw, Zak Erickson, Hannah Erickson, Heidi Fisher, Kate Forsmark, Richard Judge, Kort Kirkeby,
Alec Lambert, Libby Lee, Claire Leedy, Bryan Lees, Mindi Lundberg, Abe Margo, Buck Meyer, Margaret
O'Brien, Addison Ochs, Jake Okun, Jack Poole, Morgan Proko, Chris Roche, Olivia Shaw, Chelsey
Sherwood, Craig Smith, Ali Sutphin, Alex Swain, James Treacy, Charlie Waddell, and Jeff Weaver for
assistance with data collection. Stephanie Andreescu, Raul Gutierrez, Tamara Hea rtsill -Sea I ley, Nolan
Hahn, Jeffery Lapp, Todd Lutte, Robert Montgomerie, Sofia Olivero Lora, Kathryn Quesnell, Jose Soto,
and Cynthia Van Der Wiele assisted with plant identification.
Numerous researchers and land managers with local expertise assisted with the selection of study
reaches to calibrate the method: Susie Adams, Laurie Alexander, Dan Allen, Carla Atkinson, Brent
Aulenbach, Debbie Arnwine, Scott Bailey, Joe Bartlett, Mary Becker, Taylor Bell, Sean Beyke, Emery
Boose, Rick Chormann, Joshua Clemmons, Matt Cohen, Shannon Curtis, Daniel Dauwalter, Daragh
Deegan, Janet Dewey, John Dorney, Jon Duncan, Bob Easter, Mike Fargione, Jacob Ferguson, Brock
Freyer, Bill Gawley, Cynthia Gilmour, Natalie Griffith, Kevin Grimsley, Brandon Hall, Steve Hamilton,
Russell Hardee, Andy Harrison, Blaine Hastings, Tamara Heartsill-Scalley, Katy Hofmeister, Darrin Hunt,
Jeremiah Jackson, Rhett Jackson, Allan James, Carrie Jenson, Nate Jones, Tom Jordan, Joshua Keeley,
Sean Kelly, Vicky Kelly, Julie Kelso, Jeanine Lackey, Bryan Lees, Mike Lott, Dan Marion, Jason Martin,
Gustavo Martinez, Bruce Means, Carl Neilson, Jules NeSmith, Jami Nettles, C. Nicholas, Greg Pond, Kai
Rains, Carlos Ramos-Scharron, Jamie Robb, Mary Rocky, Carlos Rodriguez, Randy Sarver, Kim Sash,
Kristen Selikoff, Stephanie Siemke, Knight Silas Cox, Chelsea Smith, Doug Smith, Eric Snyder, Tedmund
Soileau, Matthew Stahman, Emily Stephan, Carl Trettin, Ross Vander Vorste, Robert Voss, Peter
Wampler, Glenn Wilson, Brandon Yates, Shawyn Yeamans, and Margaret Zimmer.
This work was funded through EPA contract 68HERC21D0008 to Ecosystem Planning and Restoration
and EPA contracts EP-C-16-006 and 68HERC22D0002 to ESS Group.
Disclaimers
This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and
approved for publication. Any mention of trade names, manufacturers or products does not imply an
endorsement by the United States (U.S.) Government or the U.S. Environmental Protection Agency.
The EPA and its employees do not endorse any commercial products, services, or enterprises. The
contents of this report are not to be used for advertising, publication, or promotional purposes.
Citation of trade names does not constitute an official endorsement or approval of the use of such
commercial products. All product names and trademarks cited are the property of their respective
owners. The findings of this report are not to be construed as an official Department of the Army or
the U.S. Environmental Protection Agency position unless so designated by other authorized
documents. Destroy this report when no longer needed. Do not return it to the originator.
v
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Table of Contents
SECTION 1: INTRODUCTION AND BACKGROUND 1
1.1 The SDAMs for the NE and SE 4
1.2 Intended use and limitations 5
1.3 Development of the NE and SE SDAMs 6
SECTION 2: OVERVIEW OF THE NE AND SE SDAMS AND THE ASSESSMENT PROCESS 9
2.1 Considerations for assessing streamflow duration and interpreting indicators 9
2.1.1 Clean Water Act jurisdiction 9
2.1.2 Scales of assessment 9
2.1.3 Spatial variability 9
2.1.4 Temporal variability 10
2.1.5 Ditches and modified natural streams 10
2.1.6 Other disturbances 10
2.1.7 Multi-threaded systems 11
SECTION 3: DATA COLLECTION 12
3.1 Conduct desktop reconnaissance 12
3.2 Prepare sampling gear 14
3.3 Order of operations for completing the NE and SE SDAM field assessments 14
3.4 Timing of sampling 15
3.5 Assessment reach considerations 16
3.5.1 Reach placement 16
3.5.2 Reach length 17
3.5.3 How many assessment reaches are needed? 17
3.6 Photo-documentation 17
3.7 Conducting assessments and completing the field form 18
3.7.1 General reach information 18
3.7.2 Assessment reach sketch 23
3.8 How to measure indicators of streamflow duration 23
3.8.1 Bankfull channel width 25
3.8.2 Entrenchment Ratio (NE only) 25
3.8.3 Aquatic macroinvertebrate indicators 26
3.8.4 Slope (NE only) 29
3.8.5 Shading 30
3.8.6 Prevalence of rooted upland plants in streambed (SE only) 31
3.8.7 Particle size of stream substrate (SE only) 34
3.8.8 Prevalence of fibrous roots in streambed (SE only) 36
3.8.9 Drainage Area 37
3.8.10 Elevation 40
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3.8.11 Average Monthly Precipitation for May, June, and July (SE only) 41
3.9 Additional notes and photographs 41
SECTION 4: DATA INTERPRETATION AND USING THE WEB APPLICATION 42
4.1 Outcomes of NE and SE SDAM classification 42
4.2 Applications of the NE and SE SDAMs outside the intended area 43
4.3 What to do when a more specific classification is needed 43
4.3.1 Review historical aerial imagery 43
4.3.2 Conduct additional assessments at the same reach 45
4.3.3 Conduct assessments at nearby reaches 46
4.3.4 Conduct reach revisits during regionally appropriate wet and dry seasons 46
4.3.5 Collect hydro logic data 46
SECTION 5: REFERENCES 47
APPENDIX A. GLOSSARY OF TERMS 51
APPENDIX B. GUIDE TO AQUATIC INVERTEBRATE ORDERS AND FAMILIES IN THE EASTERN UNITED
STATES 55
General insect anatomy 55
Insect Orders and Families 56
Ephemeroptera (mayflies) 56
Plecoptera (stoneflies) 59
Trichoptera (caddisflies) 61
Coleoptera (beetles) 65
Odonata (dragonflies and damselflies) 68
Megaloptera (dobsonflies, alderflies) 70
Diptera (true flies) 71
Hemiptera (true bugs) 73
Mollusk Families (mussels, clams, and snails) 75
Crustacean Orders (crayfish, amphipods, and isopods) 77
Other: Annelida, Acariformes, and Turbellaria (worms, leeches, water mites, and flatworms) 79
Phylum Annelida, Class Oligochaeta 79
Phylum Annelida, Class Hirudinea 79
Superorder Acariformes (Phylum Arachnida) 80
Class Turbellaria (Phylum Platyhelminthes) 80
APPENDIX C. FIELD FORMS
Appendix CI: Combined field form for the NE and SE SDAMs
Appendix C2: Field form for the NE SDAM
Appendix C3: Field form for the SE SDAM
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Table of Figures
Figure 1. Streams of different flow classes 2
Figure 2. Map of regional streamflow duration methods 3
Figure 3. Locations of ephemeral, intermittent, and perennial stream reaches used to calibrate the NE
and SESDAMs 6
Figure 4. Bankfull measurement and photo point locations 19
Figure 5. Measuring bankfull width 20
Figure 6. Examples of difficult conditions that may interfere with the observation or interpretation of
indicators 22
Figure 7. Examples of estimating surface and subsurface flow, and isolated pools 23
Figure 8. Measurement of entrenchment is based on the ratio of the flood-prone width to the bankfull
width 25
Figure 9. Examples of evidence of aquatic macroinvertebrates in dry channels 27
Figure 10. Examples of terrestrial macroinvertebrates you may find in a dry channel 28
Figure 11. Schematic illustration of slope measurement using a clinometer 30
Figure 12. Representation of the mirrored surface of a convex spherical densiometer showing the
position for taping the mirror and the intersection points used for the densiometer reading 31
Figure 13. National Wetland Plant List (NWPL) regions that overlap with the SE SDAM region 32
Figure 14. Examples illustrating scoring levels for the Prevalence of Rooted Upland Plants in the
Streambed indicator 34
Figure 15. Examples illustrating scoring levels for the Particle Size of Stream Substrate indicator 36
Figure 16. Example of fibrous roots (left) vs. woody roots (right) 37
Figure 17. Calculating drainage area using StreamStats 39
Figure 18. Calculating drainage area using The National Map Viewer 40
Figure 19. Examples of using aerial imagery to support streamflow duration classification 45
Table of Tables
Table 1. Distribution of streamflow duration classes across the NE and SE study reaches 6
Table 2. Examples of online resources for generating local flora lists 13
Table 3. Scoring guidance for the BMI indicator 29
Table 4. Scoring guidance for the Prevalence of Rooted Upland Plants in the Streambed indicator 33
Table 5. Scoring guidance for Particle Size of Stream Substrate indicator 35
Table 6. Scoring guidance for the Fibrous Roots in Streambed indicator 37
viii
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Section 1: Introduction and Background
Section 1: Introduction and Background
Streams exhibit a diverse range of hydrologic regimes, and the hydrologic regime strongly influences
the physical, chemical, and biological characteristics of active stream channels and adjacent riparian
areas. Thus, information describing a stream's hydrologic regime is useful to support resource
management decisions, including Clean Water Act Section 404 decisions. One important aspect of the
hydrologic regime is streamflow duration—the length of time that a stream sustains surface flow.
However, hydrologic data to determine flow duration has not been collected for most stream reaches
nationwide. Although maps, hydrologic models, and other data resources exist (e.g., the National
Hydrography Dataset, Moore et al. 2019), these may exclude small headwater streams and unnamed
second- or third-order tributaries, and limitations on accuracy and spatial or temporal resolution may
reduce their utility for many management applications (Hall et al. 1998, Nadeau and Rains 2007, Fritz
et al. 2013). Therefore, rapid, field-based methods are needed to determine flow duration class at the
reach scale (defined in Section 2: Overview of the NE and SE SDAMs and the Assessment Process) in
the absence of long-term hydrologic data (Fritz et al. 2020).
These methods are intended to classify stream reaches into one of three streamflow duration classes1:
Ephemeral reaches are channels that flow only in direct response to precipitation. Water typically
flows only during and/or shortly after large precipitation events, the streambed is always above the
water table, and stormwater runoff is the primary water source.
Intermittent reaches are channels that contain sustained flowing water for only part of the year,
typically during the wet season, where the streambed may be below the water table and/or where
the snowmelt from surrounding uplands provides sustained flow. The flow may vary greatly with
stormwater runoff.
Perennial reaches are channels that contain flowing water continuously during a year of normal
rainfall, often with the streambed located below the water table for most of the year. Groundwater
typically supplies the baseflow for perennial reaches, but the baseflow may also be supplemented
by stormwater runoff and/or snowmelt.
Example photographs and hydrographs of stream reaches in each class are shown in Figure 1.
1 The definitions used for development of this manual are consistent with the definitions used to develop the SDAMs for
the Pacific Northwest, Arid West, Western Mountains, and Great Plains.
1
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Section 1: Introduction and Background
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Figure 1. Streams of different flow classes. Photos of stream reaches iri each streamflow duration class are shown at left,
with corresponding visualizations of daily flowing vs dry periods of these reaches, including flow classification, on the right.
Daily flowing vs dry observations are derived from Stream Temperature, Intermittency, and Conductivity (STIC) loggers
deployed in the channel thalweg in erosional or riffle habitat in each study reach (Chapin et al. 2014, Kelso et al. 2023), For
these loggers, the presence of flowing surface water is inferred from raw intensity values that are higher than logger-
specific intensity values calibrated to distilled water (yellow lines). Blue areas above the yellow lines denote flowing periods
and black bars denote field visits when logger data were downloaded, and indicator data were collected.
2
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Section 1: Introduction and Background
These classes describe the typical patterns exhibited by a stream reach over multiple years, although
observed patterns in a single year may vary due to extreme and transient climatic events (e.g., severe
droughts). Although flow duration classes are not strictly defined by their sources of flow (e.g., storm
runoff, groundwater, snowmelt), the duration is often related to the relative importance of different
flow sources to stream reaches and the stability of their contributions. Perennial reaches have year-
round surface flow in the absence of drought conditions. Intermittent reaches have one or more
periods of extended surface flow in most years, where the flow is sustained by sources other than
surface runoff in direct response to precipitation, such as groundwater, melting snowpack, irrigation,
reservoir operations, or wastewater discharges. Ephemeral reaches have a surface flow for short
periods and only in direct response to precipitation.
This manual describes the final Streamflow Duration Assessment Methods (SDAMs) intended to
distinguish flow duration classes of stream reaches in the Northeast (NE) and Southeast (SE) regions of
the United States as defined in Synthesizing the Scientific Foundation for Ordinary High-Water Mark
Delineation in Fluvial Systems (Wohl et al. 2016), which is based largely on vegetation type and
precipitation levels (Figure 2). In the Northeast, snowmelt contributes at least some flow to streams
and rivers during the year while the Southeast is dominated by rainfall runoff other than snowmelt,
including tropical storms and hurricanes.
Pacific
Northwest
Great
Plains
Arid
West
Northeast
Western
Mountains
Figure 2. Map of regional streamflow duration methods.
Based on data analysis, distinct NE and SE SDAMs provide higher classification accuracy than a single
stratified method, though certain indicators are used in both methods. The NE and SE SDAMs are
3
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Section 1: Introduction and Background
based on biological and geomorphological indicators measured in the field as well as geospatial and
climatic indicators determined using desktop methods. Biological indicators, known to respond to
gradients of streamflow duration (Fritz et al. 2020, Fritz et al. 2023), have notable advantages for
assessing natural resources. The primary advantage is their ability to reflect long-term environmental
conditions (e.g., Karr et al. 1986, Rosenberg and Resh 1993). This characteristic makes them well suited
for assessing streamflow duration, because some species reflect the aggregate hydrologic conditions
that a stream has experienced over multiple years. As a result, relatively rapid field observations of
biological indicators made at a single point in time can provide long-term insights into streamflow
duration and other hydrological characteristics of a stream reach. Geomorphological, geospatial, and
climatic indicators can also be rapidly measured and provide information about the hydrologic drivers
of streamflow duration (Fritz et al. 2008, Olson and Brouillette 2006, Russell et al. 2014, Jensen et al.
2018). For example, wide channels in areas with low precipitation are associated with shorter
durations of streamflow; in contrast, in wetter areas, narrow channels are typically associated with
headwaters, where the contributing catchments may be too small to generate long-duration flows.
1.1 The SDAMs for the NE and SE
This manual describes two methods that use a small
number of indicators to predict the streamflow
duration class of stream reaches in the NE and SE. Beta
SDAMs for the NE and SE were released in April 2023
(James et al. 2023). After additional data collection,
analysis, and user feedback, the final SDAMs were
developed, reflecting somewhat different indicators
from the beta methods. For more information on the
development of these SDAMs or SDAMs for other U.S.
regions, please refer to the U.S. Environmental
Protection Agency's (EPA's) SPAM website.
Biological indicators
plants in the streambed (SE only)
• Prevalence of fibrous roots in the
• Benthic Macroinvertebrate Index
(BMI)
• Total aquatic macroinvertebrate
abundance (SE only)
• Shading
• Prevalence of rooted upland
Indicators of the NE and SE SDAMs
streambed (SE only)
The NE and SE SDAMs assign reaches to one of six
possible classifications: ephemeral, intermittent,
perennial, at least intermittent, less than perennial,
and needs more information. An at least intermittent
classification occurs when an intermittent or perennial
classification cannot be made with high confidence,
but an ephemeral classification can be ruled out. A less
than perennial classification occurs when an
ephemeral or intermittent classification cannot be
made with high confidence, but a perennial
classification can be ruled out. If no class can be
determined with confidence, the stream is classified as
needs more information.
Geomorphological indicators
• Bankfull channel width
• Entrenchment ratio (NE only)
• Slope (NE only)
• Particle size of stream substrate
(SE only)
Geospatial/Climatic indicators
• Drainage area
• Elevation
• Average monthly precipitation
(May-July) (SE only)
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Section 1: Introduction and Background
Because the NE and SE SDAMs share many indicators in common, and because many practitioners
work in both regions, the two methods are presented in a combined manual. When assessing reaches
near the boundary between regions or in areas more closely matching the characteristics of a different
SDAM region, practitioners are encouraged to measure all indicators required for both methods,
although some indicators may only be used for one method.
The NE and SE methods were developed using a machine learning model known as a random forest.
Random forest models are increasingly common in the environmental sciences because of their
superior performance in handling complex relationships among indicators used to predict
classifications (Cutler et al. 2007). In some cases, a random forest model can be simplified into a
decision tree or table (e.g., Nadeau et al. 2015, Mazor et al. 2021); however, that was not possible for
the NE or SE models. To obtain a flow classification for an individual assessment reach, there is an
open-access, user-friendly web application for entering indicator data and running the region-specific
random forest model. No data entered into the web application are visible to or stored by the EPA or
any other agency.
1.2 Intended use and limitations
The NE and SE SDAMs are intended to support field classification of streamflow duration at the reach
scale in streams with defined channels (having a bed and banks) in the NE and SE regions. Section 3.5
Assessment reach considerations discusses when more than one reach should be assessed to classify
streamflow duration for a stream segment longer than the assessment reach. Use of the SDAMs may
inform a range of activities where information on streamflow duration is useful, including jurisdictional
determinations under the Clean Water Act; however, the classification resulting from use of an SDAM
is not in itself a jurisdictional determination. SDAMs are not mandatory for completing a Clean Water
Act jurisdictional determination, nor are they intended to supersede more direct measures of
streamflow duration (e.g., long-term records from stream gages). Other sources of information, such
as aerial imagery, reach photographs, traditional ecological knowledge, and local expertise, can
supplement the SDAMs when classifying streamflow duration (Fritz et al. 2020).
Although the NE and SE SDAMs are intended for use in both natural and altered stream systems, some
alterations may complicate the interpretation of field-measured indicators or potentially lead to
incorrect conclusions. For example, streams managed as flood control channels may undergo frequent
maintenance to remove some or all vegetation in the channel and along the banks of the assessment
reach. Although some biological indicators recover quickly from these disturbances, the results from
assessments conducted shortly after such disturbances may be misleading. In addition, these types of
channels may not display channel features that result from natural geomorphic processes, such as a
typical particle size of stream substrate and entrenchment ratio.
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Section 1: Introduction and Background
1.3 Development of the NE and SE SDAMs
due to map scale some dots represent more than one site).
These methods resulted from a multi-year study conducted in 366 total study reaches across the NE
region (209) and SE region (157) following the process described in Fritz et al. (2020). Of these, data
from 358 sites (or reaches) where streamflow duration class could be determined from hydrologic data
were used to develop the SDAMs (Figure 3). Streamflow duration class was determined using
continuous (hourly interval) hydrological data from loggers deployed at 213 study reaches during the
data collection period. Streamflow duration classes were determined at an additional 40 study reaches
from U.S. Geological Survey (USGS) stream gages. Multiple sources of hydrologic data (e.g., inactive
USGS stream gage data, published studies, consultation with local experts) were used to classify the
remaining study reaches (105), for which data from continuous loggers were not available. Reaches
were distributed across flow duration classes as shown in Table 1.
Table 1. Distribution of streamflow duration classes across the NE and SE study reaches.
Stream Class Northeast Southeast
Ephemeral
41
34
Intermittent
95
72
Perennial
69
47
Total 205 153
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Section 1: Introduction and Background
Development of the SDAMs followed the process steps below (Fritz et al. 2020):
Preparation
• Conducted a literature review (James et al. 2022):
- Identified existing SDAMs, focusing on those originating in the NE or SE or developed using a
similar approach (see Nadeau 2015; NCDWQ2010).
- Identified 40 potential field biological, hydrological, and geomorphological characteristics related
to streamflow duration for evaluation in the NE and SE.
• Identified candidate study reaches with known streamflow duration class, representing diverse
environmental settings throughout the region.
Implementation
• Publish User Manual, data analysis report, and data used to develop the method.
• Publish web application and code.
• Publish training materials to support implementation.
• Train the the EPA and Corps staff on the method and how to train others.
Eighty percent of sites in the development data set were used for method calibration, while twenty
percent were withheld to provide an independent test of method performance.2 Based on this
withheld subset, the final methods correctly classified 73% of NE reaches and 67% of SE reaches among
2 Note, Table 1 above includes all sites used in method development, those used to calibrate the model, and the subset of
sites withheld for determining accuracy.
7
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Section 1: Introduction and Background
three classes (perennial vs. intermittent vs. ephemeral). Accuracy was much higher for differentiating
ephemeral from at least intermittent reaches (88% for the NE and 91% for the SE), and moderately
higher when differentiating perennial from less than perennial reaches (84% for the NE and 75% for the
SE). Generally, misclassifications between intermittent and perennial reaches were more common than
misclassifications between ephemeral and intermittent reaches in both regions. The ability of the NE
and SE SDAMs to discriminate ephemeral more accurately and consistently from at least intermittent
reaches is consistent with previous studies evaluating streamflow duration indicators and assessment
methods (Fritz et al. 2008 and 2013, Nadeau et al. 2015, Mazor et al. 2021) and other regional SDAMs
developed through this effort (Mazor et al. 2024, James et al. 2024).
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Section 2: Overview of the NE and SE SDAMs and the Assessment Process
Section 2: Overview of the NE and SE SDAMs and the Assessment Process
2.1 Considerations for assessing streamflow duration and interpreting indicators
2.1.1 Clean Water Act jurisdiction
Regulatory agencies evaluate aquatic resources for jurisdiction based on applicable regulations,
guidance, and policy. The NE and SE SDAMs do not incorporate that broad scope of analysis. Rather,
the methods provide information that may be used to inform jurisdictional decisions because they help
determine streamflow duration as ephemeral, intermittent, or perennial in the absence of a hydrologic
record.
2.1.2 Scales of assessment
The NE and SE SDAMs apply to an assessment reach, the length of which should be 40x the mean
bankfull channel width. Regardless of channel width, reaches must be a minimum of 40 m and no
longer than 200 m. The minimum reach-length of 40 m ensures that a sufficient area has been
assessed to evaluate indicators. Quantification and observations of indicators are focused on the
bankfull channel. However, ancillary information from outside the assessment reach (such as
surrounding land use) is also recorded.
2.1.3 Spatial variability
Indicators of streamflow duration (and other biological, hydrologic, and geomorphic characteristics of
streams) vary in their strength of expression within and among reaches in a stream system. The main
natural drivers of spatial variation are generally the physiographic province (e.g., geology and soils) and
climate (e.g., seasonal patterns of precipitation, snowmelt, and evapotranspiration). For example,
certain indicators, such as shading from riparian vegetation, may be more strongly expressed in a
floodplain with deep alluvial soils than they would be in a reach underlain by shallow bedrock, even if
both reaches have a similar duration of flow. Therefore, understanding the sources of spatial variability
in streamflow indicators will help ensure that assessments are conducted within relatively
homogenous reaches.
Common sources of variation within a stream system that may affect the expression of indicators
include:
• Natural longitudinal changes in channel gradient and size, and valley width (e.g., going from a
confined canyon to an alluvial fan, or going from wide to narrow valley).
• Other natural sources of variation, such as bedrock material (limestones, sandstones, shales,
conglomerates, and lignite) or water source (runoff, springs, summer rains, and groundwater).
• Drought or unusually high precipitation.
• Transitions in land use with different water use patterns (e.g., from commercial forest to
pasture, from pasture to cultivated farmland, or cultivated farmland to an urban setting), or
changes in management practices (e.g., intensification of grazing).
• Stream management and manipulation, such as diversions, water importation, dam operations,
and habitat modification (e.g., streambed armoring).
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Section 2: Overview of the NE and SE SDAMs and the Assessment Process
2.1.4 Temporal variability
Temporal variability in indicators may affect streamflow duration assessment in two ways: interannual
(e.g., year-to-year) variability and intra-annual (e.g., seasonal) variability. These methods were
developed to be robust to both types of temporal variability and are intended to classify streams based
on their long-term patterns in either flowing or dry conditions. However, both long-term sources of
temporal variability (such as El Nino-related climatic cycles) and short-term sources (such as scouring
storms before sampling) may influence the ability to measure or interpret indicators at the time of
assessment. Timing of management practices, such as dam operations, channel clearing, or
groundwater pumping, may also affect the flow duration assessment.
Certain indicators are more sensitive to temporal variability than others. For example, after a scouring
flood event aquatic macroinvertebrates may be displaced from a stream reach. In contrast, rooted
upland plants, if present, will likely remain. Similarly, longer-lived aquatic macroinvertebrates may be
able to colonize an ephemeral to intermittent reach during wet years, depending on the presence of
upstream or downstream refugia; however, changes in flow regimes may take several years to result in
changes to vegetation in the stream channel or the riparian corridor.
2.1.5 Ditches and modified natural streams
Assessment of streamflow duration is sometimes needed in canals, ditches, and modified natural
streams that are primarily used to convey water. These systems tend to have altered flow regimes
compared to natural systems with similar drainage areas (Bannister 1979, Buchanan et al. 2012, Davis
and Harden 2012, Epting et al. 2018), and the NE and SE SDAMs may determine if these flow regimes
support indicators consistent with different streamflow duration classes. Thus, the SDAMs may be
applied to these systems when streamflow duration information is needed.
Geomorphological indicators (e.g., bankfull channel width and slope; sometimes drainage area if
ditching is extensive) may be difficult to assess in straightened or heavily modified systems. Indicator
measurements should be based on present-day conditions, not historic conditions. Assessors should
note the degrees to which channel geomorphology reflects natural processes or if it reflects the effects
of management activities.
2.1.6 Other disturbances
Assessors should be alert for natural or human-induced disturbances that either alter streamflow
duration directly or modify the ability to measure indicators. Streamflow duration can be directly
affected by groundwater withdrawals, flow diversions, urbanization and stormwater management,
septic inflows, agricultural and irrigation practices, effluent dominance, or other activities. In the
method development data set, disturbed reaches were identified as those in urban or agricultural
settings or those with notable impacts from grazing, mining, or other human activities. The SE SDAM
had slightly lower accuracy in assessing disturbed reaches compared to undisturbed reaches for
identification between the three flow classifications and an even smaller difference in accuracy when
assessing ephemeral versus at least intermittent flow. The opposite was true of the NE SDAM, where
classification results for undisturbed sites had slightly lower accuracy than for disturbed sites for
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Section 2: Overview of the NE and SE SDAMs and the Assessment Process
identification between the three flow classes, however like in the SE there was an even smaller
difference in accuracy for when assessing ephemeral versus at least intermittent flow.
Streamflow duration indicators can also be affected by disturbances that may not substantially affect
streamflow duration (for instance, grading, grazing, recent fire, riparian vegetation management, and
bank stabilization); in extreme cases, these disturbances may eliminate specific indicators (e.g.,
absence of aquatic macroinvertebrates in channels that have undergone recent grading activity).
Logging, mining, and impoundments can affect both vegetation and geomorphological indicators (e.g.,
Choi et al. 2012, Jaeger 2015). Some long-term alterations or disturbances (e.g., impoundments) can
make streamflow duration class more predictable by reducing year-to-year variation in flow duration
and/or indicators. Discussion of how specific indicators are affected by disturbance is provided below
in Section 3: Data Collection. Assessors should describe disturbances in the "Notes on disturbances or
difficult site conditions" section of the field form.
2.1.7 Multi-threaded systems
Assessors should identify the lateral extent of the active channel, based on the outer limits of ordinary
high-water mark (OHWM). and apply the method to that area. That is, do not perform separate
assessments on each of the main and secondary channels within a multi-threaded system. Some
indicators may be more apparent in the main channel versus the secondary channels; note these
differences on the field form. Upland islands within the OHWM should not be included in the
assessment.
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Section 3: Data Collection
Section 3: Data Collection
3.1 Conduct desktop reconnaissance
Before an assessment, desktop reconnaissance helps ensure a successful assessment of a stream.
During desktop reconnaissance, assessors evaluate reach
accessibility and set expectations for conditions that may
affect field sampling. In addition, assessors can begin to
compile additional data that may inform determination of
streamflow duration, such as location of nearby stream
gages.
This stage of the evaluation is crucial for determining reach
access. The reach or project area should be plotted on a
map to determine access routes and whether landowner permissions are required. Safety concerns or
hazards that may affect sampling should be identified, such as road closures, controlled burns, or
hunting seasons. These access constraints are sometimes the most challenging aspect of
environmental field activities, and desktop reconnaissance can reduce these difficulties. Also, assessors
can determine if inaccessible portions of the reach (e.g., those on adjacent private property) have
consistent geomorphology or other attributes, compared with accessible portions.
Desktop reconnaissance can also help identify features that may affect assessment reach placement or
determine the number of assessment reaches required for a project. Look for natural and artificial
features that may affect streamflow duration at the reach—particularly those that may not be evident
during the field visit or that are on inaccessible land outside the assessment area. These features
include sharp transitions in geomorphology, upstream dams or reservoirs, springs, storm drains and
major tributaries. It may be possible to see bedrock outcrops or other features that modify streamflow
duration in sparsely vegetated areas.
A preliminary assessment of adjacent land use may be ascertained during desktop reconnaissance. This
preliminary assessment should be verified during the field visit.
Evaluating watershed characteristics during desktop reconnaissance can produce useful information
that will help assessors anticipate field conditions or provide contextual data to help interpret results.
The USGS StreamStats tool, as well as the EPA's WATERS GeoViewer. provide convenient online access
to watershed information for most assessment reaches in the United States, such as drainage area,
soils, land use or impervious cover in the catchment, or modeled bankfull channel dimensions and
discharge.
Assessors should consider consulting local experts and agencies to gain further insights about reach
conditions and request additional available data. For example, state agencies may have records on
water quality sampling indicating times when the reach was sampled and when it was dry. Local
experts may have information about changes in the reach's streamflow.
Desktop Reconnaissance for:
• Access, permissions and permits;
• Reach placement;
• Watershed and site context;
• Flora and fauna lists; and
• Drainage area
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Section 3: Data Collection
Local or regional flora lists of species known to grow in the vicinity of an assessment reach may be
available to assist with plant identification, which can be helpful for determining whether a plant is
considered an 'upland' plant (see 3.8.6 Prevalence of upland plants in the streambed). Several online
databases can generate regionally appropriate flora lists and/or assist with identification (Table 2).
Note that there are four National Wetland Plant List (NWPL) regions that overlap with the area covered
by the NE SDAM and three that overlap with the area covered by the SE SDAM; consult the appropriate
list for your location.
Table 2. Examples of online resources for generating local flora lists.
| Resource
Geographic coverage |
National Wetland Plant List
United States and territories
The Biota of North America Program (BONAP)
Vascular Flora Taxonomic Data Center
United States and territories
USDA Plants Database
United States and territories
Ladv Bird Johnson Wildflower Center
Continental U.S. (native species only)
Atlas of Florida Plants
Florida
Tennessee-Kentucky Plant Atlas
Tennessee and Kentucky
Preliminary assessments of drainage area, which are used in the both the NE and SE SDAMs as an
indicator, can also be completed before visiting the site. However, this calculation may need to be
adjusted later depending on the reach's location confirmed in the field.
Lastly, desktop reconnaissance helps determine if permits are required to collect aquatic
macroinvertebrates. Threatened and endangered species may be expected in the area, and stream
assessment activities may require additional permits from appropriate federal, Tribal, and state
agencies. Additional information on threatened or endangered species may be found on the U.S. Fish
and Wildlife Service's Environmental Conservation Online System, as well as at state resource agencies
and natural heritage programs.
Additional desktop reconnaissance tools can be found on the SDAM training and support materials
website.
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Section 3: Data Collection
3.2 Prepare sampling gear
The following gear is suggested for completion of the NE and SE SDAMs:
• This manual and field forms (paper or digital).
• Clipboard, pencils, permanent markers, field notebook.
• Flagging tape.
• Maps and aerial photographs (1:250 scale if possible).
• Global Positioning System (GPS) to identify the downstream boundary of the reach assessed. A
smartphone that includes a GPS may be a suitable substitute.
• Tape measures - for measuring bankfull channel width and reach length.
• Clinometer or range finder with slope measurement and stadia rod - for measuring slope (NE
Only).
• Kick-net or small net and tray to sample aquatic macroinvertebrates.
• Hand lens - to assist with plant and aquatic macroinvertebrate identification.
• Digital camera (or smartphone with camera) plus charger. Ideally, use a camera that
automatically records metadata, such as time, date, directionality, and location, as part of the
EXIF data associated with the photograph.
• Shovel, soil auger, rock hammer, hand trowel, pick or other digging tools to facilitate
hydrological observations of subsurface flow.
• Convex spherical densiometer, taped to restrict assessment to the forward-facing 17 grid
intersections (see the Shading indicator for information on how to prepare the densiometer).
• Appropriate regional plant field guides and/or web applications (e.g., iNaturalist).
• Plastic bags or plant press for collecting plant vouchers.
• Benthic macroinvertebrate field guides (e.g., A Guide to Common Freshwater Invertebrates of
North America, Voshell 2002) and/or web applications (e.g., PocketMacros3).
• Vials filled with 70% ethanol and sealable plastic bags for collection of biological specimens,
with sample labels printed on waterproof paper.
• The U.S. Army Corps of Engineers List of wetland plants for sites to be visited.
• Boots or waders.
• First-aid kit, sunscreen, insect repellant, and appropriate clothing.
Ensure that all equipment is functional before each assessment visit and has been cleaned off-site
between assessment visits to prevent the spread of invasive species. Sampling gear that comes into
contact with the water (such as nets and boots or waders) should be properly decontaminated to
prevent the spread of aquatic invasive species. Stop Aquatic Hitchhikers, an initiative of Aquatic
Nuisance Species Task Force sponsored by USFWS, provides resources and links.
3.3 Order of operations for completing the NE and SE SDAM field assessments
After completing the in-office activities described above, the following general workflow is
recommended for efficiency in the field:
3 https://www.macroinvertebrates.org/app/download
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Section 3: Data Collection
1. Walk Assessment Reach (avoid walking in channel)
•Confirm assessment reach placement in the field (3.5.1).
•Measure the bankfull channel width at 3 locations and calculate average to determine
assessment reach length and identify reach boundaries (3.5.2). Record average bankfull
channel width in Step 2. Measure or visually assess flood prone width at each of the
bankfull locations, making sure it is representative of the reach overall (NE only).
•Record coordinates of downstream reach boundary from center of channel and
photograph reach.
•Begin to note expression and strength of field indicators.
•Take photographs at middle and upstream end of reach.
•Start sketching assessment reach on field form.
2. Record General Reach Site Information on Field Form (3.7.1)
3. Evaluate Indicators (3.8)
•Collect aquatic macroinvertebrates from reach, starting from downstream end.
•Measure slope (NE only).
•Sort/identify and count aquatic macroinvertebrates. If two practitioners are available,
one should proceed with other measurements while the other conducts this step.
•Measure percent shading at top, middle and bottom of reach.
•Determine prevalence of upland plants in the channel (SE only).
•Assess the particle size of stream substrate and/or difference of channel substrate
material from surrounding uplands (SE only).
•Assess the expression and degree of fibrous roots in the streambed (SE only).
•Complete sketch of the assessment reach on the field form.
4. Review Field Form for Completeness
5. Calculate Drainage area and enter Data into Web Application (in office)
•Calculate drainage area using StreamStats or the National Map viewer.
•Elevation and average monthly precipitation May-July (SE only) wil be automatically
retrieved when coordinates are input into web application.
3.4 Timing of sampling
Ideally, application of the NE and SE SDAMs should occur during the growing season when many
aquatic macroinvertebrates are most active and when any plants rooted in the channel are more
readily identifiable. Assessments may be made during other times of the year, but there is an increased
likelihood of specific indicators being dormant or difficult to observe at the time of assessment,
especially in northern parts of the NE, where the presence of snow and channel ice during the colder
months may also be a factor. That said, most of the indicators included in the methods persist well
beyond a single growing season (e.g., rooted upland plants) or are not dependent on the growing
season (e.g., geomorphological indicators), reducing the sensitivity of the methods to the timing of
sampling.
The protocol may be used in flowing streams as well as in dry or drying streams. However, care should
be taken to avoid sampling during flooding conditions and assessors should wait at least one week
after large storm events that impact vegetation and sediment in the active stream channel before
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Section 3: Data Collection
collecting data to allow aquatic macroinvertebrates and other biological indicators to recover (e.g.,
Angradi 1997, McCord et al. 2009, Smith et al. 2019). In general, aquatic macroinvertebrate abundance
is suppressed during and shortly after major channel-scouring events, potentially leading to inaccurate
assessments. Recent rainfall can interfere with measurements (e.g., by washing away aquatic
macroinvertebrates). Assessors should note recent rainfall events on the field form and consider the
timing of field evaluations to assess each indicator's applicability. Local weather data and drought
information should be reviewed before assessing a reach or interpreting indicators. Evaluating
antecedent precipitation data from nearby weather stations after each sampling event helps to
determine if storms may have affected data collection and informs interpretation of SDAM data. The
Antecedent Precipitation Tool (APT; U.S. Army Corps of Engineers 2023) can also be helpful for
evaluating recent precipitation conditions at a site relative to the 30-year average.
3.5 Assessment reach considerations
3.5.1 Reach placement
Stream assessments should begin by first walking the channel's length, to the extent feasible, from the
target downstream end to the top of the assessment reach. This initial review of the reach allows the
assessor to examine the channel's overall form, landscape, parent material, and variation within these
attributes as they develop or disappear upstream and downstream. This helps determine whether
adjustments to assessment reach boundaries are needed, or whether multiple assessment reaches are
needed to adequately characterize streamflow duration throughout the project area. Walking
alongside, rather than in, the channel is recommended for the initial review to avoid unnecessary
disturbance to the stream. Walking alongside the channel also allows the assessor to observe the
surrounding landscape's characteristics, such as land use and sources of flow (e.g., stormwater pipes,
springs, seeps, and upstream tributaries).
The assessor should document the areas along the stream channel where various sources (e.g.,
stormflow, tributaries, or groundwater) or sinks of water (alluvial fans, abrupt changes in bed slope,
etc.) may cause abrupt changes in flow duration. When practical, assessment reaches should have
relatively uniform channel morphology. When evaluating the reach's homogeneity, focus on
permanent features that control streamflow duration (such as valley gradient and width) rather than
on the presence or absence of surface water. Project areas that include confluences with large
tributaries, significant changes in geologic confinement, or other features that may affect flow duration
may require separate assessments above and below the feature.
For some applications, reach placement is dictated by project requirements. For example, a small
project area may be fully covered by a single assessment reach. In these cases, assessment reaches
may contain diverse segments with different streamflow duration classes (e.g., a primarily perennial
reach with a short intermittent portion where the flow goes subsurface). In these cases, the portions of
the reach with long-duration flows will likely have a greater influence on the outcome than the
portions with short-duration flows, depending on each portion's relative size.
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Section 3: Data Collection
Natural features, such as bedrock outcrops or valley confinements, and non-natural features like
culverts or road crossings may alter hydrologic characteristics in their immediate vicinity. For example,
culverts may create plunge pools, and drainage from roadways is often directed to roadside ditches
that enter the stream near crossings, leading to a potential increase in indicators of long streamflow
duration. Specific applications may require that these areas be included in the assessment, even
though they are atypical of the larger assessment reach. For other applications, the area of influence
may be avoided by moving the reach at least 10 m upstream or at least 10 m downstream.
3.5.2 Reach length
An assessment reach should have a length equal to 40bankfullchannel-widths, with a minimum
length of 40 m and a maximum of 200 m. An assessment reach should not be less than 40 m in length
to ensure that sufficient area is assessed to observe and appropriately measure indicators.
Assessments based on reaches shorter than 40 m may not detect all indicators and could provide
inaccurate classifications.
Bankfull channel width is averaged from measurements at three locations: at the bottom of the reach,
15 m upstream, and 30 m upstream from the bottom of the reach, or at three locations that are
representative of the reach as a whole. See Section 3.7.1 General reach information and Section 3.8.1
Bankfull channel width for more guidance on measuring bankfull channel width. Width measurements
are made at bankfull elevation, perpendicular to the thalweg (i.e., the deepest point within the channel
that generally has the greatest portion of flow); how to determine bankfull elevation is discussed in
Section 3.7.1 General reach information. In multi-thread systems, the bankfull width is measured for
the entire active channel, based on the outer limits of the OHWM. Reach length is measured along the
thalweg (Figure 4). If access constraints require a shorter assessment reach than recommended above,
the actual assessed reach-length should be noted on the field form along with an explanation for why a
shortened reach was necessary.
Note that bankfull channel width is also an indicator of streamflow duration, as described below in
Section 3.8.1 Bankfull channel width.
3.5.3 How many assessment reaches are needed?
The outcome of an assessment applies to the assessed reach and may also apply to adjacent reaches
some distance upstream or downstream if the same conditions are present. The factors affecting
spatial variability of streamflow duration indicators (described above) dictate how far from an
assessment reach a classification applies. More than one assessment may be necessary for a large or
heterogenous project area and multiple assessments are usually preferable to a single assessment. In
areas that include the confluence of large tributaries, road crossings, or other features that may alter
hydrology, multiple assessment reaches may be required (e.g., one above and one below the feature).
3.6 Photo-documentation
Photographs can provide strong evidence to support conclusions resulting from application of the NE
and SE SDAMs, and extensive photo-documentation is recommended. Taking several photos of the
reach condition and any disturbances or modifications relevant to making a final streamflow duration
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Section 3: Data Collection
classification is strongly recommended. Specifically, the following photos should be taken as part of
every assessment:
• A photograph from the top (upstream) end of the reach, looking downstream.
• Two photographs from the middle of the reach, one looking upstream and one looking
downstream.
• A photograph from the bottom (downstream) end of the reach, looking upstream.
Photographs that illustrate the following are also strongly recommended:
• Extent of rooted upland plants in channel.
• Prevalence of fibrous roots in streambed.
• Particle size and/or stream substrate sorting.
• Disturbed or unusual conditions that may affect the measurement or interpretation of
indicators.
3.7 Conducting assessments and completing the field form
3.7.1 General reach information
After walking the reach and determining the appropriate boundaries for the assessment area, record
on the field form the project name, reach code or identifier, waterway name, assessor(s) name(s), and
the date of the assessment visit. These data provide essential context for understanding the
assessment but are not indicators for determining streamflow duration class.
Coordinates
Record the coordinates (latitude and longitude) of the downstream end of the reach from the center of
the channel. When determining Global Positioning System (GPS) coordinates in the field for the
assessment reach, use the World Geodetic System 1984 (WGS84) datum and record coordinates in
decimal degrees format; this information is used for entering coordinates into the web application (see
Section 4 Data Interpretation and Using the Web Application). If possible, set the GPS receiver setting
to use the Wide Area Augmentation System (WAAS) or Differential GPS (DGPS) augmentation systems
to increase coordinate accuracy. Record the GPS unit used and any information your GPS or cell phone
application has regarding signal strength or spatial uncertainty with the obtained coordinates.
Document nearby roads, buildings, tributary confluences, and other features that can help corroborate
the geospatial location of the assessment reach with the coordinates recorded in the field with your
planned assessment location by confirming them on a topographic map, aerial imagery, or Geographic
Information System (GIS) software.
Weather conditions
Note current weather conditions (e.g., rain and intensity, sun, clouds, snow). If known, note
precipitation within the previous week on the datasheet, and consider delaying sampling, if
appropriate (see Section 3.4 Timing of sampling). If rescheduling is not possible, note whether the
streambed is recently scoured, or if turbidity or high water is likely to affect the measurement of
indicators.
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Section 3: Data Collection
Surrounding land use
A preliminary assessment of surrounding land use should be conducted during desktop reconnaissance
(see Section 3.1 Conduct desktop reconnaissance). Once at the site, verify whether the preliminary
assessment is correct, making sure to note evidence of human activities that may not be evident in
aerial imagery.
Indicate the dominant land-use around the reach within a 100-m buffer. Check up to two of the
following:
• Urban/industrial/residential (buildings, pavement, or other anthropogenically hardened
surfaces).
• Agricultural (e.g., farmland, crops, vineyard, pasture).
• Developed open space (e.g., golf course, sports fields).
• Forested.
• Other natural.
• Other (describe).
Bankfull channel width
Measure bankfull channel width values (to nearest 0.1 m) at 0, 15, and 30 m above the downstream
end of the reach or at three locations spread out over approximately one-third of the expected reach
length and record values on the field form (Figure 4 and Figure 5). Note, this approach replicates how
the data used to develop these SDAMs were collected at study reaches across the NE and SE regions.
Widths should be measured perpendicular to the thalweg. In multi-threaded systems, width
measurements should span all channels within the OHWM. Calculate the average width.
Flow
# Photopoint location
— Bankfull width measurement
Figure 4. Bankfull measurement and photo point locations. Bankfull is represented by the yellow area and the
blue line represents the thalweg of the channel. Bankfull width should be measured at three locations that are
representative of the expected reach length.
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Section 3: Data Collection
Figure 5. Measuring bankfull width, image credit: james Treacy
The bankfull width4 is the portion of the channel that contains the bankfull discharge, which is a flow
event that occurs frequently (typically every 1.01 to 5 years; David and Hamill 2024), but that does not
include larger flood events. The bankfuli discharge has an important role in forming the physical
dimensions of the channel. For many stream channels, the bankfull elevation (from where bankfull
width is measured) can be identified in the field by an obvious slope break that differentiates the
channel from a relatively flat floodplain terrace higher than the channel or by a transition from
exposed stream sediments or more water- and scour-tolerant vegetation (e.g., willows) to terrestrial
and intolerant vegetation (David et al. 2025). In locations without vegetation, moss growth on rocks
along the banks can be an indicator of bankfull height as can breaks in bank slope or changes in
substrate composition.
Certain indicators of bankfull height may be more or less evident in different stream types, so assessors
should evaluate multiple bankfull indicators when measuring bankfull channel width. The bankfull
width should be measured in a straight section of the stream (e.g., riffle, run, or glide if present) that is
representative of the study reach. Pools and bends in the stream or areas where the stream width is
affected by the deposition of rocks, debris, fallen trees, or other unusual constrictions or expansions
should be avoided. In the field, it may often be possible to determine the bankfull channel width using
bankfull indicators on only one bank of the stream. This point can be used as a reference to determine
the bankfull elevation on the opposite bank by creating a level line across the stream from the
identified bankfull elevation perpendicular to the stream flow.
4 Resources for bankfuli identification are found on the SPAM training materials site.
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Section 3: Data Collection
In larger systems (e.g., drainage area > 0.5 square miles), it may be helpful to compare field
measurements to bankfull channel dimensions derived from regional curves relating bankfull
dimensions to watershed characteristics. These models may be derived at a national or regional scale
(e.g., StreamStats; U.S. Geological Survey 2025) or a local scale (e.g., Texas: Asquith et al. 2020; North
Carolina: Harman et al. 1999). Bieger et al. (2015) provides regional curves for several regions of the
continental United States. If observed bankfull dimensions are substantially different from estimated
bankfull dimensions derived from regional curves (e.g., more than twice the maximum or less than half
the minimum estimates), it may be helpful to re-evaluate bankfull indicators that were used to
establish bankfull channel height. Although regional curve estimates for bankfull dimensions of small
channels (small drainage areas) may be extrapolated outside the range used to develop relationships,
such estimates have unknown errors (bias) associated with them and should be used with caution if at
all.
Note that bankfull channel width is also an indicator of streamflow duration, as described below in
Section 3.8.1 Bankfull channel width-
Describe reach length and boundaries
Record the reach length in meters as described in Section 3.5.2 Reach length. Record observations
about the reach on the field form, such as changes in land use, disturbances, or natural changes in
stream characteristics that occur immediately up or downstream. If the reach is less than 200 m and
shorter than 40 times the average bankfull channel width, explain why a shorter reach length was
appropriate. For example: "The downstream end is 30 m upstream of a culvert under a road. The
upstream end is close to a conspicuous dead tree just past a large meander, near a fence marking a
private property boundary. The reach length was shortened to 150 m to avoid private property."
Photo-documentation of reach
Record the photo ID or number on the designated part of the field form for required photographs
taken from the bottom (facing upstream), middle (facing upstream and downstream), and top (facing
downstream) of the reach (see Figure 4).
Disturbed or difficult conditions
Note any disturbances or unusual conditions that may create challenges for assessing flow duration.
Common situations include practices that alter hydrologic regimes, such as diversions, culverts,
discharges of effluent or runoff, and drought. Note circumstances that may affect stream
geomorphology, such as channelization, or vegetation removal that may affect the measurement or
interpretation of several indicators (Figure 6). Also note if the stream appears recently restored, for
example, stream armoring with large substrate or wood additions and recently planted vegetation in
the riparian zone.
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Figure 6. Examples of difficult conditions that may interfere with the observation or interpretation of indicators. Left: This
stream reach in the North Carolina Piedmont is heavily impacted by cattle through input of nutrients as well as trampling,
which may affect abundance and richness of aquatic macroinvertebrates and obscure identification of bankfull elevation,
Image credit: EPR. Right: This stream in a park in South Bend, Indiana, is surrounded by urban land uses; the addition of
urban non-point source discharges may also impact aquatic invertebrate communities.
Observed hydrology
Surface flow
Visually estimate or use a tape measure to determine the percentage of the reach length that has
flowing surface water or subsurface flow. The reach sketch should indicate where surface flow is
evident and where dry portions occur.
Subsurface flow
If the reach has discontinuous surface flow, investigate the dry portions to see if subsurface flow is
evident. Examine below the streambed by turning over cobbles and digging with a trowel. Resurfacing
flow downstream may be considered evidence of subsurface flow (Figure 7). Other evidence of
subsurface flow includes:
• Flowing surface water disappears into alluvial deposits and reappears downstream. This
scenario is common when a large, recent alluvium deposit created by a downed log or other
grade-control structure creates a sharp transition in the channel gradient or in valley
confinement.
• Water flows out of the streambed (alluvium) and into isolated pools.
• Water flows below the streambed and may be observed by moving streambed rocks or digging
a small hole in the streambed.
• Shallow subsurface water can be heard moving in the channel, particularly in steep channels
with coarse substrates.
Record the percent of the reach length with subsurface and surface flow (combined). That is, the
percent of reach length with subsurface flow should be greater than or equal to the percent of reach
length with surface flow (Figure 7).
The reach sketch should indicate where subsurface flow is evident.
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Number of isolated pools
If the reach is dry or has discontinuous surface flow, look for isolated pools within the channel that
provide aquatic habitat. If there is continuous surface flow throughout the reach, enter 0 (zero)
isolated pools. The reach sketch should indicate the location of pools in the channel or on the
floodplain (Figure 7). However, only isolated pools within the channel are counted, including isolated
pools within secondary channels that are part of the active channel and within the QHWM. Pools
connected to flowing surface water and isolated pools on the floodplain do not count. Dry pools (i.e.,
pools that contain no standing water at the time of assessment) do not count.
100% surface flow
100% surface +
subsurface flow
0 isolated pools
70% surface flow
70% surface +
subsurface flow
0 isolated pools
80% surface flow
100% surface +
subsurface flow
0 isolated pools
70% surface flow
70% surface +
subsurface flow
1 isolated pool
Figure 7. Examples of estimating surface arid subsurface flow, arid isolated pools. Orange represents the dry channel, and
blue represents surface water in the channels. White represents the floodplain outside the channel. The pool in A does not
count because it is outside the channel, whereas the pools in B and C do not count because they are connected to flowing
surface water. In contrast, the lower pool in D counts because it is isolated from any flowing surface water and is within the
channel,
3.7.2 Assessment reach sketch
Sketch the assessment reach on the field form, indicating important features, such as access points,
important geomorphological features, the extent of dry or aquatic habitats, riffles, pools, etc. Note
locations where photographs are taken and where channel measurements are made.
3.8 How to measure indicators of streamflow duration
Seven indicators are required for the NE SDAM, and ten indicators are required for the SE SDAM; five
indicators are shared by both methods. All must be evaluated to determine a flow classification.
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Biological indicators
• Aquatic macroinvertebrate indicators
o Benthic macroinvertebrate index (BMI)
o Total aquatic macroinvertebrate abundance (SE only)
• Shading
• Prevalence of rooted upland plants in the streambed (SE only)
• Prevalence of fibrous roots in the streambed (SE only)
Geomorphological indicators
• Bankfull channel width
• Entrenchment ratio (NE only)
• Slope (NE only)
• Particle size of stream substrate (SE only)
Geospatial/climatic indicators
• Drainage area
• Elevation
• Average monthly precipitation May-July (SE only)
BMI score and aquatic macroinvertebrate total abundance, drainage area, bankfull width, and particle
size/stream substrate sorting are positive indicators of streamflow duration. That is, a greater
abundance, strength, or size of these indicators is generally associated with longer duration flows (e.g.,
Delucchi 1988, Fritz et al. 2008, Smith et al. 2017). For example, higher benthic macroinvertebrate
abundance is associated with perennial reaches. The relationship between streamflow duration and
bankfull channel width is less straightforward. In general, in the NE and SE, wider channels are more
likely to be perennial and positioned lower in the watershed than narrower non-perennial channels
(e.g., Fritz et al. 2008, Ohio EPA 2020, Svec et al. 2005). Rooted upland plants and fibrous roots in the
streambed are negative indicators of streamflow duration. Greater abundance or expression of rooted
upland plants or fibrous roots in the assessment reach is associated with shorter flow duration classes.
For consistency with the other indicators in terms of its relationship to evidence of perennial flow, the
scoring for both indicators is reversed by characterizing its rarity or absence. Climatic indicators, like
precipitation, have been shown to be highly correlated with flow duration and the timing of drying
(Hammond et al. 2021). The average precipitation across certain months may be fundamental to
whether and/or when drying will occur in SE streams.
These indicators are based on what is observed at the time of assessment, not on what would be
predicted to occur if the channel were wet, or in the absence of disturbances or modifications.
Disturbances and modifications (e.g., vegetation management, channel hardening, diversions) should
be described in the "Notes" section of the datasheet and are considered when drawing conclusions.
Common ways that disturbances can interfere with indicator measurement are described within each
indicator description, where applicable. The indicators are presented below in the order they appear
on the field forms, reflecting the recommended order of operations for efficiency in the field.
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Section 3: Data Collection
Geospatial and climatic indicators are presented last; though for drainage area, a preliminary
assessment may be completed prior to visiting the field, as discussed in Section 3.1 Conduct desktop
reconnaissance.
3.8.1 Bankfull channel width
Bankfull channel width is generally associated with streamflow duration, as wider channels tend to
reflect longer-lasting flows. However, this pattern is sometimes reversed in more arid regions and in
regions overlying alluvial geology. Bankfull channel width is measured (to the nearest 0.1 m) at three
locations during the initial layout of the assessment reach and then averaged, as described in Section
3.5 Assessment reach considerations. In multi-threaded channels, the width of the entire active
channel is measured, based on the outer limits of the OHWM. Wohl et al. (2016) describe the active
channel as the portion of the valley bottom distinguished by one or more of the following
characteristics:
• Channels defined by erosional and depositional features created by river processes (as opposed
to upland processes, such as sheet flow or debris flow).
• The upper elevation limit at which water is contained within a channel.
• Portions of a channel generally without trunks of mature woody vegetation.
3.8.2 Entrenchment Ratio (NE only)
Entrenchment is qualitatively defined as the vertical containment of a river and the degree to which it
is incised in the valley floor (Kellerhals et al. 1972). The entrenchment ratio is the ratio of the width of
the flood-prone area to the width of the bankfull channel (Rosgen 1994). The flood-prone area width is
measured perpendicular to the reach length at the elevation that is twice the maximum bankfull depth
(Figure 8). Bankfull is the height on the streambanks during moderate high-water events when water
begins to overflow onto the floodplain and should be measured at relatively straight sections of the
stream, avoiding pools and areas where the stream width is affected by the deposition of rocks, debris,
fallen trees, or other unusual constrictions. See Section 3.7.1 General reach information and Section
3.8.1 Bankfull channel width for more on how to identify and measure bankfull elevation. In incised
entrenched streams, it is important to note that the elevation of bankfull discharge may not be at the
top of the stream bank.
Figure 8. Measurement of entrenchment is based on the ratio of the flood-prone width to the bankfull width.
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Section 3: Data Collection
After determining bankfull width at a representative location, the flood-prone width is measured to
the nearest tenth of a meter up to a maximum of 2.5 times the bankfull width:
1. Measure bankfull width at the chosen location and determine the bankfull maximum depth.
2. Identify the flood-prone depth at twice the bankfull maximum depth.
3. Measure the flood-prone width at the flood-prone depth.
4. If the flood-prone width is >2.5 times the bankfull width, record as >2.5 X bankfull width.
5. Repeat measurement of flood-prone width at each location where bankfull width is measured,
making sure that these locations are representative of overall valley conditions. Avoid assessing
flood-prone width in places where the degree of valley constriction (whether from natural or
man-made constrictions, like hillslopes or buildings) is not characteristic of the reach.
3.8.3 Aquatic macroinvertebrate indicators
The SE SDAM has two indicators based on aquatic macroinvertebrates, and one of these indicators is
also used in the NE SDAM. Both aquatic macroinvertebrate indicators are measured from the same
sample collection effort described below.
Sample Collection Instructions
Aquatic macroinvertebrates are assessed within the defined reach. A kick-net or D-frame net is used to
collect specimens. Assessors begin sampling at the most downstream point in the assessment reach
and proceed to sample the upstream direction. Where there is rapidly flowing water, the net is placed
perpendicular against the streambed while the substrate is disturbed upstream of the net for a
minimum of one minute. This disturbance will dislodge and suspend aquatic macroinvertebrates such
that they are carried by the stream flow into the net. For slower flowing or standing water areas, jab
the net under banks, overhanging terrestrial and aquatic vegetation, leaf packs, and in log jams or
other woody material to dislodge and capture aquatic macroinvertebrates and the leaves or other light
materials the aquatic macroinvertebrates may be clinging to. Samples should be collected from at least
six distinct locations representing the different habitats occurring in the reach. Without releasing
aquatic macroinvertebrates, strain the net contents to remove fine sediments that would interfere
with observing them. Empty contents of the net into a white tray with fresh stream water for
determining abundance of individuals present.
Searching is complete when:
• At least six different locations within the reach have been sampled across the range of habitat
types and a minimum of 15 minutes of effort expended (not including sample sorting to
facilitate enumeration), or
• All available habitat in the assessment reach has been completely searched in less than 15
minutes. A search in dry stream channels with little bed or bank development and low habitat
diversity may be completed in less than 15 minutes.
During the 15-minute sampling period, search the full range of habitats present, including: water under
overhanging banks or roots, in pools and riffles, accumulations of leaf packs, woody debris, and coarse
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Section 3: Data Collection
inorganic particles (i.e., pick up rocks and loose gravel). If a reach contains both dry and wet areas,
focus on searching the wet habitats, as these are the most likely places to encounter aquatic
macroinvertebrates, but do not ignore dry areas.
Dry channels: Focus the search on areas serving as refuge, such as any remaining pools or areas of
moist substrate for living aquatic macroinvertebrates, and under cobbles and other larger bed
materials for evidence such as caddisfly casings (Figure 9) and snail shells. Exuviae of emergent
mayflies or stoneflies may be observed on dry cobbles or stream-side vegetation (Figure 9). In
summary, a sampling methodology consistent with the Xerces Society's recommendations on using
aquatic macroinvertebrates as indicators of streamflow duration (Blackburn and Mazzacano 2012), as
developed for the Pacific Northwest SDAM (Nadeau 2015), is recommended. Take care, especially in
dry channels, to only collect aquatic species and life stages. Field guides (e.g., Voshell 2002) and
identification keys (e.g., Merritt et all. 2019) and/or web applications (e.g., PocketMacros5) are
recommended, especially if users are unfamiliar with common types of aquatic macroinvertebrates.
Figure 9. Examples of evidence of aquatic macroinvertebrates in dry channels. Left: Caddisfly cases may persist under large
cobbles or boulders well after the cessation of flow. Right: Stonefly (Plecoptera) exuvia. Exuviae are left behind when
aquatic nymphs or pupae emerge from the stream and go through a final molt to metamorphose to winged adults. Image
credits: Raphael Mazor.
When searching dry channels (or dry portions of partially wet channels), be sure to avoid counting
terrestrial macroinvertebrates in the streambed. Figure 10 depicts common terrestrial taxa that may
be found near stream channels. If you are unsure whether the invertebrates you encounter are aquatic
or terrestrial, collecting a voucher specimen and identifying it in a lab setting or consulting an
entomologist is recommended.
5 https://www.macroinvertebrates.org/app/download
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Section 3: Data Collection
Figure 10. Examples of terrestrial macroinvertebrates you may find in a dry channel. Top Left: larva of soldier flies
(Stratiomyidae). Top Right: garden snail (Cornu aspersum) (Image credits: Raphael Mazor); Middle left: Earthworm
(Lumbricus terrestris) (Image credit: Ren Pedersenl; Middle right: Woodlouse or pillbug (Armadillidium vulgare) (Image
credit: Dann Thomfas CC-BY-NC-ND); Bottom right: Common pink flat-back millipede (Pseudopolydesmus serratus) (Image
credit: Ken Clark CC-BY); Bottom left: White-lip globe snail (Mesodon thyroidus, Polygyridae) (Image credit: Joe Arruda CC-
BY-NC).
3.8.3.1 Benthic Macroinvertebrate Index (BMI) score
This indicator scores the total abundance and richness of all aquatic macroinvertebrates. Richness is
based on family-level identification for aquatic insects and mollusks, order-level for crustaceans and
mites, and class or phylum for all other aquatic macroinvertebrates. When enumerating this indicator,
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Section 3: Data Collection
living material (e.g., live aquatic insect larvae or pupae) and non-living material (e.g., caddisfly cases,
shed exuviae) are considered equally. Individuals of terrestrial adult stage of aquatic insects are not
included.
Scoring for this indicator is as shown in Table 3. Though not required, identified taxa contributing to
richness should be indicated on the field form. A guide to taxa commonly encountered during field
data collection for the NE and SE SDAM effort can be found in Appendix B.
Table 3. Scoring guidance for the BMI indicator.
Score
Evidence of
perennial flows
Guidance
0
Absent
No aquatic macroinvertebrates observed.
1
Weak
Total abundance is 1 to 3.
2
Moderate
Total abundance is >4.
3
Strong
Total abundance is >10 AND richness >3, OR
Richness >5.
3.8.3.2 Total aquatic macroinvertebrate abundance (SE only)
This indicator scores the total abundance of aquatic macroinvertebrates in the reach, including insects
and non-insects. It does not require identification of aquatic macroinvertebrates; however, counted
individuals must only represent aquatic stages (or instars). Both living material (e.g., live larvae) and
non-living material (e.g., caddisfly cases, shed exuviae) are considered equally during enumeration.
Scoring is as shown below:
• No aquatic macroinvertebrates observed.
• Total abundance of aquatic macroinvertebrates is 1 or 2.
• Total abundance of aquatic macroinvertebrates is 3 to 40.
• Total abundance of aquatic macroinvertebrates is 41 or more.
3.8.4 Slope (NE only)
Slope has an indirect relationship with streamflow duration and can help modify the interpretation of
other indicators measured as part of the SDAM. Reaches with very high slopes are often ephemeral
headwaters, and lower slopes are typical of perennial mainstem reaches.
Slope is measured as the percent slope between the upper and lower extent of the assessment reach.
This task requires a two-person team (Figure 11). One person stands at bankfull elevation at the
downstream end of the reach, and a second person stands within eyesight at the opposite end of the
reach, also at bankfull elevation. This measurement requires direct line-of-sight between the lower and
upper ends of the reach. If direct line-of-sight from the bottom to top of the reach is not possible, the
slope of the longest representative portion of the reach should be 'line-of-sight' evaluated. If multiple
slope measurements are needed, the average slope of the assessment reach should be recorded (note,
calculation of the average slope would need to be weighted by the channel distance represented by
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each slope measurement). Slope should be recorded to the nearest half-percent. To convert slope
from degrees to percent multiple the tangent of the degrees by one hundred (i.e., tan(degrees)*100 =
% slope). Some low-gradient streams may have slopes that are indistinguishable from zero using this
method.
Figure 11. Schematic illustration of slope measurement using a clinometer.
3.8.5 Shading
Using a convex spherical densiometer, stream shading is estimated in terms of the percent cover of
objects (e.g., vegetation, buildings, canyon walls, etc.) that have the potential to block sunlight. The
procedure used in the NE and SE SDAMs uses the Strickler (1959) modification of a densiometer to
correct for over-estimation of stream shading that occurs with unmodified readings. Taping off (Figure
12) the lower left and right portions of the mirror emphasizes overhead structures over foreground
structures (the main source of bias in stream shading measurements).
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bufctte level
Figure 12. Representation of the mirrored surface of a convex spherical densiometer showing the position for taping the
mirror and the intersection points used for the densiometer reading. The score for the hypothetical condition (b) is 9 out of
17 possible covered intersection points within the "V" formed by the two pieces of tape.
The densiometer is read by counting the number of line intersections on the mirror that are obscured
by overhanging vegetation or other features that prevent sunlight from reaching the stream. If
measurements are being taken when leaves of deciduous woody vegetation are not fully expressed,
count all grid intersections that lie within the branches of the woody vegetation. So rather than looking
at individual tree leaves, look at the "zone of influence" of vegetative cover (Nadeau et al. 2020).
All densiometer readings should be taken at 0.3 m above the water surface (or dry streambed surface)
and with the bubble on the densiometer leveled. The densiometer should be held just far enough from
the squatting observer's body so that his/her forehead is just barely obscured by the intersection of
the two pieces of tape, when the densiometer is oriented so that the "V" of the tape is closest to the
observer's face.
Take and record four readings from the center of each of three transects spanning the width of the
bankfull channel; a) facing upstream, b) facing downstream, c) facing the left bank, and d) facing the
right bank. Each recording should be an integer value ranging from 0 to 17. The observer should
revolve around the densiometer (i.e., the densiometer pivots around a point) over the center point of
the transect (as opposed to the densiometer revolving around the observer). Read and record
densiometer readings at the top, middle, and bottom of the reach, for a total of 12 readings (four
readings at each of three transects). The indicator is then recorded as the percent of points covered by
shade-casting objects, total points covered divided by 204 and multiplied by 100.
3,8,6 Prevalence of rooted upland plants in streambed (SE only)
Few terrestrial upland plants can tolerate the conditions they would experience on the streambed of a
reach with relatively long flow durations. Prolonged inundation, soil saturation, and sheer stress create
an inhospitable environment for most upland plants, preventing their establishment or persistence.
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Thus, the prevalence of upland plants in the streambed indicates that flows have insufficient
frequency, duration, or severity to limit these species.
For this indicator, upland plants are those with FAC, FACU, and Upland (UPL) indicators or species with
No Indicator (Nl) on the most recent NWPL.6 NOTE: while some applications of the NWPL treat FAC
plants as hydrophytes, they do not count as hydrophytes for purposes of the SE SDAM. For instance,
some well-known riparian species are FAC in the NWPL regions applicable to the SE, such as Eastern
cottonwood (Populus deltoides; all applicable NWPL regions) and box elder {Acer negundo; all
applicable NWPL regions).
The SE region encompasses parts of three different NWPL regions; Atlantic and Gulf Coastal Plain
(AGCP), Eastern Mountains and Piedmont (EMP), and the Great Plains (GP) (Figure 13). Indicator status
for certain species may differ between regions; therefore, it is important to consult the correct list
when determining indicator status. For example, spicebush (Lindera benzoin), a common, widespread
shrub often found growing in riparian areas, is FACW in the ACGP and GP but FAC in the EMP.
Figure 13. National Wetland Plant List (NWPL) regions that overlap with the SE SDAM region.
What if I can't confidently identify a plant?
It may be acceptable to use environmental context and cues to determine that a plant is a non-
hydrophyte, even if taxonomic identifications cannot be made. If a plant is growing exclusively in the
channel and is absent from adjacent uplands, that may indicate the plant is a hydrophyte and should
not be considered for this indicator. Also, if a genus-level identification can be made, some genera are
6 https://nwpl.sec.usace.armv.mil/
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dominated by either upland species (e.g., Acer) or hydrophytic species (e.g., Ludwigia). Post-sampling
confirmation based on photos or collected specimens is strongly recommended. Photos can also be
used when consulting plant identification applications that use image recognition (e.g., Seek,
iNaturalist).
When assessing this indicator, the focus should be on plants rooted on the entire streambed, including
the thalweg. Upland plants growing on any part of the bank or on upland islands within the OHWM
should not be considered. A user will indicate the prevalence of upland plants growing in the
streambed along the entire reach and identify them on the field form. This indicator is scored as shown
in Table 4. Note that a lower score indicates greater prevalence of rooted upland plants in the
streambed.
Score the indicator using the guidance in Table 4; photos that demonstrate the scoring guidance are
shown in Figure 14.
This indicator is derived from the North Carolina Methodology for Identification of Intermittent and
Perennial Streams (NCDWQ 2010). As with other indicators derived from the North Carolina
Methodology, "moderate" scores (i.e., 2) are intended as an approximate midpoint between the
extremes of "poor" and "strong".
Table 4. Scoring guidance for the Prevalence of Rooted Upland Plants in the Streambed indicator.
Evidence of
Score
perennial
flows
Guidance
0
Absent
Rooted upland plants are prevalent within the streambed (greater than
75%).
1
Weak
Rooted upland plants are consistently dispersed throughout the streambed
(20-75%).
2
Moderate
Few rooted upland plants are present within the streambed (less than
20%).
3
Strong
Rooted upland plants are absent within the streambed.
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Figure 14, Examples illustrating scoring levels for the Prevalence of Rooted Upland Plants in the Streambed indicator. White
arrows identify the streambed locations with rooted upland plant species in the photos. (0) Lowbush blueberry (Vaccinium
angustifolium; FACU) is prevalent in the channel; (1) Common dittany (Cunila origanoides; Nl) is widely dispersed
throughout the streambed; (2) A few wood nettle individuals (Laportea canandensis; FAC) are found in the streambed; and
(3) The only rooted plants in the streambed are hydrophytes (Justicia americana, water willow; OBL).
3.8.7 Particle size of stream substrate (SE only)
Well-developed channels that have eroded through the soil profile often have substrate materials
dominated by larger sediment sizes, such as coarse sand, gravel, and cobble, relative to finer textured
floodplain sediments and adjacent soils. Similar sediment sizes in the stream bed and the adjacent
streamside area may indicate that stream forming processes have not been consistent enough to cut
into the soil profile typical of an intermittent or perennial stream. For instance, the bed of intermittent
or perennial streams is often comprised of coarser sediment relative to the bank area or floodplain
due to consistent stream-forming flows that have transported finer particles downstream as the
channel has eroded downward.
Evaluate whether the distribution of sediment size in the stream substrate is relatively coarser than
the adjacent floodplain or streamside area to determine if downcutting has penetrated through the
soil profile.
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Score the indicator using the guidance in Table 5; photos that demonstrate the scoring guidance are
shown in Figure 15.
This indicator is derived from the North Carolina Methodology for Identification of Intermittent and
Perennial Streams (NCDWQ 2010). As with other indicators derived from the North Carolina
Methodology, "moderate" scores (i.e., 2) are intended as an approximate midpoint between the
extremes of "poor" and "strong". Half scores (i.e., 0.5, 1.5, and 2.5), mid-way between the scores
shown in Table 5 are appropriate to allow the assessor the flexibility to characterize this indicator more
continuously.
Table 5. Scoring guidance for Particle Size of Stream Substrate indicator.
Score
Evidence of
perennial
flows
Guidance
0
Absent
The channel is poorly developed, very little to no coarse sediment is
present. There is no difference between particle size in the stream
substrate and adjacent land.
1
Weak
The channel is poorly developed through the soil profile. Some coarse
sediment is present in the streambed but is discontinuous. Particle size
differs little between the stream substrate and adjacent land.
2
Moderate
There is a well-developed channel, but it is not deeply incised through
the soil profile. Some coarse sediment is present in the streambed in a
continuous layer. Particle size differs somewhat between the stream
substrate and adjacent land.
3
Strong
The channel is well-developed through the soil profile with relatively
coarse streambed sediments compared to the riparian zone soils: coarse
sand, gravel, or cobbles in the piedmont; cobbles or boulders in the
Mountains; and medium or coarse sand in the coastal plain. Particle size
differs greatly between the stream substrate and adjacent land.
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Figure 15. Examples illustrating scoring levels for the Particle Size of Stream Substrate indicator. (0) Channel is poorly
developed, with little or no sediments coarser than adjacent land present; (1) Channel is still not well developed, but
some discontinuous areas of sediments coarser than adjacent land can be found under the leaves; (2) Channel is well
developed, but not deeply incised through the soil profile and there is a more continuous layer of coarser sediment
compared to adjacent area; (3) Channel is well developed through soil profile with coarser sediments than
surrounding riparian areas throughout.
3,8.8 Prevalence of fibrous roots in streambed (SE only)
Fibrous roots are non-woody, small diameter (<0.2.5 mm) roots that grow shallowly and can often
form dense masses in the first few inches of the soil (Figure 16). These roots are generally easy to tear
and function in water and nutrient uptake. The presence of fibrous roots reflects the incursion of
upland plants into the streambed, where the presence of water and high-energy flows might typically
limit their growth. The roots of hydrophytes and riparian trees are adapted to water flow and are more
robust (i.e., harder to tear) and should not be considered when evaluating this indicator.
When assessing this indicator, the focus should be on fibrous roots in the streambed, including the
thalweg. Roots growing in any part of the bank or on upland islands within the OHWM should not be
considered. A user will indicate the prevalence of fibrous roots growing in the streambed along the
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entire reach and identify them on the field form. This indicator is scored as shown in Table 6. Note that
a lower score indicates greater prevalence of fibrous roots in the streambed.
This indicator is derived from the North Carolina Methodology for Identification of intermittent and
Perennial Streams (NCDWQ 2010). As with other indicators derived from the North Carolina
Methodology, "moderate" scores (i.e., 2) are intended as an approximate midpoint between the
extremes of "poor" and "strong". Half scores (i.e., 0.5, 1.5, and 2.5), mid-way between the scores
shown in Table 6, are appropriate to allow the assessor the flexibility to characterize this indicator
more continuously.
Table 6. Scoring guidance for the Fibrous Roots in Streambed indicator.
Evidence of
Score
perennial
flows
Guidance
0
Absent
A strong network of fibrous roots is persistent in the stream thalweg and
surrounding area.
1
Weak
A discontinuous network of fibrous roots is present in the stream thalweg
and surrounding area.
2
Moderate
Very few fibrous roots are present anywhere in the streambed.
3
Strong
No fibrous roots are present.
Figure 16. Example of fibrous roots (left) vs. woody roots (right).
3.8.9 Drainage Area
Drainage area is rapidly calculated using one of two existing web tools, IJSGS StreamStats or The
National Map Viewer. For drainage areas less than 1 square mile, round to the nearest 0.001 square
miles. For this indicator, it is important to have accurate location coordinates, see instructions in
Section 3.7.1 General reach information. The National Map Viewer is used only when a StreamStats
calculation cannot be made due to regional unavailability or a restricted boundary, or when the
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channel is not mapped by the National Hydrography Dataset (NHD). States in which StreamStats is
currently not available at the time of publication include, but are not limited to: Florida, Louisiana,
Michigan, and Texas. See instructions below on how to calculate drainage area using StreamStats and
The National Map Viewer.
Instructions to calculate drainage area using StreamStats7:
1. Refer to field notes and sketches made during the reach assessment that identify features such
as roads, confluences, and topographic relief (see Conducting assessments and completing the
field form section). This will help confirm the reach location when calculating drainage area.
2. Go to https://streamstats.usgs.gov/ss/.
3. In the Search for a place box, enter latitude and longitude (longitude should be a negative value)
coordinates in decimal degrees separated by a comma and space, press enter, and select the
appropriate state that pops up on the left-hand panel.
4. Click the Delineate button in blue on the left-hand panel; the Delineate button will then turn
red. On the map, the red circle represents the assessment reach. Click on a blue water pixel
within the circle, and the basin will be delineated.
a. Before selecting the blue pixel, observe geographical features on the web map and
compare with field notes for coordinate selection.
i. On StreamStats different base maps are available for viewing imagery. If the
coordinate location does not fall directly on one of the blue water pixels, but the
coordinate location can be traced perpendicular to a pixel, then using that pixel is
acceptable. This should be given careful consideration because selecting a pixel
on a larger, downstream segment or parallel segment draining an adjacent
catchment would likely produce an inaccurate drainage area. Not all channels
observed in the field may be represented as blue pixels in StreamStats or as blue
lines on The National Map layer. In this case, it is best to refer to field
observations of surrounding features and compare with the web map. If the
coordinate point does not correspond to a pixel on StreamStats, The National
Map Viewer should be used.
ii. Conditions that complicate drainage area calculations include locations near
tributary junctions where three potentially different stream channels (upstream
mainstem, tributary, and mainstem) connect at a single point, and where the
coordinate location is between two parallel stream channels. In both cases, use
field notes, assessment reach sketches, and features on base map layers like
roads and topographic relief to select the appropriate pixel for the assessment
reach.
b. If the red circle does not touch a water pixel or does not border one, then clicking on the
red circle may produce an inaccurate delineation (this is especially true with changes in
elevation). In this case, use The National Map Viewer instead.
7 As of May 2025
38
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Section 3: Data Collection
5. The Basin will be delineated in yellow (Figure 17). Click Continue on the left-hand panel. Scroll
down to Basin Characteristics and check DRNAREA and then click Continue at the bottom. If the
DRNAREA is not an option (as has been observed in Oklahoma, for example), use CONTDA
(contributing drainage area), if neither DRNAREA nor CONTDA are available, use The National
Map Viewer instead.
6. Select Open Report to see the area measurement. If the area measurement is less than 1 sq,
mile, round to the nearest 0.001 sq. mile as your input into the web application.
Instructions to calculate drainage area using The National Map Viewer8:
1. Go to https://apps.nationalmap.gov/viewer/.
2. On the green toolbar along the right, click on the top button, Basemap. Select USGS National
Map, additional base maps are also available and may be useful for finding the location on the
map. Not all channels observed in the field may be represented as blue lines on the USGS
National Map. In this case, it is best to refer to field observations of surrounding features and
compare with the base maps.
3. Click on the next button down, Layers. Scroll down the Layers menu and click on: NHD Plus
High-Resolution Dataset, Watershed Boundary Dataset, and 3DEP Elevation - Auto Contours to
make them visible. The fine pink lines represent catchment boundaries for NHD Plus.
4. In the white search bar on the upper left, enter the latitude coordinate, a comma and space,
and then the longitude coordinate (which should be a negative value). Coordinates should be in
decimal degrees. Press enter and a black circle will appear on the map.
8 As of May 2025
39
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Section 3: Data Collection
5. Zoom out (using either button on the left or mouse scroll wheel) to see the surrounding
topographic contour lines to delineate the basin.
6. On the toolbar, select the button with a ruler, the Measurement tool. Click the Area button.
7. Start at the black circle and begin to draw a polygon by left clicking and moving the cursor along
the desired boundary. A measurement box will appear on the lower left.
8. Where possible, trace the Hydrologic Unit boundary; otherwise, use the contour lines for the
delineation. Single left click at each corner or wherever the boundary is not a straight line.
Concave curvature (contour lines bending away) represents the valley containing the channels
whereas convex curvature (bending toward) represents the ridge. Continue around the entire
watershed perimeter, double click to complete the polygon.
9. In the Measurement tool box select Square Miles in the unit dropdown menu. If the area is less
than 1 square mile, change the units to Hectares and then convert hectares to square miles
(multiply by 0.00386). Round the area to the nearest 0.001 sq. mile as your input into the web
application (Figure 18),
^USGS
sauce lot • chmnging nortd
USCS Home
Contact USCS
Search USGS
topoBuilder
Figure 18. Calculating drainage area using The National Map Viewer. Converting hectares to square miles and rounding
results in 0.017 square miles (4.52 * 0.00386 = 0.01745, rounds to 0.017).
3.8.10 Elevation
This indicator uses elevation data from the Amazon Web Services (AWS) terrain tiles dataset.9 The
SDAM web application will retrieve this value based on coordinates entered or a selected location on
the map when selecting the appropriate regional SDAM (see Section 4 Data Interpretation and Using
the Web Application). Therefore, it is important to have accurate location coordinates for the
9 https://registrv.opendata.aws/terrain-tiles/.
40
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Section 3: Data Collection
downstream end of the reach, see instructions in Section 3.7.1 General reach information. Note, if the
coordinates used in StreamStats or The National Map Viewer to delineate the drainage area are
different than those collected in the field, use the coordinates from StreamStats or the The National
Map Viewer in the SDAM web application to retrieve the elevation.
To obtain the elevation without using coordinates or the map to determine the appropriate regional
SDAM in the web application, enter coordinates where prompted in the indicators section of the web
application.
3.8.11 Average Monthly Precipitation for May, June, and July (SE only)
This indicator is calculated using the 30-year average precipitation from the PRISM (Parameter-
elevation Regression on Independent Slopes Model) Climate Group statistical mapping system from
May, June, and July.10 The average monthly precipitation will be automatically calculated by the web
application based on the coordinates entered or point on the map selected. Note, if the coordinates
used in StreamStats or The National Map Viewer to delineate the drainage area are different than
those collected in the field, use the coordinates from StreamStats or The National Map Viewer in the
SDAM web application.
To obtain the average monthly precipitation without using coordinates or the map to determine the
appropriate regional SDAM in the web application, enter coordinates where prompted in the indicators
section of the web application.
3.9 Additional notes and photographs
After assessing and recording all the indicators described above, provide any additional notes about
the assessment including whether any fish were present in the reach (except mosquito fish, Gambusia
spp.); include photographs in the photo log.
10 See https://prism.oregonstate.edu/normals/
41
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Section 4: Data Interpretation
Section 4: Data Interpretation and Using the Web Application
The NE and SE SDAMs rely on random forest models to make classifications; therefore, the EPA has
developed a free, open-access web application that runs the model for each assessment reach and is
used to obtain a flow classification. This application allows assessors to input data from assessments,
including ordinal scores and non-ordinal information like number of aquatic macroinvertebrates. In
addition, users have the option to produce a PDF report, which may be included as documentation of
SDAM results. No data entered into the web application are stored or submitted to the EPA or other
agencies.
The web application walks users through three steps in analyzing data from an SDAM. First, the user
selects the desired regional SDAM (either by entering coordinates, clicking on a map, or selecting from
a drop-down list). The coordinates field of the web application uses decimal degrees format of the
World Geodetic System 1984 (WGS84) datum. Then the user enters field data on each indicator
required for the selected SDAM. At this point, the user can run the model and obtain the resulting
classification. The third step, report production, is optional. Users may enter additional information
about the assessment (such as date of the site visit, notes, and photos of indicators) and produce a PDF
report. A link at the top of the web application provides Supporting Materials including User Manuals.
Field Forms. Training Videos and more.
4.1 Outcomes of NE and SE SDAM classification
As described in Section 1.1 The SDAM for the Northeast and Southeast, application of the SDAM can
result in one of six possible classifications:
• Ephemeral
• Intermittent
• Perennial
• At least intermittent
• Less than perennial
• Needs more information
The first three streamflow duration classifications correspond to the three classes of streams used to
calibrate the NE and SE SDAMs. These outcomes occur when the pattern of observed indicators closely
matches patterns in the calibration data, and thus a classification can be assigned with high
confidence. Single indicators of flow duration (see Nadeau 2015) were tested for the NE and SE
SDAMs, but data analysis did not suggest that their use would improve classification accuracy.
In some cases, the pattern of indicators is associated with multiple classes, and the NE and SE SDAM
models cannot assign a single classification with high confidence. However, the models may be able to
rule out an ephemeral classification with high confidence or a perennial classification with high
confidence. In the former case, the outcome is at least intermittent, meaning that there is a high
likelihood that the stream is either perennial or intermittent, but not ephemeral. In the latter case, the
outcome is less than perennial, meaning that there is a high likelihood that the stream is either
42
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Section 4: Data Interpretation
intermittent or ephemeral, but not perennial. In both cases, the two classes (i.e., perennial vs.
intermittent and intermittent vs. ephemeral) cannot be distinguished with confidence. In some
instances, this information may be sufficient for management decisions, although additional
assessment may be warranted. Two outcomes, at least intermittent and less than perennial, were rare
in the NE and SE SDAM development data sets: less than 4% of the time for both classifications. The
needs more information outcome is possible and generally occurs when no classification can be made
with confidence, but this did not occur in the development data sets for either the NE or SE regions.
4.2 Applications of the NE and SE SDAMs outside the intended area
The NE and SE SDAMs are intended only for application to these regions as shown in Figure 2. The
online web application allows the user to apply the protocol to reaches outside of these regions;
however, classifications resulting from these applications are for informational purposes only. For
example, it may be helpful to assess reaches with more than one regional SDAM near regional
boundaries. The online web application allows the users to apply indicator data collected from
reaches outside the NE or SE regions to generate NE or SE model classifications. Reports generated
from such applications will identify the SDAM region in which the assessed reach was located.
4.3 What to do when a more specific
classification is needed
If the application of the NE or SE SDAM results in
needs more information, it means that no
classification can be made with confidence. If an
assessment's outcome is ambiguous about the
specific flow duration class (i.e., less than perennial
or at least intermittent), it may help to examine
other lines of evidence or conduct additional
assessments, as described below in approximate
order of increasing effort.
In much of the NE and SE, forest cover obscuring the channel
often prevents the use of sequences of aerial imagery to
provide information about streamflow duration. In settings
where forest cover is absent or less dense, as well as in
certain areas along the western margins of the NE and SE
regions (e.g., Texas and Oklahoma), the use of Google Earth's
time slider and USGS Earth Explorer offer a convenient
method of reviewing historical imagery (however, dates
indicated by Google Earth time slider may be approximate or
not accurate). If surface water is observed in all interpretable
images across multiple years (especially during dry seasons), this may provide evidence that the reach
When a more specific classification is needed:
•
Review historical aerial imagery
•
Conduct additional assessments at the
same reach
•
Conduct assessment at similar nearby
reaches
•
Conduct reach revisits during regionally
appropriate wet or dry seasons
•
Collect hydrologic data
4.3.1 Review historical aerial imagery
Considerations for aerial imagery
• Accurate dates of images
• Changes in reach or watershed
conditions since image was
taken
• Seasonal and recent climatic
conditions for each image
43
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Section 4: Data Interpretation
is likely perennial. If surface water is never observed, even when other nearby intermittent streams
show water, the consistent absence of surface water may provide evidence that the reach is likely
ephemeral (particularly if images are captured during the wet season or after major storm events). If
surface water is present in some images and dry in others, the stream may be intermittent. The
evidence for perennial flow is strong if the images with surface water occur in the dry season, and do
not coincide with recent storm events. It is also important that users consider whether conditions as
reflected by historical imagery are congruent with current conditions. For example, due to
groundwater withdrawals, a stream that once flowed perennially may now have ephemeral flow;
therefore, images from 15-20+ years in the past might not be indicative of current flow conditions.
Any time that discrete observations of flow or no flow are used to inform a determination of flow
duration class, such observations should be evaluated in the context of relatively normal climatic
conditions. Doing so ensures that flow duration class is not determined based on observations of flow
or no flow during abnormally wet or abnormally dry periods. The Antecedent Precipitation Tool (U.S.
Army Corps of Engineers 2023) is a useful tool to determine if climate conditions are 'normal' for a
locale (see Section 3.4 Timing of sampling). However, aerial images may not have high enough
temporal resolution to confidently classify streams as ephemeral or perennial without additional
data. See examples in Figure 19.
44
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Section 4: Data Interpretation
Perennial reach: Tackett Creek, Claiborne County, TN
4/2008: Flowing 4/2013: Flowing
Intermittent reach: Wild Hog Creek, Joseph Williams Tallgrass Prairie Preserve,
11/2020: Flowing
Pawhuska, OK
10/2011: Dry
4/2013: Flowing
7/2022: Isolated Pools
Ephemeral reach: Tributary to Brushy Creek, near Riesel, TX
Sir.1
eM
¦
: M
12/2009: Isolated Pools
12/2012: Dry
• y
5/2021: Isolated Pools
Figure 19. Examples of using aerial imagery to support streamflow duration classification. Images were taken from Google
Earth using the time slider.
4.3.2 Conduct additional assessments at the same reach
Some indicators may be difficult to detect or interpret due to short-term disturbances, floods, severe
drought, or other conditions that affect the sampling event's validity. A repeat application of the
SDAM, even a few weeks later when effects from the disturbance have abated, may be sufficient to
provide a determination. Similarly, conducting an additional evaluation during a different season may
improve the ability to identify vegetation and collect aquatic macroinvertebrates, leading to a more
conclusive assessment.
45
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Section 4: Data Interpretation
4.3.3 Conduct assessments at nearby reaches
Indicators may provide more conclusive results at reaches upstream from the assessment reach or
downstream from the assessment reach, and if those locations represent similar conditions may be
useful for interpreting ambiguous results. For example, there should be no significant discharges,
diversions, or confluences between the new and original assessment locations, and they should have
similar geomorphology. See Section 3.5 Assessment reach considerations for additional information.
4.3.4 Conduct reach revisits during regionally appropriate wet and dry seasons
A single, well-timed assessment may provide sufficient hydrologic evidence about streamflow duration.
As with observations from aerial imagery, any time onsite observations of flow or absence of flow are
used to inform a determination of flow duration class, such observations should be evaluated in the
context of normal climatic conditions. Doing so ensures that flow duration class is not determined
based on hydrologic observations of flow that occurred during abnormally wet or abnormally dry
periods. The previously mentioned APT can provide this information.
4.3.5 Collect hydrologic data
Properly deployed loggers, stream gauges, or wildlife cameras can provide direct evidence about
streamflow duration at ambiguous assessment reaches. It may be possible to distinguish intermittent
from ephemeral streams in just a single season with these tools, assuming typical precipitation.
46
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Section 5: References
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Appendix A: Glossary of Terms
Appendix A. Glossary of Terms
Term Definition
Abdomen
The terminal section of an arthropod body.
Active channel
A portion of the valley bottom that can be distinguished based on the
three primary criteria of (i) channels defined by erosional and
depositional forms created by river processes, (ii) the upper elevation
limit at which water is contained within a channel, and (iii) portions of a
channel without mature woody vegetation. Braided systems have
multiple threads and channel bars that are all part of the active channel.
Alluvial
Refers to natural, channelized runoff from terrestrial terrain, and the
material borne or deposited by such runoff.
Assessment reach
The length of reach, ranging from 40 m to 200 m, where SDAM
indicators are measured.
Aquatic
macroinvertebrates
Invertebrate organisms that require aquatic environments for parts or
all of their life cycle and are visible without the use of a microscope (i.e.,
> 0.5 mm body length). Includes bottom dwelling or benthic
macroinvertebrates.
Bank
The side of an active channel, typically associated with a steeper side
gradient than the adjacent streambed, floodplain, or valley bottom.
Bankfull elevation
The elevation associated with a shift in the hydraulic geometry of the
channel and the transition point between the channel and the
floodplain. In unconstrained settings, this is the height of the water in
the channel just when it begins to flow onto the floodplain.
Bankfull width
Width of the stream channel at bankfull elevation.
Braided system
A stream with a wide, relatively horizontal channel bed over which
during low flows, water forms an interlacing pattern of splitting into
numerous small conveyances that coalesce a short distance
downstream. Same as multi-threaded system.
Canal
An artificial or formerly natural waterway used to convey water between
locations, possibly in both directions. Same as ditch.
Catchment
An area of land, bounded by a drainage divide, which drains to a channel
or waterbody. Synonymous with watershed.
Channel
A feature in fluvial systems consisting of a streambed and its opposing
banks which confines and conveys surface water flow. A braided system
consists of multiple channels, which may include inactive or abandoned
channels.
Confinement
The degree to which levees, terraces, hillsides, or canyon walls prevent
the lateral migration of a fluvial channel.
Culvert
A drain or covered channel that crosses under a road, pathway, or
railway.
Ditch
An artificial or formerly natural waterway used to convey water between
locations, possibly in both directions. Same as canal.
51
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Appendix A: Glossary of Terms
Dorsal
Upper surface of abdomen, or back when viewed from above.
Ephemeral
Channels that flow only in direct response to precipitation. Water
typically flows at the surface only during and/or shortly after large
precipitation events, the streambed is always above the water table, and
stormwater runoff is the primary water source.
Exuviae
The shed exoskeletons of arthropods typically left behind when an
aquatic larva or nymph becomes a winged adult. Singular: exuvium.
FAC
Facultative plants. They are equally likely to occur in wetlands and non-
wetlands.
FACU
Facultative upland plants. They usually occur in non-wetlands but are
occasionally found in wetlands.
FACW
Facultative wetland plants. They usually occur in wetlands but may occur
in non-wetlands.
Fibrous Roots
Non-woody, small diameter (<0.10 in) roots that often form dense
masses in the first few inches of the soil. They are often easily torn and
are not adapted to flowing conditions.
Floodplain
The bench or broad flat area of a fluvial channel that corresponds to the
height of bankfull flow. It is a relatively flat depositional area that is
periodically flooded (as evidenced by deposits of fine sediment, wrack
lines, vertical zonation of plant communities, etc.).
Flood-prone width
Width of floodplain at the flood-prone elevation (2x maximum bankfull
depth)
Groundwater
Water that is underground in soil, pores, or crevices in rocks.
Head
The anterior-most section of an arthropod body, where mouthparts,
eyes, and other sensory organs are located. The head is typically (but not
always) distinct from the rest of the body.
Hydrophyte
Plants that are adapted to inundated conditions found in wetlands and
riparian areas.
Hyporheic
The saturated zone under a river or stream, including the substrate and
water-filled spaces between the particles.
Indicator
For the NE and SE SDAMs, indicators are rapid, generally field-based
measurements that are used to predict streamflow duration class.
Instar
A phase between two periods of molting in arthropods (i.e., insects).
Intermittent
Channels that contain sustained flowing surface water for only part of
the year, typically during the wet season, where the streambed may be
below the water table and/or where the snowmelt from surrounding
uplands provides sustained flow. The flow may vary greatly with
stormwater runoff.
Larva
An immature stage of an insect or other invertebrates. Several insects
have aquatic larval stages, such as mayflies, stoneflies, and caddisflies.
Immature salamanders are sometimes also described as larvae. Plural:
larvae.
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Appendix A: Glossary of Terms
Low-flow channel
In braided systems, the main channel with the lowest thalweg elevation.
In intermittent or ephemeral reaches, the low-flow channel typically
retains flow longer than other channels.
Multi-threaded
system
A stream with a wide, relatively horizontal channel bed over which
during low flows, water forms an interlacing pattern of splitting into
numerous small conveyances that coalesce a short distance
downstream. Same as braided system.
Nl
Plants that have no assigned wetland indicator (e.g., FACW, FACU) in a
specific National Wetland Plant List region.
OBL
Obligate wetland plants. They almost always occur in wetlands.
Ordinary high-
water mark
(OHWM)
The line on the shore established by the fluctuations of water and
indicated by physical characteristics, such as a clear natural line
impressed on the bank, shelving, changes in the character of the soil,
destruction of terrestrial vegetation, the presence of litter and debris, or
other appropriate means that consider the characteristics of the
surrounding areas. See 33 CFR 328.3. An OHWM is required to establish
lateral extent of U.S. Army Corps of Engineers jurisdiction in non-tidal
streams. See 33 CFR 328.4.
Perennial
Channels that contain flowing surface water continuously during a year
of normal rainfall, often with the streambed located below the water
table for most of the year. Groundwater typically supplies the baseflow
for perennial reaches, but the baseflow may also be supplemented by
stormwater runoff and/or snowmelt.
Pool
A depression in a channel where water velocity is slow and suspended
particles tend to deposit. Pools typically retain surface water longer than
other portions of intermittent or ephemeral streams.
Proleg
Leg-like extensions on the abdomen (never the thorax) of some insect
larvae. Typically, prolegs are unsegmented.
Pupa
An immature stage of insect orders with complete metamorphosis,
occurring between the larval and adult stage. Pupal stages are typically
immobile.
Reach
A length of stream that generally has consistent geomorphological and
biological characteristics.
Riffle
A shallow portion of a channel where water velocity and turbulence are
high, typically with coarse substrate (cobble and gravels). Riffles typically
dry out earlier than other portions of intermittent or ephemeral
streams, and harbor higher abundance and diversity of aquatic
macroinvertebrates.
Riparian
A transitional area between the channel and adjacent upland
ecosystems.
Rooted upland
plants
Plants rooted in the streambed that have wetland indicator statuses of
FAC, FACU, UPL, and Nl.
53
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Appendix A: Glossary of Terms
Runoff
Surface flow of water caused by precipitation or irrigation over
saturated or impervious surfaces.
Sclerotized
Hardened, as in the tough plates covering various body parts in some
arthropods.
Scour
Concentrated erosive action of flowing water in streams that removes
and carries material away from the bed or banks. Algal and invertebrate
abundance is typically depressed after scouring events.
Secondary channel
A subsidiary channel that branches from the main channel and trend
parallel or subparallel to the main channel before rejoining it
downstream.
Streambed
The bottom of a stream channel between the banks over which water
and sediment are transported during periods of flow.
Thalweg
The line along the deepest flow path within the channel.
Thorax
The middle section of an arthropod body where legs and wing pads (if
present) are attached.
Tributary
A stream that conveys water and sediment to a larger waterbody
downstream.
UPL
Upland plants. They almost always occur in non-wetlands.
Uplands
Any portion of a drainage basin outside the river corridor.
Valley width
The portion of the valley within which the fluvial channel is able to
migrate without cutting into hill slopes, terraces, or artificial structures.
Ventral
Underside of abdomen, or belly when viewed from below.
Watershed
An area of land, bounded by a drainage divide, which drains to a channel
or waterbody. Synonymous with catchment.
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Appendix B: Guide to Aquatic invertebrate Orders and Families in the Eastern United States
Appendix B. Guide to Aquatic Invertebrate Orders and Families in the
Eastern United States
To determine richness for the BMI indicator, assessors must distinguish aquatic insects and
mollusks to the family level, crustaceans and mites to the order level, and all other non-insects
to the class or phylum level. For convenience, we provide a guide to common taxa encountered
during field data collection at SDAM study sites for the NE and SE.
All photographs are from the Macroinvertebrates.org website, an online reference for
identification of aquatic insects of eastern North America, unless otherwise noted.
General insect anatomy
Dorsal view of a mayfly (Ephemeroptera) nymph
antennae
head
thorax
wing pads
abdomen
gills
cerci
i
Illustrated by Lisa Schoriberg
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Insect Orders and Families
Ephemeroptera (mayflies)
Mayfly larvae have abdominal gills and generally three cerci (tails), though some species have two. A
single tarsal claw is present, and wing pads are usually visible. Adult mayflies are short-lived and
terrestrial but may be found in large breeding swarms near waterbodies. Identification to family level is
needed for richness.
Single
tarsal claw
Three cerci
f
Wing pads
Abdominal gills
Heptageniidae (flat-headed
mayflies). Heptageniid
mayflies often have a
flattened appearance, and
cling to the undersides of
cobbles in fast-flowing water.
Heptageniid mayflies were
among the most common and
abundant taxa encountered
during data collection.
Baetidae (small minnow
mayflies). This family has a
streamlined appearance and
swimming motion similar to a
minnow. This specimen is
Baetis. In some species of
Baetis, only two cerci are
evident. Baetid mayflies were
the second most encountered
mayfly during NE and SE data
collection. Image credit:
California Department of Fish
and Wildlife (CADFW).
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Cm*
Abdominal gills with
long 'prongs'
Leptophlebiidae (prong-gilled
mayflies). This family of
mayflies prefers gravel-
bottomed streams and is
often found in woody debris
or among roots protruding
from the bank. They are flat
bodied and tend to cling to
substrate. Their gills often
have long forked prongs,
giving this family its common
name. Image credit: James
Treacy.
Mmm
Ephemerellidae (spiny crawler
mayflies). This family tends to
be found in riffles and at the
margins of flowing water and
swim with a 'floppy' motion.
Gills have a 'spine' type shape
and are absent from
abdominal segment two (just
below wing pads).
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Ameletidae (comb-mouthed
minnow mayflies). Often
found in cold, fast-flowing
mountain streams. Similar
streamlined shape to
Baetidae, but antennae are
much shorter. Family
represented by one genus,
Ameletus,
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Plecoptera (stoneflies)
Stonefly larvae usually have tuft-like gills on the thorax (and sometimes also on the first few abdominal
segments), two (not one) tarsal claws at the end of each leg, and always have two (never three) cerci,
making them easily distinguishable from mayflies. Wing pads are usually visible. There is no pupal
stage. All stonefly larvae are aquatic, and adults are terrestrial.
Two cerci
No abdominal gills
Two tarsal claws
Perlidae (common
stoneflies). The Perlidae
family is large and
conspicuous, often with
ornate patterns on the
head and thorax. This
family has gills on the
thorax (not abdomen).
Perlids were the most
common and abundant
stoneflies identified during
NE and SE data collection
outside winter and early
spring.
Capniidae (small winter
stoneflies). Members of
this family have long,
slender bodies with no
thoracic or abdominal gills.
Capniids were the most
common and abundant
stonefly collected during
winter and early spring
surveys.
Leuctridae (rolled winged
stoneflies). Members of
this family are very similar
in appearance to Capniid
stoneflies; no thoracic or
abdominal gills are
present.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Perlodidae (stripetails).
Members of this family
have a patterned head and
thorax and often
longitudinal black-and-
yellow striping on the
abdomen. However, unlike
the Perlids, no abdominal
or thoracic gills are
present.
Thoracic gills
Long hindlegs
Divergent
hindwings
Nemouridae (nemourid
stoneflies). This family is
relatively small; it is
distinguished from other
stonefly families by
hindwings that diverge
conspicuously from the
boxy axis, and long
hindlegs that can extend to
the tip of the abdomen.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Trichoptera (caddisflies)
Caddisflies are closely related to moths and butterflies. Unlike mayflies and stoneflies, they have a
pupal stage and undergo complete metamorphosis. Many taxa build conspicuous cases or retreats that
may persist in dry streams. Some have filamentous gills on the ventral side (underside) of the abdomen
(as opposed to the plate-like gills on the dorsal side (back) of the abdomen, as seen with mayflies).
Their abdomen ends in two anal prolegs, each with a sclerotized hook, rather than long tail-like cerci.
No wing pads are visible, but the thorax is usually dark and hardened (i.e., sclerotized) on the top, with
the abdomen being completely membranous. Caddisfly larvae are generally C-shaped. All larvae and
pupal stages are aquatic, and all adults are terrestrial,
Sclerotized thoracic
Hydropsychidae (net-
spinner caddisflies). This
group lives within nets
made out of silk,
pebbles, and other
materials. All thoracic
segments are
sclerotized and a setal
'fan' is present on the
prolegs. Hydropsychids
were the most common
caddisfly (and one of
the most common
families overall)
collected during NE and
SE field sampling.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Limnephilidae (northern
case-makers).
Limnephilids are a large
group of roaming
caddisflies that build
cases out of diverse
materials, such as
pebbles, sand, leaf
segments, and twigs.
4*
I
T-shaped labrum
Philopotamidae (finger-
net caddisflies). Like
hyd ropsychid
caddisflies, members of
this family build a net
retreat but are often
found roaming free. It is
distinguished from
other families of
caddisflies by its T-
shaped labrum
(extendable
mouthpart).
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Lepidostomatidae (scaly
mouth caddisflies).
Members of this group
are most commonly
found in mountainous
regions in small streams
or the edges of large
rivers. Cases are of
various materials and
shapes, though a four-
sided case constructed
of square pieces of
leaves is most
commonly found. The
lepidostomatids are the
only trichopteran family
with very small
antennae situated
directly next to the
eyes.
Polycentropodidae
(trumpet-net, tube
maker caddisflies).
Members of this family
do not utilize a case;
instead, they construct
a tubular silken net.
Only the first thoracic
segment is sclerotized;
the anal prolegs are
long and freely
moveable.
A-
prolegs
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Long anal
prolegs
Rhyacophilidae (free-
roaming caddisflies).
This family is usually
found wandering freely
on the undersides of
boulders and cobbles,
actively hunting for
prey. Notice the long
anal prolegs, which have
large, sclerotized claws.
Members of this family
often have well defined
segments, giving them a
beaded appearance.
Some species have a
striking blue-green
coloration, which may
fade when preserved in
alcohol. Image credit:
CADFW.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Coleoptera (beetles)
The order Coleoptera can include both aquatic larvae and adults, unlike most of the insect orders
covered in this Appendix. All adult beetles have hardened forewings known as elytra, though no
wingpads are visible on larvae. Larvae have diverse morphology, typically with eyespots present but
compound eyes absent, legs with four to five segments, and no lateral gills on the abdomen or thorax
(if gills are present, they are often at the tip of abdomen). Beetle larvae can also look superficially like
caddisfly larvae; however, their bodies usually show a greater degree of sclerotization (including the
abdomen), and they usually have prominent chewing and/or piercing mouthparts.
Dytiscidae (diving beetles). Larvae
have less sclerotization than other
beetles, but generally have some
hardening of the abdomen (in
1
contrast to caddisflies). Dytiscidae
was the most common and abundant
beetle family collected during NE and
SE field sampling.
Tufted gills
Elmidae (riffle beetles). Elmid beetle
larvae have a completely sclerotized
body and tufted gills at the tip of the
abdomen. Adult elmids are typically
very small (1 to 8 mm). They
frequently have rows of indentations
along the elytra, relatively long legs
ending in proportionally long claws,
and thread-like antennae.
Tufted gills
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Psephenidae (water pennies). The
larvae of this family are fully aquatic;
however, adults are terrestrial and
rarely observed as they are relatively
short lived. Larvae are round and flat,
often found clinging like suction cups
to cobbles in fast-flowing streams;
their legs are only visible from the
ventral side. Their unusual shape
makes them unmistakable for any
other aquatic insect larvae.
Gyrinidae (whirligig beetles). The
larvae of this family have lateral,
abdominal gills, unlike most of the
larvae of aquatic Coleopteran families.
Larvae also have four hooks on the
last abdominal segment. Adults have
compound eyes on the dorsal and
ventral surface, giving them a four-
eyed appearance. Adult beetles often
zip around in swirling motions along
the surface of the water, giving them
their common name.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Hydrophilidae (water scavenger
beetles). The larvae of some genera
are easily recognized by lateral
filaments along the abdomen (not
gills; Berosus (left), though most taxa
do not have these filaments (e.g.,
Tropisternus, below)
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Odonata (dragonflies and damselfiies)
Dragonflies and damselfiies have large, predatory aquatic larvae. They have a conspicuous labial mask
held under the head (see below), which extends to capture prey nearby. Larvae of dragonflies tend to
have stout, robust bodies (round or elongated) and abdomens that end with 5 stiff points. In contrast,
larvae of damselfiies have abdomens that end in three paddle-like gills. Both have wing pads that are
evident in mature specimens and neither have external gills along the length of their abdomens, unlike
mayflies and caddisflies.
Labial mask
Flat labial mask
Gomphidae (clubtail
dragonflies). This family is
distinguished by its short,
four-segmented antennae,
the third of which is much
larger than all the other
segments (the final segment
may be very small). The labial
mask is relatively flat.
Cordulegastridae (spiketail
dragonflies). This family has
hairy abdomens that taper at
the midpoint. The labral mask
has spoon-like palps that
cover the face on the ventral
side.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
3 gills
Calopterygidae (broad-
winged damselflies; left):
Calopterygidae can be
distinguished from other
damselflies by the long first
antennal segment (indicated
with an arrow).
Coenagrionidae (narrow-
winged damselflies; right)
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Megaloptera (dobsonflies, alderflies)
Megaloptera have long-lived aquatic larvae and terrestrial adults. Larvae can be quite large and
imposing. The order is distinguished by the presence of lateral filaments on the abdomen. Mouthparts
have large pinchers, and each leg is tipped with small two-parted pinchers.
Corydalidae (dobsonflies). Also
called hellgrammites. Large and
centipede-like. Lack C-shaped
bodies of caddisflies and have
lateral filaments instead of gills
along the abdomen. Image credit:
CADFW.
Sialidae (alderflies). Usually much
smaller than dobsonflies. Also
distinguished from Corydalidae by
the abdomen ending in a single
'tail', rather than in two prolegs.
Lateral filaments
\
/
Single, long 'tail'
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Diptera (true flies)
Dipterans are a diverse group of insects, of which some have an aquatic larval and/or pupal stage.
Aquatic dipteran larvae are soft-bodied and legless (although they may have prolegs). Some families
have conspicuous head capsules (e.g., Simuliidae, Chironomidae).
Head
capsule
\
Labral fan
V
Chironomidae (non-biting midges).
Chironomidae are among the
most numerous and widespread
aquatic invertebrates in
waterbodies. Some species have
hemoglobin pigments to help
them extract oxygen from hypoxic
water, giving them a blood-red
appearance. They have a distinct
head capsule, a c-shaped body,
and prolegs on the thorax and
abdomen (no segmented legs like
caddisflies). This family was the
most common and abundant of
all taxa collected during field
sampling to develop the NE and
SE SDAMs, for all sampling
periods.
Dixidae (meniscus midges). Similar
to Chironomids but have addition
of flat lobes fringed with hair on
the last abdominal segment.
Simuliidae (black flies). The base
of the abdomen in this family is
swollen, giving them a "bowling
pin" appearance. Have two labral
fans they use to filter particles
from the stream.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Tipulidae (crane flies). Larvae of
this family are sometimes the
largest aquatic insects
encountered in a stream (aside
from dobsonflies). They are
legless, appear to be headless (the
head is withdrawn into the body),
and sometimes have conspicuous
anal papillae at the end of the
abdomen.
Culicidoe (mosquitos). Mosquito
larvae hang at the water surface
and breath air through a tube at
the tip of the abdomen. When
disturbed, they "wriggle" and
swim away from the surface.
Image credit: MO Department of
Conservation.
A
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Hemiptera (true bugs)
Hemipterans have partially hardened, partially membranous forewings (hemelytra), unlike beetles, and
piercing mouthparts. They do not undergo complete metamorphosis, and juvenile stages generally
resemble adults. While aquatic families of this order are included as taxa in the BMI score, they are not
found along the bottom of the streambed ('benthic'). Instead, they are usually found striding, skating,
or rowing across the water surface.
Veiiidae (small water striders).
They have stouter bodies and
shorter legs than water striders in
family Gerridae (see below). Most
common and abundant
hemipteran family collected during
NE and SE SDAM field sampling.
Gerridae (large water striders or
skaters).
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Corixidae (water boatmen). These
insects have oar-like front-legs,
which they use to paddle through
the water.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Mollusk Families (mussels, clams, and snails)
.'WWHTOWmW;
The freshwater mussels are
represented by the families
Margaritiferidae and Unionidae.
The Unionidae are much better
represented in the East. Both
families include many
endangered and protected
species and should not be
disturbed or collected during
assessments. Freshwater mussels
are distinguished by their large
size, with individuals often
reaching several inches in length.
Different shell sizes and shapes
of Elliptio complariata (Eastern
elliptio) are shown, this is a
common Unionid species found
in most of the Eastern coastal
states. Image credit; M.
Marchand.
Corbiculidae (Asian clam). Asian
clams are introduced non-native
species that have become
widespread in many areas of the
U.S. In contrast to mussels,
freshwater clams have a more
symmetrical shape and a sturdier
shell. They rarely reach more
than an inch in diameter. Image
credit: John Joseph Giacinto.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Physidae (bladder snails).
Physidae are among the most
common snails in streams. They
are left-handed, meaning that
the opening is on the left side if
the spire is pointed away from
you, and typically have fewer,
wider whorls than other snails.
Planorbidae (ramshorn snails).
Ramshorn snails have a flattened,
disc-like appearance, and lack a
conspicuous spire that many
other snails have.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Crustacean Orders (crayfish, amphipods, arid isopods)
Decapoda (crayfish). Crayfish are
familiar occupants of streams;
however, many species are vulnerable
or critically imperiled, particularly in the
southeastern states where diversity is
highest. For this reason, they should
not be collected during assessments.
Image credit: NC Wildlife Resources
Commission.
Amphipoda (amphipods, also known as
scuds or side-swimmers). Amphipods
resemble shrimp in form and are
usually compressed laterally. They do
not have a carapace (the hard covering
of the thorax common in other
Crustacea), and most or all thoracic
segments are distinct and bear leglike
appendages, image credit: Scott Bauer.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Isopoda (isopods). Unlike arnphipods,
isopods are usually flattened
dorsoventrally (top to bottom). Isopods
are many-segmented, with head,
thorax, and abdomen not immediately
distinct, and have seven pairs of legs.
Some looks similar to terrestrial
isopods, like pillbugs (aka roly-poly or
wood louse)
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Other: Annelida, Acariformes, and Turbellaria (worms, leeches, water mites, and flatworms)
r
Phylum Annelida, Class Oligochaeta.
Segmented worms. Aquatic species are
often red or reddish in color due to a
hemoglobin-type substance that
enables them to live in oxygen-
depleted water. Image credit: NW
Nature.
Phylum Annelida, Class Hirudinea.
Leeches. This image depicts a species in
the Macrobdella genus, which is
common in freshwater habitats of
North America, image credit: Gabrielle
Dunham CC-BY-NC.
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Appendix B: Guide to Aquatic Invertebrate Orders and Families in the Eastern United States
Superorder Acariformes (Phylum
Arachnida). Group that includes aquatic
mites. Biological sampling will generally
find adults, as most larvae are attached
to host plants or animals. This image
depicts a member of the Hydrachna
genus. Image credit: Water Mites of
North America Project.
Class Turbellaria (Phylum
Platyhelminthes). Flatworm group that
is not exclusively comprised of parasitic
species. A common group found in
freshwater habitats are the Planarians,
which include members of the Girardia
genus depicted here. Image credit; Alex
Parry CC-BY-NC.
80
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Appendix C. Field Forms
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Appendix CI: Combined field form for the NE and SE SDAMs
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Northeast and Southeast SDAMs Field Form
June 2025
Page 1 of 6
Northeast and Southeast SDAMs
General site information
Project name or number:
Region ~ Northeast
~ Southeast
Site code or identifier:
Assessor( s):
Waterway name:
Visit date:
Current precipitation:
~ None
~ Rain ~ Snow/Ice
~ Light
~ Moderate
~ Heavy
Notes:
Recent weather: (e.g.,
precipitation in prior week):
Coordinates at downstream end
(decimal degrees), Device:
Lat (N):
Long (E):
Datum:
Surrounding land-use within 100 m (check one or two):
~ Urban/industrial/residential
~ Agricultural (farmland, crops, vineyards, pasture)
~ Developed open space (e.g., golf course)
~ Forested
~ Other natural
~ Other:
Describe reach boundaries:
Mean bankfull channel width
(nearest 0.1 m):
(Indicator 1)
Reach length (m):
40x width
min 40 m
max 200 m
Site photographs:
Enter photo ID.
Tod down: Mid down:
Mid up: Bottom up:
Disturbed or difficult conditions (check all that apply):
~ None ~ Discharges
~ Recent flood or debris flow ~ Drought
~ Stream modifications (e.g., channelization) ~ Vegetation removal/limitations
~ Diversions ~ Other (explain in notes)
Notes on disturbances or difficult site conditions:
Observed hydrology: Comments on observed hydrology:
% of reach with surface flow
% of reach with sub-surface or surface flow
# of isolated pools
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Northeast and Southeast SDAMs Field Form
June 2025 Page 2 of 6
Site sketch:
1. Mean bankfull channel width (m) (NE and SE) (nearest 0.1 m, copy from first page of field form)
Notes about mean bankfull channel width:
2. Entrenchment ratio (NE only)
Measure at relatively straight section of reach avoiding pools and bends
in the stream. Max entrenchment ratio value is 2.5. Entrenchment ratio
of Locations 1+2+3 / 3 = Average entrenchment ratio.
Average
entrenchment
ratio:
Bankfull
width (m)
Flood-prone
width (m)
Entrenchment Ratio
(Flood-prone /Bankful)
Check if Flood-prone width
is >2.5x bankfull width
Location 1
Location 2
Location 3
Notes:
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Northeast and Southeast SDAMs Field Form
June 2025
Page 3 of 6
Aquatic macroinvertebrate indicators
Collect aquatic macroinvertebrates from at least 6 locations in the assessment reach, searching all suitable habitats on the
streambed (including dry habitats, if present).
Taxa/Notes:
4. Total aquatic macroinvertebrate abundance (SE only)
Mark the appropriate box for the total number of aquatic macroinvertebrates observed.
~ No aquatic macroinvertebrates observed.
~ Total abundance is 1 or 2.
~ Total abundance is 3 to 40.
~ Total abundance is 41 or more.
Notes on total aquatic macroinvertebrate abundance:
5. Slope (NE only)
Using a clinometer or other device, record the slope at bankfull as a percent, up to the nearest half-percent. If multiple
sights are needed to cover the entire reach, record each and calculate a weighted average to get slope:
3. BMI Score (NE and SE)
(0-3)
0 (Absent) No aquatic macroinvertebrates observed.
1 (Weak) Total abundance is 1 to 3.
2 (Moderate) Total abundance >4
3 (Strong) Total abundance >10 and richness >3 OR Total abundance < 10 and richness >5
Note: Richness is based on family-level identification for aquatic insects and mollusks, order-level
for crustaceans and mites, and class or phylum for all other aquatic macroinvertebrates.
1).
2).
3).
% slope
_% slope
_% slope
% of reach
_% of reach
% of reach
4) % slope % of reach
Notes about slope:
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Northeast and Southeast SDAMs Field Form
June 2025
Page 4 of 6
6. Shading (NE and SE)
At the center of three transects, use a modified convex spherical densiometer (see section 3.8.5 of the NE and SE SDAM) to
record the number of points covered by trees, canyon walls, buildings, or other structures that provide shade (up to 17
points per location). Calculate percent shading as the percentage of points covered by such structures (total points covered
divided by 204).
Percent shading:
Downstream Middle transect Upstream transect
transect
Facing upstream
117
117
117
Facing right bank
117
117
117
Total number of points covered:
Facing downstream
117
117
117
/204 * 100%
Facing left bank
117
117
117
Notes on shading:
7. Prevalence of rooted upland plants in streambed (SE only)
Evaluate the prevalence of rooted upland plants (i.e., plants rated as FAC, FACU, UPL, or not listed in
the regionally appropriate National Wetland Plant List) in the streambed.
(0-3)
0 (Poor) Rooted upland plants are prevalent within the streambed/thalweg (>75%).
1 (Weak) Rooted upland plants are consistently dispersed throughout the streambed/thalweg (20-
75%).
2 (Moderate) There are a few rooted upland plants present within the streambed/thalweg (<20%).
3 (Strong) Rooted upland plants are absent from the streambed/thalweg.
Upland Species
Notes
Photo ID
Notes on rooted upland plants:
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Northeast and Southeast SDAMs Field Form
June 2025 Page 5 of 6
8. Particle size of stream substrate (SE only)
(0-3)
Half scores (0.5,1.5,
2.5) are allowed.
Compare substrate on the channel bed to the banks and adjacent floodplain.
0 (Absent) The channel is poorly developed, very little to no coarse sediment is present. There
is no difference between particle size in the stream substrate and adjacent land.
1 (Weak) The channel is poorly developed through the soil profile. Some coarse sediment is
present in the streambed but is discontinuous. Particle size differs little between the stream
substrate and adjacent land.
2 (Moderate) There is a well-developed channel, but it is not deeply incised through the soil
profile. Some coarse sediment is present in the streambed in a continuous layer. Particle size
differs somewhat between the stream substrate and adjacent land.
3 (Strong) The channel is well-developed through the soil profile with relatively coarse
streambed sediments compared to the riparian zone soils: coarse sand, gravel, or cobbles in
the piedmont; cobbles or boulders in the mountains, and medium or coarse sand in the
coastal plain. Particle size differs greatly between the stream substrate and adjacent land.
Notes about particle size of stream substrate:
9. Prevalence of fibrous roots in the streambed (SE only)
Evaluate the extent of fibrous roots in the streambed.
(0-3)
Half scores (0.5,1.5,
2.5) are allowed.
0 (Absent) A strong network of fibrous roots is persistent in the stream thalweg and
surrounding area.
1 (Weak) A discontinuous network of fibrous roots is present in the stream thalweg and
surrounding area.
2 (Moderate) Very few fibrous roots are present anywhere in the streambed.
3 (Strong) No fibrous roots are present.
Notes about fibrous roots:
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Northeast and Southeast SDAMs Field Form
June 2025 Page 6 of 6
10. Drainage area (NE and SE) (in square miles, if < 1 round to the nearest 0.001)
Notes about Drainage, including method/tool(s) used to calculate:
11. Elevation (NE and SE) (m)
12. Average monthly precipitation for May, June, July (SE only) (mm)
Photo log
Indicate if any other photographs taken during the assessment:
Photo ID
Description
Additional notes about the assessment including observations of fish (other than mosquitofish,
Gambusia sp.):
Model classification:
~ Ephemeral
~ At least intermittent
~ Intermittent
~ Less than perennial
~ Perennial
~ Needs more information
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Appendix C2: Field form for the NE SDAM
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Northeast SDAM Field Form
June 2025
Page 1 of 4
Northeast Streamflow Duration Assessment Method
General site information
Project name or number:
Site code or identifier:
Assessor( s):
Waterway name:
Visit date:
Current precipitation:
~ None
~ Rain ~ Snow/Ice
~ Light
~ Moderate
~ Heavy
Notes:
Recent weather: (e.g.,
precipitation in prior week):
Coordinates at downstream end
(decimal degrees), Device:
Lat (N):
Long (E):
Datum:
Surrounding land-use within 100 m (check one or two):
~ Urban/industrial/residential
~ Agricultural (farmland, crops, vineyards, pasture)
~ Developed open space (e.g., golf course)
~ Forested
~ Other natural
~ Other:
Describe reach boundaries:
Mean bankfull channel width
(nearest 0.1 m):
(Indicator 1)
Reach length (m):
40x width
min 40 m
max 200 m
Site photographs:
Enter photo ID.
Tod down: Mid down:
Mid up: Bottom up:
Disturbed or difficult conditions (check all that apply):
~ None ~ Discharges
~ Recent flood or debris flow ~ Drought
~ Stream modifications (e.g., channelization) ~ Vegetation removal/limitations
~ Diversions ~ Other (explain in notes)
Notes on disturbances or difficult site conditions:
Observed hydrology: Comments on observed hydrology:
% of reach with surface flow
% of reach with sub-surface or surface flow
# of isolated pools
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Northeast SDAM Field Form
June 2025
Site sketch:
Page 2 of 4
1. Mean bankfull channel width (m) (nearest 0.1m, copy from first page of field form)
Notes about mean bankfull channel width:
2. Entrenchment ratio
Measure at relatively straight section of reach avoiding pools and bends
in the stream. Max entrenchment ratio value is 2.5. Entrenchment ratio
of Locations 1+2+3 / 3 = Average entrenchment ratio.
Average
entrenchment
ratio:
Bankfull
width (m)
Flood-prone
width (m)
Entrenchment Ratio
(Flood-prone /Bankful)
Check if Flood-prone width
is >2.5x bankfull width
Location 1
Location 2
Location 3
Notes:
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Northeast SDAM Field Form
June 2025
Page 3 of 4
3. Aquatic macroinvertebrates: BMI Score
Collect aquatic macroinvertebrates from at least 6 locations in the assessment reach, searching all suitable habitats on the
streambed (including dry habitats, if present).
0 (Absent) No aquatic macroinvertebrates observed.
1 (Weak) Total abundance is 1 to 3.
^ ^ 2 (Moderate) Total abundance >4
3 (Strong) Total abundance >10 and richness >3 OR Total abundance < 10 and richness >5
Note: Richness is based on family-level identification for aquatic insects and mollusks, order-
level for crustaceans and mites, and class or phylum for all other aquatic macroinvertebrates.
Taxa/Notes:
4. Slope
Using a clinometer or other device, record the slope at bankfull as a percent, up to the nearest half-percent. If multiple
sights are needed to cover the entire reach, record each and calculate a weighted average to get slope:
1 ) % slope % of reach
2 ) % slope % of reach
3) % slope % of reach
4) % slope % of reach
Notes about slope:
5. Shading
At the center of three transects, use a modified convex spherical densiometer (see Section 2.8.5 of the NE and SE SDAM) to
record the number of points covered by trees, canyon walls, buildings, or other structures that provide shade (up to 17
points per location). Calculate percent shading as the percentage of points covered by such structures (total points covered
divided by 204).
Percent Downstream Middle transect Upstream transect
shading: transect
Facing upstream
/17
/17
/17
Facing right bank
117
117
117
Total number of points covered:
Facing downstream
117
117
117
/204 * 100%
Facing left bank
117
117
117
Notes on shading:
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Northeast SDAM Field Form
June 2025 Page 4 of 4
6. Drainage area (in square miles, if < 1 round to the nearest 0.001)
Notes about Drainage are including method/tool(s) used to calculate:
7. Elevation (m)
Photo log
Indicate if any other photographs taken during the assessment:
Photo ID
Description
Additional notes about the assessment including observations of fish (other than mosquitofish,
Gambusia sp.):
Model classification:
~ Ephemeral
~ At least intermittent
~ Intermittent
~ Less than perennial
~ Perennial
~ Needs more information
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Appendix C3: Field form for the SE SDAM
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Southeast SDAM Field Form
June 2025
Page 1 of 5
Southeast Streamflow Duration Assessment Method
General site information
Project name or number:
Site code or identifier:
Assessor( s):
Waterway name:
Visit date:
Current precipitation:
~ None
~ Rain ~ Snow/Ice
~ Light
~ Moderate
~ Heavy
Notes:
Recent weather: (e.g.,
precipitation in prior week):
Coordinates at downstream end
(decimal degrees), Device:
Lat (N):
Long (E):
Datum:
Surrounding land-use within 100 m (check one or two):
~ Urban/industrial/residential
~ Agricultural (farmland, crops, vineyards, pasture)
~ Developed open space (e.g., golf course)
~ Forested
~ Other natural
~ Other:
Describe reach boundaries:
Mean bankfull channel width
(nearest 0.1 m):
(Indicator 1)
Reach length (m):
40x width
min 40 m
max 200 m
Site photographs:
Enter photo ID.
Tod down: Mid down:
Mid up: Bottom up:
Disturbed or difficult conditions (check all that apply):
~ None ~ Discharges
~ Recent flood or debris flow ~ Drought
~ Stream modifications (e.g., channelization) ~ Vegetation removal/limitations
~ Diversions ~ Other (explain in notes)
Notes on disturbances or difficult site conditions:
Observed hydrology: Comments on observed hydrology:
% of reach with surface flow
% of reach with sub-surface or surface flow
# of isolated pools
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Southeast SDAM Field Form
June 2025
Site sketch:
Page 2 of 5
1. Mean bankfull channel width (m) (nearest 0.1m, copy from first page of field form)
Notes about mean bankfull channel width:
Aquatic macroinvertebrate indicators
Collect aquatic macroinvertebrates from at least 6 locations in the assessment reach, searching all suitable habitats on the
streambed (including dry habitats, if present).
2. BMI Score
0 (Absent) No aquatic macroinvertebrates observed.
1 (Weak) Total abundance is 1 to 3.
2 (Moderate) Total abundance >4
3 (Strong) Total abundance >10 and richness >3 OR Total abundance < 10 and richness >5
Note: Richness is based on family-level identification for aquatic insects and mollusks, order-
level for crustaceans and mites, and class or phylum for all other aquatic macroinvertebrates.
Taxa/Notes:
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Southeast SDAM Field Form
June 2025
Page 3 of 5
3. Total aquatic macroinvertebrate abundance
Mark the appropriate box for the total number of aquatic macroinvertebrates observed.
~ No aquatic macroinvertebrates observed.
~ Total abundance is 1 or 2.
~ Total abundance is 3 to 40.
~ Total abundance is 41 or more.
Notes on total aquatic macroinvertebrate abundance:
4. Shading
At the center of three transects, use a modified convex spherical densiometer (see Section 3.8.5 of the NE and SE SDAM) to
record the number of points covered by trees, canyon walls, buildings, or other structures that provide shade (up to 17
points per location). Calculate percent shading as the percentage of points covered by such structures (total points covered
divided by 204).
Percent Downstream Middle transect Upstream transect
shading: transect
Facing upstream
117
117
117
Facing right bank
117
117
117
Total number of points covered:
Facing downstream
117
117
117
/204 * 100%
Facing left bank
117
117
117
Notes on shading:
5. Prevalence of rooted upland plants in streambed
Evaluate the prevalence of rooted upland plants (i.e., plants rated as FAC, FACU, UPL, or not listed in the
regionally appropriate National Wetland Plant List) in the streambed.
(0-3)
0 (Poor) Rooted upland plants are prevalent within the streambed/thalweg (>75%).
1 (Weak) Rooted upland plants are consistently dispersed throughout the streambed/thalweg (20-
75%).
2 (Moderate) There are a few rooted upland plants present within the streambed/thalweg (<20%).
3 (Strong) Rooted upland plants are absent from the streambed/thalweg.
Upland Species
Notes
Photo ID
Notes on rooted upland plants:
-------
Southeast SDAM Field Form
June 2025 Page 4 of 5
6. Particle size of stream substrate
(0-3)
Half scores (0.5,1.5,
2.5) are allowed.
Compare substrate on the channel bed to the banks and adjacent floodplain.
0 (Absent) The channel is poorly developed, very little to no coarse sediment is present. There
is no difference between particle size in the stream substrate and adjacent land.
1 (Weak) The channel is poorly developed through the soil profile. Some coarse sediment is
present in the streambed but is discontinuous. Particle size differs little between the stream
substrate and adjacent land.
2 (Moderate) There is a well-developed channel, but it is not deeply incised through the soil
profile. Some coarse sediment is present in the streambed in a continuous layer. Particle size
differs somewhat between the stream substrate and adjacent land.
3 (Strong) The channel is well-developed through the soil profile with relatively coarse
streambed sediments compared to the riparian zone soils: coarse sand, gravel, or cobbles in
the piedmont; cobbles or boulders in the mountains, and medium or coarse sand in the
coastal plain. Particle size differs greatly between the stream substrate and adjacent land.
Notes about particle size of stream substrate:
7. Prevalence of fibrous roots in the streambed
Evaluate the extent of fibrous roots in the streambed.
(0-3)
Half scores (0.5,1.5,
2.5) are allowed.
0 (Absent) A strong network of fibrous roots is persistent in the stream thalweg and
surrounding area.
1 (Weak) A discontinuous network of fibrous roots is present in the stream thalweg and
surrounding area.
2 (Moderate) Very few fibrous roots are present anywhere in the streambed.
3 (Strong) No fibrous roots are present.
Notes about fibrous roots:
8. Drainage area (in square miles, if < 1 round to the nearest 0.001)
Notes about Drainage, including method/tool(s) used to calculate:
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Southeast SDAM Field Form
June 2025 Page 5 of 5
9. Elevation (m)
10. Average monthly precipitation for May, June, July (SE only) (mm)
Photo log
Indicate if any other photographs taken during the assessment:
Photo ID
Description
Additional notes about the assessment including observations of fish (other than mosquitofish,
Gambusia sp.):
Model classification:
~ Ephemeral
~ At least intermittent
~ Intermittent
~ Less than perennial
~ Perennial
~ Needs more information
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