User Manual for a Beta Streamflow
Duration Assessment Method for the
Great Plains of the United States
oEPA
United States
Environmental Protection
Agency
US Army Corps
of Engineers®
\ EPDC
• ^ ENGINEER RESEARCH & DEVELOPMENT CENTER
Version 1.0
September 2022
EPA-840-B-22009
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User Manual for a Beta Streamflow
Duration Assessment Method for the Great
Plains of the United States
Prepared by Amy James1, Tracie-Lynn Nadeau2,3, Ken M. Fritz4, Brian Topping2, Rachel Fertik
Edgerton2, Julia Kelso5, and Raphael Mazor6.
1 Ecosystem Planning and Restoration. Raleigh, NC
2 U.S. Environmental Protection Agency—Office of Wetlands, Oceans, and Watersheds.
Washington, D.C.
3 U.S. Environmental Protection Agency—Region 10. Portland, OR
4 U.S. Environmental Protection Agency—Office of Research and Development. Cincinnati, OH
5 Oak Ridge Institute of Science and Education (ORISE) Fellow at U.S. Environmental Protection
Agency—Office of Wetlands, Oceans, and Watersheds. Washington, D.C. (former)
6Southern California Coastal Water Research Project. Costa Mesa, CA
The following members of the National Steering Committee, and the Regional Steering
Committee for the Great Plains, provided input and technical review:
Version 1.0
September 2022
National
Tunis McElwain
U.S. Army Corps of Engineers
Regulatory Branch
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
Regulatory Branch
Washington, DC
Rose Kwok
U.S. Environmental Protection Agency
Office of Wetlands, Oceans and Watersheds
Washington, DC
Regional
Micah Bennett, Kerryann Weaver,
and Ed Hammer
U.S. Environmental Protection Agency
Region 5
Loribeth Tanner and Chelsey Sherwood
U.S. Environmental Protection Agency
Region 6
Dallas, TX
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Gabriel DuPree and Shawn Henderson
U.S. Environmental Protection Agency
Region 7
Lenexa, KS
Kristen Brown
U.S. Army Corps of Engineers
Regulatory Branch
Rock Island District
Faye Healy and April Marcangeli
U.S. Army Corps of Engineers
Regulatory Branch
St. Paul District
Rob Hoffman
U.S. Army Corps of Engineers
Regulatory Branch
Tulsa District
Billy Bunch and Rachel Harrington
U.S. Environmental Protection Agency
Region 8
Denver, CO
Wayne Fitzpatrick and Elizabeth Shelton
U.S. Army Corps of Engineers
Regulatory Branch
Galveston District
Jeremy Grauf
U.S. Army Corps of Engineers
Regulatory Branch
Omaha District
Andrew Blackburn
U.S. Army Corps of Engineers
Regulatory Branch
Chicago District
Suggested citation:
James, A., Nadeau, T.-L., Fritz, K.M., Topping, B., Fertik Edgerton, R., Kelso, J., and Mazor, R.
2022. User Manual for a Beta Streamflow Duration Assessment Method for the Great Plains of
the United States. Version 1.0. Document No. EPA-840-B-22009.
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, and
Anne Holt for assistance with data management, and Abe Margo, Alex Martinez, Addison Ochs,
Morgan Proko, Alec Lambert, Zak Erickson, Alex Berryman, Jack Poole, Joe Kiel, Joe Klein,
Jackson Bates, Buck Meyer, Margaret O'Brien, Elliot Broder, Jason Glover, and James Treacy for
assistance with data collection.
Numerous researchers and land managers with local expertise assisted with the selection of
study reaches to calibrate the method: Tim Bonner, Jeffrey Brenkenridge, Taylor Dorn, Tim
Fallon, John Genet, Linda Hansen, Garret Hecker, Stephanie Kampf, Kort Kirkeby, Ji Yeow Law,
John Lyons, Kyle McLean, Miranda Meehan, Steve Robinson, Mateo Scoggins, Patrick Trier,
Linda Vance, Ross Vander Vorste, and Jason Zhang.
This work was funded through EPA contracts EP-C-17-001 and 68HERC21D0008 to Ecosystem
Planning and Restoration and EPA contract EP-C-16-006 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. 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.
i
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Table of Contents
Section 1: Introduction and Background 1
The beta method for the Great Plains 4
Intended use and limitations 5
Development of the beta SDAM GP 6
How the beta SDAM GP differs from other regional SDAMs 7
Section 2: Overview of the Beta SDAM GP and the Assessment Process 10
Considerations for assessing streamflow duration and interpreting indicators 10
Clean Water Act Jurisdiction 10
Scales of assessment 10
Spatial variability 10
Temporal variability 11
Ditches and modified natural streams 11
Other disturbances 12
Multi-threaded systems 12
Section 3: Data Collection 13
Order of operations in completing the beta SDAM GP assessment 13
Conduct desktop reconnaissance 14
Optional: Perform preliminary assessment of sinuosity 15
Prepare sampling gear 15
Timing of sampling 16
Assessment reach size, selection, and placement 17
Walking the assessment reach 18
How many assessment reaches are needed? 19
Photo-documentation 19
Conducting assessments and completing the field form 20
General reach information 20
Assessment reach sketch 24
How to measure indicators of streamflow duration 24
1. EPT family richness 25
2. Percent shading 28
ii
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3. Number of hydrophytic plant species 29
4. Absence of rooted upland plants in streambed 34
5. Bankfull channel width 36
6. Sinuosity 36
7. Floodplain and channel dimensions 38
8. Particle size or stream substrate sorting 39
9. Northern or Southern Great Plains 41
Additional notes and photographs 42
Section 4: Data Interpretation and using the web application 43
Outcomes of beta SDAM GP classification 43
Applications of the Beta SDAM GP outside the intended area 43
What to do if more information about streamflow duration is desired? 44
Conduct additional assessments at the same reach 44
Conduct evaluations at nearby reaches 44
Review historical aerial imagery 44
Conduct reach revisits during regionally appropriate wet and dry seasons 46
Collect additional hydrologic data 46
References 47
Appendix A. Glossary of terms 51
Appendix B. Guide to Commonly Found EPT 55
General insect anatomy 55
Ephemeroptera (mayflies) larvae 56
Plecoptera (stonefly) larvae 62
Trichoptera (caddisfly) larvae and pupae 67
Trichopteran Look-Alikes to Watch Out For 76
Appendix C. Field Forms 78
iii
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Table of Figures
Figure 1. Streams of different flow classes 2
Figure 2. Map of flow duration study regions 3
Figure 3. Locations of ephemeral, intermittent, and perennial stream reaches used to calibrate
the beta SDAM GP 6
Figure 4. Status of the development of regional SDAMs at the time of this manual's publication..
9
Figure 5. Measuring bankfull width 21
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. Examples of evidence of EPT in dry channels 28
Figure 9. Representation of the mirrored surface of a convex spherical densiometer 29
Figure 10. National Wetland Plant List (NWPL) regions that overlap with the beta SDAM GP
region 30
Figure 11. Local conditions that support growth of hydrophytes 31
Figure 12. Long-lived species only represented by young specimens 31
Figure 13. Water-stressed riparian trees near Oro Grande on the Mojave River 32
Figure 14. Examples of plants determined to be hydrophytes based on context 34
Figure 15. Example of an ephemeral stream with rooted upland vegetation growing in the
channel 35
Figure 16. Scoring guidance for the Sinuosity indicator 37
Figure 17. Sinuosity measurements in a multi-threaded system 38
Figure 18. Measurement of entrenchment is based on the ratio of the flood-prone width to the
bankfull width 39
Figure 19. Different levels of particle size/stream substrate sorting 41
Figure 20. Examples of using aerial imagery to support streamflow duration classification 45
Table of Tables
Table 1. General differences and similarities among regional SDAMs developed by the EPA 8
Table 2. Online resources for generating local flora lists 15
Table 3. Scoring guidance for the Absence of Rooted Upland Plants indicator 35
Table 4. Scoring guidance for the Sinuosity indicator 37
Table 5. Scoring guidance for Floodplain and Channel Dimensions indicator 39
Table 6. Scoring guidance for Particle Size/Streambed Sorting indicator 40
iv
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Section li 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
their 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, McKay et al. 2014), they
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,
there is a need for rapid, field-based methods to determine flow duration class at the reach
scale (defined in Section 2) in the absence of long-term hydrologic data (Fritz et al. 2020).
This method is 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
SDAM for the Pacific Northwest and the beta SDAMs for the Arid West and Western Mountains.
1
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Section 1; Introduction and Background
- -x)
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Perennial stream reach
Tributary to Trout Brook, Chequamegon National Forest, Wl
Apr 2021
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Jan 2020 Hiar 2020 May 2020 Jul 2020 Sep 2020 tJov 2020
Intermittent stream reach
Flume Canyon, Lincoln National Forest, NM
Jan 2321
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Jap 2D20 Hit 2020 May 2D20 Jul 2020 Sep 2B20 Nov 2020 ]an 2021 Hai 2021 May 2021
Ephemeral stream reach
Tributary to North Fork Solomon River (at Kirwin Reservoir), Kirwin National Wildlife Refuge, KS
Figure 1. Streams of different flow classes. Photos of stream reaches in each streamflow duration class are shown
at left, with corresponding visualizations of daily flowing vs dry periods of these reaches on the right, including flow
classification. 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. in review). 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 was
downloaded and indicator data was 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 flow 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 beta Streamflow Duration Assessment Method (SDAM) that is
intended to distinguish flow duration classes of stream reaches in the Northern and Southern
Great Plains regions of the United States (hereafter referred to as the Great Plains, or GP) 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. The Great Plains were delineated based on the importance of snowmelt to river
discharge, as their boundary approximately follows the line south of which mean annual
snowfall is less than 0.7 meters (m) (2 feet (ft); Wohl et al. 2016) (Figure 2).
- "'rf
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Alaska
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Arid
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Figure 2. Map of flow duration study regions. The beta SDAM GP applies to the Northern and Southern Great Plains
as shown.
3
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Section li Introduction and Background
The beta SDAM GP is based on biological, geomorphological, and regional location indicators.
Biological indicators, known to respond to gradients of streamflow duration (Fritz et al. 2020),
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 indicators can also be rapidly measured
and provide information about the hydrologic drivers of streamflow duration. 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. Across large regions, the interaction and interpretation of biological and geomorphic
indicators may vary; therefore, the inclusion of a regional location indicator can account for
such variation and allow a single method to accurately classify flow duration of reaches over a
large area.
The beta method for the Great Plains
This manual describes a protocol that uses a small number of indicators to predict the
streamflow duration class of stream reaches in the GP. All indicators except one are measured
during a single field visit. The method is being made available as a beta version for a one-year
preliminary implementation period to allow the user community to provide feedback before a
final SDAM GP is produced. For more information on the development of the beta SDAM GP,
please see the Great Plains Data Supplement
(https://www.epa.gov/svstem/files/documents/2022~09/devel~eval~of~the~beta~sdam~for~the~
gp.pdf). For more information on the development of SDAMs for other U.S. regions, please
refer to EPA's SDAM website: https://www.epa.gov/streamflow~duration~assessment.
The beta SDAM GP assigns reaches to one of four possible classifications: ephemeral,
intermittent, perennial, and at least intermittent. The latter classification occurs when an
intermittent or perennial classification cannot be made with high confidence, but an ephemeral
classification can be ruled out. The protocol uses a machine learning model known as 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. We have developed an open-access, user-friendly web application for
entering indicator data and running the developed random forest model to obtain the
classification for individual assessment reaches.
4
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Section li Introduction and Background
The beta SDAM GP is based on nine indicators listed below:
Biological indicators
• The number (richness) of Ephemeroptera (mayflies), Plecoptera (stoneflies), and
Trichoptera (caddisflies) [EPT] families.
• Percent shading.
• Number of hydrophytic plant species.
• Absence of rooted upland plants in the streambed.
Geomorphological indicators
• Bankfull channel width.
• Sinuosity.
• Floodplain and channel dimensions.
• Particle size or stream substrate sorting.
Regional location indicator
• Northern or Southern Great Plains.
Intended use and limitations
The beta SDAM GP is intended to support field classification of streamflow duration at the
reach scale in streams with defined channels (having a bed and banks) in the GP regions. Use of
the beta SDAM GP may inform a range of activities where information on streamflow duration
is useful, including jurisdictional determinations under the Clean Water Act; however, the beta
SDAM GP is not in itself a jurisdictional determination. The method is not 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 beta SDAM GP when classifying
streamflow duration (Fritz et al. 2020).
Although the beta SDAM GP is 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.
Poor water quality in streams may affect biological indicators—notably, the presence of EPT
taxa. For example, streams in watersheds dominated by agricultural or urban uses may have
lower species richness or other evidence of impact to populations of EPT taxa (e.g., Quist and
Schultz 2014, Whiles et al. 2014, Wang et al. 2007). Several studies have documented strong
5
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Section 1; Introduction and Background
correlations of EPT taxa measures with high concentrations of nutrients (e.g., Wang et al. 2007,
Heatherly et al, 2007) and sediment deposition has been found to be inversely related to EPA
taxa richness or density (Quist and Schultz 201, Zweig and Rabeni 2001). Consequently, the
beta SDAM GP may fail to identify perennial reaches as perennial in situations where water
quality has been severely degraded by nutrients, sediment, or other stressors such that EPT
taxa are reduced or eliminated.
Development of the beta SDAM GP
PERENNIAL
INTERMITTENT
EPHEMERAL
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Figure 3. Locations of ephemeral, intermittent, and perennial stream reaches used to calibrate the beta SDAM GP.
This method resulted from a multi-year study conducted in 293 locations across the Great
Plains following the process described in Fritz et al. (2020). Of these, data from 251 sites (or
reaches) where flow class could be determined from direct hydrologic data were used to
develop the beta SDAM GP (Figure 3). Of these 251 reaches, 71 were ephemeral, 100 were
intermittent, and 80 were perennial. Streamflow duration class was directly determined from
continuous (hourly interval) data loggers deployed at the study reaches (152) or from active
USGS stream gages (29). Multiple sources of hydrologic data (e.g., inactive USGS stream gage
data, published studies, consultation with local experts) were used to classify the remaining
reaches (70), that did not have continuous data loggers deployed for this study. The Northern
and Southern Great Plains were assessed simultaneously and analyzed both as combined and
separate datasets.
Development of the beta SDAM GP followed the process steps below (Fritz et al. 2020):
• Conducted a literature review (James et al. 2022) with two goals:
o identified existing SDAMs, focusing on those originating in the Great Plains or
developed using a similar approach (see Nadeau 2015; NMED 2011).
6
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Section li Introduction and Background
o Identified (27) potential biological, hydrological, and geomorphological field
indicators of streamflow duration for evaluation in the Great Plains.
• Identified candidate study reaches with known streamflow duration class, representing
diverse environmental settings throughout the region.
• Collected field indicator data at study reaches.
• Evaluated 95 candidate metrics from the field data and GIS metrics for their ability to
discriminate among streamflow duration classes. GIS metrics included climatic measures
that characterize hydrologic drivers of streamflow duration (e.g., long-term precipitation
and temperature) and are straightforward to calculate.
• Calibrated a classification model using a machine learning algorithm (i.e., random
forest).
• Refined and simplified the final beta method for rapid and consistent application.
The final beta method correctly classified 68% of study reaches among three classes (perennial
vs. intermittent vs. ephemeral), while 87% of study reaches were classified correctly between
two classes (ephemeral vs. at least intermittent). Generally, misclassifications among
intermittent and perennial reaches were more common than misclassifications among
ephemeral and intermittent reaches. The ability of the beta SDAM GP 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, 2013, Nadeau et al. 2015).
How the beta SDAM GP differs from other regional SDAMs
The beta SDAM GP is the fourth method resulting from an EPA-led effort to develop SDAMs for
nationwide coverage of the USA (Figure 4). The first was developed for the Pacific Northwest
(PNW; Nadeau et al. 2015) and finalized in 2015 (Nadeau 2015). The second and third methods,
for the Arid West (AW; Mazor et al. 2021a) and the Western Mountains (WM; Mazor et al.
2021b), were made available as beta versions for a preliminary implementation period while
the EPA and its partners continue an expanded data collection effort to inform the refinement
of the final SDAMs for these regions (anticipated in 2023). The four tools differ in several
respects, due in part to resources and time availability to gather data, but primarily to optimize
performance of the data-driven tool in each region. Differences between the four SDAMs are
summarized in Table 1.
7
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Section 1: Introduction and Background
Table 1. General differences and similarities among regional SDAMs developed by the EPA.
Great Plains (beta)
(Sept 2022)
Western Mountains
(beta)
(Dec 2021)
Arid West (beta)
(March 2021)
Pacific Northwest
(Nov 2015)
Collection of
data used to
develop the
method
Blend of
instrumented and
single-visit reaches,
similar to the
Western Mountains
Blend of single-visit
reaches (where
streamflow duration
was already well
characterized) and
instrumented reaches
(where continuous
hydrologic data was
generated to classify
streamflow duration).
Single-visit reaches
alone. Minimal
collection of new
hydrologic data.
Extensive
collection of
hydrologic data.
Types of
indicators
Biological,
geomorphological,
and regional
location
Biological,
geomorphological,
and climatic
Biological
Biological and
geomorphological
Single
indicators?
None
Fish
Fish
Algal cover >10%
Fish
Aquatic life stages
of snakes or
amphibians
Type of tool
Random forest
model
Random forest model
Classification table
(simplified from
random forest
model)
Decision tree
(simplified from
random forest
model)
Stratification
None (strata used
as indicator)
Snow-influence
None
None
Classifications
Perennial,
intermittent,
ephemeral, and at
least intermittent.
Perennial,
intermittent,
ephemeral, and at
least intermittent.
Perennial,
intermittent,
ephemeral, at least
intermittent, and
need more
information.
Perennial,
intermittent,
ephemeral, and at
least intermittent.
Aquatic
invertebrate
identification
Required at Family
level for EPT only
Required at Family
level
Required at Order
level
Required at Family
level
Hydrophytic
plant
identification
Required
None
Required
Required
Field time
required
Up to 2 hours
Up to 2 hours
Up to 2 hours
Up to 2 hours
8
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Section 1; Introduction and Background
Regional SDAMS
Completed beta version
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Figure 4. Status of the development of regional SDAMs at the time of this manual's publication.
9
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Section 2: Overview of the beta SDAM GP and the assessment process
Section 2: Overview of the Beta SDAM GP and the Assessment Process
Considerations for assessing streamflow duration and interpreting indicators
Clean Water Act Jurisdiction
Regulatory agencies evaluate aquatic resources based on current regulations, guidance, and
policy. The beta SDAM GP does not incorporate that broad scope of analysis. Rather, the
method provides information that may support timely jurisdictional decisions because it helps
determine streamflow duration class.
Scales of assessment
The beta SDAM GP protocol applies to an assessment reach, the length of which scales with the
mean bankfull channel width. Regardless of channel width, reaches are required to be a
minimum of 40 meters and no longer than 200 meters. The minimum reach-length of 40 m is
necessary to ensure that a sufficient area has been assessed to observe indicators.
Quantification and observations of indicators are restricted to the bankfull channel and within
one-half bankfull channel width from the top of each bank. However, ancillary information from
outside the assessment reach (such as surrounding land use) is also recorded.
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 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 include:
• Longitudinal changes in stream indicators are related to increasing duration and volume
of flow. As streams gain or lose streamflow, the expression of indicators changes.
• Longitudinal changes are due to channel gradient and valley width, which affect physical
processes, and they may directly or indirectly affect the expression of indicators. Sharp
transitions in valley gradient or width (e.g., going from a confined canyon to an alluvial
fan) can be associated with changes in streamflow duration.
• The size of the stream; streams develop different channel dimensions due to differences
in flow magnitude, sediment loads, landscape position, land-use history, and other
factors.
• Other natural sources of variation, such as bedrock material (limestones, sandstones,
shales, conglomerates, and lignite) or water source (runoff, springs, summer rains, and
10
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Section 2: Overview of the beta SDAM GP and the assessment process
groundwater). Drought or unusually high precipitation events should also be noted by
the user.
• Transitions in land use with different water use (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) that affect the
expression of indicators.
• Stream management and manipulation, such as diversions, water importation, dam
operations, and habitat modification (e.g., streambed armoring), can also influence
biological, hydrological, and physical characteristics of streams.
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. This
method was developed to be robust to both types of temporal variability and is 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.
Some indicators are highly responsive to temporal variability. For example, the GP is known to
experience high intensity, short-lived flood events. After these scouring events, aquatic
invertebrates (including EPT) may be displaced from a stream reach. In contrast, rooted
hydrophytic plants, if present, will likely remain. Similarly, EPT 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 riparian corridor. For example, willows with well-established root
systems are likely to survive in an intermittent reach experiencing severe drought, even when
flow in a single year is insufficient to support EPT. Through the inclusion of multiple indicators
having different lifespans and life-history traits, beta SDAM GP classifications reflect both
recent and long-term patterns in flow duration.
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 (Carlson et al. 2019), and
the beta SDAM GP may determine if these flow regimes support indicators consistent with
different streamflow duration classes. Thus, the beta SDAM GP may be applied to these
systems when streamflow duration information is needed.
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Section 2: Overview of the beta SDAM GP and the assessment process
Geomorphological indicators (specifically, bankfull channel width and sinuosity) 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 if the channel
geomorphology reflects natural processes or if it reflects the effects of management activities.
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, the beta SDAM GP
classified disturbed reaches with similar accuracy as undisturbed reaches.
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 invertebrates in channels that have undergone
recent grading activity). Groundwater pumping, impoundments, and diversions can affect both
vegetation and geomorphological indicators (e.g., Friedman et al. 1997). 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 the section on data
collection. Assessors should describe disturbances in the "Notes on disturbances or difficult
assessment reach conditions" section of the field form.
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 channel 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 assessment form.
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Section 3: Data Collection
Section 3: Data Collection
Order of operations in completing the beta SDAM GP assessment
The following general workflow is recommended for efficiency in the field:
In the office:
1. Conduct desktop reconnaissance.
a. Confirm location in Northern or Southern GP with reach latitude/longitude.
b. Optional: Perform preliminary assessment of sinuosity.
c. Determine if placement of assessment reach will need to be adjusted to
avoid changes in stream order/tributaries (and account for major
disturbances, if project constraints allow).
d. Download and have available appropriate USACE wetland plant lists.
2. Prepare sampling gear.
On-site:
3. Walk the assessment reach.
a. Record the bankfull channel width at three locations and calculate the
average to determine the assessment reach length (40 x bankfull width;
minimum: 40 m, maximum: 200 m).
b. Identify the reach boundaries.
c. Record the coordinates of the downstream boundary of the assessment
reach from the center of the channel, photograph the assessment reach, and
collect densiometer readings.
d. Continue taking photographs and collecting densiometer readings at the
middle and top of the assessment reach, noting where best to assess
floodplain and channel dimensions, searching for EPT taxa, and identifying
hyd rophytic vegetation.
e. Start sketching the assessment reach on the field form
4. Record general reach site information on the field form
(https://www.epa.gov/svstem/files/documents/2022~09/beta~sdam~for~the~gp~
field~forms.pdf).
5. Evaluate the remaining indicators:
a. Collect and identify EPT families.
b. Assess channel and floodplain dimension.
c. Assess degree of substrate sorting and/or difference of channel substrate
material from surrounding uplands.
d. Record number of hydrophytic vegetation taxa.
e. Assess upland plants growing in the channel and their abundance.
f. Assess channel sinuosity.
g. Complete sketch of the assessment reach on the field form.
6. Review the field form for completeness.
7. Enter data into the web application to get a classification
(https://ecosvstemplanningrestoration.shinyapps.io/beta sdam gp/).
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Section 3: Data Collection
If more than one user is conducting the field assessment, it may be efficient for one person to
collect, identify and count EPT families while the other is completing the remaining tasks in
steps 3-5.
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 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.
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 USEPA 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 discharge.
• USGS StreamStats: https://streamstats.uses.gov/ss/
• USEPA WATERS GeoViewer: https://www.epa.eov/waterdata/waters-eeoviewer
Assessors should consider consulting local experts and agencies to gain additional insights
about reach conditions and see if additional data are available. For example, state agencies may
have records on water quality sampling, indicating times when the reach was sampled, and
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Section 3: Data Collection
when it was dry. Local experts may have information about changes in the reach's streamflow
duration.
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 may be helpful for determining a plant's
hydrophytic status. Nearby public land managers (such as U.S. Forest Service or the National
Park Service) should be consulted to see if they have lists of common riparian plants in the
vicinity of the assessment reach. Several online databases can generate regionally appropriate
flora lists and/or assist with identification (Table 3). Note that there are three National Wetland
Plant List (NWPL) regions that overlap with the region covered by the beta SDAM GP; consult
the appropriate list for your location (see further discussion under Number of Hydrophytic Plant
Species. Indicator #3)
Table 2. Examples of online resources for generating local flora lists.
Resource Geographic coverage
United States and territories
4} : y United States and territories
Illinois, Michigan, Minnesota, and Wisconsin
Continental U.S. (native species only)
¦ v.- v Kansas
Includes Montana, Wyoming, Colorado, and New
Mexico
Minnesota
Desktop reconnaissance also helps determine if permits are required to collect aquatic
invertebrates. Threatened and endangered species may be expected in the area, and stream
assessment activities may require additional permits from appropriate federal and state
agencies.
Optional: Perform preliminary assessment of sinuosity
A preliminary score for sinuosity may be obtained during desktop reconnassiance. Desktop
measurement of this indicator using aerial imagery can be quite accurate in some settings, but
unclear and difficult in others, and may not always reflect present-day conditions; therefore,
field confirmation is always required.
Prepare sampling gear
The following gear is suggested for completion of the beta SDAM GP. Ensure that all equipment
is functional before each assessment visit. Also ensure that all equipment has been cleaned off-
site between assessment visits to prevent the spread of invasive species.
• This manual, and copies of paper field forms.
• Clipboard/pencils/permanent markers.
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Section 3: Data Collection
• Field notebook.
• Maps and aerial photographs (1:250 scale if possible).
• Global Positioning System (GPS) - used 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, reach length, flood-prone width,
and valley length.
• Pocket rod or leveling rod/meter stick - for determining max bankfull depth for flood-
prone width measurement.
• Kick-net or small net and tray - used to sample aquatic macroinvertebrates.
• Hand lens - to assist with macroinvertebrate and plant identification.
• Digital camera (or smartphone with camera), plus charger. Ideally, use a digital 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.
• Sand-gauge card.
• Convex spherical densiometer, taped to restrict assessment to the forward-facing 17
assessment points (see Percent Shading, Indicator #2 for information on how to prepare
the densiometer).
• Aquatic macroinvertebrate field guides that focus on EPT (e.g., Guide to Aquatic
Invertebrates of the Upper Midwest, Bouchard et al. 2004).
• Vials filled with 70% ethanol and sealable plastic bags for collection of biological
specimens, with sample labels printed on waterproof paper.
• Hydrophytic plant identification guides (e.g., Wetland and Aquatic Plants of the
Northern Great Plains, Chadde 2019).
• The U.S. Army Corps of Engineers List of wetland plants for sites to be visited -
http://wetland-plants.usace.army.mil/.
• First-aid kit, sunscreen, insect repellant, and appropriate clothing.
Timing of sampling
Ideally, beta SDAM GP application should occur during the growing season when many aquatic
macroinvertebrates are most active, and most macroinvertebrates and hydrophytes are 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 GP, where the presence of snow and channel ice during the
colder months may also be a factor. However, most of the indicators included in the method
persist well beyond a single growing season (e.g., hydrophytic vegetation) or are not dependent
on it (e.g., geomorphological indicators), reducing the sensitivity of the method 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
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Section 3: Data Collection
one week after large storm events that impact vegetation and sediment in the active stream
channel before collecting data to allow aquatic invertebrates and other biological indicators to
recover (Grimm and Fisher 1989; Hax and Golladay 1998; Fritz and Dodds 2004). In general,
aquatic invertebrate 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. Field evaluations should not be completed within one week of
significant rainfall that results in surface runoff. 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 beta SDAM GP data.
The Antecedent Precipitation Tool (APT; U.S. Army Corps of Engineers 2020a) can also be
helpful for evaluating recent precipitation conditions at a site relative to the 30 year average -
https://www.epa.eov/wotus/antecedent-precipitation-tool-apt.
Assessment reach size, selection, and placement
An assessment reach should have a length equal to 40 bankfull channel-widths, with a
minimum of 40 m (to ensure that sufficient area is assessed to observe indicators) and a
maximum length of 200 m. Bankfull channel width is averaged from measurements at three
locations (e.g., at the downstream end, at 15 m, and at 30 m upstream from the downstream
end). Width measurements are made at bankfull elevation, perpendicular to the thalweg (i.e.,
the point within the channel with the greatest portion of flow). In single-thread systems, the
channel-width is the same as the bankfull width. In multi-thread systems, the width is
measured for the entire active channel, based on the outer limits of the OHWM. Reach length is
measured along the thalweg. If access constraints require a shorter assessment reach than
needed, the actual assessed reach-length should be noted on the field form, along with an
explanation for why a shortened reach was necessary.
Assessors should look for indicators of bankfull elevation when measuring bankfull channel
width. These indicators include:
• The presence of a floodplain at the elevation of initial flooding.
• The elevation associated with the highest depositional features.
• An obvious slope break that differentiates the channel from a relatively flat floodplain
terrace higher than the channel.
• A transition from exposed sediments to terrestrial vegetation.
• Moss growth on rocks along the banks.
• Evidence of recent flooding.
• Presence of drift material caught on overhanging vegetation.
• Transition from flood- and scour-tolerant vegetation to that which is relatively
intolerant.
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Section 3: Data Collection
Certain indicators 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), 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
should be avoided. In the field, it may often be possible to determine the bankfull stage on only
one bank of the stream. However, 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.
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.
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 up-
or downstream.
Note that bankfull channel width is also an indicator of streamflow duration, as described
below under Bankfull Channel Width, Indicator #5 and is used to assess the floodplain and
channel dimensions indicator (i.e., entrenchment ratio; Indicator #6). Associated
measurements needed for entrenchment ratio may be collected when bankfull channel width is
measured.
Walking the assessment reach
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 investigation may 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 where information is needed. 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
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Section 3: Data Collection
to observe the surrounding landscape's characteristics, such as land use and sources of flow
(e.g., stormwater pipes, springs, seeps, and upstream tributaries).
Once the walk is complete, the assessor can document the areas along the stream channel
where various sources (e.g., stormflow, tributaries, or groundwater) or sinks (alluvial fans,
abrupt changes in bed slope, etc.) of water 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. Regardless of whether the assessment reach is
shifted, shortened, or multiple reaches are assessed, an assessment reach should not be less
than 40 m in length to ensure that indicators are measured appropriately. Assessments based
on reaches shorter than 40 m may not detect indicators that would be recorded by assessments
with the recommended size and may thus provide inaccurate classifications.
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 up- or down-stream 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 the hydrology, multiple assessment reaches may be required
(e.g., one above and one below the feature).
Photo-documentation
Photographs can provide strong evidence to support conclusions resulting from a beta SDAM
GP application, 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 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:
• Hydrophytic plant identifications, showing diagnostic features and extent within the
reach.
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Section 3: Data Collection
• EPT and evidence of EPT (e.g., caddisfly casings), if practical.
• Extent of upland rooted plants in channel.
• Sinuosity or lack thereof.
• Particle size and/or stream substrate sorting.
• Floodplain and channel dimensions.
• Disturbed or unusual conditions that may affect the measurement or interpretation of
indicators.
Conducting assessments and completing the field form
General reach information
After walking the reach and determining the appropriate boundaries for the assessment area,
enter 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 of the downstream end of the reach from the center of the channel.
These can be used to determine if the reach is in the Northern or Southern GP.
Weather conditions
Note current weather conditions. If known, note precipitation within the previous week on the
datasheet, and consider delaying sampling, if possible. If rescheduling is not possible, note
whether the streambed is recently scoured, and if turbidity is likely to affect the measurement
of indicators.
Surrounding land use
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 and reach length
Record the bankfull channel width values (to nearest 0.1 m) that were measured at three
locations (Figure 5). Widths should be measured perpendicular to the thalweg. In braided
systems, widths should span all channels within the OHWM. Taking measurements at 0, 15, and
30 m above the downstream end of the reach or approximately one-third of the expected reach
length is recommended. Calculate the average width.
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Section 3; Data Collection
Record the reach length (m), which should be 40 times the average bankfull channel width, but
no less than 40 rn and no more than 200 m, and measured along the thalweg (i.e., along the
deepest points within the channel) with a tape measure. In multi-thread systems, measure
reach-length along the thalweg of the deepest channel. If circumstances require a shorter reach
length, enter the assessed reach's actual length. Justification for an assessment reach length
shorter than 40 m should be provided in "Describe reach boundaries."
Figure 5. Measuring bankfull width. Image credit: James Treacy
Describe reach boundaries
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 check 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.
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,
21
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Section 3; Data Collection
culverts, discharges of effluent or runoff, and drought. Note circumstances that may limit the
growth of hydrophytes and/or 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.
Figure 6. Examples of difficult conditions that may interfere with the observation or interpretation of indicators.
Left: As the San Marcos River progresses through the city of San Marcos in Texas, its banks have been hardened
and the natural riparian vegetation has been removed (though there is still aquatic vegetation apparent in the
channel itself). The removal of in-stream and riparian zone habitat and addition of urban non-point source
discharges may also impact aquatic invertebrate communities, especially those more sensitive to water quality
disturbances (e.g., many EPTtaxa). Right: Keenan Creek in Wisconsin has been straightened and channelized,
affecting naturally occurring stream pattern (e.g., sinuosity), and profile (e.g., entrenchment). Image credits: James
Treacy.
Observed hydrology
Surface flow
Visually estimate or use the 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
is 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.
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Section 3: Data Collection
• 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.
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
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
OHWM. 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.
1 Ik
Y
i
" f7
•J
I
1
I
1
\
•
*
r
f
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 and subsurface flow, and isolated pools. Orange represents the dry
channel and blue represents surface water in the channels. White represents the floodplain outside the channel.
23
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Section 3: Data Collection
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.
Assessment reach sketch
On the data sheet, sketch the assessment reach, 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.
How to measure indicators of streamflow duration
Assessments are based on the measurement of nine indicators of streamflow duration:
Biological indicators
• EPT family richness
• Percent shading
• Number of hydrophytic plant species
• Absence of rooted upland plants in the streambed
Geomorphological indicators
• Bankfull channel width
• Sinuosity
• Floodplain and channel dimensions
• Particle size or stream substrate sorting
Regional location indicator
• Northern or Southern Great Plains
EPT family richness, percent shading, number of hydrophytic plant species, sinuosity, floodplain
and channel dimensions, and particle size/stream substrate sorting are positive indicators of
streamflow duration. That is, a greater abundance or strength of these indicators is generally
associated with longer duration flows (e.g., Dodds et al. 2004, Burk and Kennedy 2013, Billi et
al. 2018). For example, higher EPT taxa abundance or stronger sinuosity are both associated
with perennial reaches. The relationship between streamflow duration and bankfull channel
width is less straightforward. In general, wider channels and more sinuous channels are more
likely to be perennial and positioned lower in the watershed than narrower and less sinuous
non-perennial channels. Wetter portions of the Great Plains will also have more riparian
vegetation (Borchert 1950) and cohesive bank material (Hecker et al. 2019) that is conducive
for meandering channel pattern than drier portions which are expected to have less sinuous
channels. The regional location indicator considers large scale differences in climate and other
geographic factors across the Great Plains that affects flow duration (Hammond et al. 2021).
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Section 3: Data Collection
However, a wide range of streamflow duration occurs in a variety of climatic settings and in
both narrow and wide channels. The regional location indicators affect the way other indicators
are interpreted, and they were included in the method because they greatly improve the
overall accuracy of resulting classifications. Rooted upland plants are a negative indicator of
streamflow duration. Greater abundance or expression of rooted upland plants in the
assessment reach is associated with shorter flow duration classes. To be consistent with the
other indicators in terms of its relationship to evidence of perennial flow, the scoring for the
rooted upland plants indicator is reversed by characterizing its rarity or absence.
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. Within each indicator description, common ways that
disturbances can interfere with indicator measurement are described.
1. EPT family richness
Mayflies, stoneflies, and caddisflies are aquatic insects that require the presence of water (and
in many cases flowing water) for their growth and development for at least part of their life
cycle. Mayflies, stoneflies, and caddisflies (called "EPT" taxa, after their orders: Ephemeroptera,
Plecoptera, and Trichoptera) are widespread aquatic insects that are often found in perennial
and intermittent streams but are not typically found in ephemeral streams or are represented
by fewer taxa (e.g., King et al. 2015, Stagliano 2005). For this indicator, the number of EPT
families (not individuals), up to 5 or more, should be enumerated. Living material (e.g., live
larvae or pupae), and non-living material (e.g., caddisfly cases, shed exuviae) are equally
considered for this indicator. Images highlighting diagnostic features are in the call-out box, and
photos of EPT families commonly found in the GP are provided in Appendix B.
A series of photos (if feasible) should be taken of any taxa in question to allow further
identification to be made off-site, if necessary. If the identification is uncertain, then describe
any distinguishing features that were observed in the notes. Alternatively, specimens may be
preserved in 70% ethanol and identities confirmed in a lab setting with an appropriate
taxonomic key or identification guide (e.g., Merritt et al. 2019) or by consultation with an
entomologist.
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Section 3; Data Collection
Identification of mayflies, stone/lies, and caddisflies
Mayflies (Ephemeroptera)
cerci
Image by Dieter Tracey
Stoneflies (Plecoptera)
Stonefly nymphs have gills along the thorax, and
two claws at the end of each leg. They have two
cerci, whereas mayflies usually have three. Like
mayflies, stoneflies lack a pupal stage and
instead metamorphose directly into winged
adults, and their exuviae can be found alongside
dry or flowing streams.
Mayfly nymphs may be readily identified by
the presence of plate- or feather-like gills
along sides or top of the abdomen. They
typically have three cerci ("tails"), although in
some species, they appear to have two. They
have only one claw at the end of each foot, in
contrast to stoneflies (which have two). They
lack a pupal phase, but their exuviae may be
abundant on streamside vegetation and
emergent boulders at certain times of the
year.
^ t
Image by I racey Saxby
Thoracic sclerites
Image by Tracey Saxby
Caddisflies (Trichoptera)
Caddisfly larvae typically have a C-shaped body ending in
two hooks. Thread-like gills may be found along the
underside of the abdomen, and three pairs of legs under the
thorax (setting them apart from some fly larvae, that may
otherwise look similar). The top of thorax may be partly or
fully hardened ("sclerotized"). Caddisfly larvae and pupae
are aquatic, and they are often found with cases made of
sand, pebbles, twigs, leaves, or small snail shells. Most
larvae are free roaming, but a few families build larval
retreats in fixed locations under cobbles and boulders. One
family (Rhyacophilidae) lacks a case or larval retreat,
although it builds pupal cases out of pebbles and fine-
grained sand. Caddis larval and pupal cases are often the
most easily observed sign of aquatic invertebrates in a dry
stream.
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Section 3: Data Collection
EPT are assessed within the defined reach. A kick-net or D-frame net and a hand lens are used
to, respectively, collect and identify specimens. Assessors begin sampling at the most
downstream point in the assessment reach and proceed to sample the upstream direction. The
net is placed perpendicular against the streambed while the substrate is disturbed upstream of
the net for a minimum of one minute. Jab the net under banks, overhanging terrestrial and
aquatic vegetation, leaf packs, and in log jams or other woody material. Samples should be
collected from at least six distinct locations representing the different habitats occurring in the
reach. Empty contents of the net into a white tray with fresh water for determining the number
of EPT families present. Many EPT can appear cryptic and/or the same until seen against a
contrasting color background, and some can be pea-sized or smaller.
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 specimen
identification time), 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 inorganic particles (pick up rocks and loose gravel).
Dry channels: Focus the search on areas serving as refuge such as any remaining pools or areas
of moist substrate for living macroinvertebrates, and under cobbles and other larger bed
materials for caddisfly casings (Figure 8). Exuviae of emergent mayflies or stoneflies may be
observed on dry cobbles or stream-side vegetation (Figure 8). In summary, sampling
methodology consistent with the Xerces Society's recommendations on using aquatic
macroinvertebrates as indicators of streamflow duration (Mazzacano and Black 2008), as
developed for the SDAM PNW (Nadeau 2015) is recommended.
If a reach contains both dry and wet areas, focus on searching the wet habitats, as these are the
most likely places to encounter EPT. However, do not ignore dry areas.
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Section 3; Data Collection
Figure 8. Examples of evidence of EPT 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.
2. Percent shading
Data used to develop the beta SDAM GP indicated that perennial and intermittent reaches
generally had higher levels of shading than ephemeral streams. This outcome suggests that
riparian corridors along streams with longer flow durations have a greater ability to support
woody vegetation (e.g., gallery forests) in the Great Plains. Using a convex spherical
densiometer, stream shading is estimated in terms of percent cover of objects (vegetation,
buildings, etc.) that block sunlight. The method described uses the Strickler (1959) modification
of a densiometer to correct for over-estimation of stream shading that occurs with unmodified
readings. Taping off (Figure 9) the lower left and right portions of the mirror emphasizes
overhead structures over foreground structures (the main source of bias in stream shading
measurements).
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. Consider the "zone of influence" of vegetative cover expected during the growing
season (Nadeau et al. 2018).
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
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Section 3; Data Collection
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 (integer values ranging 0 to 17) from the center of the channel at
upstream, middle, and downstream locations in the reach: a) facing upstream, b) facing
downstream, c) facing the left bank, d) facing the right bank. The observer and the densiometer
should revolve together over the center point of the transect to keep the "V" oriented as
above.
© ©
Figure 9. 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 (figure from Ode
et al. 2016).
3. Number of hydrophytic plant species
For the beta SDAM GP, hydrophytes are defined as those with a Facultative Wetland (FACW) or
Obligate (OBL) wetland indicator status in the National Wetland Plant List2 (NWPL, USAGE
2020b). The GP region encompasses all or parts of three different NWPL regions: the Great
Plains, Midwest (MW), and Northcentral Northeast (NCNE) (Figure 10). Indicator status for
certain species may differ between regions; therefore, it is important to consult the correct list
when determining indicator status. For example, stinging nettle (Urtica dioica), a common,
widespread herb often found growing in riparian zones, is FACW in the MW but FAC in the GP
and NCNE.
2 https://cwbi-app.sec.usace.army.mil/nwpl_static/v34/home/home.html
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Section 3; Data Collection
Figure 10. National Wetland Plant List (NWPL) regions that overlap with the beta SDAM GP region.
Hydrophytic plant species that exhibit an odd or unusual distribution pattern in the assessment
reach should not be considered among the number of hydrophytic plant species present.
Examples of odd or unusual distribution patterns are described below; all Figures are from the
Arid West and are strictly for illustrative purposes.
• Isolated individuals, or small patches covering only a small portion of the total
assessment area (e.g., < 2%) and only found in one location (as opposed to plants
sparsely distributed throughout the reach). Local conditions may support the growth of
hydrophytes in otherwise unsuitable conditions. In more arid regions, this can occur at
road crossings, where road runoff increases water availability to vegetation (Figure 11).
• Long-lived species exclusively represented by seedlings or plants less than one-year old.
A large flood may promote the growth of hydrophytes in streams that are normally too
dry to sustain them (Figure 12).
• Old specimens clearly in decline. This scenario may be a sign of major long-term
reductions in water availability due to changes in water use practices or to extreme
and/or persistent drought (Figure 13).
These species may be recorded on the field form, along with notes explaining the unusual
distribution patterns observed, but should not be among the number of hydrophyte species
entered for this beta SDAM GP indicator.
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Section 3; Data Collection
Figure 11. Local conditions that support growth of hydrophytes. In Ridgecrest, CA, a culvert at an ephemeral stream
crossing disrupts the movement of water, sustaining the growth of hydrophytes in the immediate vicinity. Photo
credit: Cara Clark.
Figure 12. Long-lived species only
represented by young specimens.
Red alders (Alnus rubra), while
abundant at Mission Creek in the
Mojave Desert, were only observed
as seedlings. Photo credit: Raphael
Mazor.
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Section 3; Data Collection
Figure 13. Water-stressed riparian trees near Oro Grande on the Mojave River. Reproduced from Lines (1999).
Identify up to five hydrophytic plant species growing within the channel or up to one half-
channel width from the channel of the assessment reach that do not have unusual or odd
distribution patterns. Hydrophytes growing at greater distances from the channel may be
supported by local water sources not related to streamflow in the assessment reach, In general,
a focus on the most dominant species in the reach is efficient; focusing on species where
confidence in identification is highest is acceptable. Take photos of each plant species, focusing
on diagnostic features and photos that illustrate the abundance and environmental context
where the species grows.
If the site is devoid of vegetation, check the box marked "No vegetation within reach."
Common questions about identifying hydrophytes
Are FACW and OBL plants equally important?
Yes. For this method, OBL and FACW plants are equally important indicators of streamflow
duration.
Do Facultative (FAC) or Facultative Upland (FACU) status plants count?
No. Although some applications of the NWPL treat FAC or FACU plants as hydrophytes, they do
not count towards this indicator for the beta SDAM GP. For instance, some important, high-
profile riparian species are FAC in some or all of the NWPL regions applicable to the Great
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Section 3: Data Collection
Plains, such as American sycamore (Platanus occidentalis; GP NWPL region), Eastern
cottonwood (Populus deltoides; all applicable NWPL regions), green ash (Fraxinus
pennsylvanica; GP NWPL region), and box elder (Acer negundo; all applicable NWPL regions).
This exclusion in no way lessens the ecological importance or conservation value of these
plants, but rather indicates their relative tolerance for drier conditions than FACW or OBL
species.
What if a species is not included in the NWPL?
If a plant is not included in the NWPL, assume that it is not a hydrophyte unless environmental
context strongly indicates otherwise. (See "What if I can't confidently identify a dominant
plant?" below.)
Is genus-level identification okay?
It depends on the genus. Consult the NWPL. Some genera contain high levels of diversity (e.g.,
Carex), while others are dominated by wetland species (e.g., Ludwigia). For instance, across the
GP, nearly all willow (Salix) species are hydrophytes (though there are a few exceptions), so
genus-level identifications of willows are usually acceptable. Post-sampling confirmation based
on photos or collected specimens is recommended.
What if I can't confidently identify a dominant plant?
It may be acceptable to use environmental context and cues to determine that a plant is a
hydrophyte, even if taxonomic identifications cannot be made. Examples include submerged or
emergent macrophytes, or plants observed to grow exclusively in saturated soil and absent
from adjacent uplands (Figure 14). Post-sampling confirmation based on photos or collected
specimens is strongly recommended. Photo documentation should convey this context. Photo
confirmation is particularly important if the only hydrophyte observed in an assessment cannot
be identified on-site. Photos can also be used when consulting plant identification applications
that use image recognition (e.g, Seek, iNaturalist).
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Section 3; Data Collection
Figure 14. Examples of plants determined to be hydrophytes based on context. Left: An emergent macrophyte
growing within the channel. Right: Sedges and cattails growing exclusively in the streamside zone absent from
adjacent uplands.
What if a hydrophytic plant species covers <2% of the assessment area (channel width plus 1A
channel width on both sides of the channel x reach length) and is represented only by seedlings
and/or dead/dying individuals?
Do not consider the species among the number of hydrophyte plant species present in the
reach. The species with such distributions can be photographed and noted for additional
information on the reach.
4. Absence of rooted upland plants in streambed
Upland plant species are usually unable to establish in streams having longer streamflow
duration, as prolonged soil saturation provides less than ideal growth conditions for these
species. Surface flow can limit plant establishment by displacing seeds or otherwise preventing
germination and growth. Therefore, reaches where rooted upland plants cover much of the
streambed may indicate ephemeral or intermittent flow. For the beta SDAM GP, upland plants
are those with FAC, FACU and Upland (UPL) indicators on the most recent NWPL or species with
No Indicator (Nl).
When assessing this indicator, the focus should be on plants rooted in the streambed; plants
growing on any part of the bank should not be considered (Figure 15). Evaluate the entire
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Section 3; Data Collection
length of the reach for this indicator and choose the score from Table 3 that best characterizes
the predominant condition in the reach. Intermediary scoring (i.e., 0,5,1.5, 2.5) of the ordinal
scores shown in Table 3 are appropriate to allow the accessor flexibility to characterize this
indicator more continuously. Note that a higher score is given for the absence of rooted upland
plants in the streambed.
Table 3. Scoring guidance for the Absence of Rooted Upland Plants indicator
Score
Evidence of
perennial
flows
Guidance
0
Poor
Rooted upland plants are prevalent within the streambed/thalweg.
1
Weak
Rooted upland plants are consistently dispersed throughout the
streambed/thalweg.
2
Moderate
Few rooted upland plants are present within the
streambed/thalweg.
3
Strong
Rooted upland plants are absent within the streambed/thalweg.
Figure 15. Example of an ephemeral stream with rooted upland vegetation growing in the channel.
Where vegetation is growing within the streambed of Safe Dolan Creek in Texas, it is dominated by Texas sotol
fDasylirion texanumj and Ashe juniper (Juniperus ashei), both of which have no indicator (Nl) on the National
Wetland Plant List for the Great Plains region.
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Section 3: Data Collection
5. 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. While this reversed pattern is more common
in a region like the Arid West, it may also occur within the Great Plains, particularly near its
boundary with the Arid West (parts of New Mexico, Texas, and Wyoming). 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 the assessment reach size, selection, and
placement section. In multi-threaded channels, the width of the entire active channel is
measured for this indicator, based on the outer limits of the OHWM. Wohl et al. (2016)
described 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.
6. Sinuosity
Sinuosity is a measure of the curviness of a stream channel and is measured as the ratio of the
stream length to valley length (Figure 16). When the two lengths are equal, the ratio is 1, and
sinuosity is considered low; that is, the stream flows in a straight channel from the top to the
bottom of the reach. In contrast, when the stream channel follows a meandering path, the
stream length will be greater than the valley length, and the ratio will be greater than 1; a
higher ratio reflects a more meandering path.
Sinuosity is caused by hydraulic processes that deposit sediment on one side of a reach while
eroding it from another. It is typically highest in sand- and gravel-bed stream-reaches, and
lowest in confined stream-reaches within canyons. Local features resistant to erosion (such as
bedrock outcrops or logjams) may increase sinuosity as well. Although it has no direct
relationship with streamflow duration (that is, it is neither a driver of, nor a response to,
streamflow duration), perennial reaches more frequently exhibit the conditions necessary to
produce meanders than ephemeral streams (Billi et al. 2018). As such, it is an effective indicator
of streamflow duration in the Great Plains.
Sinuosity may be assessed in a number of ways in both the field and from a desktop usingGIS or
interpretation of aerial imagery. For the beta SDAM GP, field measurement is preferred, and
whenever desktop estimates are used, field confirmation is required.
In the field, sinuosity may be visually estimated, or measured using a surveyor's level. Although
the length of the assessment reach may too short to properly characterize sinuosity for certain
stream reaches, the beta SDAM GP is calibrated for estimates made at reaches ranging from 40
to 200 m in length (i.e., 40 times the bankfull channel width
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Section 3: Data Collection
To score this indicator, compare the measured sinuosity value to the guidance in Table 4 and
Figure 16. In multi-threaded systems, the sinuosity measurement should be based on the
dominant (i.e., lowest elevation) channel, and not the entire active channel (Figure 17). In
modified channels, score the sinuosity observed, not what would be expected in a natural
system.
Table 4. Scoring guidance for the Sinuosity indicator.
Score
Evidence of
perennial
flows
Guidance
0
Poor
Ratio of valley length: Stream length < 1.05.
Stream is completely straight with no bends
1
Weak
Ratio between 1.05 and 1.2.
Stream has very few bends, and mostly straight section.
2
Moderate
Ratio between 1.2 and 1.4.
Stream has good sinuosity with some straight sections.
3
Strong
Ratio > 1.4.
Stream has numerous, closely spaced bends with few straight
sections.
Poor(0)
1.0 to 1.05
Weak(l) Moderate (2) Strong (3)
1.05 to 1.2 1.2 to 1.4 Above 1.4
Stream length: 200 m
Valley length: 107 m
Sinuosity = 200/107 =
1.87
Figure 16. Scoring guidance for the Sinuosity indicator. Values in parentheses are sinuosity scores and ranges are
for ratios of stream length to valley length. Shown (top) are two example stream channels for each range of stream
length to valley length and (bottom) an example that identifies the stream length, valley length, and ratio
calculation.
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Section 3; Data Collection
Figure 17. Sinuosity measurements in a multi-threaded system. The stream length (dashed blue line) is measured in
the dominant (i.e., lowest elevation) channel. Valley length is represented by the solid red line.
7, Floodplain and channel dimensions
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 18). Bankfull is the height on the streambanks during
moderate high-water events when water begins to overflow onto the floodplain. 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. Further discussion of identifying bankfull and measuring bankfull
width can be found in the assessment reach size, selection, and placement section.
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Section 3: Data Collection
After determining bankfull width at a representative location (e.g., one of the locations where
bankfull width was measured to determine reach length), the floodplain and channel dimension
indicator can be visually scored or measured following:
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. Divide the flood-prone width by the bankfull width to estimate the entrenchment ratio.
5. If necessary, conduct this assessment at multiple locations to determine the
entrenchment ratio typical of the reach.
Score the indicator using Table 5.
Table 5. Scoring guidance for Floodplain and Channel Dimensions indicator.
Score
Evidence of
perennial
flows
Guidance
0.0
Poor
Ratio of flood-prone width to bankfull width < 1.2.
Stream is incised, with a noticeably confined channel. Floodplain is
narrow or absent, and typically disconnected from the channel.
1.5
Moderate
Ratio between 1.2 and 2.5.
Stream is moderately confined. Floodplain is present but may only
be active during larger floods.
3.0
Strong
Ratio > 2.5.
Stream is minimally confined, with a wide, active floodplain.
8. Particle size or stream substrate sorting
Well-developed streams 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 floodplain sediments and adjacent soils. Similar sediment sizes in the stream bed and the
adjacent stream side 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. The
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Section 3: Data Collection
bed in ephemeral channels is typically soil, having the same or similar soil texture as areas
adjacent to the channel, and often having differentiated soil horizons.
This indicator can be evaluated in two ways:
1) In channel versus outside channel: Determine if the sediment texture on the bed of the
channel is similar to sediment texture adjacent to the channel (e.g., on banks or
adjacent floodplain). If this is the case, then there is evidence that erosive forces have
not been active enough to down cut the channel and support an intermittent or
perennial system. Stormflow runoff resulting from human development can form
incised ephemeral or intermittent channels; however, these channels often still have
little to no coarse substrates.
2) Substrate sorting: Look at the particle size distribution on the channel bed. For lower
gradient channels dominated by sand substrate, the user may need to identify sorting
across coarse versus fine sand.
Regardless of the approach used to assess channel sediments (e.g., pebble count, sand-gauge
reference card), evaluate an area adjacent to but not in the channel for comparison purposes.
Avoid adjacent areas with dense vegetation and recent soil disturbance.
Score the indicator using the guidance in Table 6; photos that demonstrate the scoring
guidance are shown in Figure 19. Intermediary scoring (i.e., 0.75, 2.25) of the ordinal scores
shown in Table 6 are appropriate to allow the accessor flexibility to characterize this indicator
more continuously.
Table 6. Scoring guidance for Particle Size/Streambed Sorting indicator.
Score Evidence of Guidance
perennial
flows
0.0
Poor
Particle sizes in the channel are similar or comparable to particle sizes in
areas close to but not in the channel. Substrate sorting is not readily
observed in the channel.
1.5
Moderate
Particle sizes in the channel are moderately similar to particle sizes in
areas close to but not in the channel. Various sized substrates are
present in the channel and are represented by a higher ratio of larger
particles (gravel/cobble).
3.0
Strong
Particle sizes in the channel are noticeably different from particle sizes
in areas close to but not in the channel. There is a clear distribution of
various sized substrates in the channel with finer particles accumulating
in the pools, and larger particles accumulating in the riffles/runs.
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Section 3; Data Collection
Figure 19. Different levels of particle
size/stream substrate sorting. Top photo:
Dry channel in Texas where the in channel
particle size of material is similar to
surrounding uplands (score ofO); Middle
photo: This Montana stream shows signs of
increased sorting in the middle of the
channel, with slightly larger particles than
surrounding uplands (score of 1.5); Bottom
photo: Particle sizes in this North Dakota
channel located are much larger compared
to surrounding uplands and a high level of
sorting can be seen in the riffle in the
middle of the photo (score of 3).
9, Northern or Southern Great Plains
Whether a reach is within the Northern or Southern Great Plains (Figure 2) is an indicator of
flow duration (Figure 2). The following states lie only in the Northern GP: CO, I A, IL, KS, MN,
MO, MT, ND, NE, SD, Wl, and WY. NM, OK, and TX lie in both the Northern and Southern GP
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Section 3: Data Collection
regions. The web application identifies the correct region for the assessment reach, as well as
determines if a site is in an adjacent region (e.g., the Arid West) not covered by the beta SDAM
GP.
Additional notes and photographs
After assessing and recording all the indicators described above, provide any additional notes
about the assessment, and include photographs in the photo log.
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Section 4: Data interpretation
Section 4: Data Interpretation and using the web application
Because the beta SDAM GP relies on a random forest model to make classifications, we have
developed a free, open-access web application
(https://ecosvstemplanninerestoration.shinyapps.io/beta sdam gp/) that allows assessors to
input data from assessments and obtain a classification. In addition, users have the option to
produce a PDF report in a standardized format, which may then be included in any
documentation that requires incorporation of SDAM results.
The web application provides three tabs. The first tab provides background information about
the method. The second tab is where users can enter geographic coordinates or select the
region (Northern or Southern Great Plains) as well as enter field data needed to obtain a
classification and additional information (such as assessment date) and photographs needed to
produce a standard report. The third tab provides links to additional resources. Classifications
may be obtained without producing a report. No data submitted to the web application is
stored or submitted to the EPA or other agencies.
Outcomes of beta SDAM GP classification
Application of the beta SDAM GP can result in one of four possible classifications:
• Ephemeral
• Intermittent
• Perennial
• At least intermittent
The first three streamflow duration classifications correspond to the three classes of streams
used to calibrate the beta SDAM GP (i.e., perennial, intermittent, or ephemeral streams). 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.
In some cases, the pattern of indicators is associated with multiple classes, and the beta SDAM
GP model cannot assign a single classification with high confidence. However, the beta SDAM
GP model may be able to rule out an ephemeral classification with high confidence. In this case,
the outcome is at least intermittent, meaning that there is a high likelihood that the stream is
either perennial or intermittent. In this circumstance, however, the two classes cannot be
distinguished with confidence. In some cases, this information may be sufficient for
management decisions, although additional assessment may be warranted. The at least
intermittent outcome was rare in the beta SDAM GP development data set.
Applications of the Beta SDAM GP outside the intended area
The beta SDAM GP is intended only for application to the GP regions shown in Figure 2. The
online web application allows the user to apply the protocol to reaches outside the GP;
however, classifications resulting from these applications are for informational purposes only.
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Section 4: Data interpretation
For example, it may be helpful to assess reaches near regional boundaries. Reports generated
from such applications are accompanied by warnings.
What to do if more information about streamflow duration is desired?
The beta SDAM GP will always result in one of the four classifications described above. There
may be cases when additional information is desired. For example, conditions at the time of
assessment may have complicated the measurement of some indicators. It may help to
examine other lines of evidence or conduct additional evaluations.
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 beta SDAM GP, 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 aquatic
invertebrates, leading to more conclusive assessments.
Conduct evaluations at nearby reaches
Indicators may provide more conclusive results at reaches up- or downstream from the
assessment reach, as long as those locations represent similar conditions. 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 the assessment reach
size, selection, and placement section for guidance.
Review historical aerial imagery
In many parts of the Great Plains, sequences of aerial imagery can provide information about
streamflow duration. Google Earth's time slider and USGS Earth Explorer offer a convenient
method of reviewing historical imagery, particularly for areas where trees do not obscure
channels (however, Google Earth time slider may not have accurate image dates). If surface
water is observed in all interpretable images across multiple years (especially during dry
seasons), this may provide evidence that the reach 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
44
-------
Section 4; Data interpretation
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 APT (U.S.
Army Corps of Engineers 2020a) is a useful tool to determine if climate conditions are 'normal'
for a locale (see timing of sampling section). 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 20.
Perennial reach: South Loup River at Arnold, NE
HI
7/2006; Flowing
4/2017: Flowing
Intermittent reach: Tributary to North Fork Grand River, Dakota Prairie Grasslands, SD
Ephemeral reach: Tributary to East Carrizo Creek, Pike and San Isabel National Forests, CO
r / J-e ..
' - ¦'
I
K
¦
sSBi I
• ,v
¦ 191$ . 5. , '¦! —v.'
m
¦n
6/2005: Dry
v .....- :y.
Mr T1
10/2011; Dry
10/2016: Dry
Figure 20. Examples of using aerial imagery to support streamflow duration classification. Images were taken from
Google Earth using the time slider.
45
-------
Section 4: Data interpretation
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.
Collect additional 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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References
References
Billi, P., B. Demissie, J. Nyssen, G. Moges, and M. Fazzini. 2018. Meander hydromorphology of
ephemeral streams: Similarities and differences with perennial rivers. Geomorphology
319:35-46.
Blackburn, M., and C. Mazzacano. 2012. Using aquatic macroinvertebrates as indicators of
streamflow duration: Washington and Idaho indicators. The Xerces Society, Portland,
OR.
Borchert, J.R. 1950. The climate of the central North American grassland. Annals of the
Association of American Geographers 40:1-39.
Bouchard, R.W., Jr., L.C. Ferrington, Jr., and M.L. Karius. 2004. Guide to Aquatic Invertebrates of
the Upper Midwest. University of Minnesota Press. 183 pp.
Burk, R. A., and J. H. Kennedy. 2013. Invertebrate communities of groundwater-dependent
refugia with varying hydrology and riparian cover during a supraseasonal drought.
Journal of Freshwater Ecology 28:251-270.
Carlson, E.A., D.J. Cooper, D.M. Merritt, B.C. Kondratieff, and R.M. Waskom. 2019. Irrigation
canals are newly created streams of semi-arid agricultural regions. Science of the Total
Environment 646: 770-781.
Chadde, S. 2019. Wetland and Aquatic Plants of the Northern Great Plains: A Field Guide for
North and South Dakota, Nebraska, eastern Montana and eastern Wyoming. Orchard
Innovations. 342 pp.
Dodds, W. K., K. Gido, M. R. Whiles, K. M. Fritz, and W. J. Matthews. 2004. Life on the edge: the
ecology of Great Plains prairie streams. Bioscience 54:205-216.
Friedman, J.M., M.L. Scott, and G.T. Auble. 1997. Water management and cottonwood forest
dynamics along prairie streams. Pages 49-71 in F.L. Knopf and F.B. Samson (eds), Ecology
and Conservation of Great Plains Vertebrates. Springer-Verlag, NY.
Fritz, K.M. and W.K. Dodds. 2004. Resistance and resilience of macroinvertebrates to drying and
flood in a tallgrass prairie stream system. Hydrobiologia 527:99-112.
Fritz, K. M., B. R. Johnson, and D. M. Walters. 2008. Physical indicators of hydrologic
permanence in forested headwater streams. Journal of the North American
Benthological Society 27:690-704.
Fritz, K. M., W. R. Wenerick, and M. S. Kostich. 2013. A Validation Study of a Rapid Field-Based
Rating System for Discriminating Among Flow Permanence Classes of Headwater
Streams in South Carolina. Environmental Management 52:1286-1298
Fritz, K. M., T.-L. Nadeau, J. E. Kelso, W. S. Beck, R. D. Mazor, R. A. Harrington, and B. J. Topping.
2020. Classifying Streamflow Duration: The Scientific Basis and an Operational
Framework for Method Development. Water 12:2545.
Grimm, N.B., and S.G. Fisher. 1989. Stability of Periphyton and Macroinvertebrates to
Disturbance by Flash Floods in a Desert Stream. Journal of the North American
Benthological Society 8:293-307.
Hall, R. K., P. Husby, G. Wolinsky, O. Hansen, and M. Mares. 1998. Site access and sample frame
issues for R-EMAP Central Valley, California, stream assessment. Environmental
Monitoring and Assessment 51:357-367.
47
-------
References
Hammond, J.C., M. Zimmer, M. Shanafield, K. Kaiser, S.E. Godsey, et al. 2020. Spatial patterns
and drivers of nonperennial flow regimes in the contiguous U.S. Geophysical Research
Letters 48(2).
Hax, C.L. and S.W. Golladay. 1998. Flow disturbance of macroinvertebrates inhabitating
sediments and woody debris in a prairie stream. American Midland Naturalist 139:210-
223.
Heatherly, T., M.R. Whiles, T.V. Royer, and M.B. David. 2007. Relationships between water
quality, habitat quality, and macroinvertebrate assemblages in Illinois streams. Journal
of Environmental Quality 36(6): 1653-1660.
Hecker, G.A., M.A. Meehan, and J.E. Norland. 2019. Plant community influences on intermittent
stream stability in the Great Plains. Rangeland Ecology & Management 72:112-119.
James, A., K. McCune, and R. Mazor. 2022. Review of Flow Duration Methods and Indicators of
Flow Duration in the Scientific Literature, Great Plains of the United States. Document
No. EPA-840-B-22006. (Available from:
https://www.epa.gov/system/files/documents/2022-09/FlowDurationLitReview-gp.pdf)
Karr, J. R., K. D. Fausch, P. R. Angermeier, and I. J. Schlosser. 1986. Assessment of Biological
Integrity in Running Waters: A Method and Its Rationale. Special Publication 5, Illinois
Natural History Survey.
Kellerhals, R., C.R. Neill, and D.I. Bray. 1972. Hydraulic and geomorphic characteristics of rivers
in Alberta. Research Council of Alberta, River Engineering and Surface Hydrology Report
72-1:52 pp.
Kelso, J.E., W. Saulnier, K.M. Fritz, T-L. Nadeau, and B. Topping. In draft. The stream
intermittency visualization dashboard: a Shiny web application to evaluate high-
frequency logger data and daily flow observations.
King, R. S., Scoggins, M., & Porras, A. 2015. Stream biodiversity is disproportionately lost to
urbanization when flow permanence declines: evidence from southwestern North
America. Freshwater Science, 35(1), 340-352.
Lines, G.C. 1999. Health of native riparian vegetation and its relation to hydrologic conditions
along the Mojave River, southern California: U.S. Geological Survey Water-Resources
Investigations Report 99-4112, 28 p.
Mazor, R. D., B. J. Topping, T.-L. Nadeau, K. M. Fritz, J. E. Kelso, R. A. Harrington, W. S. Beck, K.
McCune, H. Lowman, A. Aaron, R. Leidy, J. T. Robb, and G. C. L. David. 2021a. User
Manual for a Beta Streamflow Duration Assessment Method for the Arid West of the
United States. Version 1.0. Document No. EPA 800-K-21001. (Available from:
https://www.epa.gov/sites/production/files/2021-
03/documents/user_man ual_beta_sdam_aw.pdf)
Mazor, R. D., B. J. Topping, T.-L. Nadeau, K. M. Fritz, J. E. Kelso, R. A. Harrington, W. S. Beck, K.
McCune, A. Allen, R. Leidy, J. T. Robb, G. C. L. David, and L. Tanner. 2021b. User Manual
for a Beta Streamflow Duration Assessment Method for the Western Mountains of the
United States. Version 1.0. Document No. EPA-840-B-21008. (Available from:
https://www.epa.gov/system/files/documents/2021-12/beta-sdam-for-the-wm-user-
manual.pdf)
Mazzacano, C., and S. H. Black. 2008. Using aquatic macroinvertebrates as indicators of
streamflow duration. Page 28. The Xerces Society, Portland, OR.
48
-------
References
McKay, L., T. Bondelid, T. Dewald, J. Johnson, R. Moore, and A. Rea. 2014. NHDPIus Version 2:
User Guide. Page 173. U.S. Environmental Protection Agency. (Available from:
https://nctc.fws.gov/courses/references/tutorials/geospatial/CSP7306/Readings/NHDPI
usV2_User_Guide.pdf)
Merritt, R. W., K. W. Cummins, and M. B. Berg (Eds.). 2019. An introduction to the aquatic
insects of North America.
Nadeau, T.-L., and M. C. Rains. 2007. Hydrological Connectivity Between Headwater Streams
and Downstream Waters: How Science Can Inform Policy. Journal of the American
Water Resources Association 43:118-133.
Nadeau, T.-L. 2015. Streamflow Duration Assessment Method for the Pacific Northwest.
Document No. EPA-910-K-14-001, U.S. Environmental Protection Agency, Region 10,
Seattle, WA.
Nadeau, T.-L., S. G. Leibowitz, P. J. Wigington, J. L. Ebersole, K. M. Fritz, R. A. Coulombe, R. L.
Comeleo, and K. A. Blocksom. 2015. Validation of Rapid Assessment Methods to
Determine Streamflow Duration Classes in the Pacific Northwest, USA. Environmental
Management 56:34-53.
Nadeau, T-L D. Hicks, C. Trowbridge, N. Maness, R. Coulombe, and N. Czarnomski. 2018. Stream
Function Assessment Method for Oregon (SFAM, Version 1.0) Oregon Dept. of State
Lands, Salem, OR, Document No. EPA-910-D-18-001, U.S. Environmental Protection
Agency, Region 10, Seattle, WA. (Available from:
https://www.oregon.gov/dsl/WW/Documents/SFAM-user-manual-vl-l.pdf)
New Mexico Environment Department (NMED). 2011. Hydrology protocol for the
determination of uses supported by ephemeral, intermittent, and perennial waters.
Page 35. Surface Water Quality Bureau, New Mexico Environment Department,
Albuquerque, NM.
Ode, P.R., E.E. Fetscher, and L.B. Busse. 2016. Standard Operating Procedures for the Collection
of Field Data for Bioassessments of California Wadeable Streams: Benthic
Macroinvertebrates, Algae, and Physical Habitat. California State Water Resources
Control Board Surface Water Ambient Monitoring Program (SWAMP) Bioassessment
SOP 004.
Quist, M.C., and R.D. Schultz. 2014. Effects of management legacies on stream fish and aquatic
benthic macroinvertebrate assemblages. Environmental Management 54: 449-464.
Rosenberg, D. M., and V. H. Resh (Eds.). 1993. Freshwater biomonitoring and benthic
macroinvertebrates. Chapman & Hall, New York.
Stagliano, D.M. 2005. Aquatic Community Classification and Ecosystem Diversity in Montana's
Missouri River Watershed. Report to the Bureau of Land Management. Montana Natural
Heritage Program, Helena, MT.
Strickler, G.S. 1959. Use of the densiometer to estimate density of forest canopy on permanent
sample plots. PNW Old Series Research Notes No. 180, p. 1-5.
U.S. Army Corps of Engineers (USACE). 2020a. Antecedent Precipitation Tool (APT).
USACE. 2020b. National Wetland Plant List, version 3.5. Engineer Research and Development
Center Cold Regions Research and Engineering Laboratory. Hanover, NH.
49
-------
References
Voshell, J. R. 2002. A guide to common freshwater invertebrates of North America. McDonald &
Woodward Pub, Blacksburg, Va.
Wang, L., D.M. Robertson, and P.J. Garrison. 2007. Linkages between nutrients and
assemblages of macroinvertebrates and fish in wadeable streams: implication to
nutrient criteria development. Environmental Management 39:194-212.
Whiles, M., B. Brock, A. Franzen, and S.C. Dinsmore. 2000. Stream invertebrate communities,
water quality, and land-use patterns in an agricultural drainage basin of northeastern
Nebraska, USA. Environmental Management 26: 563-576.
Wohl, E., M. K. Mersel, A. O. Allen, K. M. Fritz, S. L. Kichefski, R. W. Lichvar, T.-L. Nadeau, B. J.
Topping, P. H. Tier, and F. B. Vanderbilt. 2016. Synthesizing the Scientific Foundation for
Ordinary High Water Mark Delineation in Fluvial Systems. Page 217. Wetlands
Regulatory Assistance Program ERDC/CCREL SR-16-5, U.S. Army Corps of Engineers
Engineer Research and Development Center. (Available from:
https://apps.dtic.mil/sti/pdfs/AD1025116.pdf)
Zweig, L.D., and C.F. Rabeni. 2001. Biomonitoring for deposited sediment using benthic
invertebrates: a test on 4 Missouri streams. Journal of the North American Benthological
Society 20(4).
50
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Appendices
Term
Abdomen
Active channel
Alluvial
Assessment reach
Bank
Bankfull elevation
Bankfull width
Braided system
Benthic
macroinvertebrates
Canal
Catchment
Cerci
Channel
Confinement
Culvert
Ditch
Dorsal
The terminal section of an arthropod body.
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.
Refers to natural, channelized runoff from terrestrial terrain, and the
material borne or deposited by such runoff.
The length of reach, ranging from 40 m to 200 m, where beta SDAM GP
indicators are measured.
The side of an active channel, typically associated with a steeper side
gradient than the adjacent channel bed, floodplain, or valley bottom.
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.
Width of the stream channel at bankfull elevation
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 system downstream.
Same as multi-threaded system.
Invertebrate organisms found at the bottom of waterbodies and visible
without the use of a microscope (i.e., > 0.5 mm body length).
An artificial or formerly natural waterway used to convey water between
locations, possibly in both directions. Same as ditch.
An area of land, bounded by a drainage divide, which drains to a channel
or waterbody. Synonymous with watershed.
The tail-like filaments at the posterior end of some arthropods'
abdomens. Singular: cerucs.
A feature in fluvial systems consisting of a bed and its opposing banks
which confines and conveys surface water flow. A braided system
consists of multiple channels, including inactive or abandoned channels.
The degree to which levees, terraces, hillsides, or canyon walls prevent
the lateral migration of a fluvial channel.
A drain or covered channel that crosses under a road, pathway, or
railway.
An artificial or formerly natural waterway used to convey water between
locations, possibly in both directions. Same as canal.
Upper surface of abdomen, or back when viewed from above.
51
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Appendices
Entrenchment ratio
Ephemeral
EPT
Exuviae
FAC
FACU
FACW
Floodplain
Flood-prone area
Groundwater
Head
Hydrophyte
Hyporheic
Indicator
Intermittent
Larva
Ratio of the flood-prone area width to the bankfull channel width, used
as part of scoring the Floodplain and Channel Dimensions indicator.
Ephemeral streams are 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.
Ephemeroptera, Plecoptera, Trichoptera
The shed exoskeletons of arthropods typically left behind when an
aquatic larva or nymph becomes a winged adult. Singular: exuvium.
Facultative plants. They are equally likely to occur in wetlands and non-
wetlands.
Facultative upland plants. They usually occur in non-wetlands but are
occasionally found in wetlands.
Facultative wetland plants. They usually occur in wetlands but may occur
in non-wetlands.
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.)
Width of floodplain at the flood-prone elevation (2x maximum bankfull
depth)
Water found underground in soil, pores, or crevices in rocks.
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.
Plants that are adapted to inundated conditions found in wetlands and
riparian areas.
The saturated zone under a river or stream, including the substrate and
water-filled spaces between the particles.
A measurement of environmental conditions. For the beta SDAM GP,
indicators are rapid, generally field-based measurements that predict
streamflow duration class.
Intermittent reaches are 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.
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.
52
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Appendices
Low-flow channel
Macrophyte
Metamorphosis
Multi-threaded
system
Nl
Nymph
OBL
Ordinary high-
water mark
(OHWM)
Perennial
Pool
Proleg
Pupa
In braided systems, the low-flow channel is the main channel with the
lowest thalweg elevation. In intermittent or ephemeral reaches, the low-
flow channel typically retains flow longer than other channels.
Aquatic plants.
The process of transforming from one life stage to another. The term
may apply to the transformation from larval to adult insects, as well as
to amphibians (e.g., the transformation from tadpoles to adult frogs).
Newly transformed frogs are sometimes called metamorphs. Insects
with incomplete metamorphosis (e.g., mayflies and stoneflies) transition
directly from larval to adult stages, whereas insects with complete
metamorphosis (e.g., caddisflies) go through a pupal stage.
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 system downstream.
Same as braided system.
Plants that have no assigned wetland indicator (e.g., FACW, FACU) in a
specific National Wetland Plant List region.
An immature stage of an insect. The term only applies to insect orders
that lack complete metamorphosis (i.e., groups that lack a pupal stage
and transform directly from larva to adult). Mayflies and stoneflies are
examples of aquatic insects that have larvae known as nymphs.
Obligate wetland plants. They almost always occur in wetlands.
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 USACE jurisdiction in non-tidal streams. See 33 CFR
328.4.
Perennial reaches are 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.
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.
Leg-like extensions on the abdomen (never the thorax) of some insect
larvae. Typically, prolegs are unsegmented.
An immature stage of insect orders with complete metamorphosis,
occurring between the larval and adult stage. Pupal stages are typically
53
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Appendices
Reach
Riffle
Riparian
Rooted upland
plants
Runoff
SAV
Sclerotized
Scour
Secondary channel
Sinuosity
Streambed
Thalweg
Thorax
Tributary
UPL
Uplands
Valley width
Ventral
Watershed
immobile. Caddisflies are an example of an aquatic insect order with a
pupal stage. Plural: pupae.
A length of stream that generally has consistent geomorphological and
biological characteristics.
A shallow portion of a channel where water velocity and turbulence is
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
invertebrates.
A transitional area between the channel and adjacent terrestrial
ecosystems.
Plants rooted in the streambed that have wetland indicator statuses of
FAC, FACU, UPL, and NI
Surface flow of water caused by precipitation or irrigation over
saturated or impervious surfaces.
Submerged aquatic vegetation. This class is treated the same as OBL in
current versions of the National Wetland Plant List.
Hardened, as in the tough plates covering various body parts in some
arthropods.
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.
A subsidiary channel that branches from the main channel and trend
parallel or subparallel to the main channel before rejoining it
downstream.
Ratio of stream length (measured at the thalweg) to valley length.
The bottom of a stream channel between the banks that is inundated
during baseflow conditions.
The line along the deepest flowpath within the channel.
The middle section of an arthropod body where legs and wing pads (if
present) are attached.
A stream that conveys water and sediment to a larger waterbody
downstream.
Upland plants. They almost always occur in non-wetlands.
Any portion of a drainage basin outside the river corridor.
The portion of the valley within which the fluvial channel is able to
migrate without cutting into hill slopes, terraces, or artificial structures.
The under surface of the abdomen; from below.
An area of land, bounded by a drainage divide, which drains to a channel
or waterbody. Synonymous with catchment.
54
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Appendices
Appendix B, Guide to Commonly Found EPT
Assessors need to identify different EPT taxa in the field. This appendix will help assessors
recognize common EPT taxa and how to distinguish EPT from other aquatic macroinvertebrates.
Credits are indicated under each photograph:
• CADFW: Digital Reference Collection of California Benthic Macroinvertebrates,
maintained by the Aquatic Bioassessment Lab of the California Department of Fish and
• Macroinvertebrates.org: Macroinvertebrates.org website, an online reference for
identification of aquatic insects of eastern North America.
• NAAMDRC: North America Macroinvertebrate Digital Reference Collection
(https://sciencebase.usgs.gov/naamdrc/), maintained by the U.S. Geological Survey
(Walters et al. 2017).
Another potentially useful reference is the digital key to the aquatic insects of North Dakota, at
https://www.waterbugkey.vcsu.edu/index.htm.
General insect anatomy
Dorsal view of a mayfly (Ephemt roptera) nymph
Familiarity with basic terms of insect anatomy can help distinguish EPT from other aquatic
macroinvertebrates (from Mazzacano and Blackburn 2015).
Wildlife.
"f
55
-------
Appendices
Ephemeroptera (mayflies) larvae
Mayflies have abdominal gills and generally have three cerci (tails), though a few species may
have two cerci. Wing pads are usually visible. All adult mayflies are short-lived and terrestrial
but may be found in large breeding swarms near waterbodies.
kjtX 1
Three
cerci
Abdominal
gills
Wirig pads
Baetidae (small minnow mayflies). This family has a streamlined appearance and appears to
swim like a minnow. This specimen is Baetis. In some species of Baetis, only two cerci are
evident. Baetidae was the most common and abundant EPT family collected during the field
sampling to develop the beta SDAM GP. Image credit: CADFW.
56
-------
Appendices
Semi-hardened
square gills
Caenidae (square-gilled mayflies). This family of mayflies prefers slow moving or stagnant water
where there is an abundance of loose sediment. The square, semi-operculate (i.e., hardened)
gills that generally have a fringe of long hairs set this family apart from other mayflies. This
specimen is Caen is; Caenidae was often the second most common and/or abundant mayfly
family collected (after Baetidae) during the field sampling to develop the beta SDAM GP. Image
credit: Macroinvertebrates.org
57
-------
Appendices
Heptageniidae (flat-headed mayflies), Heptageniid mayflies often have a flattened appearance,
and cling to the undersides of cobbles in fast-flowing water. Still, they have the single tarsal
claws, abdominal gills, and three cerci typical of mayflies. This specimen is Maccaffertium; there
are a few Maccaffertium species present in the GP (e.g., M. exiguum, M. mediopunctatum).
Image credit: Macroinvertebrates.org.
58
-------
Appendices
Enlarged
plate-like
abdominal gill
Leptohyphidae (little stout crawler mayflies). This family of mayflies has a pair of enlarged,
hardened (i.e., sclerotized) abdominal gills that can cover the smaller, translucent abdominal
gills. The family typically has three cerci, but the right one has broken off in this specimen.
Image credit: CADFW.
59
-------
Appendices
Feather-like
abdominal gills
Ephemeridae (burrowing mayflies). This family of mayflies prefers to burrow in soft, silty
sediments. Although it is more common in lakes, it may be found in pools and slow-moving
portions of rivers. The long feathery gills and single tarsal claws make this recognizable as a
mayfly. This specimen is a Hexagenia; Hexagenia limbata is widespread throughout the Great
Plains. Image credit: Macroinvertebrates.org
60
-------
Appendices
Abdominal gills with
long 'prongs'
Leptophlebiidae (prong-gilled mayflies). This family of mayflies prefers gravel-bottomed
streams, in woody debris or among roots protruding from the bank. They tend to be dingers
with relatively flat bodies. The gills often have long forked prongs, giving this family its name.
These specimens are Leptophlebia, which have lost large parts of their gills and tails. Image
credit: James Treacy.
61
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Appendices
Plecoptera (stonefly) larvae
Nine families of stoneflies are found in North America, though stonefly diversity in the Great
Plains is relatively low. Stoneflies 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.
No abdominal
gills
\ Two tarsal
claws
Periidae (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) and has
glossae much shorter than the paraglossae (see image on next page). Perlids were the most
common and abundant stoneflies identified during field sampling to develop the beta SDAM
GP. This specimen is Neoperla. Image credit: Macroinvertebrates.org.
Thoracic
gills Two cerci
62
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Appendices
Glossae
Perlidae. Mouthparts can be seen in this view (Acroneuria). The glossae are shorter than the
paragiossae. Image credit: NAAMDRC.
63
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Appendices
Abdomen
striping
a
CV
/
gti up! jm* ^
HP rV Itl I J \ m
\ \
v - m 31
Perlodidae (stripetails). Members of this family have a patterned head and thorax and often
longitudinal black-and-yellow striping on the abdomen. While most Perlodids are predators,
some species in this group are also facultative shredders or collector-gatherers. They can often
be found clinging to the substrate, plants, or other materials in the stream. This specimen is
Isoperla, which is represented by several species that can found in part of the GP including I.
longiseta and I. quinquepunctata. Image credit; Macroinvertebrates.org.
64
-------
Appendices
Thoracic
gills
Long
hindlegs
Divergent
hindwings
Nemouridae (nemourid stoneflies). This family is relatively small and contains species that
prefer smaller rivers, streams, and springs. 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. This specimen is Amphinemura. Image credit: Macroinvertebrates.org.
65
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Appendices
Capniidae (small winter stoneflies, also known as snowflies). Members of this family have long,
slender bodies with no thoracic or abdominal gills, They are shredders and so the glossae and
paraglossae are approximately equal (in contrast to Perlids). The hind legs do not extend past
the abdomen and there is a pleural fold (see below) that connects the abdominal segments (1-9
segments). The family Leuctridae is very similar to Capniidae, but this pleural fold is less evident
and does not usually extend past abdominal segment 7. This specimen is AHocapnia
(Capniidae); representatives of this genus that overlap with the GP include A. granulata and A.
rickeri. Image credit: Macroinvertebrates.org,.
Image credit: NAAMDRC
66
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Appendices
Trichoptera (caddisfly) larvae and pupae
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
thorax
Abdominal
gills
Anal proleg with
sclerotized hooks
67
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Appendices
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. This
specimen is Pycnopsyche; representatives of this genus that overlap with the GP include P.
guttifera and P. subfasciata. Image credit: Macroinvertebrates.org.
Sclerotized
thorax
3 pairs of setae
(hairs) on last Abdomfrl^
segment of thorax sclerite
Anterior opening
Posterior opening
Glossosomatidae (saddle case-maker). This family has a distinctive case with two openings
(although these are sealed in pupal cases). The larvae are distinguished from other caddisfly
68
-------
Appendices
families by having only one sclerotized thoracic segment, a small sclerite on the next-to-last
segment of the abdomen, and three pairs of setae (small hairs) on the last segment of the
thorax. Image credit: Macroinvertebrates.org.
CrlQrr\ti7QrJ
Polycentropodidae (trumpet-net, tube maker caddisflies). Members of this family prefer pools
and areas of lesser current in streams and do not utilize a case; instead, they construct a
tubular silken net. Only the first thoracic segment is sclerotized and no sclerotization occurs on
the abdomen. The anal prolegs are long and freely moveable. This specimen is Nyctiophylax;
representatives of this genus that overlap with the GP include N. affinis and N. moestus. Image
credit: Macroinvertebrates.org.
Long anal
prolegs
69
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Appendices
\.
1
Leptoceridae (long-horried caddisflies). Members of this family are relatively small when
mature but have the 'largest' antennae of the caddisflies. The antennae are still quite small but
can be seen in profile. They can be found in a variety of habitats including still and flowing
water and use plant or mineral materials or even pure silk to create their cases. This specimen
is Nectopsyche; there are several representatives of this genus in the GP including N. albida and
N. exquisita. The hind pair of legs in some genera, like Nectopsyche sp.; are much longer than
the front and middle pairs. However, not all Leptoceridae show this characteristic. Image credit:
Macroinvertebrates.org.
70
-------
Appendices
Rhyacophiiidae (free-roaming caddisflies). This family is usually found wandering freely on the
undersides of boulders and cobbles, actively hunting for prey. Abdominal gills are present, but
not evident in this photograph. Notice the long anal prolegs, which have large, sclerotized
claws. Some species of this family have a striking blue-green coloration, which may fade when
preserved in alcohol. Image credit: CADFW.
71
-------
Appendices
Sclerotized
thoracic
segments
/
¦ h t
> ^
m
Hydroptilidae (micro caddisflies). These are small caddisflies (2-4 mm long) that build purse-like
cases out of sand grains. They may be very abundant, but hard to see due to their size. Image
credit: CADFW.
72
-------
Appendices
Hel i copsychi dae
- Hel icopsyche sp.
M
Helicopsychidae (snail case-makers) are unusual in that they build spiral-shaped, snail-like
cases. Mnemonic device to remember name is they build "cases that are in a "helix". Image
credit: CADFW.
73
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Appendices
Hydropsychidae (net-spinner caddisflies). This group lives within nets in fixed locations out of
silk, pebbles, and other materials. These nets are usually located in fast-flowing areas and on
large, stable particles (such as large cobbles and boulders). Like a spider in a web, they wander
about the retreat to catch prey that gets caught in the net. Turning over a boulder typically
destroys these nets, but the larvae may be found crawling among the remains of the net,
Hydropsychids were the most common caddisfly (and one of the most common families overall)
collected during field sampling to develop the beta SDAM GP. Image credit: CADFW.
74
-------
Appendices
a* * *
a
^ <. vV ' -
¦L\;
* ^
x T-shaped
Philopotamidae (finger-net caddisflies). Like hydropsychid caddisflies, this family builds a
retreat, but it is often found roaming free. It is distinguished from other families of caddisflies
by its T-shaped labrum (extendable mouthpart). This specimen is Chimarra sp, Image credit;
Macroinvertebrates.org.
75
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Appendices
Trichopteran Look-Alikes to Watch Out For
Other insect orders that include aquatic life stages have species that look superficially similar to
caddisflies, and may be mistaken for them, especially if no case is present or the caddisfly is
separated from its case or net during collection. These should not be counted as EPT taxa for
Indicator 1, Examples include Elmid beetle and Chironomid midge larvae.
Sclerotized body
& 4 "•
-
Tufted gills
Hinged lid
Tufted gills
Elmidae (riffle beetle, larvae). These small insect larvae have a completely sclerotized body,
unlike caddisflies which only have the thorax sclerotized. In addition, there are no gills along the
abdomen, as in the caddisflies. Instead, gills are found at the tip of the abdomen (where the
caddisfly's two anal prolegs with hooks would be found). The tufted gills may be withdrawn into
a cavity that has a hinged lid. Image credit: Macroinvertebrates.org.
76
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Appendices
Thoracic
proleg
Anal
prolegs
Chironomidae (non-biting midges),
Chironomidae are among the most numerous
and widespread aquatic invertebrates in
water bodies. Compared to the caddisflies,
their heads are small compared to the body
and contained in a distinctive head capsule.
And while they have prolegs on the thorax
and abdomen (anal prolegs), they do not
have 3 sets of segmented legs as caddisflies
do. Image credit: Top row:
Macroinvertebrates.org. Bottom row:
CADFW.
A\\
»
77
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Appendices
Appendix C. Field Forms
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Field form beta Streamflow Duration Assessment Method for the Great Plains
Revision Date: August 24, 2022 Page 1 of 6
Beta Streamflow Duration Assessment Method - Great Plains
General site information
Project name or number:
Site code or identifier:
Assessor(s):
Waterway name:
Visit date:
Current weather conditions (check one): Notes on current or recent weather
~ Storm/heavy rain conditions (e.g., precipitation in previous
~ Steady rain week):
~ Intermittent rain
~ Snowing
~ Cloudy ( % cover)
~ Clear/Sunny
Coordinates at downstream end
(decimal degrees):
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
(m)
(Indicator 5)
Reach length (m):
40x width; min 40 m; max 200 m.
Site photographs:
Enter photo ID or check if completed
Top down: Mid down:
Mid up: Bottom up:
Disturbed or difficult conditions (check all that apply): Notes on disturbances or difficult site conditions:
~ Recent flood or debris flow
~ Stream modifications (e.g., channelization)
~ Diversions
~ Discharges
~ Drought
~ Vegetation removal/limitations
~ Other (explain in notes)
~ None
Observed hydrology: Comments on observed hydrology:
% of reach with surface flow
% of reach with sub-surface or surface flow
# of isolated pools
Site sketch:
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Field form beta Streamflow Duration Assessment Method for the Great Plains
Revision Date: August 24, 2022 Page 2 of 6
1. EPT Family Richness
Collect aquatic invertebrates from at least 6 locations in the assessment reach and determine if any specimens of EPT
(Ephemeroptera, Plecoptera, Trichoptera) are present. Identify EPT to family and enumerate up to 5 taxa.
Check one
Taxon
Mayfly
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Field form beta Streamflow Duration Assessment Method for the Great Plains
Revision Date: August 24, 2022 Page 3 of 6
3. Number of Hydrophytic Plant Species
Record up to 5 hydrophytic plant species (FACW or OBL in the Great Plains, Midwest, or Northeast-Northcentral regional
wetland plant lists, depending on location) within the assessment area: within the channel or up to one half-channel width.
Explain in notes if species has an odd distribution (e.g., covers less than 2% of assessment area, long-lived species solely
represented by seedlings, or long-lived species solely represented by specimens in decline), or if there is uncertainty about the
identification. Enter photo ID, or check if photo is taken.
Check if applicable:
Species
~ No vegetation in assessment area
Odd
distribution? Notes
Photo
ID
~ Number of hydrophytic plant species identified from the assessment reach without odd distribution (Enter zero
if none were found).
Notes on hydrophytic vegetation:
4. Absence of Rooted Upland Plants in Streambed
Scoring guidance:
Absence of
0: (Poor) Rooted upland plants are prevalent within the streambed/thalweg.
Rooted Upland
1: (Weak) Rooted upland plants are consistently dispersed throughout the streambed/thalweg.
Plants in
2: (Moderate) Few rooted upland plants are present within the streambed/thalweg.
Streambed
3: (Strong) Rooted upland plants are absent within the streambed/thalweg.
score (0-3)
Recommended photos (record in photolog, below):
Half-scores are allowed
1) channel vegetation, and
2) upland vegetation
Notes:
5. Bankfull channel width (copy from first page of field form)
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Field form beta Streamflow Duration Assessment Method for the Great Plains
Revision Date: August 24, 2022 Page 4 of 6
6. Sinuosity
Sinuosity score (0-3)
Stream length: 200 m
Valley length: 107 m
Sinuosity = 200/107 = 1.87
Scoring guidance:
0: Poor
1.0 to 1.05
1: Weak
1.05 to 1.2
2: Moderate
1.2 to 1.4
3: Strong
Above 1.4
7. Floodplain and Channel Dimensions
Floodplain and
Channel
Dimensions
score (0-3)
2x Maximum Bankfull Depth
Flood-prone Width (S? 2x Max Bankfull Depth
Entrenchment Ratio (Flood-prone Width/Bankfull Width)
Scoring guidance:
0: (Poor) Ratio of flood-prone width to bankfull width < 1.2.
1.5: (Moderate) Ratio between 1.2 and 2.5. Stream is moderately confined. Floodplain is present
but may only be active during larger floods. Stream is incised, with a noticeably confined
channel. Floodplain is narrow or absent, and typically disconnected from the channel
3: (Strong) Ratio >2.5. Stream is minimally confined, with a wide, active floodplain.
8. Particle Size or Stream Substrate Sorting
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Field form beta Streamflow Duration Assessment Method for the Great Plains
Revision Date: August 24, 2022 Page 5 of 6
Particle Size or
Stream
Substrate
Sorting
score (0-3)
Half-scores are allowed
Scoring guidance:
0: (Poor) Particle sizes in the channel are similar or comparable to particle sizes in areas close to
but not in the channel. Substrate sorting is not readily observed in the channel.
1.5: (Moderate) Particle sizes in the channel are moderately similar to particle sizes in areas close
to but not in the channel. Various sized substrates are present in the channel and are
represented by a higher ratio of larger particles (gravel/cobble).
3: (Strong) Particle sizes in the channel are noticeably different from particle sizes in areas close
to but not in the channel. There is a clear distribution of various sized substrates in the channel
with finer particles accumulating in the pools, and larger particles accumulating in the
riffles/runs.
Notes:
9. Northern or Southern Plains
If the project is within CO, IA, IL, KS, MN, MO, MT, ND, NE, SD, WI, or WY, it is within the Northern Plains.
NM, OK, and TX lie in both regions; check map in Figure 2 in user manual, or input latitude and longitude from
page 1 of the field form into the web application to calculate for these states.
Northern Plains Q Southern Plains
Photo log
Indicate if any other photographs taken during the assessment:
Photo ID Description
Additional notes about the assessment:
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Field form beta Streamflow Duration Assessment Method for the Great Plains
Revision Date: August 24, 2022 Page 6 of 6
Model Classification:
r~l Ephemeral
f1 At least intermittent
LJ Intermittent
1 Perennial
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