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United States , ,Q A_nw r«r«c
Environmental Protection uoMrmy oorps
Agency °f Engineers ®
Portland District
U.S. Environmental Protection Agency, Region 10
U.S. Army Corps of Engineers, Portland District
Appropriate Citation: Nadeau, T-L. 2011 Streamflow Duration Assessment Method for Oregon,
U.S. Environmental Protection Agency, Region 10, Document No. EPA 910-R-11-002.
Photo Credits
Front cover (Top to Bottom, Left to Right): Rob Coulombe (2nd row), David Beugli (top row),
Lindsey Webb (1st and 2nd in 3rd row), Russ Klassen (3rd in 3rd row), Tracie Nadeau (4th row)
Inside collage (Clockwise from Upper Left): Gail Heine, Jess Jordan, Russ Klassen,
Lindsey Webb, Randy Cameleo (Oregon hydrologic landscape map)
Inside back cover collage (Clockwise from Upper Left): Jim Wigington, Blake Hatteberg,
Lindsey Webb, Blake Hatteberg, Rob Coulombe, Nicole Peirce, Rob Coulombe (center)
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Table of Contents
PURPOSE iii
ACKNOWLEDGMENTS iii
Section 1: Introduction 1
Background 2
Interim Version 2
Oregon Method Validation Study 2
Current Method: Changes from the Interim Version 3
Relevant Definitions 4
Considerations When Assessing Indicators of Streamflow 5
Spatial Variability 5
Reach Selection 6
Recent Precipitation 6
Ditches and Modified Natural Streams 7
Disturbed or Altered Streams 7
Section 2: Conducting Field Assessments 8
Suggested Field Equipment 8
General Guidance for Completing the Field Assessment Form 8
Observed Hydrology 9
Indicators of Streamflow Duration 10
Macroinvertebrate Indicators (1 - 3) 12
Additional Indicators (4 and 5) 13
Ancillary Information 14
Section 3: Drawing Conclusions 16
Appendix A: References Consulted 19
Appendix B: Streamflow Duration Field Assessment Form 27
Streamflow Duration Assessment Method for Oregon
November 2011
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PURPOSE
The purpose of this manual and accompanying
field assessment form is to guide natural
resource professionals in evaluating the
described indicators of stream flow to help
distinguish between ephemeral, intermittent
and perennial streams. This method has
been developed and tested for applicability
across Oregon, from the humid west side
of the Cascade Mountains to the semi-arid
eastern two-thirds of the state. Section 1
contains an introduction to the method,
including definitions of key terms, method
development and validation, and sources of
variability. Section 2 provides assessment
guidance and describes the indicators. The final
section describes how to draw conclusions
based on the assessed indicators of flow.
This method can be used to distinguish
between perennial, intermittent, and
ephemeral streams, but is primarily designed
to distinguish ephemeral streams from
intermittent and perennial streams in a single
site visit. It provides a scientifically supported,
rapid assessment framework to support
best professional judgment in a consistent,
robust and repeatable way. While use of this
method may inform a more robust stream
assessment, it was specifically developed
for the purpose of determining streamflow
duration and does not provide a stand-alone
assessment of stream function or condition.
ACKNOWLEDGMENTS
This method has come together through
the hard work of many people. The
interim version, released in March 2009
and co-authored by Brian Topping (U.S.
Environmental Protection Agency; US EPA),
myself, and Mike Turaski (U.S. Army Corps
of Engineers, Portland District; USAGE),
was particularly improved by the critical
review and input from participants in an
initial, several day field verification workshop
(September 2007): Scott Hoffman Black, The
Xerces Society for Invertebrate Conservation
(Xerces Society); Kyle Blasch, United States
Geological Survey (USGS) Arizona Water
Science Center; Ken Fritz, USEPA Office
of Research and Development (ORD); Jim
Goudzwaard, USAGE Portland District;
Sarina Jepsen, Xerces Society; Jess Jordan,
Oregon Department of State Lands (ODSL);
Periann Russell, North Carolina Division
of Water Quality; Yvonne Vallette, USEPA
Oregon Operations Office; Jim Wigington,
USEPA ORD; and Molly Wood, USGS Idaho
Water Science Center. Jess Jordan, Peter
Ryan, Nicole Peirce, and Russ Klassen of
ODSL also contributed critical review and
assistance in field testing the interim version.
A validation study, which we conducted
in Oregon and provides the data-driven
revisions resulting in this, the revised Oregon
Method, owes all to a committed group of
colleagues: Jim Wigington, Scott Leibowitz,
Ken Fritz, Joe Ebersole, and Randy Cameleo,
USEPA ORD; Rob Coulombe, Lindsey
Webb, Blake Hatteberg, Shawn Majors,
and Rachel LovellFord (CSS-Dynamac
Corporation); Jess Jordan (currently USAGE
Seattle District) and Mike Turaski variously
collaborated, designed, implemented, analyzed
or otherwise contributed to the study. Rob
Coulombe and the Dynamac crew, with
their extensive time in the field, have been
particularly instrumental in improving the
on-the-ground usability of the method.
Streamflow Duration Assessment Method for Oregon
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Celeste Mazzacano and Scott Hoffman Black
(Xerces Society) completed a literature
review and synthesis identifying taxa and
life stages of macroinvertebrates occurring
in Oregon streams to identify the perennial
indicators presented in Table 1, as well as
produced the associated macroinvertebrate
field guide. Chris Rombough (Rombough
Biological) and Jess Jordan developed the
herpetofauna water-dependent life history
stages presented in Table 2. Shannon Hubler
(Oregon Department of Environmental
Quality; DEQ) provided data from DEQ's
statewide stream monitoring database.
Several others have contributed helpful
review and input along the way, including:
Janine Castro, U.S. Fish and Wildlife Service;
Stephen Lancaster, Oregon State University
(OSU), Dept. of Geosciences; Judith Li,
OSU, Dept. of Fisheries and Wildlife; Mark
Rains, University of South Florida, Dept. of
Geology, as well as many practitioners who
participated in training sessions on using
the interim version held around the state.
Photographs and figures are
credited within the document.
With many thanks to all,
Tracie-Lynn Nadeau, USEPA Region 10,
Oregon Operations Office, Portland, Oregon
Nadeau.tracie@epa.gov
Streamflow Duration Assessment Method for Oregon
November 2011
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Section 1: Introduction
A stream* can be described as a channel
containing flowing surface water including:
• Stormflow - increased streamflow
resulting from the relatively rapid runoff
of precipitation from the land as interflow
(rapid, unsaturated, subsurface flow),
overland flow, or saturated flow from
surface water tables close to the stream, or;
• Baseflow - flow resulting from
ground water entering the stream or
sustained melt water from glaciers
and snowmelt (observed during long
gaps between rainfall events), or;
• A combination of both stormflow
and baseflow, and;
• Contributions of discharge from
upstream tributaries as stormflow
or baseflow, if present.
*Note: For the purposes of this method
the descriptor 'stream' is attached to the
channel, and applies regardless of whether
flow dries up seasonally or otherwise.
As a stream flows from its origin, water
may be derived primarily from stormflow,
baseflow, or some combination of the two.
Streams typically continue to accumulate
water from stormflow, baseflow and other
tributaries as they flow downstream. As
streams accumulate flow they commonly
transition along a gradient from ephemeral
to intermittent and perennial, but sometimes
quickly transition from ephemeral to perennial
in high gradient systems, or transition from
perennial to ephemeral or to total cessation of
surface flow. Often these changes are gradual
and may not be obvious to the casual observer.
There are, however, indicators of streamflow
that collectively can be used to characterize
the flow duration of a stream along a particular
reach as ephemeral, intermittent or perennial.
In this manual, duration encompasses the
concept of the cumulative time period of
flow over the course of a year, which may
vary interannually with climate, groundwater
withdrawal or streamflow diversion, and other
water use patterns. This manual presents
an indicator-based method for assessing
streamflow duration in the state of Oregon.
This method and accompanying assessment
form are designed to assist the user in
distinguishing between ephemeral, intermittent
and perennial streams throughout Oregon.
Stream systems can be characterized by
interactions among hydrologic, geomorphic
(physical) and biological processes. These
attributes, or dominant processes, vary along
the length of a stream related to flow duration
(Figure 1). To identify the indicators and
distinguish ephemeral streams from intermittent
streams or intermittent streams from perennial
streams using the information presented in this
manual, the evaluator should have experience
making field observations in streams.
Trans*.
Opfrtitio-n
FIGURE 1. Hydrologic and geomorphic
characteristics in relation to drainage
area (FISRWG 1998).
Streamflow Duration Assessment Method for Oregon
November 2011
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Background
Interim Version
The interim version of this method was
developed, in part, based on the experiences
and progress of the North Carolina Division
of Water Quality on their Identification
Methods for the Origins of Intermittent and
Perennial Streams.'* The North Carolina Stream
Identification Method (NC Method), a tool
used to guide rapid assessment of intermittent
and perennial streams, was developed
and tested based on documented scientific
principles in hydrology, geomorphology
and biology. Version 1 of the method was
implemented in 1998 after review from the
academic and regulatory community. Since
1998, several major revisions have been made
as experience and science advanced. The NC
Method is viewed as an evolving document
that will continue to change over time.
Starting from that base, experts in relevant
academic and professional fields were
consulted in the development of the Streamflow
Duration Assessment Method for Oregon
(Oregon Method). A team of experts from the
USEPA Region 10 Oregon Operations Office
and Office of Research and Development,
USAGE Portland District, USGS Idaho and
Arizona Water Science Centers, Oregon
Department of State Lands, and North
Carolina Division of Water Quality conducted
a one week field assessment of the method
in the five major physiographic and climatic
regions of Oregon. The field assessment
compared the draft Oregon Method to known
flow durations for headwater streams in the
Coast Range, Willamette Valley Lowlands,
Cascade Range, Great Basin, and the High
Desert Plateau. In addition, several other
efforts informed selection of appropriate
indicators, identification of potential problems
1 Available at: http://h2o.enr.state.nc.us/ncwetlands/
documents/NC_Stream_ID_Manual.pdf
in the field, and development of meaningful
indicator descriptions and scoring, including:
review of the scientific literature; beta-testing
by the USAGE Portland District, USEPA
Oregon Operations Office, and Oregon
Department of State Lands; development
of a Xerces Society report "Using Aquatic
Macroinvertebrates as Indicators of Streamflow
Duration;" external peer-review; and results
of the first phase of a USEPA field validation
study of the Oregon Method including more
than 170 streams from both the humid and
semi-arid sides of the Cascade Range.
The resulting interim version of the Streamflow
duration assessment method, which scores 21
geomorphic, hydrologic, and biologic stream
attributes based on abundance and prominence,
was released via joint USACE/USEPA/ODSL
Public Notice in March 20092. Conclusions
of Streamflow duration in the interim version
are based on the additive score of the assessed
stream attributes. The Oregon Method was
made available as an interim version to allow
practitioners such as stream ecologists, aquatic
ecologists, hydrologists, and wetland scientists
the opportunity to provide comment on their
experiences using the method during the two-
year field validation study of the method.
Oregon Method Validation Study
To meet our objectives of developing a rapid
Streamflow duration assessment method
that is consistent, robust, repeatable, and
applicable across the state of Oregon, we
undertook a two-year field validation study
of the interim version of the Oregon Method.
The study included 177 streams ranging
across the hydrologic settings of Oregon,
with an approximately equal distribution of
streams from the humid west and semi-arid
east side of the Cascade Range, and in the
perennial, intermittent, and ephemeral classes.
2 Available at: http://www.epa.gov/region10/pdf/
water/sdam/interim_sdam_oregon_march2009.pdf
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Study design maximized representation of a
diversity of hydrologic landscapes, based on
a hydrologic classification framework that
includes indices of annual climate, seasonality,
aquifer permeability, terrain, and soil
permeability (Wigington et al. 2011, in review).
The study addressed three primary questions:
1) Are these 21 stream attributes the most
predictive indicators of streamflow?; 2) Does
each indicator provide independent value
to the determination of stream class?; and
3) Are there redundancies in the indicators
which affect determination of stream class?
To address these questions, the interim
version of the Oregon Method was applied
to the 177 study stream reaches over the
course of three field seasons—two dry
seasons and one wet season; in Oregon,
where the delivery of precipitation is greatest
during the winter months, these correspond
to late summer/early fall and late spring,
respectively. Supplemental data were also
collected at each site, particularly for those
indicators that were considered problematic.
Results of the validation study found the
interim, 21 indicator version of the method
correctly determined known streamflow
duration 62% of the time. Extensive data
analyses revealed that several indicators
appeared to have the strongest explanatory
power in separating the perennial, intermittent,
and ephemeral stream classes. Furthermore,
several of the geomorphic indicators (seven
of the 21 total indicators) correlated with each
other, indicating that they were measuring
the same thing. Results of the validation
study are being published separately.
Current Method: Changes
from the Interim Version
Analysis of data collected during the two-year
validation study informed revisions to the
Oregon Method, which resulted in a general
model (method) across space and time, and
maximized accuracy. The current method
presented here relies on five indicators that
are evaluated using a decision-tree, similar to
using a dichotomous key. As with the interim
version of the method (March 2009), the
presence of certain vertebrate organisms that
require the sustained presence of water for
their growth and development are included as
single indicators of an intermittent stream.
The five-indicator method correctly determined
known streamflow duration classes 78% of
the time, compared with 62% of the time with
the 21-indicator interim method. Accuracy
rates for distinguishing between ephemeral
and "at least intermittent" streams were
81% for the interim version and 92% for
the current five indicator method. Thus, the
current method presented is significantly
more accurate than the interim version.
Based on our own extensive observations and
feedback consistently received from users,
the interim version of the Oregon Method:
• contained some subjective indicators that
were difficult to consistently assess; and
• overweighted geomorphic indicators, which
in some situations (e.g. high slope) led to
false conclusions because flow magnitude,
rather than flow duration, was being scored.
The current decision-tree method is based
on stream attributes—four biological
and one physical— that are measurable,
rather than subjective, and does not
include geomorphic indicators of flow.
Furthermore, the current method appears
to be more resilient to recent physical
alterations or modifications to a stream.
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Relevant Definitions
As used by this method:
Channel is an area that contains
flowing water (continuously or not)
that is confined by banks and a bed.
Dry Channel is an area confined by
banks and a bed that at times contains
flowing water, but at the time of
assessment does not contain flowing
water (it may contain disconnected pools
with no sign of connecting flow).
Wet Channel is an area confined by
banks and a bed that contains flowing
water at the time of assessment
(flow may be interstitial).
Ephemeral Stream flows only in direct
response to precipitation. Water typically flows
only during and shortly after large precipitation
events. An ephemeral stream may or may not
have a well-defined channel, the streambed is
always above the water table, and stormwater
runoff is the primary source of water. An
ephemeral stream typically lacks biological,
hydrological and in some instances physical
characteristics commonly associated with the
continuous or intermittent conveyance of water.
Ground water occurs at the subsurface under
saturated conditions and contains water that
is free to move under the influence of gravity,
often horizontally to stream channels when a
confining layer blocks downward percolation.
Hyporheic Zone is the zone under and
adjacent to the channel where stream
water infiltrates, mixes with local and/or
regional groundwater, and returns to the
stream. The dimensions of the hyporheic
zone are controlled by the distribution and
characteristics of alluvial deposits and by
hydraulic gradients between streams and
local groundwater. It may be up to two
to three feet deep in small streams, and is
the site of both biological and chemical
activity associated with stream function.
Intermittent Stream is a channel that contains
water for only part of the year, typically
during winter and spring when the streambed
may be below the water table and/or when
snowmelt from surrounding uplands provides
sustained flow. The channel may or may not
be well-defined. The flow may vary greatly
with stormwater runoff. An intermittent stream
may lack the biological and hydrological
characteristics commonly associated with
the continuous conveyance of water.
Normal Precipitation is defined as the 30-year
average, provided by National Oceanographic
and Atmospheric Administration National
Climatic Data Center, computed at the
end of each decade. These data are
available as annual and monthly means.
Perennial Stream contains water continuously
during a year of normal rainfall, often with
the streambed located below the water table
for most of the year. Groundwater supplies
the baseflow for perennial streams, but flow
is also supplemented by stormwater runoff
and snowmelt. A perennial stream exhibits
the typical biological, hydrological, and
physical characteristics commonly associated
with the continuous conveyance of water.
Stream Origin is the point where flow first
appears on the land surface with enough
force to disturb the substrate creating a
lasting sign of flow. Stream origins are often
wetlands, springs, seeps or headcuts.
Swales can be wetlands or uplands (when
assessed under the USAGE 1987 Wetlands
Delineation Manual or appropriate Regional
supplements) and primarily serve as a vegetated
flow path occurring in a slight depression in the
landscape but lacking differentiation between
bed and bank. Swales often connect uplands
to wetlands or streams, connect wetlands
Streamflow Duration Assessment Method for Oregon
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together, or connect upstream and downstream
reaches of small streams that flow through a
colluvial fan or an abrupt change in grade.
Thalweg is the deepest part of a stream
channel and the last part of the stream to
contain flowing water as a stream dries up. As
used in this method, the thalweg comprises
the "lowest flow" pathway and typically spans
approximately 5 to 20% of the channel width.
Water Table is the surface elevation of the
saturated zone below which all interconnected
voids are filled with water and at which
the pressure is atmospheric, commonly
identified as the top of the local (i.e.,
floodplain) or regional groundwater aquifer.
Considerations When Assessing
Indicators of Streamflow
Spatial Variability
Spatial variations in stream indicators occur
within and among stream systems. Sources
of variation between stream systems in
Oregon are due primarily to physiographic
province (geology and soils) and climate
(seasonal patterns of precipitation, snowmelt,
and evapotranspiration). For example,
riffles and pools result from in-channel
structures and these structures can vary
between rocks and boulders in the mountains
and roots and wood debris in the alluvial
valleys. The method was designed to apply
to all stream systems within the diverse
hydrologic landscape regions of Oregon.
A substantial amount of variability can also
occur along the length of a given stream
system. Common sources of variation
within a stream system include:
• Longitudinal changes in stream indicators
related to increasing duration and volume
of flow. As streams gain or lose Streamflow,
the presence of indicators changes.
• Longitudinal changes due to variables
such as channel gradient and valley width,
which affect physical processes and thus
may directly or indirectly affect indicators.
• Temporal variation of flow related
to seasonal precipitation and
evapotranspiration pattern. For instance,
in western Oregon the strong seasonal
rainfall pattern - several months of wet
weather followed by several months of
dry weather - supports the establishment
of intermittent streams. Due to these long
periods of rain many of the intermittent
streams in Oregon carry 80 - 90% of
the yearly discharge associated with a
perennial stream of the same size.
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• Transitions in land use, for instance from
commercial forest to pasture/grazing,
from pasture grazing to cultivated farm,
or cultivated farm to an urban setting.
• The size of the stream; streams develop
different channel dimensions due to
differences in flow magnitude, landscape
position, land use history, and other factors.
Reach Selection
This manual lays out a method for assessing
indicators of streamflow duration. However,
flow characteristics often vary along the
length of a stream, resulting in gradual
transitions in flow duration. Recognizing
that in many streams flow duration exists on
a continuum, choosing the reach on which
to conduct an assessment can influence the
resulting conclusion about flow duration.
Assessments should be made for a
representative reach, rather than at one point
of a stream. A representative reach for
stream assessments is equivalent to 35 - 40
channel widths of the stream (Peck et al.
2006). Reach length is measured along the
thalweg. For narrow streams, the length of
the assessment reach should be a minimum
of 30 meters. If the assessment reach is near
a culvert or road crossing, the assessment
reach should begin a minimum of 10 meters
from the culvert or road crossing feature.
Assessments should begin by first walking the
length of the channel, to the extent feasible,
from the stream origin to the downstream
confluence with a larger stream. This initial
review of the site allows the evaluator to
examine the overall form of the channel,
landscape, and parent material, and variation
within these attributes as the channel develops
or disappears upstream and downstream. We
recommend walking alongside, rather than
in, the channel for the initial review to avoid
unnecessary disturbance to the stream and
maximize the opportunity to observe single
indicator organisms (i.e. fish and herpetological
species). Walking the channel also allows
the assessor to observe characteristics of the
watershed such as land use and sources of flow
(e.g. stormwater pipes, springs, seeps, and
upstream tributaries). Once these observations
are made, the assessor can identify the
areas along the stream channel where these
various sources (stormflow, tributaries or
groundwater) or sinks (alluvial fans, abrupt
change in bed slope, etc.) of water may cause
abrupt changes in flow duration. Similarly, the
assessor can identify if the stream segment in
question is generally uniform or might best
be assessed as two or more distinct reaches.
For some purposes (e.g. regulatory) the reach
in question will often be predetermined by
property ownership or proposed activities;
the above process for assessing the stream
should be followed to the extent possible,
and if the reach in question is generally
uniform one assessment is appropriate. If
the reach in question is not uniform, two
or more assessments are recommended
to fully describe the changes along the
reach. Regardless of the number of reaches
assessed, decisions should be made in
conjunction with best professional judgment
to reach a conclusion on flow duration as
ephemeral, intermittent, or perennial.
Recent Precipitation
The rate and duration of flow in stream
channels is influenced by climate and by
recent weather. Recent rainfall can influence
the presence of indicators. Evaluators
should note recent rainfall events on the
assessment form, and consider the timing
of field evaluations in assessing the
applicability of individual indicators.
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Ditches and Modified Natural Streams
This method can be used, in combination
with best professional judgment, to
assess the flow duration of natural
streams, modified natural streams, and
ditches dug in wetlands or uplands.
When assessing a reach that is a ditch or
modified natural stream, it is important to
walk the entire reach and locate the inflow
point or origin as well as the downstream
terminus of flow (most often a confluence with
another channel). Similarly, any disturbance
or modifications to the stream channel should
be noted on the assessment form, especially
if it affects applicability of assessment
indicators. For highly modified streams,
an alternative assessment method may be
necessary to identify flow duration. Visiting the
site multiple times or conducting hydrologic
monitoring may also be necessary. For all
assessments, disturbances or modifications
to the stream or its catchment that may
affect the presence of the streamflow
duration indicators should be noted.
Disturbed or Altered Streams
Assessors should be alert for natural or human-
induced disturbances that affect streamflow
duration and/or the presence of indicators.
Streamflow duration can be directly affected by
flow diversions, urbanization and stormwater
management, septic inflows, agricultural and
irrigation practices, vegetation management,
or other activities. The presence of indicators
can be affected by changes in streamflow,
and can also be affected by disturbances
that may not substantially affect streamflow
(for instance, grading, grazing, recent fire,
beaver activity, riparian management, culvert
installation, and bank stabilization). Such
disturbances should be described in the
"Notes" section of the field assessment
form. Similarly, natural sources of variation
should also be noted such as fractured bedrock,
volcanic parent material, recent or large relic
colluvial activity (landslides or debris flows),
and drought or unusually high precipitation.
Urbanized and impaired streams experiencing
multiple stressors may be poor in biologic
species, raising concerns about the effective
application of this method in those situations
given the importance of macroinvertebrate
indicators in drawing conclusions. A recent
query of Oregon Department of Environmental
Quality's statewide monitoring data of
primarily perennial streams, which includes the
most impaired streams in the state, indicated
that of more than 2000 macroinvertebrate
samples collected, all had at least one mayfly
(Ephemeroptera) individual. Additionally, only
37 samples had less than 6 mayfly individuals;
these low counts could be due to very high
levels of disturbance or sampling error.3 Based
on these data, the Oregon Method should be
widely applicable across Oregon streams,
except in extreme instances of disturbance.
3 Shannon Hubler, Oregon Department
of Environmental Quality, June 2011
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Section 2: Conducting
Field Assessments
Suggested Field Equipment
• This manual, associated assessment
forms, and an all-weather notebook.
• Macroinvertebrate and herpetological field
guides (e.g. Macroinvertebrate s of the
Pacific Northwest, Adams and Vaughan,
2003; Stream Insects of the Pacific
Northwest, Edwards, 2008; Amphibians
of Oregon, Washington and British
Columbia, Corkran and Thorns, 1996).
• Hydrophytic plant identification guides (e.g.
Wetland Plants of Oregon and Washington,
Guard 1995; A Field Guide to Common
Wetland Plants of Western Washington
and Northwest Oregon, Cooke,1997) and
current wetland indicator status list .4
• Global Positioning System (GPS)
- used to identify the boundaries
of the reach assessed.
• Camera - used to photograph
and document site features.
• Clinometer - used to measure
channel slope.5
• Tape measure
• Kicknet or small net and tray - used to
sample aquatic insects and amphibians.
• Hand lens
• Polarized sun glasses - for eliminating
surface glare when looking for fish,
amphibians, and macroinvertebrates.
• Shovel, rock hammer, pick or
other digging tool - to facilitate
hydrological observations/
determination of hyporheic flow.
4 Available at: http://geo.usace.army.
mil/wetland_plants/index.html
5 Channel slope can also be determined
from topographic maps or surveys.
General Guidance for Completing
the Field Assessment Form
The Streamflow Duration Assessment Method
for Oregon relies upon the assessment of
five indicators of flow duration and on the
assessor's understanding of the site. As
with wetland delineation, for best results
we recommend that the method be applied
during the growing season. As described in
the Ditches and Modified Natural Streams
section above, be aware that modifications
to the site or areas upstream of the site may
affect the presence of the indicators. Similarly,
natural variation such as interannual variation
in precipitation can affect the presence of the
indicators used in this method. Therefore, it
is important to accurately complete the entire
field assessment form, including information
for date, project, evaluator, waterway name
and location, recent precipitation, observed
hydrologic status, and channel width.
If the stream does not have a defined channel
(i.e., bed and banks are not apparent),
estimate the width of the flow path and
describe in the "Additional Notes" section.
Any other relevant observations should
also be recorded in the "Additional Notes"
section of the form. These may include the
local geology, runoff rates, hydrologic unit
codes, evidence of stream modifications
or hydrologic alterations upstream of the
assessment area (e.g. dams, diversions,
storm water discharge), and recent land clearing
activities upstream. All pertinent observations
should be recorded on the form, including a
clear and repeatable way of identifying the
boundaries of the reach being assessed and
the reasons for choosing those boundaries.
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Observed Hydrology
Observed hydrology in the assessment reach
informs determination of streamflow duration.
The field evaluator should record hydrological
observations describing percentage of
assessment reach with surface flow, percentage
of reach with any flow (surface or hyporheic),
and number of pools in the reach in the
designated area of the assessment form.
STREAM REACH FLOW
• Observe the stream for the entire
length of the assessment reach.
• Visually estimate the percentage of the
reach length that has flowing surface water.
• Estimate the percentage of the reach length
that has flowing surface water or sub-
surface (hyporheic) flow (see below).
• If there is uncertainty about how to best
characterize a particular assessment reach,
specific observations should be described
on the assessment form, using diagrams
or pictures in support of observations.
HYPORHEIC FLOW
Because it occurs below the surface of
the streambed, hyporheic flow is not
easily observed. However, there are
some observable signs of the presence
of hyporheic flow, including:
• Flowing surface water disappearing
into alluvium deposits, and reappearing
downstream. This is common when there is
a large, recent alluvium deposit created by a
downed log or other grade-control structure.
• Water flowing out of the streambed
(alluvium) and into isolated pools.
• Flowing water below the surface
of the streambed, observed by
moving streambed rocks or digging
a small hole in the streambed.
At sites where the observed surface flow
is less than 100%, look for evidence of
hyporheic flow and use best professional
judgment in entering observations on the data
form. Figure 2 (A- D) provides examples of
how to record hydrological observations.
FIGURE 2, Examples of recording hydrological
observations (R. Coulombe).
2A:
Recorded Observation
% of reach with surface flow = 70%
% of reach with any flow = 70%
isolated pools = 0
Flow
upper reach boundary
Flowing surf ace water in
the upper 70% of reach
Lower reach boundary
2B:
Recorded Observation
% of reach with surface flow = 80%
% of reach with any flow = 100%
isolated pools = 0
Flow) —f£—t f i—upper reach boundary
Flowing surface water In
upper 70% of reach
Flowing surface water [n
the lower 10% of reach
Lower reach boundary
Streamflow Duration Assessment Method for Oregon
November 2011
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Figure 2C: There is pooling (left photo) near the bottom
of the study reach; surface water is flowing into this
area, but there is none flowing out and there is no sign
of flowing water below the pooled area (right photo),
Recorded Observation
% reach with surface flow = 90% (no observed
surface flow along the lowest 10% of the reach)
% reach with any flow =90% (there was no
evidence ofhyporheic flow below the pooled
area or immediately below the reach)
Figure 2D: There is NO evidence of flowing
water into or out of this long pool; yellow lines
are the assessment reach boundaries,
Recorded Observation
% of reach with surface flow = 0%
% of reach with any flow = 0%
# of pools = 1
Observation comment - "One long stagnant
pool covering most of the reach,"
Indicators of Streamflow Duration
Identification of stream type is accomplished
by evaluating five indicators of Streamflow
duration, which are then considered
sequentially using a decision-tree. Natural
disturbances such as recent landslides and
wildfires could mask the presence of some
indicators. Similarly, human modifications
to streams, such as toxic pollution or
cement lined channels, could also preclude
some indicators from forming. These
situations should be explained in the
"Notes" section of the assessment form.
Indicator assessment is based on direct
observation and should not include
predictions of what could or should be
present. Disturbances and modifications to
the stream should be described in the "Notes"
section of the assessment form and taken into
consideration when drawing conclusions from
the information collected. It is also important
to explain the rationale behind conclusions
reached, and when necessary that rationale
should be supported with photos and other
documentation of the reach condition and
any disturbances or modifications that were
taken into consideration. Stream reaches
are categorized as perennial, intermittent, or
ephemeral on the basis of five indicators. To
apply this method, all indicators should first
be evaluated, and the field assessment form
(Appendix B) completed. The indicators are
then considered sequentially, similar to using a
dichotomous key (see Drawing Conclusions).
The answers to each step of the key determine
the relevant indicator for the next step.
Macro!nvertebrate Indicators (1 - 3)
Many macroinvertebrates require the presence
of water, and in many cases flowing water,
for their growth and development. Such
macroinvertebrates are good indicators of
Streamflow duration because they require
aquatic habitat to complete specific life stages.
M Streamflow Duration Assessment Method for Oregon
November 2011
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For example, clams cannot survive outside
of water, in contrast to some stoneflies or
alderflies that resist desiccation in some seasons
of the year by burrowing into the hyporheic
zone. Some macroinvertebrates can survive
short periods of drying in damp soils below the
surface, or in egg or larval stages resistant to
drying. Others are quick to colonize temporary
water and complete the aquatic portion of
their life cycle during the wettest part of the
year when sustained flows are most likely.
The three macroinvertebrate indicators used
here are assessed within the defined reach
using a single search. The assessment for all
three macroinvertebrate indicators requires a
minimum 15 minute search time to sample the
range of habitats present, including water under
overhanging banks or roots, accumulations
of organic debris (e.g. leaves), woody debris,
and the substrate (pick up rocks and loose
gravel, also look for empty clam shells
washed up on the bank in the coarse sand).
A kicknet or D-frame net and a hand lens are
required to collect and identify specimens.
Begin sampling at the most downstream point
in the assessment reach and move upstream
to each new sampling site. Place the kicknet
perpendicular against the streambed and
stir the substrate upstream of the net for a
minimum of one minute, empty contents
of the net into a white tray with fresh water
for counting and identification. Many
individuals will appear the same until seen
against a contrasted color background, and
some bivalves and other macroinvertebrates
can be pea-sized or smaller. Sweeping grass
and shrubs in the riparian zone immediately
adjacent to the active channel with a funnel-
shaped insect net may collect emergent aquatic
insects such as stoneflies or caddisflies.
Dry channels: The reach should first be
walked to ascertain whether it is completely
dry, or if areas of standing water where aquatic
macroinvertebrates may collect remain. Focus
the search on areas of likely refuge such as any
remaining pools or areas of moist substrate
for living macroinvertebrates, the sandy
channel margins for mussel and aquatic snail
shells, and under cobbles and other larger
bed materials for caddisfly casings. Casings
of emergent mayflies or stoneflies may be
observed on dry cobbles or on stream-side
vegetation. In summary, we recommend a
methodology consistent to that recommended
by the Xerces Society report on using aquatic
macroinvertebrates as indicators of streamflow
duration (Mazzacano and Black, 2008).
SEARCHING IS COMPLETE WHEN:
• at least 6 samples have been collected
across the range of habitat types and 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. In dry stream channels
with little bed/bank representation and
little habitat diversity, a search may be
completed in less than 15 minutes.
The 15 minute estimate for searching
does not reflect time spent on identifying
individuals, rather it is wholly focused
on the searching and gathering effort. It
is important to complete the search for
macroinvertebrates, as described above, prior
to indentifying taxa necessary to evaluate the
three indicators. The data sheet includes an
area for noting observed macroinvertebrates.
Streamflow Duration Assessment Method for Oregon
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Notes:
These indicators do not differentiate
between live organisms and shells,
casings, and exuviae (i.e., the external
coverings of larvae and nymphs). In other
words, mussel shells are treated the same as
live mussels, and caddisfly cases are treated
the same as live caddisflies (Figure 3).
The assessment is based only on what
is observed, not on what would be
predicted to occur if the channel were
wet, or in the absence of disturbances
or modifications. Disturbances and
modifications should be described in the
"Notes" section of the data form and taken
into account when drawing conclusions.
Figure 3: Example of caddisfly casings of: A) the
Limnephilidae family (photo: L, Webb), and B) abundant
casings from an intermittent stream in the Ochoco
Mountains, central Oregon (photo: J, Wigington),
I. PRESENCE OF AQUATIC
MACROINVERTEBRATES
Are there aquatic macroinvertebrates
in the assessment reach? If at
least one macroinvertebrate (or
macroinvertebrate shell, casing, or
exuviae) is present, the answer is "yes." *
This indicator includes the range of
macroinvertebrates typically associated
with stream habitats including: Coleoptera
(aquatic beetles), Diptera (true flies),
Ephemeroptera (mayflies), Megaloptera
(dobsonflies and alderflies), Mollusca
(snails and clams), Odonata (dragonflies
and damselflies), Plecoptera (stoneflies),
Trichoptera (caddisflies), and Astacoidea
(crayfish). Macroinvertebrates of the Pacific
Northwest (Adams and Vaughan, 2003)
and Stream Insects of the Pacific Northwest
(Edwards, 2008) provide useful, compact
field guides for general identification
of several aquatic macroinvertebrate
families found in Oregon streams.
*Exception: If the ONLY macroinvertebrate
present is Culicidae (mosquito)
larvae/pupae, which is an ephemeral
indicator taxon (Mazzacano and
Black, 2008), the answer is "no."
2. PRESENCE OF 6 OR MORE
EPHEMEROPTERA
Are 6 or more individuals of the Order
Ephemeroptera present in the assessment
reach? If at least six Ephemeroptera
are present, the answer is "yes."
Ephemeroptera (mayflies) are present in
many stream systems. Adults are short-lived
and are commonly observed in swarms over
streams. Immature mayflies are aquatic
and have the following characteristics:
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• Short and bristle-like antenna;
• Four to nine pairs of leaf-like or
fan-like gills usually visible along
the sides of the abdomen;
• Three (rarely two) long filaments
at rear of abdomen.
3. PRESENCE OF PERENNIAL
INDICATOR TAXA
Are there perennial indicator taxa
in the assessment reach? If at least
one individual (or macroinvertebrate
shell, casing, or exuviae) of such taxa
is present, the answer is "yes."
Certain macroinvertebrate taxa are
associated with the prolonged presence
of water. Based on a literature review and
synthesis completed by the Xerces Society
for Invertebrate Conservation (Mazzacano
and Black, 2008)6, several taxa and
lifestages of macroinvertebrates occurring
in Oregon streams have been identified
as "Perennial Indicators" (Table 1).
Table 1: Perennial Indicator Taxa and Life Stages
Any lifestage of:
• Juga spp. (pluerocerid snail)
• Margaritiferidae, Unionidae
(freshwater mussels; less likely in
small, high-gradient streams)
Larvae/pupae of:
• Philopotamidae (finger-net caddisfly)
• Hydropsychidae (net-spinning caddisfly)
• Rhyacophilidae (freeliving caddisfly)
• Glossosomatidae (saddle case-maker caddisfly;
especially in forested headwater streams)
Nymphs of:
• Pteronarcyidae (giant stonefly)
• Perlidae(golden stonefly)
Larvae of:
• Elmidae (riffle beetle)
• Psephenidae (water penny;
especially in eastern Oregon)
Larvae/nymphs of:
• Gomphidae (clubtail dragonfly; especially
in larger streams of eastern Oregon)
• Cordulegastridae (biddies; especially in
larger streams of eastern Oregon)
6 Available at: http://www.xerces.
org/aquatic-invertebrates/
Additional Indicators (4 and 5)
4. WETLAND PLANTS IN OR
NEAR STREAMBED
Within the assessment channel, and within
one-half channel width of the stream
on either bank, are there plants with a
wetland indicator status of FACW or OBL,
or is there submerged aquatic vegetation
present? If so, the answer is "yes."
The USAGE wetland delineation procedure
uses a plant species classification system
which identifies hydrophytic plants. Likewise,
the presence of hydrophytic plants can
be used as an indicator of the duration of
soil saturation in or near stream channels.
Intermittent and perennial streams will often
have obligate wetland (OBL) and facultative
wetland (FACW) plants or submerged aquatic
vegetation (S AV) growing in or immediately
adjacent to the streambed. S AV grows
completely underwater. To determine the
wetland indicator status of a plant, consult
the National Wetland Plant List (NWPL).
The NWPL, formerly called the National
List of Plant Species that Occur in Wetlands
and last updated in 1993, is currently
being revised by the USAGE, the U.S.
Fish and Wildlife Service, USEPA, and the
Natural Resource Conservation Service.
The release date of the final list will be
published in the Federal Register. Until
then, the draft NWPL can be accessed at:
http://wetland_plants.usace.army.mil/.
The wetland plant indicator is assessed
based on the single most hydrophytic
wetland plant found in or within one-half
channel width of the assessed reach, even
if that plant is not a dominant species.
Streamflow Duration Assessment Method for Oregon
November 2011
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Notes:
• Abundance and prevalence
throughout the reach is not a factor
in determining this indicator.
• While it is sometimes most convenient
to take plant samples off-site for
identification at a later date, please note
that several aquatic plant species are
protected by state and federal laws.
5. SLOPE
What is the 'straight line' slope, as measured
with a clinometer, from the beginning of
the reach to the end of the reach? Is it
greater than or equal to 10.5%? To 16%?
Channel slope is measured as percent slope
between the lower and upper extent of
the assessment reach. This is most easily
accomplished by a two-person team, with
one individual standing in the thalweg at the
downstream extent of the reach and, using
a clinometer, sighting a location at eye-
level at the upper extent of the reach, (e.g.
if team members are of the same height,
one individual standing in the thalweg at
the lower end of the reach would 'site' the
eyes of the crew member standing in the
thalweg at the upper end of the reach).
This measurement requires direct line-of-
site between the lower and upper ends of the
reach. If direct line-of-site from the bottom
to top of the reach is not possible, the slope
of the longest representative portion of the
reach should be 'line-of-site' evaluated.
Note: This measurement is not necessarily
the same as the 'average water-surface slope'
which is often evaluated as part of stream
ecological assessments including USEPA's
Environmental Monitoring and Assessment
Program (EMAP) (Peck et al., 2006) and
Oregon Department of Fish and Wildlife's
Aquatic Inventory (Moore et al., 2006).
Ancillary Information
The presence of these features should be
noted and briefly described, if applicable,
as indicated on the assessment form.
Riparian Corridor: Is there a distinct
change in vegetation between the
surrounding uplands and the riparian zone,
or corridor, along the stream channel?
Intermittent and perennial streams often
support riparian areas that contrast markedly
with adjacent upland plant communities.
A distinct change in vegetation between
the surrounding lands and the riparian
area (top of bank and adjacent areas) may
indicate the presence of seasonal moisture.
Erosion and Deposition: Does the channel
show evidence of fluvial erosion in the
form of undercut banks, scour marks,
channel downcutting, or other features of
channel incision? Are there depositional
features such as bars or recent deposits
of materials in the stream channel?
Undercut banks and scour marks are the
most common signs of fluvial erosion for
streams in a floodplain system. In steeper
landscapes, channel downcutting and
incision may occur. Alluvium may be
deposited as sand silt, gravel and cobble.
Sometimes there may be depositional
features along the side of the channel
or on the lee side of obstructions in the
channel (e.g. in the hydraulic shadow
of logs, boulders, etc.). Erosion and
deposition processes differ between
bedrock and alluvial channels; note if the
streambed consists primarily of bedrock.
Floodplain connectivity: Is there an active
floodplain at the bankfull elevation?
A floodplain is a level area near a stream
channel, constructed by the stream
and overflowed during moderate flow
Streamflow Duration Assessment Method for Oregon
November 2011
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events if there is still connectivity. An
active floodplain (at current bankfull
elevation, such that it is inundated
on an approximate 2-year recurrence
interval) shows characteristics such as
drift lines, sediment and debris deposits
on the surface or surrounding plants, or
flattening of vegetation. The floodplain
of incised streams may be restricted to
within the channel itself and the previous
floodplain (now a terrace) may be
inundated rarely or infrequently, if at all.
Streamflow Duration Assessment Method for Oregon
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Section 3: Drawing
Conclusions
Results of the five-indicator field evaluation,
applied to the assessment decision-tree (Figure
4; also included on the field assessment
form), are used to make a finding as to
whether the assessed stream has perennial,
intermittent, or ephemeral streamflow.
In addition, the method indicates a stream
is at least intermittent when either of the
two following criteria, for the presence
of fish or for the presence of specific
herpetological species, is met.
Single Indicator Criteria
1. One or more fish are found
in the assessment reach.*
Fish are an obvious indicator of flow presence
and duration. Fluctuating water levels of
intermittent and ephemeral streams provide
unstable and stressful habitat conditions
for some fish communities. However, the
strongly seasonal precipitation pattern in
Oregon means intermittent streams may
flow continuously for several months; thus,
some native fish species have evolved to use
intermittent streams for significant portions
of their lifespan (e.g. Wigington et al. 2006).
When looking for fish, all available habitats
should be searched, including pools, riffles,
root clumps, and other obstructions. In
small streams, the majority of fish species
usually inhabit pools and runs. Also, fish will
seek cover if disturbed, so we recommend
checking several areas along the sampling
reach, especially underneath undercut banks
and other places likely to provide cover.
*Exception: Non-native fish, with the
exception of mosquito fish (Gambusia spp.)
that has been placed as a vector control, are
also included in the assessment. If Gambusia
spp. is encountered as the only fish species
present, its placement as a vector control
at the site must be documented, along with
an explanation of why the single indicator
('presence of fish') conclusion does not apply.
2. One or more individuals of an
amphibian or snake life stage (adult,
juvenile, larva, or eggs) identified as
obligate or facultative wet (Table 2)
are present in the assessment reach.
Amphibians, by definition, are associated
with aquatic habitats, and some amphibians
require aquatic habitat for much or all of their
lives. In Oregon, there are likewise three
snake species that require aquatic habitat
Figure 4: Decision tree for drawing conclusions from assessed indicators
Are aquatic
macro-invertebrates
present?
(Indicator 1)
If Yes: Are 6 or
more individuals
of the Order
Ephemeroptera
present?
(Indicator 2)
If No: Are SAV,
FACW, orOBL
plants present?
(Indicator 4)
If Yes: Are
perennial indicator
taxa present?
(Indicator 3)
If No:
INTERMITTENT
If Yes: What is the
slope?
(Indicator 5)
If No:
EPHEMERAL
If Yes:
PERENNIAL
If No: What is the
slope?
(Indicator 5)
Slope < 10.5%: ]
INTERMITTENT J
Slope > 10.5%:
EPHEMERAL
J
Slope < 16%:
INTERMITTENT
J
Slope > 16%
PERENNIAL
J
Streamflow Duration Assessment Method for Oregon
November 2011
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for significant portions of their life cycle.
This indicator focuses on the life history
stages of salamanders, frogs, toads, and
snake species that require aquatic habitat
by indicating life history stages for these
species as facultative (FAC), facultative
wet (FACW), or obligate (OBL).7
7 The designations "FAC", "FACW", and "OBL"
are based on a review of the scientific literature
and current understanding of the life history
stages of these herpetological species.
This indicator is assessed using a minimum
20 minute search time, within one channel
width from the top of both stream banks, to
sample the range of habitats present This
search can be conducted concurrently with
the macroinvertebrate search (Indicators
1-3) for greatest efficiency. Various life
stages of frogs and salamanders can be found
under rocks, on stream banks and on the
bottom of the stream channel. They may also
appear in benthic samples. Using kicknets
or smaller nets and light colored tubs for
Species
Common Name
Water-Dependent Life Stages
Eggs
Larva /
Tadpole
Juve.
Adult
Aquatic Salamanders
Ambystoma gracile
Ambystoma macrodactylum
Ambystoma tigrinum
Taricha granulosa
Dicamptodon cope/
Dicamptodon tenebrosus
Rhyacotriton spp.
Northwest Salamander
Long-toed Salamander
Tiger Salamander (rare)
Roughskin Newt
Cope's Giant Salamander
Pacific Giant Salamander
Torrent Salamanders (rare)
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
FACW
FACW
FACW
FAC
OBL
OBL
OBL
FACW
FACW
FACW
FAC
OBL
FACW
OBL
Frogs and Toads
Ascaphus truei
Spea intermontana
Bufo boreas
Bufo woodhousii
Pseudacris regilla
Rana aurora
Rana boylii
Rana cascadae
Rana catesbeiana
Rana pretiosa
Rana luteiventris
Tailed Frog
Great Basin Spadefoot
(Eastern Oregon)
Western Toad
Woodhouse's Toad
(Eastern Oregonl
Pacific Treefrog
Red-Legged Frog
Foothill Yellow-Legged Frog
Cascades Frog
Bullfrog
Oregon Spotted Frog
Columbia Spotted Frog
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
OBL
FAC
FAC
FAC
FACW
FACW
OBL
FACW
FACW
OBL
OBL
OBL
FAC
FAC
FAC
FAC
FACW
OBL
FACW
FACW
OBL
OBL
Snakes
Thamnophis atratus
Thamnophis elegans
Thamnophis sirtalis
Western Aquatic Garter
Snake (SW Oregon)
Wandering Garter Snake
Common Garter Snake
OBL
FACW
FACW
OBL
FACW
FACW
Table 2: Water-dependent life stages of amphibians and snakes of the Pacific Northwest, OBL - obligate, requires
surface or hyporheic water; FACW - facultative wet, strong preference for surface or hyporheic water; FAC -
facultative, uses but does not depend on surface or hyporheic water. These designations are based on a review
of the scientific literature and current understanding of the life history stages of these herpetological species.
Streamflow Duration Assessment Method for Oregon
November 2011
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specimen collection and identification is
recommended. Certain frogs and tadpoles, as
well as adult and larval salamanders typically
inhabit the shallow, slower moving waters of
stream pools and near the sides of banks.
Amphibians of Oregon, Washington, and
British Columbia (Corkran and Thorns,
1996) is a useful field guide for identifying
amphibians of the Pacific Northwest.
Note: Vertebrates must be identified at the
assessment site, and left at the site following
identification. We recommend that a series of
photos be taken of any species in question to
allow further identification to be done off-site,
if necessary. Please note that several animal
species, including fish and amphibian species,
are protected by state and federal laws.
ADDITIONAL CONSIDERATIONS
If the stream does not have a bed and banks,
is covered with wetland plant species,
and/or indicators cannot be assessed, it
may be more appropriate to consider the
reach as a swale, wetland, or upland.
As discussed in the introductory sections, if
the channel does not meet the decision-tree
or single indicator criteria and the evaluator
believes the channel to be perennial or
intermittent, the evidence supporting this
assertion should be clearly described on the
assessment form. This may occur in highly
polluted or recently manipulated streams; in
those cases, the indicators that could potentially
be there were it not for the pollution/
manipulation should be described in the
"Additional Notes" section of the field form.
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Appendix A: References
Consulted
Adams, J. and M. Vaughan, 2003.
Macroinvertebrates of the Pacific
Northwest: A Field Guide. The
Xerces Society, Portland, OR.
Adams, J., M. Vaughan and S.H. Black,
2004. Stream Bugs as Biomonitors:
Guide to Pacific Northwest
Macroinvertebrate Monitoring. The
Xerces Society, Portland, OR.
Adams, M.J. and R.B. Bury, 2002. The endemic
headwater stream amphibians of the
American Northwest: associations
with environmental gradients in a large
forested preserve. Global Ecology
& Biogeography 11:169-178.
Anderson, R. J., B.P Bledsoe and W.C. Hession,
2004. Width of streams and rivers in
response to vegetation, bank material, and
other factors. Journal of American Water
Resources Association 40:1159-1172.
Arp, C.D., M.N. Gooseff, M.A. Baker and
W. Wurtsbaugh, 2006. Surface-water
hydrodynamics and regimes of a small
mountain stream-lake ecosystem.
Journal of Hydrology 329:500- 513.
Barbour, M.T., J. Gerritsen, B.D. Snyder and J.B.
Stribling, 1999. Rapid Bioassessment
Protocols for Use in Streams and
Wadeable Rivers: Periphyton, Benthic
Macroinvertebrates and Fish, Second
Edition. EPA 841-B-99-002. U.S.
Environmental Protection Agency,
Office of Water; Washington, D.C.
Bencala, K.E., 2005. Hyporheic exchange flows.
In: Anderson, M. and J.J. McDonnell (Eds).
Encyclopedia of Hydrological Sciences,
Volume 3. John Wiley and Sons, New York.
Benda, L., M.A. Hassan, M. Church, and C.L.
May, 2005. Geomorphology of steepland
headwaters: the transition from hillslopes
to channels. Journal of American Water
Resources Association 41:835-851.
Bendix, J. and C.R. Hupp, 2000. Hydrological
and Geomorphological Impacts
on Riparian Plant Communities.
Hydrological Processes 14:2977-2990.
Beyer, P., 2006. Variability in channel form
in a free-flowing dryland river. River
Research and Applications 22:203-217.
Biek, R., L.S. Mills and R.B. Bury, 2002. Terrestrial
and stream amphibians across clearcut-
forest interfaces in the Siskiyou Mountains,
Oregon. Northwest Science 76:129-140.
Bohn, C.C. and J.G. King, 2000. Stream channel
responses to streamflow diversion on small
streams of the Snake River drainage, Idaho.
Res. Pap. RMRS-RP-20. Ogden, UT: US
Department of Agriculture, Forest Service,
Rocky Mountain Research Station. 19p.
Boulton, A. J., 2003. Parallels and contrasts
in the effects of drought on stream
macroinvertebrate assemblages.
Freshwater Biology 48:1173-1185.
Brady, N.C. and R.R. Weil, 1999. The Nature
and Properties of Soils. Third Edition.
Prentice Hall, Upper Saddle River, NJ.
Bragg, O.M., A.R. Black, R.W Duck, and
J.S. Rowan, 2005. Approaching the
physical-biological interface in rivers:
a review of methods for ecological
evaluation of flow regimes. Progress in
Physical Geography 29:4:506-531.
Brostoff, W, R. Lichvar and S. Sprecher,
2001. Delineating Play as in the Arid
Southwest a Literature Review. U.S.
Army Corps of Engineers, Engineer
Research and Development Center
(ERDCTR-01-4),pp. 1-25.
Brummer, C.J. and D.R. Montgomery,
2003. Downstream coarsening
in headwater channels. Water
Resources Research 39:ESG1-14.
Bunn, S.E., M.C. Thorns, S.K. Hamilton and
S.J. Capon, 2006. Flow variability in
dryland rivers: boom, bust and the bits in
between. River Res. Applic. 22:179-186.
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Streamflow Duration Assessment Method for Oregon
November 2011
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Appendix B: Streamflow Duration Field Assessment Form
Project # / Name
Assessor
Address
Date
Waterway Name
Reach Boundaries
Coordinates at i_at.
downstream end
(ddd.mm.ss)
Long.
N
W
Precipitation w/in 48 hours (cm)
Channel Width (m)
D Disturbed Site / Difficult
Situation (Describe in "Notes")
% of reach w/observed surface flow_
Observed
Hydrology
% of reach w/any flow (surface or hyporheic).
# of pools observed
o
1
%
.0
O
Observed Wetland Plants
(and indicator status):
Observed Macroinvertebrates:
Taxon Indicator Ephemer- # of
Status optera? Individuals
o
'•5
1. Are aquatic macroinvertebrates present?
Yes
No
2. Are 6 or more individuals of the Order Ephemeroptera present?
Yes
No
3. Are perennial indicator taxa present? (refer to Table 1)
Yes
No
4. Are FACW, OBL, or SAV plants present? (Within y2 channel width)
Yes
No
5. What is the Slope? (In percent, measured for the valley, not the stream)
c
o
'55
"o
o
O
Are aquatic
macroinvertebrates
present?
(Indicator 1)
If Yes: Are 6 or
more individuals
of the Order
Ephemeroptera
present?
(Indicator 2)
If No: Are SAV,
FACW, or OBL
plants present?
(Indicator4)
If Yes: Are perennial
indicator taxa
present?
(Indicator 3)
If No:
INTERMITTENT
If Yes: What is the
slope?
(Indicator 5)
If No:
EPHEMERAL
If Yes: PERENNIAL
If No: What is the
slope?
(Indicator 5)
Slope < 16%:
INTERMITTENT
>16%:\
LNNIAL J
Slopes
PERENNIAL
Slope < 10.5%:
INTERMITTENT
D
Slopes 10.5%:
EPHEMERAL
D
Single Indicators:
D Fish
n Amphibians
Finding:
Ephemeral
Intermittent
Perennial
Streamflow Duration Assessment Method for Oregon
November 2011
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Notes:
single indicator conclusions, description of disturbances or modifications that may
interfere with indicators, etc.)
Difficult Situation:
n Prolonged Abnormal Rainfall / Snowpack
D Below Average
O Above Average
D Natural or Anthropogenic Disturbance
n Other:
Describe situation. For disturbed streams, note extent,
type, and history of disturbance.
Additional Notes: (sketch of site, description of photos, comments on hydrological observations, etc.) Attach
additional sheets as necessary.
Ancillary Information:
D Riparian Corridor
D Erosion and Deposition
D Floodplain Connectivity
Observed Amphibians, Snake, and Fish:
Taxa
Life
History
Stage
Location
Observed
Number of
Individuals
Observed
Streamflow Duration Assessment Method for Oregon
November 2011
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United States
Environmental Protection
Agency
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