**BASELINE ASSESSMENT OF STREAM HABITAT AND MACROINVERTEBRATE
COMMUNITIES IN AND ADJACENT TO THE DAMASCUS AREA URBAN GROWTH BOUNDARY
EXPANSION, OREGON**

**2006 FINAL REPORT**

Prepared by

Michael B. Cole

ABR, Inc.\--Environmental Research & Services

P.O. Box 249

Forest Grove, Oregon 97116

and

Lori A. Hennings

Metro

600 NE Grand Ave.

Portland, OR 97232-2736

**EXECUTIVE SUMMARY**

-   Portland, Oregon's Urban Growth Boundary (UGB) was expanded in 2003
    by more than 12,000 acres in the Damascus area, representing the
    single largest expansion of the UGB since its establishment. The
    primary objective of this study was to characterize current benthic
    macroinvertebrate, water quality, and physical habitat conditions in
    streams occurring within and adjacent to the expansion area. A
    secondary objective of the study was to investigate the effects of
    forested buffers within the study area on macroinvertebrate
    communities.

-   Macroinvertebrate communities, physical habitat, and water chemistry
    were sampled from 40 study reaches in and adjacent to the expansion
    area between September 29 and October 15, 2003, including six
    reaches on the Clackamas River and 34 reaches in smaller drainages,
    including Rock, Richardson, Noyer, NF Deep, Butler, and Kelly
    creeks.

-   Macroinvertebrate data were analyzed using both multimetric and
    multivariate techniques. Riffle samples were analyzed using the
    Oregon Department of Environmental Quality's ten-metric set and
    scoring criteria. Impairment levels were assigned to benthic
    communities from each reach based on these results. Multivariate
    ordination was used to examine the data for patterns in
    macroinvertebrate community composition, followed by correlation
    with environmental variables to detect relationships between
    macroinvertebrate community composition and physicochemical
    conditions.

-   Study stream reaches encompassed a wide range of riparian and stream
    channel conditions. Riparian conditions varied widely, but on the
    four larger tributary systems: Rock, Richardson, Noyer, and NF Deep
    creeks, riparian zones were largely intact and often extended 50-100
    m out from each bank, particularly in the lower reaches of these
    systems. Streams occurring within the study area ranged in size,
    gradient, substrate composition, and relative frequencies of
    different habitat types. Using the Rosgen Level II geomorphic
    classification system, a number of stream channel types occurred in
    the study area; the most common were B3 and G3 channels, with 11 of
    the of the former and 8 of the latter type occurring in the sample
    of 34 reaches.

-   NMS of 3^rd^- to 5^th^-order reaches produced a 3-dimensional
    ordination that explained 74% of the original variation among
    samples. Axis one accounted for 2/3 of that explained variation.
    Environmental variables significantly correlated with axis one
    included specific conductance and a number of land use/land cover
    variables. Land use land cover variables that were significantly
    correlated with NMS axis 1 were % forested area for 1500 m upstream
    at 50, 100, and 200-m wide, and numerous land use/cover variables at
    various widths extending the entire upstream length.

-   Macroinvertebrate community conditions, as indicated by multimetric
    scores, ranged from 10 to 42 among sampled reaches. Communities in
    most reaches were classified as slightly or moderately impaired, as
    13 reaches scored in the slightly impaired range and 17 reaches
    scored in the moderately impaired range. Six reaches scored in the
    severely impaired range, while only one reach, located in Richardson
    Creek, scored in the unimpaired range. Clackamas River reaches all
    scored as moderately impaired, ranging from 24 to 28.

-   A distinct longitudinal trend occurred in four of the larger
    watersheds in the study area. The three Noyer Creek reaches were
    scored as slightly, moderately, and severely impaired from
    downstream to upstream. A similar longitudinal trend was observed
    among North Fork Deep Creek riffle sample scores, as scores
    increased from 10 (severely impaired) to 26 (moderately impaired)
    from upstream to downstream. Rock Creek, and to a lesser extent,
    Richardson Creek, also showed longitudinal trends of increasing
    multimetric scores from upstream to downstream.

-   Macroinvertebrate impairment class was significantly related to
    several variables describing forested riparian conditions. Three of
    the six variables (those where land use percentages were calculated
    for the entire upstream distance) were significant at alpha = 0.01,
    while two of the remaining three (those buffered for 1500 m
    upstream) were significant at alpha = 0.05. Percent forested cover
    in a 200-m buffer was more significant than forested cover within
    100 or 50-m buffers (alpha = 0.026~200~, 0.046~100~, 0.063~50~).

-   This study characterized baseline benthic biological conditions in
    streams occurring throughout the Damascus UGB expansion area. The
    data can be used to track changes over time in response to
    urbanization of the watershed, but only with adequate
    characterization of current spatial and temporal variability within
    the watershed.

**TABLE OF CONTENTS**

[LIST OF FIGURES iii](#list-of-figures)

[LIST OF TABLES iv](#list-of-tables)

[ACKNOWLEDGMENTS vi](#acknowledgments)

[INTRODUCTION 1](#introduction)

[STUDY AREA 2](#study-area)

[METHODS 3](#methods)

[STUDY REACH SELECTION 3](#study-reach-selection)

[FIELD DATA COLLECTION 3](#field-data-collection)

[SAMPLE SORTING AND MACROINVERTEBRATE IDENTIFICATION
6](#sample-sorting-and-macroinvertebrate-identification)

[QUALITY ASSURANCE 6](#quality-assurance)

[DATA ANALYSIS 6](#data-analysis)

[*Multivariate Pattern Analysis* 7](#multivariate-pattern-analysis)

[*Multimetric Analysis* 8](#multimetric-analysis)

[RESULTS 10](#results)

[DISCUSSION 13](#discussion)

[MONITORING STRATEGY 18](#monitoring-strategy)

[LITERATURE CITED 20](#literature-cited)

# LIST OF FIGURES

[Figure 1. Location maps of 40 stream and river reaches sampled for
macroinvertebrates, water quality, and physical habitat in and adjacent
to the Damascus area urban growth boundary expansion, Clackamas County,
Oregon, fall 2003. 32](#__RefHeading___Toc140899292)

[Figure 2. NMS ordination biplot of macroinvertebrate samples collected
from 34 stream reaches in and adjacent to the Damascus area urban growth
boundary expansion, Oregon, fall 2003. Environmental variables that were
significantly correlated (p \< 0.01) with NMS axes Vector lines point in
the direction that the stated variable increases; longer lines indicate
a stronger correlation. 33](#__RefHeading___Toc140899293)

[Figure 3. NMS ordination biplots of macroinvertebrate samples collected
from 19 moderate-gradient (\>1.5%) stream reaches in and adjacent to the
Damascus area urban growth boundary expansion, Oregon, fall 2003.
Environmental variables that were significantly correlated (p \< 0.01)
with NMS axes Vector lines point in the direction that the stated
variable increases; longer lines indicate a stronger correlation.
34](#__RefHeading___Toc140899294)

[Figure 4. NMS ordination biplot of macroinvertebrate samples collected
from 19 moderate-gradient (\>1.5%) stream reaches in and adjacent to the
Damascus area urban growth boundary expansion, Oregon, fall 2003. The
vector line represents the significance and direction of the correlation
between Multimetric Scores and NMS axis 1.
35](#__RefHeading___Toc140899295)

[Figure 5. Frequency of multimetric scores of macroinvertebrate
communities sampled from 31 stream reaches in and adjacent to the
Damascus area urban growth boundary expansion, Oregon, fall 2003.
36](#__RefHeading___Toc140899296)

[Figure 6. Macroinvertebrate community multimetric scores from the four
Clackamas River tributaries occurring in and adjacent to the Damascus
area urban growth boundary expansion, Clackamas County, Oregon, fall
2003. Scores from sample reaches are arranged from downstream to
upstream on each graph to illustrate longitudinal trends in community
conditions on each system. 37](#__RefHeading___Toc140899297)

[Figure 7. Relationships between macroinvertebrate metrics (including
Multimetric Scores) and specific conductance, the only field-measured
environmental variable that was significantly correlated with metric
scores calculated from macroinvertebrate samples collected from 3^rd^
through 5^th^-order streams in and adjacent to the Damascus area urban
growth boundary expansion, Clackamas County, Oregon, fall 2003.
38](#__RefHeading___Toc140899298)

[Figure 8. Relationships between Multimetric Scores and land use/cover
variables that were significantly with these scores calculated from
macroinvertebrate samples collected from 3^rd^ through 5^th^-order
streams in and adjacent to the Damascus area urban growth boundary
expansion, Clackamas County, Oregon, fall 2003.
39](#__RefHeading___Toc140899299)

[Figure 9. Relationships between percent forested cover (using six
different GIS buffer dimensions) and macroinvertebrate community
impairment in stream reaches sampled for macroinvertebrates in and
adjacent to the Damascus area urban growth boundary expansion, Clackamas
County, Oregon, fall 2003. The first three buffer variables are percent
forested area within the stated width for the entire upstream distance.
One asterisk indicates a significant effect of impairment class on
percent forest cover at alpha = 0.05; two asterisks indicate a
significant effect of impairment class on percent forest cover at alpha
= 0.01. 40](#__RefHeading___Toc140899300)

# LIST OF TABLES

[Table 1. Stream reaches sampled for macroinvertebrates, physical
habitat, and water quality in and adjacent to the Damascus area urban
growth boundary expansion, Oregon, fall 2003.
22](#__RefHeading___Toc140899174)

[Table 2. Environmental variables measured in the field for
characterizing stream reaches in and adjacent to the Damascus area urban
growth boundary expansion, Oregon, fall 2003.
24](#__RefHeading___Toc140899175)

[Table 3. Buffer dimensions use to calculate percent land use/cover
adjacent to stream reaches sampled for macroinvertebrates, physical
habitat, and water chemistry in and adjacent to the Damascus area urban
growth boundary expansion, Oregon, fall 2003.
25](#__RefHeading___Toc140899176)

[Table 4. Metric set and scoring criteria (WQIW 1999) used to assess
condition of macroinvertebrate communities sampled in and adjacent to
the Damascus area urban growth boundary expansion, Clackamas County,
Oregon, fall 2003. 26](#__RefHeading___Toc140899177)

[Table 5. Occurrence of Rosgen stream channel types in streams sampled
for macroinvertebrates, physical habitat, and water chemistry in and
adjacent to the Damascus area urban growth boundary expansion, Clackamas
County, Oregon, fall 2003 27](#__RefHeading___Toc140899178)

[Table 6. Environmental conditions of 31 stream reaches from which
riffles were sampled for macroinvertebrates in and adjacent to the
Damascus area urban growth boundary expansion, Clackamas County, Oregon,
fall 2003. 28](#__RefHeading___Toc140899179)

[Table 7. Environmental variables significantly correlated (at **α** =
0.01) with NMS axes resulting from ordination of macroinvertebrate data
from 3^rd^, 4^th^, and 5^th^-order stream reaches sampled in and
adjacent to the Damascus area urban growth boundary expansion, Oregon,
fall 2003. 29](#__RefHeading___Toc140899180)

[Table 8. Descriptive statistics of macroinvertebrate community metrics
calculated from riffle samples collected from 31 stream reaches in and
adjacent to the Damascus area urban growth boundary expansion, Oregon,
fall 2003. 30](#__RefHeading___Toc140899181)

[Table 9. Multimetric scores and impairment classes of macroinvertebrate
communities sampled from riffles in 37 stream reaches in and adjacent to
the Damascus area urban growth boundary expansion, Clackamas County,
Oregon, fall 2003. 31](#__RefHeading___Toc140899182)

# ACKNOWLEDGMENTS

This study was funded by a grant from the US Fish and Wildlife Service /
Metro Greenspaces program. Jennifer Thompson with the US Fish and
Wildlife service administered the grant. Matt Killian and Adam Harris of
ABR, Inc. collected much of the field data for this study. Adam and
Katri Laukkanen sorted macroinvertebrate samples. J.O. Price of Metro
and Rich Blaha of ABR Inc. provided GIS support.

# INTRODUCTION

In 2002, the Urban Growth Boundary (UGB) was expanded to include more
than 12,000 acres in the Damascus area, representing the single largest
expansion of the UGB since its establishment. The expansion area is
currently dominated by agricultural and rural residential land uses,
with some small forested tracts still occurring in uplands and adjacent
to streams. A number of the larger tracts of forested land are riparian
corridors presently occurring in lower portions of several of the
drainages within the study area.

Urbanization of watersheds is known to have potentially profound effects
of aquatic habitat and aquatic life, including fish and
macroinvertebrate communities. Assessing the condition of natural
resources in the UGB expansion project area prior to urbanization will
provide baseline data of pre-urbanization ecological conditions against
which future conditions can be compared in relation to development
patterns. Monitoring physical and biological conditions in streams
before and during urbanization of the area will help determine just what
effects urban development will have on area streams.

Examining macroinvertebrate communities has gained wide acceptance as a
reliable and meaningful tool for monitoring the condition of surface
waters. Because these biological communities integrate the effects of
multiple stressors---excess nutrients, toxic chemicals, increased
temperature, excessive sediment loading, and others---they provide a
reliable measure of the overall ability of a water body to support
aquatic life. A study of macroinvertebrate communities in the upper and
middle Tualatin River basin in 2001 indicated that area
macroinvertebrate communities respond measurably to degraded stream
conditions and their condition can be related to surrounding land use
conditions (Cole 2002). A number of other regional assessments of
macroinvertebrate communities in northern Willamette Valley streams have
been performed in efforts to characterize the current condition of
aquatic resources and to establish baseline data for comparison with
future monitoring efforts (e.g. Adams 2001, Cole 2003, Cole 2004).

The primary objective of this study was to characterize current benthic
macroinvertebrate and physical habitat conditions in streams occurring
within the project area and to provide the first year of data in a
long-term study of responses of stream habitat and macroinvertebrate
communities to urbanization. A secondary objective of the study was to
investigate the effects of forested buffers within the study area on
macroinvertebrate community conditions.

# STUDY AREA

The Damascus Urban Growth boundary expansion area encompasses
approximately 12,000 acres in northwestern Clackamas County, Oregon
(Figure 1). Several tributary watersheds to the Clackamas River occur
entirely, or partially, in the southern portion of the proposed
expansion area, including (west to east) Rock Creek, Richardson Creek,
and Noyer Creek. Rock Creek, the westernmost Clackamas River tributary,
occurs almost entirely within the expansion area. All but approximately
the lower ¾ miles of Richardson Creek occurs within the proposed
expansion area. Approximately the 1/3 of the Noyer Creek drainage occurs
within the expansion area. North Fork Deep Creek, immediately to the
east of Noyer Creek, doesn't occur within the current proposed expansion
area, but was included for sampling in this study owing to its close
proximity.

Several tributaries to Johnson Creek occur in the northern portion of
the expansion area, including Kelly Creek and several smaller unnamed
tributaries. All of these tributaries drain in a generally northerly
direction. Butler Creek occurs immediately north of the proposed
expansion area and is entirely forested in its upper reaches. Sampling
for this study occurred on Kelly Creek, Butler Creek, and one unnamed
tributary in the northeast corner of the proposed expansion area.

Land use throughout the entire expansion area consists of a mosaic of
rural residential, rural, agricultural, and forested land uses. Both
upland and riparian forested areas still occur in the area. Of
particular note is the intact riparian corridors on lower North Fork
Deep, lower Noyer, lower Richardson, parts of Rock, and upper Butler
Creeks.

# METHODS

## STUDY REACH SELECTION

Because the primary purpose of this study was to characterize baseline
physical and biological conditions in streams throughout the project
area, study reaches were selected to provide relatively an even spatial
coverage of perennial stream reaches within the project area. Our intent
was to collect data at a sufficient number of sites to allow for
examination of the data for spatial variability (longitudinal
variability within and variability among drainages), while spacing
reaches far enough apart to effectively detect spatial variability in
biological conditions as reflected by varying physical and adjacent land
use conditions.

Where access and adequate flow allowed for sampling, study reaches were
established at approximately½- to 1-mile intervals along the mainstem of
each drainage, as well as on perennial tributaries. In all 34 stream
reaches were established as project reaches, with the following
breakdown among drainages: 11 in Rock Creek, 8 in Richardson Creek, 3 in
Noyer Creek, 6 in North Fork Deep Creek (including 1 in Deep Creek), 2
in Kelly Creek, 1 in Butler Creek, and 3 in an unnamed tributary to
Johnson Creek (Figure 1).

In addition to establishing sampling reaches throughout the proposed
expansion area, six sampling stations were established on the Clackamas
River to track changes in the longitudinal profile of benthic biological
conditions in the Clackamas River from above the Deep Creek confluence
to below the Rock Creek confluence.

## FIELD DATA COLLECTION

Macroinvertebrate communities, physical habitat, and water chemistry
were sampled from the 40 study reaches between September 29 and October
15, 2003. First, each study reach was marked and reach length was
measured. Each sample reach measured 20 times the average wetted width
or 75 m, whichever length was greater. Reach gradient was then measured
with a clinometer and percent riffle, pool, and glide habitat was
visually estimated. These parameters were used to categorize the study
reach as low gradient or moderate gradient (Table 1). Generally, reaches
with gradients exceeding 1.5% contained coarse (gravel, cobble, and
boulder) substrate that allowed riffles to occur at a frequency
sufficient to sample from them (\>10-15% total habitat area). Glides
were sampled from reaches that had gradients lower than 1.5%, no or
infrequent riffles (\<10% total habitat area) and predominantly sand and
finer substrates.

Macroinvertebrates were collected using Oregon Department of
Environmental Quality benthic macroinvertebrate sampling protocols (DEQ
2003). At each of the 40 study reaches, two units of the same habitat
type (riffles or glides, as described above) were randomly selected for
sampling. From each of these two units, four instream sampling points
were selected using nine-cell grid. In reaches with only one continuous
unit (most often glides in low-gradient reaches), eight instream
sampling points were selected from within this single habitat unit.

Macroinvertebrates were collected with a D-frame kicknet (12-in wide,
500-µm mesh opening) from a 30 x 30 cm (1 x 1 ft) area at each sampling
point. Larger substrates, when present, were first hand-washed inside
the net, and then placed outside of the sampled area. Then the area was
thoroughly disturbed by hand (or by foot in deeper water) to a depth of
5-10 cm. In areas with little or no discernible streamflow, the kicknet
was pulled back and forth through the water column over the disturbed
area to collect suspended materials.

The eight samples from a reach were placed together into a 500-µm sieve
and carefully washed to remove larger substrate and leaves after
inspection for clinging macroinvertebrates. The composite sample then
was placed into one or more 1-L polyethylene wide-mouth jars, labeled,
and preserved with 70% isopropyl alcohol for later sorting and
identification at the laboratory.

Following macroinvertebrate sample collection at each reach, we
collected the following water chemistry data: pH, temperature, dissolved
oxygen, and specific conductance. Temperature, dissolved oxygen, and
conductivity were measured in the field using a YSI Model 85 water
chemistry meter. We measured pH in the field with an Oakton pHTestr 3.

Physical habitat information was collected at each reach with both
visual estimate and quantitative measurement techniques (Table 2).
First, valley type was categorized by landscape features as U, V, or
open floodplain. At each of six evenly spaced channel cross sections,
wetted width, bankfull width, flood prone width, bankfull and incised
heights (measured with a surveyor's rod and fiberglass measuring tape),
and bank angles (measured with a clinometer) were measured. Canopy cover
was measured with a spherical densiometer on the left and right bank,
and in four directions (upstream, downstream, left, and right) in the
center of the channel cross section. Stream water depth was measured at
five equally-spaced locations along each cross section (30 total depth
measurements for each reach), and substrate composition (10 size
categories) and embeddedness were recorded at each of 15 equally-spaced
locations along each cross section (90 total substrate size tallies for
each reach). Substrate composition was determined by tallying particles
by size class, performed by placing a finger into the water and
classifying the size of the particle first touched as bedrock (\> 4000
mm), boulder (250-4000 mm), cobble (64-250 mm), coarse gravel (16-64
mm), fine gravel (2-16 mm), sand (0.06-2.00 mm), fines (\<0.06 mm),
wood, hardpan (firm, consolidated fines), or other. Embeddedness (%) was
visually estimated from the area immediately surrounding each sampled
particle.

Immediately following cross section surveys, large wood (\>6 in
diameter) was tallied and organic layer accumulation in depositional
zones was measured. Visual estimates or classifications were then made
of dominant bank material, percent stable bank, percent undercut bank,
dominant erosional bed material and dominant depositional bed material,
erosional habitat embeddedness (%), and depositional habitat
embeddedness (%), and instream filamentous algae cover (%) and
macrophyte cover (%).

On each bank, the riparian zone and adjacent land use characteristics
were classified and recorded. Each unique vegetation community type and
land use occurring within several hundred meters (or as far as the crew
could see, if less than this distance) was classified and recorded.
Vegetation community types included riparian forest, forested wetlands,
shrub/scrub, emergent marsh, wet meadow, upland forest, and developed.
Developed zones were placed into one of four develop classes:
residential, commercial/industrial, and agricultural. Within each
vegetation or land use zone, we estimated the width of the zone and the
percent tree, shrub, ground, and invasive species cover occurring within
the zone. buffer width (defined for this study as the area within which
natural mature vegetative communities occurred) and the dominant
adjacent land use outside the riparian buffer area were recorded.

## SAMPLE SORTING AND MACROINVERTEBRATE IDENTIFICATION

Samples were sorted to remove a 500-organism subsample from each
preserved sample following the procedures described in the Level 3
protocols (WQIW 1999) and using a Caton gridded tray, as described by
Caton (1991). Contents of the sample were first emptied onto the gridded
tray and then floated with water to evenly distribute the sample
material across the tray. Squares of material from the 30-square gridded
tray were removed to a Petri dish which then was placed under a
dissecting microscope at 7-10X to sort aquatic macroinvertebrates from
the sample matrix. Macroinvertebrates were removed from each sample
until at least 500 organisms were counted, or until the entire sample
had been sorted.

Following sample sorting, all macroinvertebrates were identified to the
level of taxonomic resolution recommended for Level 3 macroinvertebrate
assessments (WQIW 1999). Aquatic insects were keyed using Merritt and
Cummins (1996) and a number of regional and taxa-specific keys.

## QUALITY ASSURANCE

We collected duplicate composite samples at 2 of the sampled reaches in
the field. Duplicate samples were compared to assess within-site sample
variability. Additionally, a voucher collection of all macroinvertebrate
taxa identified in the study was assembled as a standard reference for
the project identification work.

## DATA ANALYSIS

Macroinvertebrate data were analyzed using both multimetric and
multivariate techniques. Data were entered into Excel spreadsheets and
formatted as needed for each analysis. Multimetic analysis employs a set
of community metrics, each of which describes an attribute of the
macroinvertebrate community that is known to be responsive to one or
more types of pollution or habitat degradation. Each community metric is
converted to a standardized score; standardized scores of all metrics
are then summed to produce a single multimetric score that is a numeric
measure of overall biological integrity. Multivariate analysis consisted
of using a combination of ordination and correlation techniques to
examine the data for relationships between macroinvertebrate community
conditions and environmental variables, an approach called indirect
gradient analysis. Owing to the large number of correlations run, we
considered the results of all correlation analyses significant at alpha
\< 0.01.

Environmental variables used in the correlation analyses with ordination
axes and multimetric scores included GIS-generated estimates of percent
coverage of land use types within buffered areas of various widths and
lengths upstream of each sample reach. Land use data used in the
independent data set for correlation analyses were calculated from 1998
satellite imagery and 2002 forest delineation data. Land use/cover types
included forested, high structure agriculture, low structure
agriculture, low vegetation, and grasses. Percent coverage of each of
these land use/cover types was calculated for buffer widths of 50, 100,
200, 400, 1000 meters in each direction from the stream and for entire
length of stream occurring upstream of each reach (Table 3).
Additionally, percent forest was calculated from 2002 forest delineation
data at these same widths and at buffer lengths extending 500 and 1500 m
above each sample reach.

Additionally, stream reaches were classified according to the Rosgen
Level II stream channel classification system using the reach-wide
channel dimension and substrate data collected in the field (Rosgen
1996). From field data, flood-prone width-to-bankfull width ratios and
width-to-depth ratios were calculated and used with channel substrate
and reach gradient information to classify channels by morphologic and
substrate conditions.

### *Multivariate Pattern Analysis*

Multivariate analyses were performed using PC-Ord Version 4 statistical
software. All other statistical analyses were performed with SPSS
Version 10.0. For all multivariate analyses, macroinvertebrate density
data were log (x+1) transformed to reduce the influence of very large
values (Krebs 1989). This type of transformation is useful when there is
a high degree of variation within attributes (taxa, in the case of this
study) or among attributes within a sample (McCune and Mefford 1999) and
has previously been used on macroinvertebrate community data prior to
performing multivariate analysis (e.g. Cole et al. 2003, Reece and
Richardson 2000, Zimmer et al. 2000, Jackson 1993). These logarithmic
density data served as the raw data for all subsequent multivariate
analyses in this study. Data were then standardized to relative
abundance (standardized in relation to row totals; e.g. Ford and Rose
2000), as data standardized in this manner in our previous work has
produced the strongest correlations between NMS axes and environmental
variables (e.g. Cole et al 2003, Cole 2002).

Non-metric multidimensional scaling (NMS) was performed using the
Sorenson (Bray-Curtis) distance measure and a minimum of 400 iterations.
NMS, a non-parametric ordination technique, was selected as the
ordination procedure because it is robust to data departures from
normality, assumes no underlying distribution of the data and, for these
reasons, is suggested to be particularly suitable for use with
ecological data (McCune and Mefford 1999).

Community data from all 40 sites were first ordinated using NMS to
examine the data for patterns in community composition among sites.
Correlation analysis was then performed between the resulting NMS axes
and environmental variables. Clear segregation of the Clackamas River
community data from the other data in the NMS prompted us to reanalyze
the data excluding the Clackamas River data from the set. This second
ordination was highly correlated with variables related to stream or
drainage size, and stream order groups were clustered, indicating a
strong influence of stream size on invertebrate community composition.
As a result, we ran the final ordinations on two subsets of the data,
1^st^ and 2^nd^-order streams and 3^rd^-5^th^-order streams, to examine
the data for relationships between environmental conditions and instream
benthic conditions. Correlations were then run between environmental
variables and the resulting NMS axes to examine the data for
relationships between physical or chemical conditions and benthic
community composition.

### *Multimetric Analysis*

All macroinvertebrate data were analyzed using multimetric analysis.
This approach employs a set of community metrics, each of which
describes an attribute of the macroinvertebrate community that is known
to be responsive to one or more types of pollution or habitat
degradation. Each community metric is converted to a standardized score;
standardized scores of all metrics are then summed to produce a single
multimetric score that is a numeric measure of overall biological
integrity. Reference condition data are required to develop and use this
type of assessment tool. Metric sets and standardized metric scoring
criteria are developed and calibrated for specific community types,
based on both geographic location and stream/habitat type. The Oregon
Department of Environmental Quality (DEQ) currently employs a 10-metric
set for use with riffle samples from higher-gradient streams in western
Oregon (WQIW 1999).

The DEQ 10-metric set includes six positive metrics that score higher in
less disturbed systems, and four negative metrics that score lower as
conditions improve (Table 4). The Modified Hilsenhoff Biotic Index
(HBI), originally developed by Hilsenhoff (1982), computes an index to
organic enrichment pollution based on the relative abundance of various
taxa at a site. Values of the index range from 1 to 10; higher scores
are interpreted as an indication of a degraded (i.e., pollution
tolerant) macroinvertebrate community. Sensitive taxa are those that are
intolerant of warm water temperatures, high sediment loads, and organic
enrichment; tolerant taxa are adapted to persist under such adverse
conditions. We used DEQ's taxa attribute coding system to assign these
classifications to taxa in the data set (DEQ, unpublished information).

Metric values first were calculated for each sample, and then were
converted to standardized scores using DEQ scoring criteria for riffle
samples from western Oregon streams (Table 4). The standardized scores
were summed to produce a multimetric score ranging between 10 and 50.
Reaches were then assigned to a level of impairment based on these total
scores.

Relationships between selected metrics and environmental variables were
then examined using nonparametric correlation analysis (Spearman's Rho)
to determine what environmental attributes were related to
macroinvertebrate community condition. Metrics for correlation analysis
were selected based on the range of values calculated from the data set.
Finally, streams of different impairment classes were tested for
differences in forested riparian conditions Kruskal-Wallis tests and a
subset of land use/cover variables that prior analyses indicated might
be most strongly related to instream biological integrity.

# RESULTS

Riffle samples were collected from 37 of 40 stream and river reaches.
Only three stream reaches contained insufficient riffle space to sample
macroinvertebrates from this habitat type. Depositional samples were
collected at these three reaches (sites 4, 18, and 19 -- all located in
the Rock Creek drainage); these data were excluded from the final NMS
analyses and from multimetric scoring.

#### ENVIRONMENTAL CONDITIONS OF SAMPLE STREAM REACHES

Study stream reaches encompassed a wide range of riparian and stream
channel conditions. Riparian conditions varied widely, but on the four
larger tributary systems: Rock, Richardson, Noyer, and NF Deep creeks,
riparian zones were largely intact and often extended 50-100 m out from
each bank, particularly in the lower reaches of these systems. The upper
reaches and headwaters of these systems tended to have less intact and
narrower riparian zones, with agricultural land uses and rural
residential areas encroaching into these areas.

Streams occurring within the study area ranged in size, gradient,
substrate composition, and relative frequencies of different habitat
types. Using the Rosgen Level II geomorphic classification system, a
number of stream channel types occurred in the study area; the most
common were B3 and G3 channels (Rosgen Level II geomorphic
characterization), with 11 of the of the former and 8 of the latter type
occurring in the sample of 34 reaches (Table 5). B3 channels are
moderately entrenched with 2-4% gradients and dominated by cobble
substrate. G3 channels are similar to B3 channels, but are more incised
and entrenched and can be indicative of channel downcutting as a result
of altered hydrology. It should also be noted that G3 channels are
particularly sensitive to disturbance and tend to significantly adjust
to changes in flow regime or sediment supply (Rosgen 1996), as could
result from intensive urban development.

Sample streams ranged from 1^st^ to 5^th^ order (not including the
Clackamas River), and included drainage areas from 112 to 18,808 acres.
Among the 31 reaches supporting riffle habitat, reach gradient ranged
from 1.5 to 6% (Table 6). Wetted widths ranged from 0.7 to 7.1 m, while
bankfull width ranged from 1.8 to 14.1 m. Riffles averaged 37% of the
total habitat area among these reaches, ranging from 10.0 to 75.0%.
Overhead canopy cover averaged 90% among these 31 reaches, ranging from
73.4 to 99.7%.

Most stream reaches were dominated by cobble substrates (21 of 34
reaches). Five reaches were dominated by gravel substrate, three each by
sand and clay, and two by bedrock. Substrate embeddedness varied widely,
ranging from 11 to 87% and averaged 33% across all 34 stream reaches
(Table 6).

**MULTIVARIATE ANALYSES**

Pattern analysis of macroinvertebrate data collected from the 34 stream
reaches, excluding the Clackamas River reaches, showed clustering of
reaches by stream order (Figure 2). Consequently, we split the dataset
into two subsets: 1^st^ and 2^nd^-order stream reaches and 3^rd^, 4^th^,
and 5^th^-order stream reaches. NMS of 3^rd^-5^th^-order reaches
produced a 3-dimensional ordination that explained 74% of the original
variation among samples. Axis one accounted for 2/3 of that explained
variation. Environmental variables significantly correlated with axis
one included specific conductance and a number of land use/land cover
variables (Table 7). Land use land cover variables that were
significantly correlated with NMS axis 1 were % forested area for 1500 m
upstream at 50, 100, and 200-m wide, and numerous land use/cover
variables at various widths extending the entire upstream length (Figure
3). Multimetric scores were also significantly correlated with NMS axis
one, with scores generally increasing from right to left, in the same
direction as increasing forest cover, decreasing agricultural land use,
and decreasing specific conductance (Figure 4). Community data showed
some clustering by drainage along axes 1 and 2 indicating that
macroinvertebrate community composition within the study area is, in
part influenced by drainage.

NMS of 1^st^ and 2^nd^-order reaches produced a 3-dimensional ordination
that explained only 26% of the original variation among samples. Only
two environmental variables were correlated with NMS axes, 1998 % low
structure agriculture in a 200-m buffer (r^2^ = 0.684, p \< 0.01) and
1998 % forested in a 200-m buffer (r^2^ = -0.698, p \< 0.01).

**MULTIMETRIC ANALYSES**

Macroinvertebrate community conditions, as indicated by multimetric
scores, ranged widely, from 10 to 42, among sampled reaches (Table 8,
Figure 5). Communities in most reaches were classified as slightly or
moderately impaired (Table 9), as 13 reaches scored in the slightly
impaired range and 17 reaches scored in the moderately impaired range.
Six reaches scored in the severely impaired range, while only one reach,
located in Richardson Creek, scored in the unimpaired range. Clackamas
River reaches all scored as moderately impaired, ranging from 24 to 28,
and showed no longitudinal trend, indicating that benthic communities
from above Deep Creek to below Rock Creek are in similar condition.

Six of eight reaches within the Richardson Creek drainage scored in the
unimpaired to slightly impaired range, while four of eight Rock Creek
reaches (from which riffles were sampled) scored in the slightly
impaired range. Three Rock Creek reaches were scored as moderately
impaired, while one Rock Creek reach was scored as severely impaired.
All six Clackamas River reaches were scored as moderately impaired.
Upper Butler Creek, a reach we had hoped might be a reference reach, was
scored as only moderately impaired.

A distinct longitudinal trend occurred in three of the four larger
watersheds in the study area (Figure 6). The three Noyer Creek reaches
were scored as slightly, moderately, and severely impaired from
downstream to upstream. A similar longitudinal trend was observed among
North Fork Deep Creek riffle sample scores, as scores increased from 10
(severely impaired) to 26 (moderately impaired) from upstream to
downstream. Rock Creek, and to a lesser extent, Richardson Creek, also
showed longitudinal trends of increasing multimetric scores from
upstream to downstream.

Total richness ranged from 13 to 36 taxa and averaged almost 27 taxa per
reach among the 31 riffle-sampled reaches. Mayfly richness ranged from 1
to 7 and averaged 3.5 taxa per reach, while stonefly and caddisfly
richness averaged 3.5 and 3.9 taxa per reach, respectively.

Multimetric Scores, modified HBI scores, and total taxa richness were
each highly significantly correlated with specific conductance
(p\<0.0001 for each correlation; Figure 7), when data from only 3^rd^,
4^th^, and 5^th^-order reaches were included in the analysis. Several
land use/cover variables were also significantly correlated with
Multimetric Scores (Figure 8). Neither multimetric scores nor other
tested metrics were significantly correlated with any other
environmental variables. Multimetric scores of samples from 1^st^ and
2^nd^-order streams were not significantly correlated with any
environmental variables.

Using six variables describing forested riparian conditions, forested
cover within riparian zones was significantly different among streams of
different impairment classes (Figure 9). Three of the six variables
(those where land use percentages were calculated for the entire
upstream distance) were significant at alpha = 0.01, while two of the
remaining three (those buffered for 1500 m upstream) were significant at
alpha = 0.05. Percent forested cover in a 200-m buffer was more
significant than forested cover within 100 or 50-m buffers (alpha =
0.026~200~, 0.046~100~, 0.063~50~).

# DISCUSSION

Riparian zones serve a number of functions critical to the maintenance
of stream ecosystems, including providing leaves and other organic
material as energy sources, providing large wood, decreasing sediments,
increasing stream shading, slowing and retaining surface runoff, and
filtering out contaminants. Macroinvertebrate community conditions
varied widely among stream reaches within the study area and generally
reflected the wide range of stream types and conditions occurring in the
study area. This variation is related to both natural variation in land
form and the resulting physical template to which macroinvertebrate
communities respond, as well as to degraded physical habitat, water
quality, and altered hydrology resulting from human activities.
Multimetric scores of macroinvertebrate communities sampled from riffles
show this wide variation in community conditions, as scores ranged 10,
the lowest possible score a sample can receive, to 42, indicating
unimpaired benthic conditions.

Among sampled drainages, Richardson Creek appears to support the most
unimpaired macroinvertebrate communities, as benthic conditions at most
sites were classified as either slightly impaired (5 sites) or
unimpaired (1 site). Our surveys indicated that intact riparian zones
occur along most of the stream reaches with late-summer flows in this
drainage, which may largely be protecting stream functions and
conditions and the resulting biology. Lower Richardson Creek has been
selected as a reference reach in previous studies because of the
relatively undisturbed characteristic of much of the lower stream and
adjacent riparian zones (Cole 2002).

Rock Creek showed more variation in macroinvertebrate community
conditions, with communities showing slight (4 sites), moderate (3
sites), and severe (1 site) impairment. Benthic conditions improved with
reaches located lower in the drainage, again indicating more favorable
physical or chemical conditions for benthic communities further
downstream. Like Richardson Creek, lower Rock Creek riparian areas are
more heavily forested than are riparian areas in the upper drainage,
suggesting that riparian buffers occurring in the lower Rock Creek
drainage also may improve instream physical and chemical conditions.

Noyer Creek and NF Deep Creek showed similar patterns of increasing
biological conditions with downstream distance. Noyer multimetric scores
improved 20 points between the first and third sites, as the uppermost
site scored 12, while the lowermost site scored 32. NF Deep Creek,
across all reaches sampled, exhibited the lowest macroinvertebrate
community scores, ranging from 10 at the uppermost site to 26 at the
lowermost site. Of all of the drainages occurring in the study area, NF
Deep Creek's upper reaches occur in a more heavily developed area than
any of the other drainages, which likely explains the low overall
biological integrity measured in this system. Both Noyer and NF Deep
creeks also have heavily forested zones occurring in their lower
reaches, while riparian zones in their upper reaches are largely
unforested. As in Rock, and to a lesser extent, Richardson Creek, both
of these systems showed progressive improvement in biological conditions
with increasing distance downstream through the forested riparian zone
sections.

These clear trends of improving biology with increasing downstream
distance through forested riparian zones suggest that these forested
riparian zones, in their current size and condition, potentially afford
these streams significant protection and even serve to improve physical
or chemical conditions, or both, to an extent that results in measurable
improvement in benthic communities. Our data indicate that sediment
levels do not appreciably improve as do biological conditions with
distance downstream.

We did not measure stream temperatures when they would be most
influential on benthic communities, during mid to late summer. Stream
shading may cool stream air temperatures in these stream corridors. This
cooling effect, coupled with any localized influence of ground water
influx, may cool water temperatures as streams flow through these areas,
producing less extreme summertime conditions that exceed the tolerance
limits of fewer taxa. Additionally, forested riparian areas slow the
rate of water influx into streams, allowing for greater retention and
removal of contaminants from surface and groundwater before entering
streams. Although we collected very little water chemistry data, even
our few data showed a correlation between specific conductance and both
Multimetric Scores and NMS axes. Previous studies in these area streams
and in the Tualatin River basin have revealed similar correlative
relationships between conductivity and benthic conditions (Cole 2002,
Cole 2003). These relationships may only be correlative and conductivity
likely covaries with some other variable that is indeed affecting
macroinvertebrate community composition; specific conductances measured
in this study ranged from 60 to 234 μS/cm, certainly not within a range
that would typically warrant concern, unless one or more ionic
constituents may be harmful to aquatic life in concentrations occurring
in parts of the watershed.

Indirect gradient analyses also revealed some potentially interesting
relationships between gradients in community composition and
environmental conditions. However, it is uncertain if at least some of
the relationships observed, particularly between community composition
and land use/cover variables, are the result of the close proximity of
sites to one another and the grouping of sites within watersheds with
similar characteristics.

*Longitudinal stream buffers.* Our study design, while allowing for
detection of longitudinal trends in biological conditions within the
study drainage, poses problems for statistical testing that assumes
independence among the sample sites. Because stream study reaches were
often spaced less than a mile apart and most of the significant
relationships between land use and community gradients were of those
land use variables buffered for the entire upstream distance,
significant relationships may have resulted from sites occurring in
close proximity to each other having both similar macroinvertebrate
communities and similar land use/land cover characteristics (especially
if buffered through the entire upstream distance).

However, there does appear to be a relationship between percent-forested
riparian area within a 1500-m longitudinal buffer and lateral buffer
widths of 50, 100, and 200 m and macroinvertebrate community
composition. No relationships between riparian forest cover and
macroinvertebrate community composition were found using a longitudinal
buffer length of 500 m, while relationships were found using an
longitudinal buffer length of 1500 m, indicating that relationships
between benthic and riparian conditions may be better revealed using
longer reach lengths, in the case of this study \~1500 m, rather than
500 m.

*Lateral stream buffers.* Results of the correlation analysis between
NMS axes and lateral buffers indicate that land use conditions within
the first three lateral buffers -- 50 m, 100 m, and 200 m -- hold the
strongest relationships to community composition than wider lateral
buffers. The strength of the relationships for the first three buffers
was similar, suggesting that land conditions within the full 200 m
strongly influence stream conditions. Also, Kruskal-Wallace tests
indicated that percent forest cover buffered to 200 m out and 1500 m
upstream better discriminated macroinvertebrate impairment classes than
did percent forested cover buffered out to only 50 m. In other words,
when the goal is to maintain or improve stream integrity, the most
important zone appears to be the area within 200 m of the stream,
laterally.

These data should be interpreted with some caution, however, because
each buffer is additive with the smaller-scale buffer(s); for example,
the 150-m lateral buffer also includes the first 100 m lateral to the
stream. Autocorrelation between 50 m, 100 m, and 200 m-wide buffers may
contribute to the apparent relationship between land uses and stream
condition. More rigorous experimental study of the relative effect of
riparian buffers of various widths on instream biology is warranted.
That said, these data clearly indicate that maintenance of riparian
buffers in the project area will be necessary to maintain biological
integrity in these drainages. In addition to these results that link
benthic conditions to riparian conditions, other local and regional work
has demonstrated the link between riparian conditions and instream
biological integrity (e.g. Cole 2002, Morley and Karr 2002), Frady et
al. 2003) and further reinforces the need for maintaining these areas.

Previous benthic studies have occurred in the study area. Most recently,
ABR, Inc. performed a study of benthic communities in a number of
northwest Clackamas County streams in fall 2002 (Cole 2003). This study
included sampling from two reaches in Rock Creek. The lowermost site,
just south of route 212, was sampled in both studies and scored a 34 in
2003 versus only 22 in 2002. The middle Rock Creek site scored a 20 in
2002 and 26 in 2003, at least falling into the same impairment class in
each of the two years. Lower Richardson Creek was sampled in both 2002
and 2003 and scored a 30 in the first year versus 28 in the second.

NF Deep Creek was sampled in 1997 as part of a study of Clackamas River
basin streams to develop a metric set for use within the watershed
(Adams 2001). Although using a slightly different metric set, the
composite scoring system for the study still ranged from 10 to 50. The
NF Deep Creek site sampled in 1997 scored a 10, the lowest possible
score, while in 2003 the NF Deep Creek site nearest the 1997 sample site
scored a 20. Adams (2001) suggested that the relatively poor benthic
conditions measured in NF Deep Creek could be related to the wastewater
treatment facility located in the watershed. Comparisons of results
between studies points to the potential spatial and temporal variation
(which obviously could not be separated) within reaches over time, even
in the absence of significant changes to the watershed and highlight
need for thorough characterization of baseline conditions that include
measures of pre-development variability in these conditions.

# MONITORING STRATEGY

This study characterized baseline benthic biological conditions in
streams occurring throughout the Damascus UGB expansion area. The data
can be used to track changes in time in response to urbanization of the
watershed, given adequate characterization of current spatial and
temporal variability.

Our sampling design allows for a relatively fine assessment of spatial
variation of benthic conditions. Changes over time at these sites would
be best detected by regular sampling (every one or two years) at all
sites to capture temporal variation and thereby allow better separation
of responses to the effects of urbanization from variation that would
otherwise occur in community conditions in response to other factors
(annual variation in streamflow, temperature, physical habitat, etc.).
However, if this level of sampling intensity is not feasible, we offer
the following strategy.

The complexity and health of natural systems is reflected in the
structure and diversity of plant and wildlife communities. For
monitoring to be meaningful, habitat and land use conditions should be
linked to wildlife and water quality. Thus, ecological conditions may be
appropriately assessed over time and space through a combination of
science-based Geographic Information Systems (GIS) measures, water
quality conditions, and biological responses to those conditions.

The water quality, habitat, and bird data collected under this grant
provide, in combination with Metro's Regionally Significant Fish and
Wildlife Habitat Inventory and GIS measures collected for Metro's Title
13, provide excellent baseline conditions and enable us to measure
changes over time.

Through Title 13, Metro has committed to measuring existing conditions
and issuing "state of the watershed" type reports every two years,
beginning December 2006 (Attachment 1). In tandem, local jurisdictions,
once they implement Title 13, will be required to report on their
regulatory and non-regulatory activities relating to Title 13. These
reports will be due in odd years and may help supplement existing
conditions by identifying, for example, areas recently restored that are
not yet visible via Metro's GIS indicators. This will help us plan for
the future.

The City of Damascus has completed the Concept Planning process and is
beginning its comprehensive planning phase, which will result in zoning
designations. This process is expected to take about three years. Prior
to that time, no substantial land use changes are expected except
permitted activities such as forest clearing, which Metro will track as
part of Title 13. Thus, significant land use changes are not anticipated
to begin for at least five years, and GIS monitoring should suffice to
detect significant changes in habitat.

If, after five years, significant changes are detected via GIS measures,
we recommend seeking funding sources to duplicate, inasmuch as is
possible, the water quality study conducted under this grant. The City
of Damascus should be involved, and current DEQ protocols should be used
to help with DEQ's TMDL process and City compliance with same.

New urban growth occurs somewhat organically due to the expense of
installing infrastructure. That is, it is likely that the majority of
new urbanization will first occur spreading southward from the Gresham
area, and eastward from Pleasant Valley. More frequent monitoring may be
appropriate in newly urbanizing areas -- for example, every two years.

As part of Metro's "state of the watershed" reports, the Monitoring
Coordinator will develop a stream-reach by stream-reach GIS-based model,
validated and calibrated with the water quality data collected here,
based on forest cover and impervious surface measures. This model has
already been developed and tested for Rock Creek, with excellent,
field-validated success. We will extend this model to the remainder of
the new urban area and use it for future conditions comparison. The GIS
model developed for Rock Creek can serve as an interim measure when
funds for measuring water quality are unavailable.

Thus, depending on land use changes and funding, we recommend
field-monitoring the new urban area every two to five years. If
possible, follow-up bird-habitat studies may be completed, but water
quality and GIS parameters will be key to monitoring this new urban
area.

# LITERATURE CITED

Adams, J. 2001. Using aquatic macroinvertebrates to assess stream
condition

in the Clackamas River Basin, Oregon. Unpublished Master's Thesis.
University of Washington.

Cole, M. B. 2002. Assessment of Macroinvertebrate Communities in
Relation to Land Use, Physical Habitat, and Water Quality in the
Tualatin River Basin, Oregon. Unpublished report prepared for Clean
Water Services, Hillsboro, Oregon. 38 pp.

Cole, M. B. 2003. Assessment of Macroinvertebrate Communities in Streams
of North Clackamas County, Oregon, 2002. Unpublished Report prepared for
Water Environment Services of Clackamas County. Oregon City, Oregon. 27
pp.

Cole, M. B. 2004. Assessment of Macroinvertebrate Communities in and
Adjacent to the City of Wilsonville, Oregon. Unpublished report prepared
for the City of Wilsonville, Oregon.

Cole, M. B., K. R. Russell, and T. J. Mabee. 2003. Relation of headwater
macroinvertebrate communities to instream and adjacent stand
characteristics in managed second growth forests of the Oregon coast
mountain range. Canadian Journal of Forest Research 33: 1433-1443.

DEQ, 2003. Benthic Macroinvertebrate Protocol for Wadeable Rivers and
Streams. Unpublished methods manual. Oregon Department of Environmental
Quality, Portland, OR.

Frady, C., B. Gerth, J. Li, and L. Hennings. Portland Metro Benthic
Invertebrate Analysis. Unpublished report prepared for Metro Regional
Services. 87 pp.

Ford, J. and C. E. Rose, 2000. Characterizing small subbasins: A case
study from coastal Oregon. Environmental Monitoring and Assessment 64:
359-377.

Hilsenhoff, W. L. 1982. Using a biotic index to evaluate water quality
in streams. Technical Bulletin No. 132. Department of Natural Resources,
Madison, WI.

Jackson, D. A. 1993. Multivariate analysis of benthic invertebrate
communities: the implication of choosing particular data
standardizations, measures of association, and ordination methods.
Hydrobiologia 268: 9-26.

Krebs, C. J. 1989. Ecological Methodology. Harper Collins Publishers,
New York, NY. 654 pp.

McCune, B., and M. J. Mefford. 1999. PC-ORD. Multivariate analysis of
ecological data, Version 4. MJM Software Design, Gleneden Beach, Oregon,
USA.

Merritt, R. W., and K. W. Cummins (eds.). 1996. An introduction to the
aquatic insects of North America. Third Edition. Kendall/Hunt Publishing
Co., Dubuque, IA. 862 pp.

Morley, S. A., and J. R. Karr. 2002. Assessing and restoring the health
or urban streams in the Puget Sound Basin. Conservation Biology 16(6):
1498-1509.

Reece, P. F., and J. S. Richardson. 2000. Benthic macroinvertebrate
assemblages of coastal and continental streams and large rivers of
southwestern British Columbia, Canada. Hydrobiologia 439: 77-89.

Rosgen, D. 1996. Applied river morphology. Wildland Hydrology, Pagosa
Springs, CO.

WQIW. 1999. Chapter 12: Stream macroinvertebrate protocol, Oregon plan
for salmon and watersheds. Water Quality Monitoring Guide Book, Version
1.03. Water Quality Interagency Workgroup for the Oregon Plan.

Zimmer, K. D., M. A. Hanson, and M. G. Butler. 2000. Factors influencing
invertebrate communities in prairie wetlands: a multivariate approach.
Canadian Journal of Fisheries and Aquatic Science 57: 76-85.

[]{#__RefHeading___Toc140899174 .anchor}Table 1. Stream reaches sampled
for macroinvertebrates, physical habitat, and water quality in and
adjacent to the Damascus area urban growth boundary expansion, Oregon,
fall 2003.

  ------- -------------- --------------------------- ----------- --------------
  Reach   Stream         Location                    High/Low    Riffle/Glide
  \#                                                 Gradient    Sample

  1       Rock Creek     lower mainstem - along Rt.  M           **R**
                         212                                     

  2       Rock Creek     middle mainstem - Weaver    M           **R**
                         property                                

  3       Rock Creek     middle mainstem - below     M           **R**
                         Sunnyside Road                          

  4       Rock Creek     middle mainstem - above     L           **G**
                         Troge Road                              

  5       Rock Creek     upper mainstem - west of    M           **R**
                         Foster Road                             

  10      Rock Creek     tributary on Blake Property M           **R**

  13      Rock Creek     tributary on Weaver         M           **R**
                         property                                

  17      Rock Creek     middle Willow Creek         M           **R**

  18      Rock Creek     lower Willow Creek          L           **G**

  19      Rock Creek     tributary on Embree         L           **G**
                         property - east of Foster               
                         Road                                    

  20      Richardson     lower - above 224 road      M           **R**
          Creek          crossing                                

  21      Richardson     middle mainstem on Bonner   M           **R**
          Creek          property                                

  23      Richardson Ck  tributary to lower          M           **R**
          trib           Richardson on Anderson                  
                         property                                

  24      Richardson Ck  tributary on Bonner         M           **R**
          trib           property                                

  27      Richardson Ck  tributary to upper          M           **R**
          trib           Richardson (may be                      
                         Richardson)                             

  28      Richardson     below confluence with tribs M           **R**
          Creek          on Alexander/\_\_\_ prop                

  29      Noyer Creek    lower mainstem              M           **R**

  30      Noyer Creek    middle mainstem             M           **R**

  31      Noyer Creek    upper mainstem              M           **R**

  33      Johnson Ck     middle mainstem - below     M           **R**
          Trib 1         Rugg Road                               

  34      Johnson Ck     upper mainstem on west side M           **R**
          Trib 1         of 242nd                                

  36      Johnson Ck     tributary to upper reaches  M           **R**
          Trib 1                                                 

  39      Kelly Creek    upper mainstem              M           **R**

  40      Kelly Creek    middle/upper mainstem       M           **R**

  41      Butler Creek   upper mainstem              M           **R**

  42      N Fk Deep      NF Deep above sampled trib  M           **R**
          Creek                                                  

  43      N Fk Deep      tributary to lower NF Deep  M           **R**
          Creek                                                  

  44      N Fk Deep      lower NF Deep - lowermost   M           **R**
          Creek          of sites on NF Deep                     

  45      Deep Creek     lower Deep Creek above NF   M           **R**
                         Deep                                    

  46      NF Deep Creek  middle NF Deep              M           **R**

  47      NF Deep Creek  middle NF Deep - uppermost  M           **R**
                         of sites on NF Deep                     

  48      Rock Creek     middle - above trib on      M           **R**
                         Weaver property                         

  49      Richardson     lower Richardson above trib M           **R**
          Creek          on Anderson property                    

  50      Richardson     middle mainstem above trib  M           **R**
          Creek          on Bonner property                      

  51      Clackamas      \~1/4 mile below Deep Creek M           **R**
          River                                                  

  52      Clackamas      \~1 mile below Deep Creek   M           **R**
          River                                                  

  53      Clackamas      \~0.5 mile above Deep Creek M           **R**
          River                                                  

  54      Clackamas      \~1 mile below Richardson   M           **R**
          River                                                  

  55      Clackamas      \~1.5 miles below Rock      M           **R**
          River          Creek                                   

  56      Clackamas      \~0.5 mile below Rock Creek M           **R**
          River                                                  
  ------- -------------- --------------------------- ----------- --------------

[]{#__RefHeading___Toc140899175 .anchor}Table 2. Environmental variables
measured in the field for characterizing stream reaches in and adjacent
to the Damascus area urban growth boundary expansion, Oregon, fall 2003.

  ---------------------------------- ---------------------------- ------------------------
  Variable                           [Q]{.underline}uantitative   [V]{.underline}isual
                                     or [C]{.underline}ategorical Estimate or
                                                                  [M]{.underline}easured
                                                                  Variable

  Reach Length                       Q                            M

  Valley Type                        C                            V

  Reach Gradient (%)                 Q                            M

  Wetted Width                       Q                            M

  Bankfull Width                     Q                            M

  Bankfull height                    Q                            M

  Mean Water Depth                   Q                            M

  Riffles (% area)                   Q                            V

  Glides (% area)                    Q                            V

  Pools (% area)                     Q                            V

  Dominant Erosional Material        C                            V

  Dominant Depositional Material     C                            V

  Substrate Composition              Q                            M

  Embeddedness (%)                   Q                            M

  Large Wood Tally                   Q                            M

  Organic layer Accumulation         Q                            V

  Filamentous algae Cover (%)        Q                            V

  Macrophyte Cover (%)               Q                            V

  Overhead Canopy Cover              Q                            M

  Dominant Bank Material             C                            V

  Stable Banks (%)                   Q                            V

  Undercut Banks (%)                 Q                            V

  Mean Riparian Buffer Width         Q                            V

  Riparian Zone Tree Cover (%)       Q                            V

  Nonnative Riparian Veg. Cover (%)  Q                            V

  Dominant Adjacent Land Use         C                            V

  Water Temperature (^o^C)           Q                            M

  pH                                 Q                            M

  Specific Conductance (µS/cm)       Q                            M

  Dissolved Oxygen (mg/L)            Q                            M
  ---------------------------------- ---------------------------- ------------------------

[]{#__RefHeading___Toc140899176 .anchor}Table 3. Buffer dimensions use
to calculate percent land use/cover adjacent to stream reaches sampled
for macroinvertebrates, physical habitat, and water chemistry in and
adjacent to the Damascus area urban growth boundary expansion, Oregon,
fall 2003.

  ----------------------- --------------------- -------------------------
                          Buffer Dimensions     

  Variable                Width                 Length

  2002 % Forested         50, 100, 200, 400,    **500, 1500**, entire
                          1000                  upstream length

  1998 Low Structure      50, 100, 200, 400,    Entire upstream length
  Agriculture             1000                  

  1998 High Structure     50, 100, 200, 400,    Entire upstream length
  Agriculture             1000                  

  1998 Forested           50, 100, 200, 400,    Entire upstream length
                          1000                  

  1998 Low Vegetation     50, 100, 200, 400,    Entire upstream length
                          1000                  

  1998 Grasses            50, 100, 200, 400,    Entire upstream length
                          1000                  
  ----------------------- --------------------- -------------------------

[]{#__RefHeading___Toc140899177 .anchor}Table 4. Metric set and scoring
criteria (WQIW 1999) used to assess condition of macroinvertebrate
communities sampled in and adjacent to the Damascus area urban growth
boundary expansion, Clackamas County, Oregon, fall 2003.

+--------------------------+-------------+-------------+-------------+
| Metric                   | ##          |             |             |
|                          | ##### Scori |             |             |
|                          | ng Criteria |             |             |
+--------------------------+-------------+-------------+-------------+
|                          | ####### 5   | ####### 3   | ####### 1   |
+--------------------------+-------------+-------------+-------------+
| **POSITIVE METRICS**     |             |             |             |
+--------------------------+-------------+-------------+-------------+
| ######## Taxa Richness   | \>35        | 19-35       | \<19        |
+--------------------------+-------------+-------------+-------------+
| Mayfly Richness          | \>8         | 4-8         | \<4         |
+--------------------------+-------------+-------------+-------------+
| Stonefly Richness        | \>5         | 3-5         | \<3         |
+--------------------------+-------------+-------------+-------------+
| Caddisfly Richness       | \>8         | 4-8         | \<4         |
+--------------------------+-------------+-------------+-------------+
| Number Sensitive Taxa    | \>4         | 2-4         | \<2         |
+--------------------------+-------------+-------------+-------------+
| \# Sediment Sensitive    | [\>]{.      | 1           | 0           |
| Taxa                     | underline}2 |             |             |
+--------------------------+-------------+-------------+-------------+
| **NEGATIVE METRICS**     |             |             |             |
+--------------------------+-------------+-------------+-------------+
| Modified HBI^1^          | \<4.0       | 4.0-5.0     | \>5.0       |
+--------------------------+-------------+-------------+-------------+
| \% Tolerant Taxa         | \<15        | 15-45       | \>45        |
+--------------------------+-------------+-------------+-------------+
| \% Sediment Tolerant     | \<10        | 10-25       | \>25        |
| Taxa                     |             |             |             |
+--------------------------+-------------+-------------+-------------+
| \% Dominant              | \<20        | 20-40       | \>40        |
+--------------------------+-------------+-------------+-------------+

^1^ Modified HBI = Modified Hilsenhoff Biotic Index

[]{#__RefHeading___Toc140899178 .anchor}Table 5. Occurrence of Rosgen
stream channel types in streams sampled for macroinvertebrates, physical
habitat, and water chemistry in and adjacent to the Damascus area urban
growth boundary expansion, Clackamas County, Oregon, fall 2003

  --------------------------------- -------------------------------------
  Channel Type                      Count

  A3                                1

  B/G3                              1

  B1                                1

  B3                                11

  B4                                2

  B5                                2

  C4                                1

  E/F5                              1

  E6                                1

  F6                                1

  G1                                1

  G3                                8

  G4                                2

  G6                                1
  --------------------------------- -------------------------------------

[]{#__RefHeading___Toc140899179 .anchor}Table 6. Environmental
conditions of 31 stream reaches from which riffles were sampled for
macroinvertebrates in and adjacent to the Damascus area urban growth
boundary expansion, Clackamas County, Oregon, fall 2003.

  ----------------------------- ---------- ---------- ---------- ----------
  Variable                      Mean       SD         Min        Max

  Drainage Area (acres)         3046.7     4017.1     112.2      18807.6

  Reach Gradient (%)            3.5        1.2        1.5        6.0

  Wetted Width (m)              2.7        1.7        0.7        7.1

  Bankfull Width (m)            5.6        3.3        1.8        14.1

  Bankfull Height (m)           2.7        4.8        0.2        18.5

  Mean Water Depth (cm)         4.1        3.5        0.3        14.2

  Riffles (% area)              37.4       18.3       10.0       75.0

  Glides (% area)               28.9       10.9       0.0        50.0

  Pools (% area)                33.7       18.9       5.0        70.0

  Coarse substrate (%)          62.0       25.4       5.6        93.3

  Sand and fines (%)            12.8       14.2       0.0        55.6

  Fines (%)                     4.4        6.6        0.0        24.4

  Hardpan (%)                   6.5        10.2       0.0        35.6

  Embeddedness (%)              33.2       18.1       11.1       86.8

  Large Wood Tally              6.6        7.7        0.0        36.0

  Filamentous algae Cover (%)   0.8        3.2        0.0        15.0

  Macrophyte Cover (%)          0.2        0.9        0.0        5.0

  Overhead Canopy Cover (%)     90.0       6.3        73.4       99.7

  Stable Banks (%)              53.9       22.2       0.0        85.0

  Undercut Banks (%)            8.3        7.7        0.0        30.0

  Mean Riparian Buffer Width    74.6       38.5       5.0        150.0
  (m)                                                            

  Riparian Zone Tree Cover (%)  62.9       20.5       2.5        87.5

  Nonnative Riparian Veg. Cover 28.5       19.9       0.0        75.0
  (%)                                                            

  Water Temperature (^o^C)      13.5       1.3        11.2       16.3

  pH                            7.5        0.2        6.9        8.0

  Specific Conductance (µS/cm)  122.6      37.6       60.0       233.8

  Dissolved Oxygen (% sat)      83.9       13.2       45.3       98.7
  ----------------------------- ---------- ---------- ---------- ----------

[]{#__RefHeading___Toc140899180 .anchor}Table 7. Environmental variables
significantly correlated (at α = 0.01) with NMS axes resulting from
ordination of macroinvertebrate data from 3^rd^, 4^th^, and 5^th^-order
stream reaches sampled in and adjacent to the Damascus area urban growth
boundary expansion, Oregon, fall 2003.

  ------------------------------- -------------- ------------ ------------
                                  Correlation                 
                                  coefficient                 
                                  (r^2^)                      

  Variable                        Axis 1         Axis 2       Axis 3

  Specific conductance            0.824          NS           NS

  02 For 50m X 1500m              -0.607         NS           NS

  02 For 100m X 1500m             -0.571         NS           NS

  02 For 200m X 1500              -0.575         NS           NS

  02 For 50m, entire upstream     -0.627         NS           NS
  dist                                                        

  98 LSA 50m, entire upstream     0.707          NS           NS
  dist                                                        

  98 LSA 100m, entire upstream    0.687          NS           NS
  dist                                                        

  98 For 100m, entire upstream    -0.572         NS           NS
  dist                                                        

  02 For 200m, entire upstream    -0.671         NS           NS
  dist                                                        

  98 For 200m, entire upstream    -0.603         NS           NS
  dist                                                        

  02 For 400m, entire upstream    -0.623         NS           NS
  dist                                                        

  98 HAS 400m, entire upstream    0.563          NS           NS
  dist                                                        

  98 For 400m, entire upstream    -0.573         NS           NS
  dist                                                        

  98 LV 400m, entire upstream     -0.583         NS           0.625
  dist                                                        

  02 For 1K, entire upstream dist NS             NS           0.615

  98 HSA 1K, entire upstream dist 0.565          NS           NS

  98 For 1K, entire upstream dist -0.568         NS           0.609

  98 LV 1K, entire upstream dist  -0.671         NS           NS

  98 Grasses 1K, entire upstream  -0.563         NS           NS
  dist                                                        
  ------------------------------- -------------- ------------ ------------

[]{#__RefHeading___Toc140899181 .anchor}Table 8. Descriptive statistics
of macroinvertebrate community metrics calculated from riffle samples
collected from 31 stream reaches in and adjacent to the Damascus area
urban growth boundary expansion, Oregon, fall 2003.

+------------------------------+---------+---------+---------+--------+
|                              | Mean    | SD      | Min     | Max    |
+------------------------------+---------+---------+---------+--------+
| ######## Taxa Richness       | 26.5    | 6.8     | 13.0    | 36.0   |
+------------------------------+---------+---------+---------+--------+
| Mayfly Richness              | 3.5     | 1.5     | 1.0     | 7.0    |
+------------------------------+---------+---------+---------+--------+
| Stonefly Richness            | 3.5     | 2.3     | 0.0     | 10.0   |
+------------------------------+---------+---------+---------+--------+
| Caddisfly Richness           | 3.9     | 2.3     | 0.0     | 8.0    |
+------------------------------+---------+---------+---------+--------+
| Number Sensitive Taxa        | 1.9     | 1.2     | 0.0     | 5.0    |
+------------------------------+---------+---------+---------+--------+
| \# Sediment Sensitive Taxa   | 0.7     | 0.9     | 0.0     | 2.0    |
+------------------------------+---------+---------+---------+--------+
| Modified HBI^1^              | 4.7     | 1.0     | 3.3     | 6.7    |
+------------------------------+---------+---------+---------+--------+
| \% Tolerant Taxa             | 19.1    | 15.4    | 0.5     | 52.7   |
+------------------------------+---------+---------+---------+--------+
| \% Sediment Tolerant Taxa    | 32.1    | 15.0    | 1.7     | 51.8   |
+------------------------------+---------+---------+---------+--------+
| \% Dominant                  | 30.0    | 10.2    | 16.3    | 55.8   |
+------------------------------+---------+---------+---------+--------+
| **Multimetric Score**        | *       | **7.9** | *       | **     |
|                              | *27.0** |         | *10.0** | 42.0** |
+------------------------------+---------+---------+---------+--------+

[]{#__RefHeading___Toc140899182 .anchor}Table 9. Multimetric scores and
impairment classes of macroinvertebrate communities sampled from riffles
in 37 stream reaches in and adjacent to the Damascus area urban growth
boundary expansion, Clackamas County, Oregon, fall 2003.

  ---------------- -------------- ------------------------------------ -----------
  Reach \#         Stream         Location                             MMS Score

  **UNIMPAIRED**                                                       

  49               Richardson     lower Richardson above trib on       42
                   Creek          Anderson property                    

  **SLIGHTLY                                                           
  IMPAIRED**                                                           

  23               Richardson Ck  tributary to lower Richardson on     38
                   trib           Anderson property                    

  21               Richardson     middle mainstem on Bonner property   38
                   Creek                                               

  28               Richardson     below confluence with tribs on       36
                   Creek          Alexander/\_\_\_ prop                

  50               Richardson     middle mainstem above trib on Bonner 34
                   Creek          property                             

  1                Rock Creek     lower mainstem - along Rt. 212       34

  29               Noyer Creek    lower mainstem                       32

  27               Richardson Ck  tributary to upper Richardson (may   32
                   trib           be Richardson)                       

  10               Rock Creek     tributary on Blake Property          32

  2                Rock Creek     middle mainstem - Weaver property    32

  48               Rock Creek     middle - above trib on Weaver        30
                                  property                             

  45               Deep Creek     lower Deep Creek above NF Deep       30

  43               N Fk Deep      tributary to lower NF Deep           30
                   Creek                                               

  39               Kelly Creek    upper mainstem                       30

  **MODERATELY                                                         
  IMPAIRED**                                                           

  56               Clackamas      \~0.5 mile below Rock Creek          28
                   River                                               

  53               Clackamas      \~0.5 mile above Deep Creek          28
                   River                                               

  52               Clackamas      \~1 mile below Deep Creek            28
                   River                                               

  41               Butler Creek   upper mainstem                       28

  36               Johnson Ck     tributary to upper reaches           28
                   Trib 1                                              

  20               Richardson     lower - above 224 road crossing      28
                   Creek                                               

  13               Rock Creek     tributary on Weaver property         28

  54               Clackamas      \~1 mile below Richardson Ck.        26
                   River                                               

  44               N Fk Deep      lower NF Deep - lowermost of sites   26
                   Creek          on NF Deep                           

  40               Kelly Creek    middle/upper mainstem                26

  3                Rock Creek     middle mainstem - below Sunnyside    26
                                  Road                                 

  55               Clackamas      \~1.5 miles below Rock Creek         24
                   River                                               

  51               Clackamas      \~1/4 mile below Deep Creek          24
                   River                                               

  5                Rock Creek     upper mainstem - west of Foster Road 24

  30               Noyer Creek    middle mainstem                      22

  24               Richardson Ck  tributary on Bonner property         22
                   trib                                                

  42               N Fk Deep      NF Deep above sampled trib           20
                   Creek                                               

  **SEVERELY                                                           
  IMPAIRED**                                                           

  34               Johnson Ck     upper mainstem on west side of 242nd 18
                   Trib 1                                              

  46               NF Deep Creek  middle NF Deep                       16

  33               Johnson Ck     middle mainstem - below Rugg Road    16
                   Trib 1                                              

  17               Rock Creek     middle Willow Creek                  16

  31               Noyer Creek    upper mainstem                       12

  47               NF Deep Creek  middle NF Deep - uppermost of sites  10
                                  on NF Deep                           
  ---------------- -------------- ------------------------------------ -----------

[]{#__RefHeading___Toc140899292
.anchor}![](media/image1.png){width="6.465972222222222in"
height="8.952083333333333in"}Figure 1. Location maps of 40 stream and
river reaches sampled for macroinvertebrates, water quality, and
physical habitat in and adjacent to the Damascus area urban growth
boundary expansion, Clackamas County, Oregon, fall 2003.

![](media/image2.png){width="5.995833333333334in"
height="5.392361111111111in"}

[]{#__RefHeading___Toc140899293 .anchor}Figure 2. NMS ordination biplot
of macroinvertebrate samples collected from 34 stream reaches in and
adjacent to the Damascus area urban growth boundary expansion, Oregon,
fall 2003. Environmental variables that were significantly correlated (p
\< 0.01) with NMS axes Vector lines point in the direction that the
stated variable increases; longer lines indicate a stronger correlation.

![](media/image3.png){width="3.2041666666666666in"
height="2.2333333333333334in"}

![](media/image4.png){width="3.1569444444444446in"
height="2.2131944444444445in"}

![](media/image5.png){width="3.1756944444444444in" height="2.20625in"}

[]{#__RefHeading___Toc140899294 .anchor}Figure 3. NMS ordination biplots
of macroinvertebrate samples collected from 19 moderate-gradient
(\>1.5%) stream reaches in and adjacent to the Damascus area urban
growth boundary expansion, Oregon, fall 2003. Environmental variables
that were significantly correlated (p \< 0.01) with NMS axes Vector
lines point in the direction that the stated variable increases; longer
lines indicate a stronger correlation.

![](media/image6.png){width="5.990972222222222in"
height="3.6354166666666665in"}

[]{#__RefHeading___Toc140899295 .anchor}Figure 4. NMS ordination biplot
of macroinvertebrate samples collected from 19 moderate-gradient
(\>1.5%) stream reaches in and adjacent to the Damascus area urban
growth boundary expansion, Oregon, fall 2003. The vector line represents
the significance and direction of the correlation between Multimetric
Scores and NMS axis 1.

![](media/image7.wmf)

[]{#__RefHeading___Toc140899296 .anchor}Figure 5. Frequency of
multimetric scores of macroinvertebrate communities sampled from 31
stream reaches in and adjacent to the Damascus area urban growth
boundary expansion, Oregon, fall 2003.

![](media/image8.wmf)

[]{#__RefHeading___Toc140899297 .anchor}Figure 6. Macroinvertebrate
community multimetric scores from the four Clackamas River tributaries
occurring in and adjacent to the Damascus area urban growth boundary
expansion, Clackamas County, Oregon, fall 2003. Scores from sample
reaches are arranged from downstream to upstream on each graph to
illustrate longitudinal trends in community conditions on each system.

![](media/image9.wmf)

[]{#__RefHeading___Toc140899298 .anchor}Figure 7. Relationships between
macroinvertebrate metrics (including Multimetric Scores) and specific
conductance, the only field-measured environmental variable that was
significantly correlated with metric scores calculated from
macroinvertebrate samples collected from 3^rd^ through 5^th^-order
streams in and adjacent to the Damascus area urban growth boundary
expansion, Clackamas County, Oregon, fall 2003.

![](media/image10.wmf)

[]{#__RefHeading___Toc140899299 .anchor}Figure 8. Relationships between
Multimetric Scores and land use/cover variables that were significantly
with these scores calculated from macroinvertebrate samples collected
from 3^rd^ through 5^th^-order streams in and adjacent to the Damascus
area urban growth boundary expansion, Clackamas County, Oregon, fall
2003.

![](media/image11.wmf)

[]{#__RefHeading___Toc140899300 .anchor}Figure 9. Relationships between
percent forested cover (using six different GIS buffer dimensions) and
macroinvertebrate community impairment in stream reaches sampled for
macroinvertebrates in and adjacent to the Damascus area urban growth
boundary expansion, Clackamas County, Oregon, fall 2003. The first three
buffer variables are percent forested area within the stated width for
the entire upstream distance. One asterisk indicates a significant
effect of impairment class on percent forest cover at alpha = 0.05; two
asterisks indicate a significant effect of impairment class on percent
forest cover at alpha = 0.01.