A biological assessment of a site on Hound Creek, Cascade County, Montana : TMDL-M10 September 3, 2003

2004·1.6 MB·English

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A BIOLOGICAL ASSESSMENT OF A SITE ON HOUND CREEK:
CASCADE COUNTY, MONTANA
TMDL-M10
September 2003
3,
STATE DOCUMENTS COLLECTIL
AUG 2 3 2004
MONTANA STATE LIBRARY
A report to HELE1N5A1.5MEO-N6TtAhNAAVE5.96?~
The Montana Department of Environmental Quality
Planning, Prevention and Assistance Division
Helena, Montana
Al Nixon, Project Officer
by
Wease Bollman
Rhithron Associates, Inc.
Missoula, Montana
May 2004
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INTRODUCTION
Aquatic invertebrates are aptly applied to bioassessment since they are known to be
important indicators ofstream ecosystemhealth (Hynes 1970). Long lives, complex life cycles
and limited mobility mean that there is ample time for the benthic community to respond to
cumulative effects ofenvironmental perturbations.
This report summarizes data collected on September 3, 2003 from asingle site on Hound
Creek in Cascade County, Montana This site lieswithin the Northwestern Glaciated Plains
ecoregion (Woods et al. 1999).
A multimetric approach to bioassessment such asthe one applied in this study uses
attributes ofthe assemblage in an integratedway to measure biotic health. A streamwithgood
biotic health is "...abalanced, integrated, adaptive system having the full range ofelements
and processes that are expected in the region's natural environment..." (Karr and Chu 1999).
The approach designed by Plafkin et al. (1989) and adapted for use in the State ofMontanahas
been defined as ". an array ofmeasures or metrics that individually provide information on
..
diverse biological attributes, and when integrated, provide an overall indication ofbiological
condition.'' (Barbouret al. 1995). Community attributesthat can contribute meaningfully to
interpretation ofbenthic datainclude assemblage structure, sensitivity ofcommunity members
to stress or pollution, and functional traits. Each metric component contributes an
independent measure ofthe biotic integrity ofa stream site; combining the components into a
total score reduces variance and increases precision ofthe assessment (Fore et al. 1996).
Effectiveness ofthe integrated metrics depends onthe applicability ofthe underlying model,
which rests on afoundation ofthree essentialelements (Bollman 1998). The first ofthese is an
appropriate stratification or classification ofstream sites, typically, byecoregion. Second,
metrics must be selected based upon their abilityto accurately express biological condition.
Third, an adequate assessment ofhabitat conditions at each site to be studied enhances the
interpretation ofmetric outcomes.
Implicit in the multimetric method and its associated habitat assessment is an
assumption ofcorrelative relationships between habitat measures and the biotic metrics, in the
absence ofwater quality impairment. These relationships mayvary regionally, requiring an
examination ofhabitat assessment elements and biotic metrics and atest ofthe presumed
relationship between them. Bollman (1998) has studied the assemblages ofthe Montana
Valleys and Foothill Prairies ecoregion and recommends abattery ofmetrics applicable to the
montane ecoregions ofwestern Montana. This metric battery has been shown to be sensitive to
impairment, relatedto measuresofhabitat integrity, and consistent over replicated samples.
METHODS
The sample was collected on September 3, 2003 by Montana Department of
Environmental Quality (Montana DEQ) personnel. The sample identifier and site location is
indicated on Figure 1 and in Table 1. The site selection and sampling method employed were
those recommended in the Montana DEQ Standard Operating Procedures forAquatic
Macroinvertebrate Sampling (Bukantis 1998). The aquatic invertebrate sample was delivered
to RhithronAssociates, Inc., Missoula, Montana, for laboratory and dataanalyses.
In the laboratory, the Montana DEQ-recommended sortingmethod was used to obtain a
subsample ofat least 300 organisms. Organismswere identified to the lowest possible
taxonomic levels consistent with Montana DEQ protocols.
Table 1. Sample designation and location. Hound Creek, September 3, 2003.
Site ID Station ID Activity ID Location Description Collection Latitude Longitude
Date
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M10HONDC01 03-U350-M u^fROMMOUTH ' 9/3/2003 47--12'-50" Ul--24'-33"
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113*14'00"W 112«4400"W U2°1400"W Ul#44-00"W 1U*14'00"W 110*44'00"W U0*1400-W WGS84lOSn^OO"W
TW"t/pMN M9I11M* la*1"0T*o'n3V3a•X3'0*0(0!M»M31J0(O11M| m4»MH7oJUX«I».!(,w»ww»9mil0,O_uO1k>ma
Figure 1. Approximate location ofsampling site. Hound Creek, September 3, 2003.
rs
Table 2. Provisional metrics and scoring criteriafor the Montana Plains ecoregions. (Bukantis,
1998).
METRICS
strong deviation from non-impaired condition and suggests severe degradation ofbiotic health. t
Scores for each metric were summed to give an overall score, the total bioassessment score, for
each site in each sampling event.
Recently, multimetric bioassessment indices using aquatic invertebrateswere developed
by Bramblett et al. (2002) for streams ofthe Plains ecoregions ofMontana These indices were
evaluated for responsiveness to anthropogenic disturbances, lack ofresponsiveness to natural
factors, and temporal stability, but no scoring criteriawere developed. Although the indices
probably need further refinement and have notyet been accepted for standard bioassessment
use by the State, metric values, scores, and assessments using the appropriate index are given
here in Table 5. To allowfor comparisonwith the Montana DEQ standard procedure, Figure 2
compares scores from each method.
For both bioassessment methods, the total score was expressed as the percent ofthe
maximum possible score and then converted into a use support classification. Criteria for use-
support designations were developed by Montana DEQ and are presented in Table 3a The
score was also translated into an impairment classification according to criteria outlined in
Table 3b.
Table3a. Criteria fortheassignmentofuse-supportclassifications / standards violation thresholds (Bukantis
1998).
%
Comparabilitytoreference Use support
>75 Full support—standards notviolated
25-75 Partial support—moderate impairment—standardsviolated
<25 Non-support—severeimpairment—standardsviolated
Table3b. Criteriafortheassignmentofimpairmentclassifications (Plafkinetal. 1989).
%
Comparability to reference Classification
> 83 nonimpaired
54-79 slightly impaired
21-50 moderately impaired
<17 severely impaired
RESULTS
Bioassessment
Table 4 itemizes each metric in the Montana DEQ battery (Bukantis 1998) and shows
individual metric scores for the Hound Creek site. Table 5 similarly shows the metrics and
scores for the revised Plains battery (Bramblett et al. 2002). Figure 2 compares the results of
the 2 bioassessment methods. The methods gave differing results when applied to these data.
*
Figure 2. Comparison oftotal bioassessment scores (reported as percent ofmaximum score).
The Montana Plains ecoregions reference (Bukantis 1998) was used to calculate the score
represented by the blue bar, and arevised Plains battery (Bramblett et al. 2002) was used to
calculate the score represented by the purple bar. Hound Creek, September 3, 2003.
Bukantis 1998
I
IBramblett et al. 2002
Hound Creek
When the Montana DEQ metric battery (Bukantis 1998) was applied to these data, the
resulting score indicated that this site on Hound Creek was non-impaired and fully supported
designated uses. When the revised metric battery (Bramblett et al. 2002) was used, the
resulting score indicated slight biological impairment and only partial support ofuses. Scores
generated by the 2 indices differed by 22 percentage points.
Aquatic invertebrate communities
Interpretations ofbiotic integrity in this report are made without reference to results of
habitat assessments, or any other information about the site that may have accompanied the
invertebrate sample. Interpretations are based entirely on: the taxonomic and functional
composition ofthe sampled invertebrate assemblage; the sensitivities, tolerances, physiology,
and habitus information for individual taxagleaned from the writer's research; the published
literature, and expert sources; and on the performance ofbioassessment metrics, described
earlierin the report, which have been demonstrated to be useful tools for interpreting potential
implications ofbenthic invertebrate assemblage composition.
Taxonomic composition ofthe sampled assemblage suggests that this site on Hound
Creekwas transitional; although the Plains influence is better defined, afewfoothill taxa (e.g.
Calineuria califomica, Rhithrogena sp.) were taken in the benthic collection. The site supported
at least 8 mayfly taxa, and the biotic indexvalue was within expectations for a Plains stream.
These findings suggest that water quality was good in this reach. Not unexpectedly, no cold-
stenotherm taxawere present in the sample. Many ofthe animals represented prefer cool-to-
warmwater, including the mayflies Fallceon quilleriand Acerpennapygmaea, and the aquatic
moth Petrophila sp.
Sixteen "clinger" taxa and 6 caddisfly taxawere collected; it appears that sediment
deposition did not limit access to clean stony substrate habitats. Ingeneral, instream habitats
were probably varied and abundant, since at least 40 discrete taxawere present at the site.
Seven semi-voltine taxawere collected, making it seem likely that the site did not experience
recent dewatering, scouring sediment pulses, toxic potiutants, or other catastrophes thatwould
limit longlife cycles. All expected functional components were present in what appeared to be
appropriate proportions.
CONCLUSION
• An assessment ofnon-impairment and full use support appears to be appropriate for
this site on Hound Creek. The benthic assemblage was diverse and sensitive, and did
not indicate any specific disturbances to water quality or habitat.
Table 4. Bioassessment metrics and scores for a single site on Hound Creek, September 3,
2003. Montana Plains ecoregions reference (Bukantis 1998).
METRIC VALUES