Revised Bioassessment Policy
from
Excerpted from Water Quality Program Policy 1-11
Revised September 2006; pp. 23-25
[Comments in brackets & italics added by
8. Specific Submittal and Assessment
Criteria
b. Bioassessment
Beneficial Uses: Aquatic life
Narrative Criterion: WAC 173-201A-070 (1)
Assessment Information and Specific Data
Requirements
Water column measurements of chemical and
physical components for rivers and streams may
not provide sufficient information to detect or
resolve all surface water problems. Biological
evaluations may detect physical habitat-related impairments
for which there are no criteria. For
this reason, bioassessment
methods are being used more frequently to identify the biological
health of the waterbody.
Although the state water quality standards do not have numeric
biocriteria limits, Ecology endorses and uses the River
Invertebrate Prediction and Classification
System (RIVPACS)
multivariate model to help identify impairments of the biologic community.
[
“Assessment Methodology for
Other Bioassessment Model Information” on following
page.]
Assessment Methodology for RIVPACS Model
Information
Ecology prefers RIVPACS over other bioassessment models because it uses established
reference site information to determine a score from the
presence of taxa relative to taxa
expected to occur. These expectations are
based on a set of “predictor variables” that are not
affected by human activities. This value identifies,
with a specified level-of-confidence,
impairment beyond that which can be attributed to natural
conditions. This biological
assessment method supplements water column data as a
direct measure for a beneficial use and
to arbitrate in assessments where water chemical
information does not provide a definitive
conclusion or criteria are not available. The use of
biological assessments can be used
effectively in TMDL studies to directly assess attainment
of the aquatic life use in a waterbody
segment.
Ecology strongly encourages the collection of
supplemental data during biological sampling
events, especially conventional and chemical pollutant
parameters that may be associated with
sources present in the waterbody.
This information is important in determining what may be
causing an impaired biological community, and is
important for confirming the appropriate
category determination.
Ecology has compiled the following information,
including field collection protocols, taxonomic
reference, and data analysis protocols for using RIVPACS
models and interpreting scores:
Field Protocols and Laboratory
Specifications: Plotnikoff, R. and
C. Wiseman. Benthic
Macroinvertebrate Biological Monitoring Protocols for Rivers and
Streams: 2001 Revision.
www.ecy.wa.gov/biblio/0103028.html
The Pacific Northwest Aquatic Monitoring
Partnership (PNAMP) protocol may be used as an
example for the variety of 8 ft2 sampling strategies that
can be used in
and streams for collecting benthic macroinvertebrates. The RIVPACS model for Western
document may be found at the following web page:
http://www.pnamp.org//web/workgroups/General/documents/General/2006_0518PNAMPmacroi
nvertdraft.doc
Taxonomic Effort: PNW Standard Effort is located on Xerces Society web page:
www.xerces.org/aquatic/standard.htm
Data Analysis: The
Freshwater Ecosystems provides publicly
available tools for calculating RIVPACS scores at the
following website:
http://129.123.10.240/WMCPortal/DesktopDefault.aspx?tabindex=0&tabid=1
Data submittals should include the RIVPACS model
score, the raw macroinvertebrate
assemblage counts, an environmental matrix reporting data
for predictor variables, and any other
applicable information detailed in section 4 of this
policy.
Assessment Methodology for Other Bioassessment Model Information
Benthic Index of Biological Integrity (B-IBI) or
other multimetric models will be evaluated to
determine their reliability as an indicator of biological
impairment prior to using the information
for assessment purposes. If the methodology does
not include established reference sites that
allow a level of confidence in the taxa results, Ecology will require a minimum of three years
of
monitoring at the site to ensure that consistent results
are being achieved. Detailed information
is required at the time of data submittal that
describes how the data are assessed to determine
whether a waterbody segment
is impaired, degraded, or unimpaired. This is especially important
if the methodology does not have numeric scores
associated with the impairment status (similar
to RIVPACS).
[
for the Puget Sound
Therefore, the three-year minimum described
above does not apply to data collected and analyzed under this
B-IBI protocol.]
Category 1 Determination
RIVPACS Model
A waterbody segment
will be placed in Category 1 based on a bioassessment
when the
RIVPACS score from the most recent year of
available macroinvertebrate assemblage data is
equal to or greater than 0.86.
Other Models
A waterbody segment
will be placed in Category 1 when at least three years in the most recent
five years of bioassessment
monitoring using the methodology show no impairment.
[
Category 2 Determination
RIVPACS Model
A waterbody segment
will be placed in Category 2 based on bioassessment
of the benthic
macroinvertebrate community when a RIVPACS score from the most
recent year of available
data results in a score less than 0.86 and at least
0.73.
Other Models
A waterbody segment
will be placed in Category 2 when at least three years in the most recent
five years of bioassessment
monitoring using the methodology show a level of degradation that
indicates the uses in the waterbody
are not impaired but starting to be degraded.
[
Category 3 Determination
A waterbody segment
will be placed in Category 3 when the available data are insufficient for
any other category determination. This information
will be maintained in Ecology’s assessment
database for future use. As additional data and
information become available, Ecology will
again assess all available data to make a new
category determination according to this policy.
Category 4 Determination
A segment will be placed in Category 4a when EPA
has approved a TMDL for pollutants
identified as stressors to the macroinvertebrate
community. A segment will be placed in
Category 4b when EPA approves use of a pollution
control project for pollutants identified as
stressors to the macroinvertebrate
community. Placement of a waterbody segment in
Category
4c for either RIVPACS or another model will be
based on pollutant data and information that
show the impairment is likely not the result of
pollutant sources but from pollution.
Category 5 Determination
RIVPACS Model
A waterbody segment
will be placed in Category 5 as biologically impaired when the RIVPACS
score calculated for the most recent year of
available macroinvertebrate assemblage data results
in a score less than 0.73 (two standard deviations
in the reference distribution of scores).
Other Models
A waterbody segment
will be placed in Category 5 as biologically impaired when at least three
years in the most recent five years of bioassessment monitoring using the methodology show a
level of degradation that indicates the uses in the waterbody are impaired.
[