^RESULTS
SCIENCE lies at the heart of the mission of the U.S. Environmental Protection Agency (EPA). The Agency must rely on cutting edge research, accurate
measurements and effective technology to implement its programs to protect the environment and human hea!th. Without sound science and credible data,
EPA can not wisely set environmental and health standards, clean up contaminated sites, measure ambient air and water quality conditions, or identify the new
technologies or practices that will reduce releases to the environment. These fact sheets shore with you some of our EPA New England's laboratory capabilities
and exemplify some of the very best science we do to meet our agency mission.
GOAL:
EPA and the New England states collaborated to develop a new system to classify water quality based on biologi-
cal conditions. This scientific framework, the Biological Condition Gradient, enables water managers to identify
and delineate incremental biological and ecological responses to stresses and disturbance, and to determine
where waterbodies fall along a gradient based on increasing ecological degradation.
KEY CONTACTS:
HILARY SNOOK
Environmental Scientist
(617) 918-8670
snook.hilary@epa.gov
KATRINA KIPP
Chief, Ecosystem Assessment
(617) 918-8309
kipp.katrina@epa.gov
ROBERT HILLCER
Senior Science Advisor
(617) 918-8660
hillger.robert@epa.gov
GENERAL INFO:
EPA NEW ENGLAND
REGIONAL LABORATORY
11 Technology Dr.
North Chelmsford. MA 01863
(617) 918-8300
www.epa.gov/ne/lab
TOLL-FREE
CUSTOMER SERVICE
1-800-EPA-7341
PROGRESS:
Historically, state water quality programs have dassifted water-
bodies to protect aquatic life and human health, based on the
uses they provide such as being swimmable. If a resource is not
meeting its designated use, it is considered impaired, instead of
unimpaired. This historical approach to categorizing waterbod-
ies into an impaired/unimpaired category does not reflect that
resources are actually degraded
wer a continuum of incremental
stresses and pollutants. As a result
a high quality waterbody may be
damaged bog before it falls into
the "impaired" category.
Degraded
1 Native Of natural condition
Minimal toss of species;
.2 some density changes may
Some replacement
of sertsttjve-rare
species; functions "
fully maintained
This situation led to the devel-
opment of the national Tiered
Aquatic Life Use (TALU) Work-
group, comprised of state,
federal and academic aquatic
resource scientists and policy
makers, including EPA and state
biologists from New England, with the primary goal of devel-
oping a scientific framework that can identify and delineate
incremental biological and ecological responses to stresses
and determine where waterbodies fall along this gradient of
disturbance. The resulting descriptive Biological Condition
Gradient (BCG) model, based on extensive data on New
England wadeable streams, provides an interpretive frame-
work for communicating technical findings of biological con-
drtion and change in relation to human and naturally induced
stresses to the waterbody in a standardized way.
Some sensitive species
maintained but notable
replacement by more
tolerant tax* attend
4 distributions; functions
largely maintained
Tolerant species show
increasing dominance; 5
sensitive species are rare;
functions altered
The BCG has six tiers of progressively deteriorating condi-
tions within which ten ecological attributes are described as
they change with increasing stress on the system (see figure).
Unstressed watersheds with abundances of highly sensitive
aquatic biota will fall in Tier 1 or Tier 2 while those with se-
verely artered habitats and highly pollutant tolerant biota will
fall in Tiers 5 or 6. Under the old impaired/unimpaired ap-
proach, a site in a natural native
condition coukj incur stresses
up until a Tier 5 was reached,
whereupon management ac-
tion would finally be taken.
The BCG allows for a much
more pre-emptive and proac-
tive approach, allowing early
detection of stresses based on
the biological and ecological
responses and implementation
of corrective management ac-
tions long before a resource
is severely degraded. This ap-
proach helps to preserve pris-
tine conditions by preventing the resources from backsliding
into degraded states, and to identify those that are in critical
need of restoration efforts.
BENEFITS:
The BCG model provides nationally consistent more refined as-
sessments and a common descriptor for ecological hearth and
integrity. This extremely useful tod has enabled New England
agencies to better protect their valuable water resources.
Severe alteration of
structure and
function
Stressor Gradient
Hiot,
&EPA
United States
Environmental Protection
Agency
EPA-901-F-09-013
April 2009
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