Restoring Illinois Water Quality with TMDLs

              The development of “Total
Maximum Daily Loads,” com-monly
known as TMDLs, for
pollutants is a method that can
be used to improve water
quality. The process of creating
and implementing TMDLs pro-vides
an opportunity for all
interested parties to help re-store
the quality of local water
bodies.
Illinois is rich in surface-water
resources. It sits amid the mighty
Mississippi, Wabash, and Ohio
Rivers and along 63 miles of
Lake Michigan shoreline. Some
87,000 miles of rivers and
streams meander through the
state, and more than 3,000
inland lakes, covering about
250,000 acres, dot its landscape.
Over the years, the quality of
some Illinois lakes, rivers, and
streams has been impaired by
pollutants from a variety of
sources. However, since the
signing of the federal Clean
Water Act (CWA) in 1972,
water quality has improved
greatly, primarily through regu-lation
of point source dis-charges.
Although great strides
have been made in restoring
our state waters, there are still
degraded lakes, streams, and
rivers that need attention. Re-storing
their quality is crucial
in maintaining a healthy envi-ronment
and ensuring the
sustainability of these waters
for all to use and enjoy.
Restoring Illinois Water
Quality With TMDLs
PHOTO BY ILLINOIS EPA
What Is a TMDL?
The establishment of a Total
Maximum Daily Load sets the
pollutant reduction goal neces-sary
to improve impaired wa-ters.
It determines the load, or
quantity, of any given pollutant
that can be allowed in a particu-lar
water body. A TMDL must
consider all potential sources
of pollutants, whether point or
nonpoint. It also takes into ac-
Illinois
Environmental
Protection Agency
Bureau of Water
P.O. Box 19276
Springfield, IL 62794-9276
IEPA/BOW
October 2003
count a margin of safety, which
reflects scientific uncertainty, as
well as the effects of seasonal
variation.
Why Develop TMDLs?
Section 303(d) of the federal
Clean Water Act requires states
to identify waters that do not
meet applicable water quality
standards or do not fully sup-port
their designated uses.
States are required to submit a
prioritized list of impaired wa-ters,
known as the 303(d) List,
to the U.S. Environmental Pro-tection
Agency for review and
approval. The CWA also requires
that a TMDL be developed for
each pollutant of an impaired
water body. Illinois EPA is re-sponsible
for carrying out the
mandates of the Clean Water
Act for the state of Illinois.
The TMDL Process
Developing TMDLs in a water-shed
begins with the collection
of vast amounts of data on fac-tors
including water quality,
point source discharge, precipi-tation,
soils, geology, topography,
and land use (construction, agri-culture,
mining, etc.) within that
specific watershed. All impaired
water-body segments within the
watershed are identified, along
with the potential pollutants
causing the impairments.
Next, Illinois EPA determines
the tools necessary to develop
the TMDL. In most cases, com-puter
models are used to calcu-late
pollutant loads. The appro-
PHOTO BY ILLINOIS EPA
WATER’S MANY USES
Every river, stream, and lake has the potential for a variety of
uses, including drinking water, aquatic life, swimming, boating,
and fish consumption. The Illinois Pollution Control Board
assigns every water body one or more designated uses,
which in turn determine the water quality standards that
apply.
By monitoring the physical, chemical, and biological aspects
of Illinois’ water bodies, the Illinois Environmental Protec-tion
Agency (Illinois EPA) determines whether the water
quality of a particular lake, river, or stream is supporting its
designated uses. The water body is classified in one of four
categories according to the Illinois EPA’s findings:
• Full support—the water body is fully supporting all of
its designated uses
• Full/threatened support—the water body is support-ing
its designated uses, but there is evidence of declining
water quality
• Partial support—the water body is supporting some
but not all of its designated uses
• Nonsupport—the water body is supporting none of its
designated uses
A water body can accumulate only a certain amount of pol-lutants
and still be able to support its designated uses. A
river, stream, or lake is considered to be “impaired” if it is
classified as partial support or nonsupport.
priate model or models are
selected based on the pollut-ants
of concern, the amount of
data available, and the type of
water body. Once the model is
selected, the data collected for
the watershed are entered, and
the model is calibrated and
verified so that the computed
values match those of known
field data. The model can then
be used to develop different
scenarios, by first determining
the amount of specific pollutants
each source contrib-utes, then
calculating the amount each
pollutant needs to be reduced,
and finally specifying how the
reduced pollutant load would
be allocated among the differ-ent
sources.
After the reduced pollutant
loads have been determined, an
implementation plan is devel-oped
for the watershed spelling
out the actions necessary to
achieve the goals. The plan
USING A WATERSHED APPROACH
A watershed is all of the area
above and below the surface of
the landscape that drains into
bodies of water (lakes, rivers,
streams, wetlands) and ground-water.
Activities in a watershed
directly affect the quality of wa-ter
resources and their desig-nated
uses. Understanding what
makes up a watershed and its
components is the first step to
improving water quality and
other natural resources.
Many water quality and eco-system
problems can best be
solved at the watershed level
rather than at the level of an
individual water body or pollut-ant
source. Watershed manage-ment
can help with the use, pro-tection,
and restoration of
natural resources, while allowing
for sustainable economic growth
and development.
Pollutants enter a water body
from different sources at differ-
PHOTO COURTESY OF SANGAMON COUNTY SWCD
water quality must be identi-fied.
By examining all potential
sources of pollutants along
with all land uses, steps can be
taken to reduce or eliminate
pollutant loads. This is best
done using a watershed ap-proach.
TMDLs are just one of many
activities and tools used during
the process of watershed
planning. A complete water-shed
plan includes recommen-dations
for best management
practices to be implemented,
the associated costs, an imple-mentation
schedule, and an
outline of the needed institu-tional
arrangements for imple-mentation.
The best planning
takes place when residents of
a watershed assume leader-ship
of the process, with Illi-nois
EPA and other natural
resource agencies providing
technical assistance.
specifies limits for point source
discharges and recommends
best management practices
(BMPs) for non-point sources. It
also estimates associated costs
and lays out a schedule for
implementation. Commitment
to the implementation plan by
the citizens who live and work
in the watershed is essential to
success in reducing the pollut-ant
loads and improving water
quality.
ent times. Point source pollution
comes by way of a direct, iden-tifiable
source, such as a pipe,
ditch, or tank. Nonpoint source
pollution accumulates through
many diffuse sources when rain-fall
and snowmelt move over
and through the ground, picking
up pollutants. Because the
methods used to control point
and nonpoint sources of pollu-tion
differ, the sources of any
pollutants that are degrading
PHOTO BY ILLINOIS EPA
Illinois Environmental Protection Agency
Bureau of Water
Watershed Management Section, Planning Unit
1021 North Grand Ave. East
P.O. Box 19276
Springfield, IL 62794-9276
217-782-3362
Public Participation
The Illinois EPA is committed
to keeping local citizens in-formed
when TMDLs are being
developed in their watershed.
Public meetings are held to
present watershed data as well
as to explain the approaches
and methods that will be used
to develop the TMDLs. The
meetings also offer a forum for
citizens to share their opinions
and concerns, for providing
additional information that may
be helpful in developing the
TMDLs, and for building part-nerships
with other interested
parties.
After the draft TMDL imple-mentation
plan is completed, a
public hearing is held to present
the results. Again, citizens have
the opportunity to share their
opinions and ask questions
concerning the plan.
Improved Water Quality
PHOTO COURTESY OF USDA NRCS
water expenses for local citi-zens
and businesses.
Protecting and restoring the
quality of Illinois waters is ulti-mately
the responsibility of
everyone. The success of a
TMDL implementation plan
typically depends on the coop-eration
of those who live and
work in the watershed. Citizens
can take ownership of their
local water bodies by adopting
suggested BMPs and encourag-ing
others to do the same. By
integrating sound science with
public support, TMDLs can be a
valuable tool for improving and
protecting our precious water
resources.
The goal of TMDLs is better
water quality for Illinois. Im-proving
our lakes, rivers, and
streams has a positive impact on
the quality and quantity of the
fish and animals that depend on
these waters for habitat, food,
breeding, and survival. This in
turn contributes to balanced,
healthy ecosystems.
Beyond the ecological benefits,
cleaner water increases oppor-tunities
for fishing, boating, and
other recreational activities and
improves the overall appear-ance
of lakes, rivers, and streams.
A cleaner source of drinking
water can mean lower treat-ment
costs, which may reduce
For more information about Illinois’ TMDL
program, visit our website at:
www.epa.state.il.us/water/tmdl