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DEFINITIONS
Beneficial
Use
Streams,
lakes, rivers, and other water bodies, have uses to
humans and other life. These uses, or beneficial
uses, are outlined in a Water
Quality Control Plan, also called the Basin
Plan of the Central Coast Region. There are 24
categories of beneficial uses, including water contact
recreation, non-water contact recreation, municipal
water supply, cold fresh water habitat, and more. Each
body of water in the state has a set of beneficial uses
it supports that may or may not include all 24.
Different beneficial uses require different water quality
control. Therefore, each beneficial use has a
set of water quality objectives designed to protect
that beneficial use. Below is a list of some
of the beneficial uses described in the Water Quality
Control Plan.
Water
used for the following purposes: domestic (homes, human
consumption, etc.), irrigation (crops, lawns), power
(hydroelectric), municipal (water supply of a city or
town), mining (hydraulic conveyance, drilling), industrial
(commerce, trade, industry), fish and wildlife preservation,
aquaculture (raising fish etc. for commercial purposes),
recreational (boating, swimming), stockwatering (for
commercial livestock), water quality, frost protection
(misting or spraying crops to prevent frost damage),
heat control (water crops to prevent heat damage), ground
water recharge, agriculture, etc.
Impaired
Waterbody
A
body of water is said to be impaired when a water quality
objective(s) or standard is not met. For example, if
an objective for nitrate is set at a maximum of 45 milligrams
per liter, and a stream has nitrate occurring at greater
than 45 milligrams per liter, then that body of water
is said to be impaired. Water
quality objectives are established to protect
Beneficial Uses.
Listed
Body of Water
A
listed waterbody is one that is designated as impaired
pursuant to Section 303(d) of the Clean Water Act (
www.tmdls.net/basics/docs/uscode303d.pdf
). As such the quality of its water is not
supporting a beneficial use(s) or violates a water quality
standard. Bodies of water that are ‘listed' are
identified on the 303(d) list.
(http://www.waterboards.ca.gov/tmdl/docs/2002reg3303dlist.pdf
).
Loading
Allocation
A
loading allocation is a portion of the total amount
of pollutant entering a waterbody that is attributed
to a particular source. In terms of a TMDL it
is a portion of the total maximum load allowed (or the
loading capacity). For example, if a TMDL states
that 1000 lbs/day of a pollutant can be discharged into
a stream from all sources, and discharger A is allowed
to discharge 100 lbs. of the 1000 lbs., then discharger
A is said to have an allocation of 100 lbs.
Loading
Capacity
The
greatest amount of loading, of a pollutant, that a water
body can receive without violating water quality objectives;
the total maximum daily load.
Priority
Ranking
Section
303(d) of the Clean Water Act mandates that states prioritize
listed water bodies. Typically, those bodies of
water having highest priority will be considered to
receive first attention.
TMDL
The
initials used for ‘Total Maximum Daily Load.'
The initials ‘TMDL' are used to denote the quantity
of a pollutant that can be assimilated by a waterbody
and still meet water quality objectives. TMDLs are also
referred to as the loading capacity or assimilative
capacity of the waterbody. TMDLs are not always identified
as daily loads, but rather monthly or annual loads,
but the term TMDL is commonly still used for familiarity.
Similarly, TMDLs are commonly, but not always,
expressed as “loads.” They can also be expressed as
concentrations or other appropriate measure.
Water
Quality Control Plan
The
State Water Resources Control Board carries out its
water quality protection authority through the adoption
of specific Water
Quality Control Plans (also referred to
as the Basin Plan). These plans establish water
quality standards for particular bodies of water.
Water Quality Control Plans also describe programs of
implementation designed to ensure that water quality
standards are met.
Water
Quality Objective
Water
quality objectives are the limits or levels of water
quality constituents or the characteristics of a waterbody
that are established for the reasonable protection of
beneficial uses of water . Water quality
objectives are numeric limits and narrative objectives
designed to ensure that bodies of water in the state
can support their designated beneficial uses.
At concentrations equal to or greater than numeric objectives,
constituents (or pollutants) are considered to have
impaired the beneficial uses of the state's water.
Sometimes, the objectives are narrative, which are qualitative
objectives. A narrative objective in the Basin Plan
might state, “Waters shall not contain biostimulatory
substances in concentrations that promote aquatic growths…”
With this narrative objective, the actual numeric limit
for the concentration is not articulated.
Water
Quality Standard
(a)
A state adopted ambient standard
for a surface or ground water body. The
standard covers the beneficial use of the water
and the water quality criteria that must be
met to protect the designated use or uses.
(b)
Pursuant to the federal Clean Water
Act, a combination of the designated beneficial
uses of water and criteria or water quality
objectives to protect those uses.
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Provisions
of State or Federal law consist of a beneficial use
or uses for the waters of the United States and water
quality criteria for such waters based upon such uses.
Water quality standards are to protect
the public health or welfare, enhance the quality of
water, and serve the purposes of the Clean Water Act
(Federal Law). California water quality
standards are composed of four parts: the designation
of beneficial uses of water, water quality objectives
designed to protect those uses, implementation
programs designed to achieve or maintain compliance
with the water quality objectives, and an anti-degradation
policy that requires water quality better than water
quality objectives to be maintained at the higher water
quality level. |
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