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LOUISIANA
WATER QUALITY & RECREATIONAL ACTIVITIES
by Kevin Savoie & Brian LeBlanc
Louisiana
is blessed with an abundance of opportunities for people to
enjoy water related activities. Good water quality is essential
to these many outdoor activities such as fishing, boating,
and swimming. Most Louisiana residents think of water pollution
as toxic chemicals emitted from industrial plants or chemicals
used along roadways or farms to control weeds and pests. These
materials can pollute surface and groundwater if their application
or emissions violate laws or exceed scientifically set standards.
Enforcement
agencies are now trying to reduce the amount of point source
and nonpoint source pollutants in surface waters to make recreational
waters cleaner. Polluted water can be harmful to swimmers
and anglers. All people using Louisiana’s waters should
understand how these pollutants could affect their favorite
recreational spots.
Definitions
Point sources originate from a pipe or identifiable
locations in a stationary or fixed facility from which pollutants
are discharged directly into a water body. Pollution sources,
which do not have a single point of origin or are not introduced
into a receiving stream from a specific outlet are considered
nonpoint sources of pollution such as runoff
from fields, farms, woodlands, urban lawns, parking lots,
and streets.
Why
Increased Enforcement?
The U.S. Clean Water Act requires that states’ waters
be safe for swimming and fishable. Limits known as Total Maximum
Daily Loads (TMDLs) are now being set for the amount of pollutants
that can be discharged into specific Louisiana water bodies
to meet their designated uses. Many bayous, lakes, and streams
in the state do not meet minimum standards set by the Environmental
Protection Agency (EPA) for one or more of their designated
uses, such as fishing, swimming, or drinking water. The Louisiana
Department of Environmental Quality (LDEQ) is implementing
the TMDL program to improve water quality in the impaired
water bodies in Louisiana.
What
are the Major Pollutants and How Do They Affect Recreational
Waters?
- Dissolved
Oxygen
Perhaps the most common impairment of surface water in many
of Louisiana’s water bodies is lack of sufficient
dissolved oxygen (DO). The level of DO is below the level
necessary for a healthy aquatic habitat during certain times
of the year. Fish and many other aquatic animals require
oxygen concentrations in various amounts. Without adequate
oxygen, some fish species may cease be present or may be
too stressed to reproduce.
Dissolved
oxygen in water bodies comes from several sources and
is sometimes naturally more abundant. For example, waters
that flow at high velocities through variable terrain
such as over rocks, sand, and logs generally obtain much
oxygen through the air-water interface and subsequent
mixing. Microscopic aquatic one-celled plants called algae
also generate oxygen in water. Substances
that can reduce oxygen concentrations are called oxygen-demanding
substances. These include organic matter such as living
and dead plant material, sediment, and fecal material
from animals and humans. The normal decay processes consume
oxygen and thus contribute to oxygen demand. High temperature
decreases water’s ability to dissolve and hold oxygen.
Cooler water will contain more dissolved oxygen than warmer
water.
- Nutrients
Excessive algae blooms can be stimulated by an over abundance
of nutrients. Nutrient over enrichment or hypoxia is a major
concern in many water bodies of Louisiana, especially in
coastal areas of the Gulf of Mexico. Two nutrients that
have the potential to become pollutants — nitrogen
and phosphorous — are essential for all plant growth,
and therefore essential for the proper function of ecosystems.
However, excessive nitrogen and phosphorous concentrations
in water can accelerate algae and plant growth in streams
and lakes, resulting in oxygen depletion or low dissolved
oxygen. When excess nutrients enter a waterway through unnecessary
or improper fertilization of lawns, gardens and farms, effluents
from sewage treatment plants, and even manure from wildlife
and livestock, the potential for over enrichment or hypoxia
can occur and result in low dissolved oxygen. Without adequate
oxygen, some fish species may cease to be present or may
become too stressed to reproduce.
- Fecal
coliform
Many of the water bodies in Louisiana that are listed as
impaired are polluted with fecal coliform bacteria and do
not meet their designated use for swimming. Fecal coliform
is a term used to describe bacteria found in the intestinal
tract of warm-blooded animals. It is essential for digestion
of food, but can cause swimmers to become sick. Sources
of these bacteria include improperly maintained sewer treatment
facilities, livestock feeding operations, and naturally
occurring on some wild animals. Surface waters are monitored
for the presence and concentration of fecal coliforms. In
addition, the presence of this pollutant may indicate the
presence of other pathogens. Some kinds of coliforms such
as E. Coli can be transmitted from cattle to humans or from
person to person. These may be harmful to human health.
Fecal material also contains nitrogen and phosphorus and
can result in nutrient over enrichment of water bodies.
- Sediment/Siltation
Sediment is the largest pollutant by volume of surface water
in the nation. It comes from agricultural sources, construction
sites and soil disturbing activities in urban settings that
leave the soil exposed to rainfall. Sediment increases the
turbidity of water, thereby reducing light penetration,
impairing photosynthesis, and altering oxygen relationships.
It may reduce the available food supply for certain aquatic
organisms. Sediment deposits can cover spawning beds, thus
affecting fish populations. Over time, increased sediment
fills lakes and reservoirs.
Sediment
can damage fish spawning areas, reduced light penetration
needed by aquatic plants, increase water purification
costs, lower recreational value, clog channels and increase
flooding, increase dredging to maintain shipping channels,
and reduce storage capacity for reservoirs.
In
addition, sediment is often rich in organic matter and
nutrients from pesticides. The potentially harmful effects
of these substances in the sediment include rapid algae
growth, oxygen depletion as organic matter and algae decompose,
fish kills from oxygen depletion, toxic effects of pesticides
on aquatic life, and unsafe drinking water caused by nitrate
or pesticide content.
The
bottom line — human activities on land impact water
quality through runoff. We all contribute to water pollution;
therefore we can all contribute to water quality improvement
through some simple practices. These include maintaining home
sewer treatment systems, soil test before applying fertilizer,
and always follow label directions and use the recommended
amounts of pesticides.
Download:
lawater_quality.pdf
(125KB)
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