Transcript All About Watersheds

Part II: Water Quality
Water quality refers to the
condition of the water:
Is it clean or is it polluted?
Water needs to be clean
enough to use the way we
want to.
Drinking water needs to be
cleaner than water that is
used only for recreation.
Water used for fishing and
swimming must be clean
enough to protect people’s
health.
Water must also be clean
enough to protect the health
of animals and plants that
depend on it for survival.
Water is an essential part of
any habitat.
Water pollution is divided
into two kinds:
•Point Source
•Non-Point Source
Point Source Pollution
Comes out of
a Pipe
Nonpoint Source Pollution
Erosion
(Sediment)
Animal Waste
(Nutrients)
Construction
Sediment harms fish and other creatures.
Lawn Fertilizer
Animal Waste
Sunlight
Small amounts
of Nitrogen
Phosphorous
and sediment
Balanced
Healthy
Bay Grasses
Algae Growth
Healthy
Habitat
Large amounts
of Nitrogen
Phosphorous
and sediment
Sunlight
Algae
Bloom
Reduced
Bay Grasses
Unhealthy
Habitat
Algae Die-off
Algae Decomposition
Plenty of
Oxygen
No
Oxygen
Shopping Center
Gas Station
You depend on your watershed
for good, clean water.
Testing, or monitoring, water
quality is needed to make sure
that water is clean enough for
human and animal health.
Water testing is divided into
two kinds:
•Biological testing
•Chemical testing
Biological Monitoring
Biological monitoring is a way to test the
water quality of a stream by finding out
what kind of benthic macroinvertebrates
are living in the stream.
• benthic means, “living on the bottom of a
body of water (such as a pond or stream)”
• macro means, “big enough to see”
• invertebrate means, “without a backbone”
Some Benthic Macroinvertebrates
that live in streams
By finding out what kinds of
macroinvertebrates live in a
stream, you can determine
how good the water quality is.
By finding out what kinds of
macroinvertebrates live in a
stream, you can determine
how good the water quality is.
Sensitivity to Pollution
Mayfly larvae are
very sensitive to
pollution.
Horsefly larvae are
tolerant of pollution.
Dragonfly larvae are
somewhat sensitive to pollution.
Most macroinvertebrates living on the
bottom of streams are the larval stage of
adult insects.
Mayfly Larvae
Mayfly Adult
To monitor a stream’s health, we collect
macroinvertebrates from stream riffles.
Another Riffle
Collect macroinvertebrates from a
stream riffle using a kick seine.
Carefully carry the net back to shore
after collecting the macroinvertebates.
Identify and count all the macroinvertebrates
Most of them are very small.
Some of the bugs are a little bigger!
These are two hellgrammites.
This is a stonefly larvae.
A water quality index score is
calculated based on the:
•Kinds
•Number
•Diversity
Of macroinvertebrates found
in the sample.
Chemical Monitoring
Chemical Monitoring
Chemical monitoring is a way to check the
water quality of a stream by performing
various tests. Common tests are:
•Temperature
•pH
•Dissolved Oxygen (DO)
•Nitrates
•Turbidity
•Bacteria (E.coli)
Temperature
• A thermometer is used to measure
water temperature.
• Living things need a fairly
constant temperature to be
healthy.
• Most living things are
healthiest in a certain range
of temperature.
Optimal Temperature Ranges for Wildlife
Above 25°C (77°F)
Lethal temperatures for salmonids
and some aquatic insects
Above 20°C (68°F)
Warm
Range
Cool
Range
Bass, bluegills, carp, catfish, crappie,
Dragonflies, trueflies, netspinners
Cool Range Between 13 and 20°C (55.4
-68°F)
Chinook, sturgeon, shad, walleye
Maflies, caddisflies, stoneflies
Cold Range Below 13°C (55.4°F)
Cold
Range
Steelhead, sockeye, rainbow trout,
brown trout, brook trout, smelt
Maflies, caddisflies, stoneflies
Temperature
Native Brook Trout prefer a
temperature below 13°C (55°F)
Temperature
Rainbow Trout and Salmon prefer a
temperature from 13°-20°C (55°- 68°F)
Temperature
Perch and Catfish prefer water
above 20°C (68°F)
Temperature
Lake Meade, Nevada
before
after
Green algae bloom at a temperature
above 25°C (77°F)
Factors that Influence
Water Temperature
1. darker water is warmer because it
converts sunlight to heat
2. overhanging trees shade streams and
keep the water cool in summer
3. runoff from paved surfaces (like roads
and parking lots) is warmer than runoff
from grass or a forest floor
pH
pH is the measure of alkalinity or acidity
of a substance such as soil or water.
•a ph of 7 is neutral
•a pH below 7 is acidic
•a pH above 7 is alkaline
All fish DEAD
pH tolerance
for most
aquatic life
All fish
DEAD
pH
Most aquatic organisms exist in a pH
range of 5.5 to 9.5.
Trout live in water that has a pH from 4.5
to 5.5.
pH
The healthiest range for fish eggs is a pH
from 6.0 to 7.2.
pH
The best range for the growth of algae is
7.5 to 8.4. Is that acidic or alkaline?
An algae bloom in Lake Meade, Nevada
pH
Carp die in five days if the pH is 4.3 or
lower. Is that acidic or alkaline?
Dissolved Oxygen (DO)
DO is the measure of the amount of oxygen
that is dissolved in the water. Oxygen
enters the water in two main ways:
turbulence
plants
All Animals (Including Fish)
Need Oxygen to Live
• DO ranges from 0 to 14 ppm.
• Most aquatic animals, such as fish and
macroinvertebrates, will die in a few
hours at DO levels as low as 2.0 ppm
• Most fish will die in a few days at DO
levels below 3.0 ppm.
• Fish grow and develop more slowly at DO
levels below 5.0 ppm.
How to Measure DO
Dissolved oxygen is measured using a
test called the Winkler Method.
•Use gloves while collecting the sample and
conducting the test to avoid contamination of
the water sample and to protect your hands
•Wear glasses or goggles to protect your eyes.
Other Chemical Tests
Other chemical tests that are useful
can measure the following:
• nutrients such as nitrogen and
phosphorous
• bacteria from animal and human waste
• turbidity is how cloudy the water
appears
• toxic substances such as pesticides,
metals and various chemicals
Turbidity
• Turbidity is a measure of the
“cloudiness” of water.
• Cloudiness is caused by suspended
solids (mainly particles of soil) and
plankton (microscopic plants and
animals)
• A healthy stream may have moderately
low levels of turbidity because plankton
are an important part of the food chain.
Turbidity
Clay and silt
particles
produce most
of the
turbidity in
this picture.
Turbidity
Higher levels of turbidity can cause
problems:
• Turbidity blocks out sunlight needed by
submerged water plants.
• Turbidity can raise water temperature
by absorbing the heat of sunlight.
• Turbidity can make it harder for
creatures to find food.
Turbidity
The secchi disk is
lowered on a line marked
for depth, and the depth
at which it disappears is
recorded to measure
turbidity.
Nitrates
Nitrate is
the first
nutrient
listed in a
fertilizer.
The numbers
(10-10-10)
indicate the
percent by
weight of
each
nutrient.
BACTERIA
Most bacteria are important in nutrient and
other biological cycles.
Excess nutrients
cause algal blooms.
As algae die and
decay, the high
bacterial load
rapidly consumes
dissolved oxygen.
Fish kill due to low
dissolved oxygen.
BACTERIA
Some bacteria can make people sick when they
drink the water, or cause infections when
people swim in it.
Thomas Jefferson Soil & Water Conservation District
2134 Berkmar Drive
Charlottesville, VA 22901
www.tjswcd.org