Part II: Water Quality Water quality refers to the condition of the water: Is it clean or is it...
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Transcript of Part II: Water Quality Water quality refers to the condition of the water: Is it clean or is it...
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
Healthy Habitat
Unhealthy Habitat
Sunlight
Small amountsof NitrogenPhosphorousand sediment
Large amountsof NitrogenPhosphorousand sediment
Healthy
Bay Grasses
Balanced
Algae Growth
Plenty of Oxygen
Algae Bloom
Sunlight
No Oxygen
Algae Die-off
Algae Decomposition
Reduced
Bay Grasses
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 MonitoringBiological 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 aresomewhat 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 MonitoringChemical 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 20°CAbove 20°C (68°F)
Bass, bluegills, carp, catfish, crappie,
Dragonflies, trueflies, netspinners
Cool Range Between 13 and 20°CCool Range Between 13 and 20°C (55.4 -68°F)
Chinook, sturgeon, shad, walleye
Maflies, caddisflies, stoneflies
Cold Range Below 13°CCold Range Below 13°C (55.4°F)
Steelhead, sockeye, rainbow trout, brown trout, brook trout, smelt
Maflies, caddisflies, stoneflies
Warm Warm RangeRange
Cool Cool RangeRange
Cold Cold RangeRange
Above 25°CAbove 25°C (77°F)
Lethal temperatures for salmonids and some aquatic insects
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
Green algae bloom at a temperature above 25°C (77°F)
Lake Meade, Nevada
before after
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 below 7 is acidic
•a pH above 7 is alkaline
•a ph of 7 is neutral
pH tolerance for most
aquatic life
All fish DEAD All fish DEAD
pHMost 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.
pHThe 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
pHCarp 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:
plants
turbulence
All Animals (Including Fish) Need Oxygen to Live
• Most aquatic animals, such as fish and macroinvertebrates, will die in a few hours at DO levels as low as 2.0 ppm
• Fish grow and develop more slowly at DO levels below 5.0 ppm.
• Most fish will die in a few days at DO levels below 3.0 ppm.
• DO ranges from 0 to 14 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 TestsOther 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.
The secchi disk is lowered on a line marked for depth, and the depth at which it disappears is recorded to measure turbidity.
Turbidity
Nitrate is the first nutrient listed in a fertilizer. The numbers (10-10-10) indicate the percent by weight of each nutrient.
Nitrates
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.
2134 Berkmar DriveCharlottesville, VA 22901
www.tjswcd.org
Thomas Jefferson Soil & Water Conservation District