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