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Note to Educator

This slide show has explanatory notes to accompany each slide.
Its primary purpose is to provide background for you, the educator, to make it easier to introduce the fundamental concepts to your students.
Be sure to review the PowerPoint prior to sharing it with your students and consider using some of the videos listed on the Watershed Game website as alternatives.
Note: In accordance with the Americans with Disabilities Act, this material is available in alternative formats upon request. Direct requests to 612-624-7708.

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Fundamental Concepts�Science Background

Science you need to understand before you play the game.

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v2018.10.03

2018.

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Definition of a watershed
Common land use categories
Background levels of sediment and phosphorus
Types and sources of pollutants
Impacts of nonpoint source water pollutants
Pollution Units (PUs) and pollutant load
Watershed Clean Water Goal

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Fundamental Concepts

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Definition of a Watershed

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A watershed is the area of land that drains to a particular lake, wetland or stream.

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Undeveloped Watershed: �What happens when it rains?

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Forested wetland

Bog

50%

10%

Definition of a Watershed

40%

This is a demonstration of a natural, undeveloped watershed (NOTE: It is an animated slide – each numbered explanation below represents one click of the mouse).

Natural, undeveloped watersheds have natural ways to use, store, and filter rainfall.

In a watershed that remains covered with natural vegetation (including forests, wetlands, streams and lakes, grasslands) most of the rainfall that hits the land is slowly:

Soaked up by vegetation to support growth, with some of it evaporating back into the atmosphere
What water does enter the soil gets filtered by natural soil processes as it soaks into the ground, helping to “lock up” excess phosphorus, sediment and other substances
This water then becomes the groundwater that helps keep many lakes and streams cooler in the summer.

Another way the land soaks up water is by storing it in wetlands like the forested wetland and bog in the picture. Wetlands act as sponges, holding water temporarily.

This gradual process, in which much of the water soaks back into the ground, is removed by vegetation, or is stored in wetlands helps protect the land from erosion or flooding.

In naturally-vegetated watersheds, studies show that roughly 50% of a typical rainfall soaks into the ground and about 40% ends up back in the atmosphere or supporting vegetative growth, leaving only about 10 % of the rainfall flowing slowly across the land.

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Common Land Use Categories

http://glei.nrri.umn.edu/default/landscape.htm

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Forested wetland

Bog

Developed Land: What happens when it rains?

50%

10%

Common Land Use Categories

40%

This is a demonstration of a developed watershed (NOTE: It is an animated slide – each numbered explanation below represents one click of the mouse).

This is the same watershed we looked at before, but now with a farm, city, and parking lots where there used to be trees and wetlands.

Now when rain hits the the urban area and flows across the parking lots and exposed soils of the farm, much less of it soaks back into the ground or gets stored in wetlands.

Because there is more water staying on the land surface and because there is less vegetation to soak it up, there is much more water flowing much more quickly across the land.
This quickly moving water takes exposed soil, fertilizer, pollutants, and other unwelcome materials to the watershed’s lakes, wetlands, and streams.

AND all that water moving so quickly can cause flooding. Note that the lake in the slide has been flooded, covering up the little shoreline cabins.

Because so much water stays on the land surface, much less is filtered through the soil to resupply the groundwater.
The surface water flowing across parking lots and rooftops can be heated by the sun, resulting in lakes and streams that are too warm.

In developed watersheds with a mixture of land uses, studies show that about 50% of typical rainfalls flows quickly over the land, with only about 10% soaking into the ground.

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Types and Sources of Pollutants

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Nutrients and Bacteria

Water Flows Too Fast

Too Much Water

Erosion

Sediment

Developed Land: Many Impacts

Road Salt and other Pollutants

Potential impacts from human activities on the land: new photo credit river keeper.

The Watershed Game only focuses on sediment (from erosion) and the nutrient phosphorus, but there are many other pollutants and problems that can result from the way we use the land.

Water Flows Too Fast: Water flowing too fast can erode soil, uproot plants, and change fish and invertebrate habitat.
Too Much Water: Too much water, in the form of flooding, causes property damage and changes habitat.
Nutrients and Bacteria: Runoff over lands and hard surfaces impacted by fertilizers, human or animal waste, and other sources can contribute excess nutrients (primarily nitrogen and phosphorus) and potentially harmful bacteria to waterways.
Road Salt and Other Pollutants: Pollutants, including road salt, gasoline, metals, and other substances deposited on hard surfaces, such as roadways, can be flushed into local waterways.
Erosion: Large volumes of quickly moving water can erode sensitive lands and stream and lake banks.
Sediment: Sediment from erosion, road and other construction, and other sources can impact waterways and smother habitat.

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Sediment and phosphorus are important and natural parts of a healthy environment!

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Background Levels of Sediment and Phosphorus

They are only pollutants when way too much enters our lakes, streams, and wetlands.

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Part of a healthy environment

Sediment

Some erosion is natural and important – enriches surrounding soil with nutrients.
Sediment-rich areas often have high biodiversity.
Deltas and river banks where sediment is deposited are often fertile agricultural areas.

Nutrients

Essential for all life.
Continuously cycling through plants, animals, and the environment to support life.

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DNA

http://upload.wikimedia.org/wikipedia/commons/4/4c/DNA_Structure%2BKey%2BLabelled.pn_NoBB.png

Background Levels of Sediment and Phosphorus

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Eroded soil

Fertilizer
Human and animal waste

Sediment

Phosphorus

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oars3rivers.org/sites/default/files/images/biomass_survey-b.jpg

Types and Sources of Pollutants

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Too Much Phosphorus

Phosphorus

Sticks to dirt and sediment particles
Usually key nutrient for triggering excess algae and aquatic plant growth
1 pound of phosphorus can yield 500 pounds of algae

Impacts of Pollutants

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Phosphorus as a pollutant

Phosphorus is sticky. It sticks to soil particles.

Think of the ball in the picture above as being the phosphate molecule and the Velcro paddles as being the soil particles.

The molecular form that phosphorus takes in water binds easily to clays and other soil particles that make up sediment.
This is important because any time that sediment is getting into waterways it also will have phosphorus hitchhiking along.

Controlling excess sediment and keeping it away from lakes, wetlands, and streams also helps reduce excess phosphorus.
Too much phosphorus is like providing a banquet table for aquatic plants and algae and can lead to excessive growth.

Though nitrogen is also needed for plant growth, it is usually more plentiful than phosphorus in freshwaters in the Midwest.

It doesn’t take much phosphorus to cause a lot of green stuff to grow in waterways.

1 pound phosphorus = 500 pounds algae.

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Some impacts

Too much plant and algae growth

Algae sometimes toxic

Loss of water clarity
Low dissolved oxygen
Loss of habitat and aquatic life
Water not swimmable, drinkable, or fishable

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Too Much Phosphorus

Impacts of Pollutants

More about impacts of phosphorus:

There is a name for the addition of excess nutrients to lakes or rivers that leads to excess plant growth. The process is called eutrophication.
Common symptoms of eutrophication include:

Too much plant and algae growth (some types of algae that do well in eutrophic conditions can be toxic to humans and animals)
Loss of water clarity caused by algae
Low dissolved oxygen caused by decomposing plant and animal matter and by plant respiration
Loss of habitat and aquatic life
Water that is not swimmable, drinkable, or fishable

Don’t forget about excess nitrogen! It can be important, especially in low nutrient lakes. Lawn fertilizer may be very high in nitrogen and runs off the land easily. Too much nitrogen can affect shoreline plant species and increase susceptibility to nuisance plant species.

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Phosphorus

“Eutrophic” lakes and rivers (green and scummy)

About 200 parts per billion*

Fertilizer and manure

We add parts per million to land
(1,000 times more concentrated)

Coca Cola

173,000 parts per billion

Impacts of Pollutants

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lowes.com/projects/images/buying-guides/Lawn-Landscaping/fert-label.jpg

*One Part Per Billion:�One sheet in a roll of toilet paper stretching from New York to London

Phosphorus: What do the numbers mean?

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Too Much Sediment

Brings phosphorus with it, increasing algae and aquatic plants
Reduces water clarity, making it hard for visual feeders like fish to find food
Reduces habitat near shore for fish and “fish food” like aquatic insects

Impacts of Pollutants

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Sediment embedded on bottom:

Reduces fish habitat

shelter
spawning areas
egg incubation areas

Insect habitat

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Very good

William Taft, MI DNR

Impacts of Pollutants

Very Good

Poor

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Sediment:

What do the numbers mean?

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Fish act stressed

Fish:

Abandon cover
Avoid turbid water
Increase respiration
Feed less
Cough more

Fish grow more slowly
Eggs hatch more slowly

Within days A few weeks

Impacts of Pollutants

Sediment: What do the numbers mean?

As the slide shows, it doesn’t take a lot of sediment to start to have impacts on fish.

The figure in this slide shows vials with different concentrations of sediment (suspended clay) in them.

At only 10 NTUs* of turbidity (not very cloudy looking to us), fish start to act stressed, and impacts get more severe as sediment concentrations go up.

Turbidity is the cloudiness or haziness of the water caused by large numbers of very small particles (mostly invisible to our eyes).

Tip: Think about being caught in a dust storm and trying to breathe. That is what fish are experiencing in high turbidity water.

NOTE: Turbidity can be caused by any kind of particle that interferes with light transmission but is often used to estimate how much sediment is in the water.

A more direct way to measure sediment in the water is Total Suspended Sediment, but it is more time-consuming to measure.

*NTU stands for Nephelopmetric Turbidity Units, which is how the instrument used to measure turbidity reports relative amounts of turbidity.

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Pollutant concentration

How strong is it?

Teaspoons sugar per cup of tea
[Micrograms per liter of phosphorus in MN waters]

Total pollutant “load”

How much over time?

Average calories consumed per person per day
[Average tons of sediment transported per year to a lake or stream]

http://www.ecy.wa.gov/programs/wq/plants/management/joysmanual/streampollution.html

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azom.com/images/Article_Images/ImageForArticle_11865(2).jpg

Pollution Units (PUs) and Pollutant Load

Pollution Units (PUs) and Pollutant Load:

The Watershed Game: Classroom Version uses Pollution Units to indicate how much pollution each land use practice is contributing to the stream and how much pollution will be reduced by the Tool Cards.

Pollution Units (PUs) are used in the Game as a simplified way to represent both pollution concentration and pollutant load, both of which are important to managing water quality.

Scientists and managers determine how much pollution is contributed by land use practices and how much can be reduced in two ways depending on what type of practice is being studied and managed.

In some cases it makes sense to look at concentrations of a particular pollutant. For example, knowing the concentration of phosphorus in a water sample helps us predict where and when there might be algal blooms.
In other cases, it is more important to look at total pollutant load to a particular lake or stream. For example, knowing how many tons of sediment have been transported to a particular lake or stream can help guide restoration.

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Clean Water Act: Fishable and swimmable water for all:

Pollutants from the watershed at or below the Clean Water Goal

Clean Water Goal is set through scientific study and water quality monitoring to

Protect human health
Protect and restore aquatic ecosystems and their watersheds

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Image: LakeSuperiorStreams.org

About MN Waters: pca.state.mn.us/index.php/about-mpca/mpca-news/featured-stories/swimmable-fishable-fixable.html

Clean Water Act: en.wikipedia.org/wiki/Clean_Water_Act

Watershed Clean Water Goal

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Questions?

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