Teacher Resource 8: Know Your Watershed
Recommended for grades 4-6
Key elements of Lesson 8:
- Learn what is a watershed and many contributing factors within it.
- Build upon your knowledge of the water cycle by learning more about storm water runoff and ground water infiltration and how they affect salmon.
- Learn about human impacts to watersheds, including your own watershed.
- Learn to use an online mapping tool to research your own watershed
Outcomes of Lesson 8:
- Students will be able to define what is a watershed and describe many characteristics.
- Students will able to demonstrate stream orders within a watershed.
- Students will be able to demonstrate an understanding of storm water pollution and impervious surfaces to streams and salmon.
- Students will be able to find their own watershed using a special online map tool.
- Students will be able to cite the impacts of human development within their own watershed.
Student Learning Activities
Resources Students will Reference for this Lesson:
Online mapping tool at ERMA.org.
A Native American Reading
Clarence Pickernell, a Quinault-Chehalis-Cowlitz Native American from Tahola, Washington told this legend in February 1951. He had heard it from his great grandmother. Pickernell pronounced the closing words rapidly – in a rhythm and with a hand movement to suggest the lapping of water against the shore.
One time when the world was young, the land west of where the Cascade Mountains now stand became very dry. This was in the early days before rains came to the earth. In the beginning of the world, moisture came up through the ground, but for some reason, it stopped coming. Plants and trees withered and died. There were no roots and no berries for food, and water in the streams became so low that salmon could no longer live there. The ancient people were hungry. At last, they sent a group of their people westward to ask Ocean for water.
“Our land is drying up,” they told him. “Send us water lest we starve and die.”
“I will send you my sons and daughters,” Ocean promised the ancient people. “They will help you.” Ocean’s sons and daughters were Clouds and Rain. They went home with the messengers from the dry country. Soon there was plenty of moisture. Plants and trees became green and grew again. Streams flowed with water, and many fish lived in them again. Roots and berries grew everywhere. There was plenty to eat. But the people were not satisfied with plenty. They wanted more. They wanted to be sure they would always have water. So they dug great pits and asked Clouds and Rain to fill them. Clouds and Rain stayed away from their father, Ocean, so long that he became lonely for them. After many moons, he sent messengers to ask that his sons and daughters be allowed to come home.
“Let my children return home,” he sent word to the ancient people. ”You have enough water for the present, and I will see that you have enough in the future.”
But the people were selfish and refused to let Clouds and Rain go. The messengers had to return to Ocean without his sons and daughters. The Ocean told his troubles to the Great Spirit.
“Punish the people for their evil ways,” prayed Ocean. “Punish them for always wanting more and more.” The Great Spirit heard his prayer. He leaned down from the sky, scooped up a great amount of earth, and made the Cascade Mountains as a wall between Ocean and the dry country. The long and deep hole left where the earth had been, Ocean soon filled with water. Today, people call it Puget Sound.
The people east of the mountains are still punished for their selfishness and greed. Ocean sends so little moisture over the range that they do not have all of the plants that grow along the coast. But they still have the pits their grandfathers dug. They are Lake Chelan and the lakes south and east of it.
Ocean still grieves for his sons and daughters who did not come home. All day and all night along the beach he calls to them and sings their mournful song: “Ab’tab lab’ tab lab’! Ab tab lab’! Ab tab lab’ tab lab’ Come Home! Come Home!”
(From The Origin of Puget Sound and the Cascade Range from Indian Legends of the Pacific Northwest
by Ella E. Clarke, University of California Press at Berkeley, 1953)
A Short Course on Watersheds
(Background information for learning activities “Water – The Constant Traveler,” and “Finding Your Ecological Address”)
WHERE IS “WATER – THE CONSTANT TRAVELLER?” WE NEED TO INSERT IT BELOW AND LINK TO IT.
All land on earth is a watershed. If you were to stand in a stream bed and look upstream at all the land that drains to it, you would be looking at the stream’s watershed. Almost all the area of a watershed is land, not water. And almost everything that occurs on that land influences the stream’s ecological health. Humans and their activities have a heavy influence on watersheds and water quality.
A river and its branching collector streams stretch throughout a watershed area and gather water along their way, and with it the particulates and pollution from activities on land. Human actions affect water quality and therefore fish, wildlife, and the natural processes within a watershed area. Once students learn the connectedness of all the living things within their watershed, they can begin to develop a sense of ecological responsibility.
For every watershed there is a drainage system that conveys rainfall to a common body of water, be that a river or a lake or the ocean. A watershed may be the drainage area surrounding a lake that has no surface outlet, or a river basin as large as that of the Columbia River. Within such a large watershed are many smaller watersheds that contribute to overall streamflow. The border between watersheds is called a divide.
A watershed is an area of land drained by a network of tributary channels (small streams, larger rivers). The physical channels of streams and rivers collect and carry runoff from rainfall, snowmelt or groundwater, conveying it eventually to estuaries and oceans.
Stream channel themselves are just a small portion of the overall surface area of a watershed. But they of course play a key role in mapping a watershed. The smallest channels in a watershed — those with no tributaries — are called first-order streams. Two first-order streams join to form a second-order stream. Two second-order channels join to form a third-order stream, and so on. First and second-order channels are commonly small, steep, or intermittent (they carry water only during wet times). Orders six or greater are larger rivers.
Natural channels increase in size as tributaries enter and add to the flow. Channels changed with erosion and deposition, and a natural channel is neither straight nor uniform.
While upstream reaches tend to be steeper with faster flowing water, gradient decreases downstream as width and depth of the channel increase. Likewise, the size of sediment in the channel tends to decrease, often with boulders in hilly or mountainous stream areas, to cobbles or pebbles in middle reaches, to sand or silt in the downstream reaches.
Streams and rivers change. In some cases, large floods cause new channels to form, leaving once-productive streams dry and barren.
Scientists who study watersheds use “stream orders” to rank streams within the watershed. A stream assigned with the number 1 is referred to as a “first order stream.” A stream assigned with the number 2 is referred to as a “second order stream.” And so on. Study the diagram as we explain how it works:
The smallest streams with no connecting streams above them are assigned the smallest number (1 — referred to as a “first order stream”). Of course, these small streams are uphill of other streams they will join on their way downhill. When first order streams join other streams on their way downhill, they are assigned a higher order number. Here’s how it works for all streams:
- When two streams of the same number join (for example, two first order streams, or two second order streams, or two third order streams, etc.), they are assigned the next highest stream order number. For example:
- Two first order streams combine to become a second order stream.
- Two second order streams combine to become a third order stream.
- Two third order streams combine to become a fourth order stream.
- And so on.
- However, when a lower order stream combines with a higher order stream, they remain at the number of the higher order stream. For example:
- A first order stream joins a third order to stream and remains a third order stream.
- A fourth order stream is joined by a third order stream and remains a fourth order stream.
Continue to study the diagram, then click it to launch the Learning Gallery where you will master how to determine stream orders within a watershed.
Learning Gallery: Stream Orders
In addition to stream orders, streams are also classified by the period of time during which flow occurs.
- Perennial streams have year-round flow 90 percent or more of the time. These are higher order streams. They have well-defined channels.
- Intermittent streams flow only during the wet season.
A Stream is the Product of its Location
The physical, chemical, and biological makeup of a stream relates to surrounding physical features of the watershed and geologic origin. Analysis of these features aids understanding of stream-watershed relationships and predicts effects of human influences on different stream types.
Factors Affecting Watersheds
Some precipitation infiltrates the soil and percolates into aquifers (groundwater storage and recharges areas). During dry summer and fall months, natural groundwater discharge is the main contributor to streamflow. Without groundwater discharge, many streams would dry up.
Overdrawing: Pumping water from an aquifer for industrial, irrigation, or domestic use reduces the volume of an aquifer, and unless withdrawals are regulated, the aquifer will eventually be depleted. Springs once fed from the water table, in turn, dry up. A drained aquifer leaves hollows in the earth, and the overlying land may settle and even collapse, permanently damaging the capacity of the aquifer and making recharge more difficult and less effective.
Climate is the type of weather a region has over a long period of time — and it drives water storage and water loss. Water comes to the watershed in seasonal cycles, principally as rain or snow. In some areas, condensation and fogdrip contribute water. The seasonal pattern of precipitation and temperature changes determines streamflow.
Climate and transpiration
In hot, dry or windy weather, bare soil and water bodies lose water to evaporation. Plant transpiration increases, drawing soil moisture from a greater depth, drying the soil out further. Transpiration is greatest during the growing season and least during cold weather when most plants are relatively dormant.
Wind may cause erosion, control the accumulation of snow in sheltered places, and may be a significant factor in snowpack melting. Wind erosion can occur wherever wind is strong and constant, or where soil is unprotected by sufficient plant cover.
The physical features of a watershed are determinative factors.
Size and slope: The size of a watershed affects the amount of water in it. Generally, a large watershed in a region receives more precipitation than a small one in the same region. Shape and slope influence surface runoff and seepage into streams. The steeper the slope, the greater is the likelihood of rapid runoff and erosion, and plant cover is more difficult to establish. Infiltration of surface water is reduced.
Storms: Orientation of a watershed relative to the direction of storm movement affects runoff and peak flows. A rainstorm moving up a watershed from the mouth releases water in the lower section before the upper sections; the lower sections pass their water peak before runoff from the higher sections arrives. On the other hand, a storm that starts at the top and moves down a watershed reverses the process.
Sun: Orientation of a watershed relative to the position of the sun cycle affects temperature, evaporation, and transpiration. Soil moisture is most rapidly lost by evaporation and transpiration on steep slopes that face the sun. Watersheds that slope away from the sun are cooler, and evaporation and transpiration are less. Slopes exposed to the sun usually support different plants than those facing away from the sun.
Wind: Orientation with regard to the prevailing winds has similar effects.
SOILS AND GEOLOGY
Soil is a thin layer of the earth’s crust. It is composed of mineral particles of all sizes and varying amounts of organic materials. It is formed from the breakdown of parent rocks to fine mineral particles during:
- Freezing and thawing in winter
- Heat expansion and cool contraction in summer
- Wind and water erosion
- The grinding action of ice
- Gravity rockfall and avalanche movement
- Rock minerals in rain and snowmelt water
- Chemical action of lichens and other plants
Soils are of two types:
- Residual soils are those developed in place from underlying rock formations and by surface plant cover. Residual soil characteristics are closely related to the parent material from which they were formed.
- Transported soils are those transported by gravity, wind or water.
Climate strongly affects soil formation. Rainfall causes leaching (the movement of dissolved particles through soil by water). Temperature affects both mechanical breakdown of rocks and the breakdown of organic material.
Soil bacteria, insects, and burrowing animals play a part in the breakdown and mixing of soil components.
Plants: Soil often determines which plants will establish a protective vegetative cover. Plants also modify and develop soil. Plant roots create soil spaces. Plant litter adds organic matter to soil and extracts water and minerals through the roots. Plant litter slows surface runoff and protects the soil surface from direct rainfall and puddling. On steep slopes, plant growth rates are slower because soil depths are shallower, limiting the capacity to hold moisture.
Soil is an irreplaceable watershed resource. While forage, timber, and water are all renewable resources dependent upon soil, soil, on the other hand, is a non-renewable and valuable resource. It may take more than a century to produce a centimeter of soil and thousands of years to produce enough soil to support a high-yield, high-quality forest, range, or agricultural crop. Soil is the basic watershed resource. Careful management and protection of soil is necessary to preserve the function and productivity of a watershed.
Grasses, forbs, shrubs and trees are the major plant cover types in a watershed. All four types contribute to organic litter and affect soil development.
While all plants in a forest have some effect on water, trees are the most important. Tree-litter fall protects the soil’s surface. Tree roots go deep into the soil and help bind it, and tree crowns provide the most shade.
A forest usually includes an understory of shrubs and a low ground cover of forbs and grasses.
Plant cover benefits a watershed. The canopy intercepts rain and reduces the force with which it strikes the ground. The canopy and stems also reduce wind velocity.
When leaves and twigs fall, they produce litter, which decomposes and is eventually incorporated into the soil. Litter protects the soil surface, allows infiltration and slows down surface runoff. Stems and roots lead water into the ground. Roots open up soil spaces for water retention and drainage as well as add organic materials to the soil. The movement of minerals from roots to canopy provides recycling. Windbreaks of trees and shrubs protect crops and reduce moisture losses from evaporation. Grasses, trees, and shrub stems along riverbanks trap sediments and floating debris during high water flows. Roots bind and stabilize stream banks and slopes to reduce slides and slumps. While all plants in a forest have some effect on water, trees are the most important.
Watershed soils and vegetation have a pronounced impact on water quality. Accordingly, human activities affect watershed quality. These include timber harvesting, livestock grazing, agriculture, recreation, and urban and industrial development.
Harvesting timber reduces plant cover density, exposing soil to the elements. It must be carefully managed and plant cover rapidly restored. In snow zones, timber harvest can affect the accumulated snow pack and modify snow melt rates. Washington’s Forest Practices Acts ensure the consideration of soil and water resources during timber harvest.
Domestic livestock tend to concentrate in certain areas when grazing. Concentrated grazing impacts plant cover and soil. While limited grazing can enhance grass cover, overgrazing can severely limit forage productivity. Improperly timed, grazing for too long, or with too many animals can alter the vegetation dramatically. Excessive trampling by grazing animals can contribute to soil compaction, accelerated runoff, and significant erosion problems.
It is important that livestock not graze beyond the carrying capacity of the land and the forage it supports. Management must consider timing, density and duration of animal use. Generally, recovery does not occur if vegetation is thinned to less than 70 percent of the natural cover. Without reseeding and other management practices, degradation will continue.
Crop production and soil science
Farmers historically have tilled (turned the soil) to prepare it for each new growing season. Tilled soil is vulnerable to wind and soil erosion and more prone to evaporation. Erosion can remove the finer and more fertile particles of soil, leading to a greater dependence upon fertilizers. Erosion carries those fertilizers — as well as herbicides and pesticides — into drainage systems. However, our growing understanding of soil science indicates that there is a better way to farm.
Topsoil can and should be an ecosystem of activity:
- Untilled topsoil with active root activity contains enzymes and biomes which promote plant growth.
- Transpiring plants “breath in” carbon dioxide from the air and “exhale” carbon through their roots. That carbon gas accumulates in the soil (called “carbon sequestration”).
- Plant roots bind soil, improving the soil’s ability to retain moisture.
Combined with year-round plant growth which protects soil from erosion, these factors create a nutrient-rich, resilient environment for plant growth which can be applied to farming.
The age-old practice of tilling exposes the soil it to air, loosening it, and damaging the essential enzymes and biomes that promote growth; it releases the carbon produced in the soil during plant transpriation to the atmosphere. The loose and exposed soil is vulnerable to evaporation, wind and water erosion, and the direct impact of rain.
Crops benefit in remarkable ways from:
- Leaving the soil untilled, and
- Mixing “cover crops” — year-round non-food crops — among the food crops.
The purpose of cover crops is to promote year-round root activity in the soil, which promotes enzymes and biomes as well as the soil’s ability to retain water, and provides cover to the soil against rain and wind. Cover crops promote healthy, year-round topsoil activity. The healthier topsoil relies on fewer-to-no fertilizers, requires less water, protects valuable soil from erosion, while trapping carbon in the soil.
No-till farming combined with cover crops can deliver equal or better capacity, in a healthier growing environment, with lower costs in water and fertilizer, all while playing a significant role in reversing climate change. For farmers, it is a win-win.
As you learned earlier in the lesson, plant cover affects the movement of water in the water cycle. Shade and mulch formed by plant litter reduce evaporation of soil moisture. Plant roots can take up available soil moisture to a greater depth than evaporation. Let’s look at an example:
Juniper and other brush are rapidly encroaching in the central and eastern Washington uplands, above the river valleys. Juniper out-competes other vegetation for available moisture, and has reduced groundcover as it expands in these areas. The effect on groundwater is triple-fold:
With less groundcover, there is increased runoff and therefore less infiltration to groundwater storage;
Juniper roots tap into groundwater storage;
Juniper has a high transpiration rate, drawing from groundwater at a higher rate, leaving less available water for groundwater discharge to streams as summer progresses. The increase in juniper has led to a decrease in summer stream flows.
Fire is one of the most widespread and destructive agents affecting plant cover. Fire has the ability to nearly remove cover and organic litter, and, in extreme cases, sterilize and change the chemistry of the surface soil. Burning converts the organic materials in plant cover, litter, and topsoil to gases and solubles (readily leached ashes). The solubles can make acid soils alkaline, which will prevent the growth of native plants that are adapted to the acidic soil. Damage to soil can vary, but it may take several seasons for soil conditions to return to normal. Without a protective canopy and litter, the soil surface is rapidly puddled and sealed by the first rains. Infiltration is greatly reduced, making runoff and erosion more rapid. Debris-laden floods often occur within fire-denuded watersheds during only slightly abnormal rainfall. Most of the water falling on a burned landscape is lost by rapid runoff. Water that infiltrates is probably lost by evaporation. Streams from burned watersheds at first carry a heavy load of salts dissolved from ashes, floating debris, and erosion sediments. Water quality may soon return to normal, except for sediment-laden high flows. Water levels fluctuate and become less dependable. These conditions may continue for several years until the plant cover becomes reestablished on the watershed.
Fire can be beneficial to a watershed when it is carefully managed. It can reduce available fuel and prevent more destructive fires. Fire thins understory seedlings that compete with larger trees for available moisture. Open forest types such as ponderosa pine are maintained by fire.
The effects of beavers on a watershed can be both positive and negative. Their actions change watershed hydrology as well as damage cover by removing trees. A beaver dam changes energy flow in its immediate area by turning part of a stream environment into a pond or swamp. If high beaver populations coincide with heavy livestock use, the results can be devastating to streams. On the other hand, their dams can be beneficial as sediment traps and fish habitat. Water held behind a beaver dam is released more slowly over a longer period of time.
Mining requires opening the earth to remove mineral resources. It is done by stripping off the surface soil, vegetation and rock layers or by drilling tunnels into the earth to reach minerals. With either method, quantities of waste material are left on the surrounding land. This waste material is subject to erosion, and along with the removal of vegetation, adds to the sediment load of streams draining the mined area. Drainage from mined areas may contain toxic mineral salts harmful to aquatic life. To minimize degradation of the watershed, waste material disposal must be controlled. Early coal mining in the mountains around Issaquah dumped so much sediment into the streams that it buried spawning gravel and contributed to the extinction of the salmon that once lived there.
Urban development involves:
- Clearing, leveling and filling land surfaces
- Constructing buildings with impermeable roofs
- Paving roads and sidewalks with impervious materials
- Installing sewage disposal systems
Such development greatly changes infiltration and runoff — increasing runoff to streams and reducing groundwater infiltration. The changes to wet season and dry season stream flow can be dramatic.
We define high-quality water as:
- Clear – carrying only limited amounts of dissolved materials, and free of floating and suspended materials
Urbanization and other human activity decreases water quality.
Point-source pollutants are defined as those that enter waterways from a specific point. Common point source pollutants are discharges from factories and municipal sewage treatment plants. Point source pollution is relatively easy to collect and treat using waste water treatment methods. Most municipal wastewater treatment facilities, including King County’s, employ secondary treatment to effectively remove waste materials with biological processes — where oxygenation and enhanced growing conditions promote bacteria and other organisms to break down dissolved organic material. Secondary treatment removes 85-90% of suspended solids and eliminates almost all disease bacteria.
Non-point-source pollution is defined as pollution that is not easily attributable to a single point. It is really a new name for an old problem: runoff and sedimentation. Non-point-source pollution comes from a variety of sources such as agriculture, urban construction, residential developments, timber harvest, roadsides, and parking lots. Sediment, fertilizers, automotive oil, animal waste, and toxic materials are all major non-point-source pollutants. The diffuse source of these pollutants (their “non-point” nature) makes them more difficult to quantify and control than point-source pollutants.
Non-point-source pollution causes more than half the water pollution problems in Washington. Some pollutants are potential health hazards to people; others are harmful to fish and aquatic organisms. Streams do have an absorption and disposal capacity for limited amounts of pollutants, but these limits are easily exceeded. For example, every time someone washes a car in the driveway, all of the soapy water and the petrochemical waste it carries runs into the gutter, down the storm drain and into the nearest stream or lake.
Urban air pollution, especially photochemical smog caused by internal combustion gasoline engine emissions and industrial smokes, contributes to acid rain. This toxic mix of chemicals kills trees and acidifies water, damaging the growth of many organisms.
Dams, concrete-lined stream channels, dikes, levees and channel bed stabilization techniques all modify the rate, volume and capacity of streamflow. They are human efforts to modify flow to meet seasonal needs of society.
Many dams are built for multiple purposes:
- Control floods
- Store water for irrigation and consumption
- Regulate flow for navigation
- Provide power generation
Dams and other impoundments: Dams affect water temperatures. If shallow, they cause water to be warmed by the sun. If deep, they can preserve cooler water. Dams used for flood control reduce stream flow peaks during wet seasons and particularly during storm events. Water stored behind a dam can be used to supplement downstream flows during the dry season, providing for irrigation and urban water consumption needs, as well as helping salmon smolt migrate to the ocean. Dams also can be used to create navigation channels for boats, as on the Columbia River. In many cases, reservoirs provide recreation and new fisheries. However, their construction destroys stream habitat used by wild fish.
Good stewardship of a watershed maintains a useful vegetative cover and protects soil characteristics beneficial to the water resource. Land owners and users of watersheds need to be aware that private, personal actions have public, societal and environmental consequences on water quality and quantity.
Stewardship balances the needs of timber, forage, minerals, recreation, food, and wildlife. Rivers, hillsides, mountaintops, and flood-formed bottom-lands are all part of one system. When the non-renewable soil and water resources are protected and maintained in good condition, the dependent renewable resources, wildlife habitat, and recreational opportunities can be supported.
To balance the interests in multiple-use watersheds, legislation and government restrictions are instituted. For instance, Washington’s Growth Management Act limits development in rural areas and protects waterways by requiring a buffer of native vegetation in riparian areas. These laws may include:
- Land Use Planning
- Permitted and prohibited land uses or types of development
- Restrictions on water use
- Limitations on water development
- Pollution control
- Building limitations
Rivers, hillsides and flood-formed plains are all part of one system called a watershed. A watershed is naturally characterized by a combination of climate, soil types, topography, vegetative cover, and, of course, how it drains. Human development and activity can damage a watershed severely, destroy habitat and degrade water quality, reminding us of the importance to carefully manage our activity and employ best practices to protect soils, vegetation and waterways.
In this Learning Activity you will create a simple and very clever model of a watershed. You will explore how gravity and slope determine flow, and consider the impacts of human development on water quality in our streams, rivers and lakes.
Watch the video > >
Additional considerations for your model
A factor not considered with your model is impervious surfaces, which are introduced to a watershed by human development. Roofs, paved streets and storm water conveyance systems transport storm water quickly and efficiently away from our living spaces to streams, rivers and lakes. They, in fact, prevent water from infiltrating into the ground. In your Salmon Journal write:
Why do we create impervious surfaces?
Write down your reasons.
Consider how your community might look without impervious surfaces and storm water conveyance systems. In your Salmon Journal, write:
Without these impervious surfaces, my community (or my neighborhood) would look and feel different, especially during the rainy season.
How might you simulate impervious surfaces in your model?
Imagine if you could create a more accurate model that demonstrates both runoff and infiltration. How would storm water behave differently? What might you use to simulate impervious surfaces in the model you have already created?
Consider the benefits of infiltration
In your Salmon Journal, write:
Where does rain water go when it infiltrates into the ground?
Hypothesize one or more answers based on what you have learned so far or from your own experience.
Consider the impacts of impervious surfaces:
- Consider the speed in which storm water travels from a roof to a gutter to a pipe. Where does the pipe go?
- Consider the speed in which storm water travels from a road surface to a curb to a storm drain. Where does the storm drain lead to?
- Does storm water travel faster or slower to its destination in these systems than it would in nature?
- Consider the impact — during a storm — to the streams and rivers which receive this storm water runoff.
- Based on what you know about the needs of salmon, how might this adversely affect them? Explain the different ways.
In your Salmon Journal, write:
How might less water infiltration due to our many impervious surfaces affect water for salmon in streams and rivers?
Hypothesize your answer(s).
Student Reading: Finding Your Ecological Address
Water runs downhill — we all know that. The instant that a drop of rain hits the earth, it begins its journey to the ocean. Of course, not all water drops make it to the ocean. Some are taken up by the roots of plants and are transpired into the air through the plants’ leaves. Some form puddles, part of which evaporate. Some filter down into underground areas (called groundwater), moving slowly downhill though out of sight. But most water drops end up as runoff — “running off” into creeks, streams and rivers. This journey may be long or short, but the ultimate destination is the same: the ocean.
A watershed is an area of land which drains water. For example, if you were to stand in a stream bed and gaze upstream at all of the land that drains water to this stream, you would be looking at this stream’s watershed. In fact, let’s say your stream is named Elks Creek — you could confidently say that the name of the watershed you are gazing at is called the “Elks Creek Watershed.” That’s because most watersheds are named after the largest and most downstream stream or river they contain. It should not surprise you that almost all the area of a “watershed” is not water — it’s land. And almost everything that happens on (or to) that land affects the quality of water in the stream that drains it.
All land on earth is in a watershed.
A watershed is drained by a network of stream channels. Streams collect surface water runoff from rain, snowmelt or underground springs and get bigger as other streams connect to them on their way downstream. The shape and pattern of a stream can vary, depending on slope, vegetation, and the type of soils and rocks in its path. A wild stream is forever evolving, always in the process of change.
Watersheds can be big or small. They can be REALLY small (a mud puddle has a watershed of only a few square feet) or really BIG (The Columbia River has a watershed area of 258,000 square miles). The BIGGEST watershed in the country is the Mississippi River, which drains all the land between the Rocky Mountains and Appalachian Mountains! That’s huge.
Watersheds are separated by ridges, called divides. Divides are the boundaries between watersheds. The Continental Divide of the U.S., for example, is in the Rocky Mountains. Amazingly, all the rain and snow falling on the west side of the divide flows into the Pacific Ocean. All the rain and snow falling on the east side of the divide, sooner or later, ends up in the Atlantic Ocean.
Let’s apply some of what you learned about the water cycle to watersheds.
Feeding a Stream
Runoff vs. Groundwater: Runoff is the gravity-powered journey of water flow downstream. Runoff erodes the rocks and soil of the watershed. Most runoff from a typical storm drains to a tributary and drains to the main arm of the watershed. But some runoff percolates into the soil as groundwater. Groundwater slowly and steadily feeds tributaries throughout a watershed. During and shortly following a storm, river levels rise as a result of runoff. But interestingly — during most other times — most of the water running in streams is from groundwater. Groundwater is like a leaky hose you can count on to keep streams flowing between storms.
The shape, slope, soils and vegetation of a watershed affect the speed of runoff, intensity of erosion, and the amount of water that can percolate into the soil. Steeper slopes cause rapid runoff and increased erosion. Exposed soils erode more easily.
Plant cover benefits a watershed. Grasses, forbs, shrubs and trees intercept rain, reducing the force with which it strikes the ground. Plant canopy buffers the wind. Roots bind the soil together, stabilizing stream banks and slopes. Plant material falls into the stream, delivering vital food to the creatures that inhabit it.
Humans remove both groundwater and water in streams from the watershed for their own uses, including irrigation, drinking, cooking and cleaning. Some of that water is returned to the watershed, usually not as clean as it was when removed.
Human activities continue to both help and hurt watersheds. Good stewardship of watersheds is essential for a clean environment and our own good health. Activities such as agriculture, recreation, timber harvest, livestock grazing, urban and industrial development, and mining can be harmful if they are not managed carefully. Good management includes such activities as:
- Planning and setting rules for how land may be developed, and setting aside areas so that they will never be developed.
- Restricting water use and and establishing rules for how (and how much or how little) we control the flow of water in nature.
- Controlling pollution.
- Involving the community in repairing watersheds and making management decisions.
Stewardship is alive and well in Washington. You can volunteer to help restore damaged watersheds, “adopt” portions of streams and rivers, or teach young people about salmon in their local creeks. We at the Friends of the Issaquah Salmon Hatchery (FISH) are presenting this lesson to teach you how to be a steward of your own local watershed and the remarkable salmon that visit each and every year to spawn.
Land, rivers and groundwater are connected by the water cycle and their watershed. Weather conditions, soil types, topography, plant cover, and drainage define the character of a watershed. Each of us has an “ecological address,” one that tells us where we live in relation to the watershed above and below us, and defined by the plants and animals that live there with us.
The state of Washington is a vast area with diverse landscapes. It has flat lowlands, gentle slopes, hills and steep mountains. Many areas are forested, others have been developed. Within this context, we will consider the water cycle and the journey that water takes through a watershed on its way, eventually, back to the ocean.
Consider this: Land is never really truly flat. When enough rain falls on a surface, the water flows in a direction, indicating a slope, no matter how gentle. Take a moment to consider the land around you (your own watershed) as you answer the following questions.
Where rainfall goes once it strikes earth?
- Does it flow, and if so, in which direction?
- Or does it soak into the ground — why or why not — and where does the water in the soil go?
- How much of that water in the soil is used up by plants — and how much of it becomes groundwater?
- Where does that groundwater go?
- How much water on the surface evaporates?
Timing is Everything (Groundwater, the Water Cycle and Salmon)
All of the water that falls to earth does eventually drain to rivers in your watershed. What changes dramatically with human development is the timing of this drainage. ___% of the water in the rivers and streams in any watershed is provided by the slow release, or trickle, of groundwater. In many areas, including Western Washington, during summer months and extended dry periods, 100% of the water you see in streams is provided by groundwater. Groundwater allows the slow discharge of water over time to streams and rivers throughout the year. Rainfall that soaks into the ground in October may not reach a stream until September, where it will provide essential, cool, clean flow for fish and their young. The nature around us has evolved and adapted over millions of years to depend on this reliable, slow release of groundwater. This includes salmon who spawn in our tributaries in the fall, and whose offspring will live in our streams for up to a year before migrating to the ocean. Salmon rely on groundwater.
Consider how Development Impacts Your Watershed:
Think about how development has changed the way that water moves through the land. Impervious surfaces (surfaces that don’t allow water to penetrate, such as roofs and paved streets) are intended to channel rainfall quickly to gutters and storm drains and to the nearest stream, river or body of water. Development has a big impact on the natural water cycle and the salmon that — over the course of millions of years — have evolved and adapted to depend on cool, clean water flow. Take a moment to think about the impacts of impervious surfaces, gutters and storm drains to the natural water cycle, as you answer the following questions.
How does development (such as houses and paved streets) affect the flow of rainwater?
- Does it affect the amount of rainwater that is allowed to soak (percolate) into the ground?
- What might the impact of less groundwater be to rivers, streams, lakes — and the fish that live in them?
- With less groundwater, how might that change a small stream in the summer?
- What might the impact of less groundwater be to rivers, streams, lakes — and the fish that live in them?
- During a storm, how do paved streets, gutters and storm drains change the quantity of water that flows directly and immediately to streams, rivers and lakes?
- Is it more or less?
- Is it a faster or slower system? (Think about what that means.)
Discover Your Watershed:
Get out a map. Walk around. Learn which streams, rivers and/or bodies of water are in your watershed. Challenge yourself to think about the development and the nature around you, and how these things affect water quality and the timing of water drainage to our rivers, streams and lakes. In the next Learning Activity (Finding Your Ecological Address), you will explore mapping further.
A salmon walks into a restaurant on a cold, fall day and sits down at a table. The waiter walks up to the salmon and asks: “Can I start you off with a warm beverage, sir?” The salmon replies: “A beverage? Yes. But make mine cold. Definitely cold.”
Salmon require water temperatures between __ and __ in order to spawn successfully. Salmon eggs and sac fry require cool, oxygenated flow through the gravel. So too do fry and smolts. Salmon love cold water. They need cold water to thrive.
One of the many perils salmon face during their lifecycle is warming water. While to you, 65 degrees may feel very cold, salmon need colder water than that. In fact, it is essential. In your Salmon Journal, write down the following questions and fill in the answers for these factors that can contribute to cool stream flows for salmon:
- ___ along the stream. (Answer: riparian habit, shade)
- ___ outdoor temperatures. (Answer: Cool to cold)
- ___ events. (Answer: Storm)
- Flow from the ____ table. (Answer: groundwater)
One of these answers is particularly important. Consider how air temperatures change by season. During fall and winter, outdoor temperatures are cool/cold, the sun sits lower in the sky, rainfall becomes generally more plentiful, and (regardless of the amount of rain), flows in creeks remain cool. During the summer, however, the tables flip. Outdoor temperatures become quite high, the sun rides higher in the sky, and because rainfall is generally less plentiful, river flows decrease, particularly toward the end of summer. The source of stream water toward the end of summer is most often entirely groundwater.
Have you ever been underground? Have you ever ventured into a cave? You may have learned that the center of the earth is actually molten magma. (It’s extremely hot way down deep, near the center of the earth.) What’s it like inside a cave? Is it a cool place or a warm place? Is it warm or cool underground? Write the following question down in your Salmon Journal:
Is it warm or cool underground?
Stop and take a moment to discuss this question with your classmates. Why might it be hot? Why might it be cool? Write down your thoughts. Remember that this is the fun of science: when you are not sure of the correct answer, hypothesize! Write down any evidence you have or prior observations you’ve made. Stop reading this until you have written down your thoughts in your journal.
Here’s an interesting bit of history: In colonial times, prior to refrigeration, people would dig large holes/caves in the ground. During cold winter months, they would saw ice blocks from frozen lake surfaces and store them in these underground holes. George Washington had this type of refrigerator at Mount Vernon (you can still visit it today) and it was able to provide ice all summer long.
Why did this work? Because the topmost layer of soil absorbs the sun’s rays, providing shade to the ground below. Also, the molten center of the earth is many thousands of miles underground and has no impact anywhere remotely near the earth’s surface.
So, is it cool or warm underground? It’s shaded. It’s nowhere near the center of the earth. If you answered “cool,” you are correct. If you answered incorrectly, think about how the correct answer contradicted your answer. Draw a single line through your incorrect answer. Next to or underneath it, write the correct answer. Be sure your incorrect answer remains legible so your can demonstrate, as a good scientist, how your understanding has evolved (changed and improved).
What might be the potential relationship between the cool underground, the water cycle, and what you know about the needs of salmon? Be sure you have space on the page in your Salmon Journal and write down this question (leaving room below it):
What is the relationship between: 1) the water cycle, 2) the fact that it is cool underground, and 3) the needs of salmon?
Sketch a quick diagram of the water cycle within a simple watershed (for example, a hill with a stream running down a gully, or small canyon). You don’t need to be fancy or “perfect” with your sketch — this is just to help you think through your answer. Use arrows to show the movement of groundwater. Think about and show where the groundwater emerges. Where does that water end up? Once you have finished drawing, write a few notes in your journal describing what you have demonstrated in your sketch so far.
If you were Mr. or Mrs. Salmon, would you prefer a glass of lukewarm water that has been sitting in the sun all day — or a cool glass of water from the refrigerator? You obviously already know that salmon prefer cold water. On hot, sunny days, salmon rely on cold water to be provided to their streams and rivers. Streams get this cold water from just two sources. Write the following question in your Salmon Journal:
On hot, sunny days, from what two sources can streams and rivers get their cold water?
Spend a few moments to think about the answer. We’ve talked about one of them. We haven’t talked about the other, but you might be able to figure it out.
Want a few hints for “the other”? Think really cold. Think mountain tops.
Ready for the answer?
Streams and rivers can get their cold water on hot, sunny days from (we’ll start with “the other” answer): 1) snow melt on mountain tops (did you get that one?), and 2) groundwater. You may have noticed that we phrased the question as “can get their cold water” because watersheds in lower elevations don’t have snowpack. Just know that melting snowpack is an essential source of river water in many important watersheds throughout Washington state.
What we have learned is that groundwater is refrigerated water! And now you can explain why. In your Salmon Journal, write:
“Groundwater is cold because”
And finish the sentence.
In your journal, write:
Here is how 1) the water cycle, 2) the fact that it is cool underground, and 3) the needs of salmon are related:
And write your explanation. Share your explanation with your class.
Continue to think about the importance of cool stream water for salmon and their young. It is essential that water remain cool year-round, including the warmest months of summer. (INCLUDE A REMINDER OF WHICH SALMON ARE IN STREAMS DURING THE SUMMER.) Groundwater, as you now know, plays a critical role.
Lastly, challenge yourself to think about the ways that human changes to a watershed can greatly reduce the amount of rainwater that soaks into the ground. We will explore this very important issue in a separate Learning Activity. (OR PERHAPS WE EXPLORED IT IN THE LEARNING ACTIVITY IN THE WATER CYCLE LESSON? CONFIRM.)
How Big is Your Watershed? How Small is Your Watershed?
It’s all relative. Remember this: you live within more than one watershed. You live in a small watershed, which is part of a bigger watershed which, in turn, is part of a bigger watershed. Remember what you learned about river orders? Watersheds work the same way.
This map shows some of the watersheds of Washington, but not all. Remember: larger watersheds (or basins) are comprised of smaller watersheds (sub-basins). And even bigger basins contain those basins (in which case, we’d call them sub-basins). Explore this idea by launching Learning Gallery ____.
Your First Look at Washington’s Watersheds
With Learning Gallery: Washington’s Watersheds we use maps to introduce you to the primary watersheds of Washington state. These watersheds are assigned WRIA (Water Resource Inventory Area, pronounced “rie-uh”) numbers.
The Puget Sound Watershed is comprised of all the sub-basins (smaller watersheds) that drain into Puget Sound, our special body of water that is home to our resident orca pod, salmon and a wide variety of wildlife.
Launch Learning Gallery: Washington’s Watersheds to begin your study.
Learning Gallery: Washington's Watersheds
Learning Gallery: Zoom In
Learn how to use a powerful online mapping tool to study our watersheds
The National Oceanic and Atmospheric Administration (NOAA – pronounced “Noah”) has created a remarkably powerful online tool that allows us to study Washington’s watersheds and waterways. This tool is called the Environmental Response Management Application (ERMA), and is intended to help emergency response managers respond quickly to catastrophic events, such as oil spills. This tool gives you, the user, the power to navigate a map of Washington state, while overlaying incredibly useful information on top, such as:
- Major rivers
- Tiny streams
- Watershed boundaries
- Locations of all dams in the state
- Environmentally sensitive areas
- And a lot more.
We can use the ERMA tool to learn the boundaries of your watershed, including the rivers and even the smallest streams within it, and how your neighborhood is connected (by water) to Puget Sound.
Learning Gallery: Master a Mapping Tool
To get started, Click Here to launch this powerful online mapping tool in a separate tab of your browser. Then launch our Learning Gallery: Learn to Use the ERMA.org Tool. Follow along with the gallery as you begin to explore the mapping tool.
(Portions of this activity were adapted from: The Stream Scene: Watersheds, Wildlife and People by Patty [Farthing] Bowers et al, Oregon Department of Fish and Wildlife, 1990)
UPDATE THIS LEARNING ACTIVITY TO USE THE ONLINE MAPPING TOOL INTRODUCED ABOVE. BE SURE TO HAVE THE STUDENTS FIND THEIR OWN LOCAL, NEIGHBORHOOD WATERSHED AND HAVE THEM MAKE OBSERVATIONS BY WALKING AROUND.
In this mapping activity, students will learn about the geologic and topographic landmarks of their community.
- All land on earth is part of a watershed. We live in a watershed.
- Definition: a watershed is the land area drained by a stream (a small watershed) or system of streams and rivers (a large watershed) to a body of water (a larger stream or river, or a lake or the ocean). The size of a watershed is relative to the drain from which you measure upstream.
- Most human activities on the land have some effect on the streams and rivers that drain the watershed.
- Reading #1 (ADD TITLE)
- Reading #2 (ADD TITLE)
- Blank page in their journal for drawing their own watershed “maps”
- Colored pencils or markers (can be shared by groups of students)
- String or yarn (about one foot per student)
Watersheds are subject to pollution from failing septic tanks, excess lawn fertilizers, carelessly disposed crankcase oil, silt resulting from disturbed soils, and a whole lot more. Watersheds are also affected by the introduction of impervious surfaces, including rooftops and paved roads, which convey water to storm drains, preventing essential groundwater recharge. Groundwater recharge is essential to provide flow to streams throughout the year.
When students gain a greater understanding of their own environment, they gain awareness of how their personal actions and community rules and regulations affect the integrity and stability of their own ecological address.
In the activities that follow, students will be asked to find their “ecological address.” Their ecological address is defined as:
- The watershed in which they live, including the large lake or the ocean into which it feeds. Students will name their watershed by the largest stream or river within it.
This is not just a great technical exercise, but an excellent conceptual one as well, challenging students to draw connections between human activity in their neighborhood to a much larger water resource.
Two Versions of this Activity: Online or Traditional Learning
We have prepared two versions for this activity: one for online in which students use a powerful online mapping tool to study their watershed, and one for traditional in-class learning without computers, which relies on a teacher-led chalkboard presentation and print-outs. Choose the option that’s right for you.
1. Online (at-home or in-class):
- Students will use the ERMA.org mapping tool to:
- Navigate to their neighborhood.
- View all streams and identify stream orders within their neighborhood.
- Identify the names of larger streams.
- Print out the map showing their neighborhood and sketch an outline of their localized neighborhood watershed. Write the stream orders on the map. Highlight or write the names of the larger streams.
- Zoom out to display the larger watershed boundary.
- Identify the largest river(s) in the larger watershed.
- Identify the body of water into which that watershed drains.
- Note the following observations in their Salmon Journal:
- ADD OBSERVATION POINTS HERE.
- BEGIN DETAILED INSTRUCTIONS HERE.
2. Traditional (in-class):
- Use one or both of the student readings to prepare students for this activity, and complete the student activity below. WHAT EXACTLY ARE THE STUDENT READINGS?
- Begin by asking students to share their home address. Write a few of them on the chalkboard. Explain that these postal addresses have been devised by society because people need to be located within their community — by family, friends, and services such as the mail, police, fire or ambulance.
- Now tell students that they all have another kind of address, called an ECOLOGICAL ADDRESS. Invite students to discuss the meaning of the word “ecological.” Just as a postal address tells people one way that they are connected to a community, an ecological address tells people how they are connected to the land on which they live, and that they can have an impact on their local environment. Moreover, their local environment is connected to a bigger environment. In this activity, their ecological address will happen to be based on their location in their local watershed — a concept which we have been learning about.
- Have students discuss the term “watershed.” Let students share their definitions from the student activity page. Try to develop a class definition, which should be approximately this: all the land area that drains into a particular body of water. Tell students that they will be locating their own ecological addresses by finding and learning about the watershed where they live.
Chalkboard instruction: To help students understand the concept of watershed, on the chalkboard, trace the outline of your hand, wrist and part of your arm. Color in the space between your fingers and label your arm “Blue River”. Tell the students that this outline is a model for a watershed area. Your fingers represent streams that feed into the larger river (your arm). The colored space between your fingers is land, where people live. Let students know that a watershed’s name is usually taken from the stream or river that serves as the main collector of all the water in the watershed. Ask students what the watershed you just drew would be called (Answer: the Blue River Watershed). Write the name on the board.
- Ask students how large they think watersheds can be, then how small they can be. They should recall some of this from their reading. Impress upon the students that large watersheds include many small watersheds.
- Work with maps: Students are now ready to work with the Washington watershed maps included in this lesson. Divide the class into pairs of students and give each pair copies of the watershed maps: 1. – Watershed Resource Inventory Areas (WRIA) in Washington State; 2. – Lake Washington-Sammamish.
- On map #1, have the students locate WRIA 8. The Lake Washington drainage basin (WRIA 8) is comprised of all the waters funneling into lake Washington then flowing out through lake Union and Salmon Bay into Puget Sound at Shilshole Bay.
- On map #2, have students locate the Sammamish River and the Cedar River. The Chittenden Locks and Lake Washington Ship Canal were constructed in 1916 and made several dramatic changes to the Puget Sound area watershed:
- Historically, Lake Washington was nine feet higher than it is today and — remarkably — it did not connect to Lake Union. Instead it drained out its southern end through what was called the (now extinct) Black River. The Cedar River would also experience a dramatic change. Originally it, too, fed the Black River, just south of Lake Washington. The Black River, carrying water from both Lake Washington and the Cedar River, fed the Duwamish River, which drained into Puget Sound.
- The project created boat passage from Lake Washington to Puget Sound. The Lake Washington Ship Canal was built to connect Lake Washington to Lake Union; in doing so, it lowered Lake Washington by nine feet. The Chittenden Locks, in turn, were built to connect Lake Union with Puget Sound. To provide adequate flow for the new shipping thoroughfare, the Cedar River was diverted from the Black River to drain into the south end of Lake Washington. The shallow Black River dried up; there is no visual evidence of it today.
- On map # 2, have students locate the Piper’s Creek watershed by drawing a line around it with colored pencil or marker. Then have them locate Bear Creek watershed in the same way with another color. With a third color, have them draw a line around the entire Kelsey Creek watershed. Use a fourth color to outline Tibbetts Creek watershed. With a fifth color, have them draw a line around the May Creek watershed. With a final color, have them draw a line around Thornton Creek. Make sure all teams have correctly identified the watersheds before asking the following questions:
- If you lived two miles north of Renton, in which watershed (or sheds) would you live? (Answer: You would actually live in the May Creek watershed, which is part of the larger South Lake Washington watershed.) Remind students that a large watershed is made up of many smaller watersheds, and that both May Creek and South Lake Washington would be correct answers to the question.
- If you lived one mile east of Bitter Lake, in which watershed would you live? (Answer: Thornton Creek or North lake Washington)
- If you visited the Mercer Slough, in which watershed would you be? (Answer: Kelsey Creek)
- If you lived less than a mile due west of Issaquah, in which watershed (or sheds) would you live? (Answer: You would live in the Tibbetts Creek watershed, which is part of the Issaquah Creek watershed, which is part of the larger Lake Sammamish watershed.)
- Suggest that everyone lives in a watershed, and ask students to explain why this is true.
- Answers include: All land has waterways running through it that drain into larger waterways. For example, in most urban areas, rainwater feeds into storm drains. The drains then feed into nearby streams or rivers.
- Using maps #3 and #4 or a state or local map that shows streams and rivers, have each student name the watershed in which he or she lives. Explain that this watershed is the student’s ecological address, and that this address describes how he or she is connected to the land and water system that drains it. In urban areas that are hilly, a city map will be needed to determine the exact watershed in which a house might be found. A student’s ecological address can include the smallest watershed they can observe as well as a larger watershed that encompasses the smaller one. Have some students share their ecological addresses while other students follow along on their own maps.
- In their journals, have students make a “map” of their ecological address. The map need not be to scale, but it should represent the watershed(s) in which they live. As an alternative or additional in-class activity, have the entire class make a larger map of the watershed on large sheets of paper.
- Have students brainstorm a list of what they think can happen to water (and affect water quality) as it moves through a watershed. Highlight the things that are caused by human activity. These might include human activities such as discarding oil in the street, failing to pick up pet waste, clearing of land (removing vegetation), or washing cars at home (where runoff will enter the storm drain). Then have students determine how and where these chemicals would travel in their watershed. They can do this by tracing the path from the smallest tributary in the smallest watershed as it empties into larger and larger watershed areas. Have students repeat the activity, this time looking at non-human influences on watersheds, such as heavy rains, wind, wildfires and other natural phenomena.
- Have students calculate the number of miles of stream and river that are in their watershed, using the “scale of miles” on the published map. To help with measurements, use string to follow a curving waterway on the map. This measurement will help make clear to students the amount of area impacted by human activities affecting the watershed system.
- Using the state or local map, locate the Issaquah Fish Hatchery. Identify its ecological address (watershed).
- Build a list of who and what uses your watershed – from people to fish to wildlife. For each, make a list of the effects on the watershed.
Key Words: ecological
IF RELEVANT, WHICH IT PROBABLY ISN’T ANYMORE, INSERT WATERSHED RESOURCE INVENTORY AREAS IN WASHINGTON STATE.
Students can use their journal to write their definition of a watershed and explain their own ecological address.
Online learning: Maps can be printed at school and sent home in student packets, or printed at a library, for use in completing the ecological address activity.