The Water Cycle and
Human Impacts
Student Packet 1 for Matter Cycling Unit
General Biology
The Water Cycle
(Trace the path of water on the picture on the next page as you read.)
Water is our most recycled resource.
Consider, for example, that the water you
bathed in this morning may have
contained the same molecules of water
that washed over a South Pacific coral
reef a million years ago! The amount of
water on Earth is basically constant, but
the distribution of water changes over
time and space due to a dynamic process
called the water cycle or hydrologic cycle.
The water cycle is powered by solar
energy and gravity. 1. Warmth from the
sun causes evaporation of water from
lakes, streams and soils and ice and snow.
Solar energy also drives a process called
transpiration—the release and
evaporation of water from tiny pores in
the leaves of plants. 2. Evaporated and
transpired water vapor is stored in the
atmosphere until it condenses and is
pulled by gravity back to earth as rain,
sleet, snow, hail, dew or frost.
3. Up to 80 percent of this precipitated
water is returned directly to the
atmosphere by evaporation. The rest may
runoff over land and into lakes and
streams or may soak into the ground.
4. Some of the water that soaks into the
ground stays in the unsaturated zone.
This zone is the rock or soil layer in which
some of the spaces between particles are
filled with air and some are filled with
water. Some of the water in the
unsaturated zone is taken up by plant
roots and returned to the atmosphere by
transpiration. The rest of the water is
pulled deeper into the ground by gravity,
filling all the cracks and spaces in the
underlying layers of soil, gravel and rock.
Water in the saturated zone is called
groundwater.
The top of the saturated zone is the
water table. Water continues to move
underground from areas of high elevation
toward lowland areas. This movement is
generally slow, from a few feet per day to
a few feet per year. Wherever the water
table meets the land surface a spring may
form or groundwater may seep into to a
lake, stream, wetland or ocean. Once
above ground, the water can evaporate
and return to the atmosphere, and the
water cycle begins again.
Human activities may affect the
quality of water at any point in the cycle.
Air pollution can change the chemical
composition of rain and snow. Runoff from
rainfall and snow melt can pick up soil,
excess plant nutrients, pesticides, animal
wastes, and municipal and industrial
pollutants as it flows over land and into
lakes and streams. Contaminated runoff
can also soak into the ground and pollute
groundwater. Water percolating through
soil and rock may pick up natural
minerals or other contaminants.
Knowledge of the water cycle can help us
understand how water becomes polluted
and how pollution can be prevented.
(http://pulse.pharmacy.arizona.edu/resour
ces/arsenic/watercycle.pdf)
Water Cycle Questions
Instructions: Please Answer the Following Questions or Draw Diagrams based on water cycle
diagram and water cycle article on page 4.
1. List all the reservoirs of water (places where water is found on earth, living and nonliving) from the diagram above.
2. List 5 processes that move water between reservoirs.
3. What are the two sources that power the water cycle?
4. What are three places groundwater from a water table may move to?
5. Describe 2 human actions that can affect the water cycle.
6. Draw a diagram to show how smoke from a factory can affect your drinking water.
Watersheds in Washington
(http://www.ecy.wa.gov/pubs/0801018.pdf)
What is a watershed? Everyone lives in a
watershed. You know your county and city, but do
you know your watershed address?
Unlike states and counties, watersheds have
natural boundaries defined by the shape of the
land and the flow of water. In basic terms, a
watershed, or basin, is all the land that drains to
the same body of water, such as a lake or river.
Smaller watersheds become part of larger
watersheds as streams feed into rivers, and rivers
flow into oceans. This means wherever you are and
wherever you go, you’re in a watershed.
What defines a healthy watershed?
Healthy watersheds perform a number of “jobs.” As
water continually cycles through, the watershed
stores and releases water and filters many
pollutants. Trees and plants help anchor soil and
absorb rain and snowmelt, so flooding and
landslides are less severe. Vegetation also provides
shade, keeping water temperatures cool and stable
so fish and other aquatic life can thrive. In a
healthy watershed, water, soil and air are clean.
People, as well as fish and wildlife, have the water,
food, shelter, and other resources they need to
survive.
Causes of Unhealthy Watersheds
Increased population and increased pollution go
hand-in-hand. In urban areas, storm water runoff
is the #1 water pollution problem. Developing land
typically creates changes in the natural water
patterns of an area. As more surfaces can’t absorb
water, polluted runoff from rain or snowfall carries
oil, fertilizers, pesticides, trash and pet waste into
lakes, streams and the Puget Sound. Bacteria from
failing septic systems are released into the earth.
Our waters, both on the surface and underground,
become contaminated.
Despite occasional high-snowfall years, such as the
winter of 2007-08, global warming and climate
change are shrinking snow packs and lengthening
droughts. Increasingly, Washington lacks water
where and when it is needed for communities and
the environment. Water cycles continuously
through a watershed sustaining life as we know it.
As water moves across and under the land from the
highest to lowest point in a watershed, it picks up
everything it touches along the way. Thus,
everybody "lives downstream." The health of our
watersheds is in danger. Many of our watersheds
are unhealthy, and all are in need of protection.
Where does YOUR drinking water come from?
Rain
at LHS
North
Creek
Sammamish
River
Lake
Washingto
n
Ballard
Locks
Where does rainwater go from here?
Puget Sound
Which watershed do you live in?
If you live near Lynnwood High School, you live in the Lake Washington Watershed.
 If you live on the West side of Lynnwood or certain parts of Seattle, you live in the Puget
Sound Watershed.
 Our drinking water in Lynnwood comes from the Sultan River and ultimately from the
snowmelt in the Cascade Mountains.

Top 5 Specific Problems that Contribute to Water Quality Problems in our Area:
(According to Washington State Department of Ecology)
1.
2.
3.
4.
5.
Dog poop left in yards or the ground.
Washing cars in your driveway or the street.
Fertilizing Lawns.
Letting Grass Clippings go down storm drains.
Failing Septic Tanks
Watershed Analysis Questions: Please answer the following 7 questions.
1.
What are the jobs of a healthy watershed?
2. According to the article, what is the number one water quality problem in urban
areas?
3.
Describe how human actions contribute to pollution in the Lake Washington
Watershed (via the water cycle).
4. The top 5 ‘specific problems’ make it harder for water treatment facilities to give us
clean water to drink. What other animals in the Puget Sound might be affected by
the problems listed above?
5. What is the job of trees, plants and soil in a healthy watershed?
6. North Road is going to be expanded soon, and storm drains are going to be placed
along the street. Which is a better solution
A. Having storm drains directly dump water into North creek (which will
eventually flow into Lake Washington), or
B. Creating a wetland pond that will collect storm water? (Note: wetland ponds
allow plants to grow and use up nutrients that are in the storm water). Explain
your answer.
7. The Washington Department of Ecology identified high petroleum (oil) levels at the
cross streets of Filbert Rd. and Filbert Dr.
a. Predict what might happen to the fish in North Creek (which is downhill on
Filbert Rd. towards Bothell-Everett Highway)?
b. What other human actions might hurt the fish in North Creek from storm
water runoff? (Use your new knowledge of top 5 problems that affect water
quality in our area and the article.)