The Myth of Water Abundance
The Okanagan Basin is our home, a very special place. It has
been home to First Nations peoples for thousands of years, and to
many others over the last century and a half. Water has always been
the basin's most valuable resource for both humans and nature.
Today, our economy, agriculture, home use, and recreation continue
to share these waters with nature. We live in a dry landscape. The
large lakes may make water look abundant but nature's yearly
resupply is very small and that is the heart of the myth of
abundance.
What is the Okanagan Basin?
A river basin or watershed is high at its edges and low in the
centre where the waters flow. The Okanagan Basin includes all the
land that feeds water to our big lakes. Kelowna, Vernon, Penticton,
and Osoyoos all lie within the Okanagan Basin. The Okanagan River
drains the lakes and flows south across the International Boundary
as a small tributary to the Columbia River.
The Highlands
The Okanagan Valley is a great trough that cuts across the
highlands of southern British Columbia. These forested highlands
are the largest part of the basin and are the source of most of our
water.
The Valley is a Busy Place!
The Okanagan Valley consists of the main lakes, valley bottom,
benchlands, and surrounding slopes. Most of us live down on the
valley bottom or on the surrounding benchlands in Kelowna, Vernon,
Penticton, and other major centres. The valley contains our lakes,
agriculture and wineries, tourist facilities and golf courses, and
industry, as well as wetland ecosystems, species at risk, and
endangered habitat. With all these competing uses, we need to plan
our growth carefully.
Okanagan Basin Waterscape - Our Water
Cycle
Dry to Really, REALLY Dry
The Okanagan Basin is dry because it lies in the rain shadow of
the Coast Mountains. This high mountain chain strips moisture from
Pacific storms, leaving little for the basin. The farther south you
go, the drier it gets. Cacti grow in the Okanagan Basin!
Our Upland Snow Catchers
Most water enters the Okanagan Basin as winter snow on the
highlands. During the spring, snowmelt infiltrates into the ground
or flows in streams to highland reservoirs and valley lakes.
We lose Most of What we Get
Only 15% of the rain and snow that falls in the basin flows to
our lakes and remains there. The rest leaves the basin through
transpiration from forests and crops, and evaporation from
lakes.
Okanagan Basin Waterscape - Our Lakes - Looks Can
be Deceiving
With so many large lakes, how could we be short of water? Well,
looks can be deceptive. Only the upper metre or two of lake water
is replenished each year by stream flow, and much of that
evaporates to the atmosphere. This thin layer is all that people
and nature can use. If we withdraw more than that, the lake levels
will start to fall.
Be Careful or we Might 'Mine' the Lake
Poorly Flushed Lakes
Most of our big lakes are composed of 'old' water. Scientists
describe the lakes as 'poorly flushed' and estimate that water
resides in Okanagan Lake about as long as an average human
lifetime. This is because outflow from the lake is small relative
to the volume of lake water. So we literally 'live with' whatever
pollutants we put into the lakes.
Okanagan Basin Waterscape - Groundwater -
Connected to Surface Water!
what is Groundwater?
A well draws groundwater from an aquifer.
Water from rain, melting snow, streams, and lakes infiltrates
into the earth. The Okanagan Basin's soil and rock are giant
sponges full of tiny pores and cracks. Below the water table, these
open spaces are filled with groundwater. A well can extract this
groundwater. Any rock or sediment that yields useful amounts of
groundwater is called an aquifer.
Disappearing Streams
Groundwater is part of the water cycle and is connected to
surface water. Most groundwater flows into streams and lakes.
Stream water can soak into the ground, feeding groundwater below
and even causing the stream to disappear. Streams flow throughout
the summer, even when it hasn't rained for weeks. This is because
water stored as groundwater slowly leaks into streams. But beware!
Wells that are overpumped can intercept this groundwater and cause
nearby streams to dry up.
The Solution - Capturing Rainfall Where it
Falls
Experts agree that capturing rain where it falls is an important
solution to urban runoff. No runoff, no problem. Yards need to act
like sponges, absorbing and storing rainwater. Lawns with a thick
underlying soil of at least 12 inches work well. So do gravel
yards. Later, the roots of the plants and grasses absorb this
stored water and return it to the atmosphere.
Urban Myth!
Many believe that street drains flow to wastewater treatment
plants. This is not true. Most street drains flow through pipes
directly into streams or lakes. These waters can carry urban
pollution from streets, driveways, parking lots, and backyards. So
be careful!
There are many, many users of Okanagan Basin water and all are
dependent on this limited supply. So, we must protect and share the
water.
Not all Water Use is the Same
Some water use occurs in streams and lakes, such as by wildlife,
fisheries, and recreation. Some water is withdrawn from the lake,
used, and returned. Municipalities return most of the water they
use as treated wastewater. Much of what is not returned is water
used outside the home for lawns and gardens. Most water used for
agricultural irrigation leaves the basin through plant
transpiration or evaporation to the atmosphere. Sources: as noted
throughout and Natural Resources Canada
Logging Instructions: To log your "find" of this earthcache,
please email with your responses to the following questions. Please
indicate "Myth of Abundance" Earthcache in the email header.
1) From GZ can you identify any of the streams that feed
rainfall and snowmelt into Okanagan Lake?,/p>
2) Report at least 2 different manners in which you can observe
water being used during your visit to GZ.