Lesson 2:
Stormwater Basins

In the previous lesson you saw how watersheds of varying sizes form natural boundaries. Now we'll look at watersheds within the City of Fort Collins.

STEP 1:  It is obvious that cities do not occur naturally.  However, unless cities were to be enclosed in a bubble they are subject to weather.  Water is one of the main components of the natural world that cities must learn to accommodate.  Water flows through cities in the form of rivers and streams.

Can you name any streams in Fort Collins?

This is the city boundary of Fort Collins.

This is all of the natural rivers, streams, and major lakes within the city. This theme shows all of the schools within the city.  Do you know where your school is?
How can we find it?

Let's do a query.

Now you can close the query builder.  Your school turned yellow.
Can you find it? Here's a hint: it's in the lower left corner.

STEP 2: Water falls onto cities in the form of rain, snow, hail, and other forms of precipitation.  Since cities change the landscape by constructing buildings, streets, and parking lots, they also change the natural watershed. The construction of the city creates a new artificial watershed.

In order to make sure that the precipitation safely flows back into streams, lakes, and ponds, the city must create a stormwater system. A stormwater system is a system of drains, pipes, and canals.  This system helps to ensure that the water will not flow through or collect in any unwanted places where it could cause damage.

Have you ever seen grates along the curbs of the roads?  These are stormdrains.
Have you ever seen any large pipes going under streets?  These are called culverts and they are part of the stormwater system, too.

The City of Fort Collins has divided its stormwater system into a number of different basins. These basins are similar to natural watersheds.

These are the stormwater basins in Fort Collins. These are artificial watersheds.
Notice that a few of the stormwater basins have natural streams that flow through them.

What stormwater basin is your school in?

What does it say after "Basin_name"?

In other words, the city's stormwater system is a modified watershed, consisting of artificial and natural components. All the water that falls onto the city flows into some combination of the pipes, streams, ponds, and lakes.

STEP 3:  The stormwater system is designed for a certain size rainfall.  But sometimes we get more rain than we expect.  We need a place to temporarily store some of the "extra" water while the system drains.

These areas are known as retention ponds.  These can be either artificial or natural lakes and ponds that detain excess rain.  Many of the artificial ponds are usually dry until it rains.  Many times parks, sports fields, and areas in subdivisions are really stormwater retention ponds.

This is all of the retention ponds within the city.  There are lots of them, how many?

What is the count? This is the number of retention ponds in Fort Collins.
Is that more than you expected?

Notice that there are many detention ponds around the school.

Within Fort Collins there are other water features that are not natural.  They are canals.  Canals are artificial streams, originally created so that farmers could water their fields.  They connect rivers, streams, lakes, and ponds.  They also cut across stormwater basins sometimes.

Do you notice how the water network within the city appear to have a messy pattern?...


Usually streams and rivers follow a pattern similar to tree branches or leaf veins where many smaller units flow into bigger and bigger units. But... when you look at the city you notice many streams that seem to cut every which way. This is because the canals flow every which way. They can carry water and anything that is in the water all the way across the city.

All of the rain that falls on our roofs, yards, driveways, and streets picks up all of the chemicals and dirt as it flows into the stormwater system. The stormwater system drains directly into our streams and rivers. It never gets cleaned at a treatment plant. Water that is used inside homes and businesses flows into a separate set of pipes that takes the 'wastewater' to a special treatment plant where the water is cleaned.

For this reason, water that runs off of cities (called 'runoff') is one of the major forms of water pollution. All of the chemicals used outdoors by people in the city (for example: soap, gasoline, oil, and fertilizer) eventually flow directly into natural streams.

Keep in mind, anything that's on your yard, sidewalk, of driveway will flow into the closest stream next time it rains. Sometimes there is one line of defense: wetlands.   Wetlands can trap the pollution before it flows too far downstream.

That's all for this lesson, we'll talk more about wetlands soon.

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