Rivers and the Water Cycle
Where does our water come from? And how did it get there? For some folks the answer is the grocery store (and Fiji) but for most of us the answer is that it flows out of the tap when we turn it on. Though the reality is that the water does not just magically appear in either place; it is a long process.
One of the most interesting things about water is that there is not really a beginning or an end to that process- there is what is referred to as ‘the water cycle’ and it points to the fact that the water we have today is the same water that we have been using since the dawn of ages, it just keeps getting recycled.
Let’s inject ourselves in to a part of the cycle that seems like a good starting point – rain. Rain water falls from the clouds, landing on our backyards, roof tops, roads, lakes, and rivers (and everything else).
Here water has two choices- it can settle into the landscape (infiltration) or it can wash away (run-off). The water that is absorbed by the landscape works its way down through layers of leaves, dirt and rock until it runs into the water table or ground water (also called an aquifer).
The water that washes away follows gravity down hills, into water drains picking up speed and debris (leaves, trash, dirt, pet waste) as it goes; this water ends up washing into our streams and creeks causing them to fill up and flow faster.
But, where did that creek come from? Our creeks start as small trickles that bubble up from the water table at a point called a ‘spring’.
These trickles of water come together as they head downhill to the ocean with each merger they increase the amount of water that runs in them and they become creeks, streams, and rivers.
This inner connection of hundreds or thousands of creeks, streams and rivers is called a watershed.
The water that flows in the Mississippi River (the largest river watershed in the country) past New Orleans could have started near Pittsburg, PA in the Ohio River or Bismarck, ND in the Missouri River or Oklahoma City, OK in the South Canadian River.
Everyone that lives in our watersheds needs some of that water to be clean enough to drink so they can live. Some people, businesses, farmers, and towns use wells (holes drilled deep into the ground) to pull water from the underground water table. This water is cleaned up as is filters its way down through the dirt, rock and clay of the earth’s crust.
It is critical for that water supply that there are areas that are clean and open enough for water to be able to be absorbed into the ground and that the ground that the water is moving through is clean.
Other communities use water pulled directly from our rivers for their drinking water. In this case it is critical that the water that is washed into those creeks, streams, and rivers or that bubbles up from springs is as clean as possible before being pulled from the river.
Once a community system [PDF] pulls that water from a river (and in some cases a well), the water is treated to federal and state required purity levels before being pumped and piped to our houses as clean drinking water.
It is only at this point that the water is able to come out of your tap when you turn the faucet on.