Created by the USGS Water Science School. Find the complete story online here.
Have you ever had the desire to strike out on your own? Maybe you've had enough of big-city life and want to build you own town way out in the unspoiled and unpopulated countryside? You might name it Dryville, since the only part of the country that is still so desolate is probably the desert!
Well, you can't begin your new town without considering water. From the smallest town to the biggest city, there always has to be a water plan. You need to be able to get water, use it, and dispose of what you don't want.
So let's say you made the big move. You and some friends have found your (desolate) spot and have moved in. How would you develop your "Water Plan for Dryville?"
From the founding day of Dryville, you need water. Drinking water is your first priority, as well as water to bathe in, clean dishes and clothes, and to wash your hands after you've cleaned that possum you caught for supper. And, of course, a toilet will come in very, very handy. So, your first priority will be to find a SOURCE of water. The obvious source is the creek or pond nearby. Maybe you can hire a beaver to create a dam in the creek and create a lake (actually, a reservoir).
In your free time go ahead and start digging a hole in the ground for a well. If you dig deep enough you might hit the water table, where there will be standing water. You'll be able to lower a bucket down to get the available groundwater. Things are starting out great -- you've already started using surface water (the creek and pond), ground water (your well), and you've even created your own water-storage system (the reservoir). So you now have a reliable source for your water needs. Time to relax? Not yet.
Since you appointed yourself mayor Horace of Dryville, you naturally chose the best spot for your home — on top of the hill. Great view, but it sure is a pain lugging pails of water (at over 8 pounds a gallon, your 100 gallons of water per day gets heavy in a hurry!) from the creek up the hill all day long. And now all your best buddies and neighbors are beginning to move in. Many of them are building on hills, too, so what you need now is a "water-supply distribution system" to get water to everyone's homes. The way to do this is to lay a system of pipes (which you make from clay from the creek bed) from the creek to each house.
The problem is, the houses are higher than the creek, and water does not flow uphill. Water does flow downhill, so you build a big water storage tank on a hill (hopefully at the highest point in town) and establish a water brigade to fill it full of water. You can run pipes from the storage tank down to everyone's home. The pipes go right to your faucet and you use gravity (it's free!) to get the water delivered. Works great -- just like it did in the big city you came from.
But you still have the problem of keeping the storage tank full. Lugging water up to it is no better than lugging it up to your house; so you need to find a way to pump the water from the creek uphill into the storage tank. Since Dryville doesn't have any industry to produce products to sell to the outside world to bring in money to buy things with yet, you need to build your own pump. And you can't use electricity since you haven't built a power plant yet (but you will). Can you think of a source of energy that can run your pump? A windmill could do the job, but in the desert there isn't always wind. Your creek! The water in your creek is flowing nicely -- so you build a paddle wheel in the river. The paddle spins in the creek's current and turns a rod that runs your homemade pump. Voila! You've got water being pumped uphill into your storage tank where gravity lets it flow to your homes.
Now everyone is enjoying running water in their homes. But it took a lot of work to build your water-supply plant ("Horace's Water Works"). Being mayor, you decide that the town of Dryville will be the owner of the new Dryville Water Plant and you'll charge everyone to get water delivered to their houses. Since the Water Plant is owned by Dryville, it has to respond to the needs of its citizens -- such as Mr. Milford, who overcooked his possum stew and started a fire in his kitchen. "Where was the Dryville Fire Department when I needed them!" he complains to the mayor. Very well, you add some fire hydrants to the water-supply pipes and now you are the Fire Chief as well as mayor.
Soon you start getting money from the citizens buying water from you - and that gives you an idea. You're going to write an acquaintance back home and tell him he needs to build another town down the road from Dryville. Then when your friend gets his town started, Dryville will offer to sell them water that you get from your public-supply system! You can build an aqueduct system to move water from Dryville to them. Of course, there will be a mark up to cover the cost of delivering the water — nothing wrong with making a little profit.
You're again happy until the first desert downpour hits. The rain flows down the hills (runoff) into Dryville's town center and suddenly you have your first flood — more unwanted water (and the mud it carries with it) to deal with. You decide to build a set of storm drains to fix this problem. Lay some more (this time BIG) pipes through town with intakes where the water collects in low spots. Storm water will flow into these pipes and be sent on its way downhill into your creek. Another problem solved.
But when the storm hit, Dryville Creek overflowed and flooded some houses that were built on the flood plain, the flat ground alongside of the creek. You can do two things here. Look at the lay of the land and decide what parts of the creek bed will flood most often when it really rains and don't allow people to build houses there, or build a dam upstream to create a reservoir to trap storm water before it floods into town. Your reservoir can then release the water slowly over a long period of time, thus preventing floods and recharging ground water.
You start thinking... a reservoir (you can call it a lake) above town could really serve a lot of purposes. A lake will provide a place for you to have fun — go swimming, boating, catch catfish, and relax. You can run your water-supply intake pipes from the lake instead of from your creek, especially since the flood destroyed your water-intake pumping station. With a dam you can release only the amount of water you want into the creek below the dam, thus making sure you have just the right amount of water running in Dryville Creek at all times. A dam would even help prevent flooding downstream because you can hold extra rainfall and runoff during a storm and slowly release it afterward. You can build a bigger paddle wheel, or, better yet, construct a real hydroelectric power plant in your dam to start generating electricity! More problems solved.