1. Controlling the Flow of the Colorado River: A Study of Dams

2. Where IS the Colorado River?  The Colorado River runs through seven states: Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada and California, before emptying out into the Sea of Cortez in Mexico.  The headwaters of the Colorado River are located in Rocky Mountain National Park in Colorado. From here, at an altitude of 9,010 feet, the Colorado begins its flow southwestward toward the Gulf of California and the Pacific Ocean.

3. Let’s find it on a map  The Colorado River is more than 1,400 miles long and its watershed covers more than 244,000 square miles!  There are several large cities in the Colorado River watershed, including Denver, Phoenix, Las Vegas, San Diego, and Los Angeles.

4. Why Do We Dam Our Rivers? It seems strange that we have built dams on almost all of our major American rivers. But there are some very practical reasons for dams, including:  Flood Control  Water Storage  Hydroelectricity

5. How do we use a dam for flood control? *Let’s say there is a huge rainstorm on our river. In a river that hasn’t been dammed, the river would overflow its banks and possibly cause damage to surrounding property. *In a river with a dam, the engineers are able to control the flow and fill of the river by a series of valves, thus avoiding potential flooding.

6. What about water storage?  This one should be obvious. When a river is backed up behind a dam, it creates a man- made lake, known as a reservoir. This practice is beneficial during drought situations because water can be stored for use at a later date.

7. Finally, hydroelectricity.  Water is used to turn a turbine, which generates electricity. This is often part of the power source in large cities. It also doesn’t cause any pollution!

8. So if dams have all these benefits, what is the problem with them? There are several potential negative effects of dams on the environment:  First, dams can cause displacement of fish populations and impact their reproduction.  Second, the temperature of the dam outflow is regulated, which can kill invertebrate populations. These tiny critters are an essential part of the food chain.  Third, the sediment build-up behind the dam doesn’t allow sediment to flow downstream. Sediment is very important for building new ground. Sediment also provides nutrients for riparian areas.

9. Dams on the Colorado River: Arizona  Davis Dam, Glen Canyon Dam, Palo Verde Diversion, Parker Dam, Imperial Diversion, Laguna Dam

10. Dams on the Colorado: Colorado  Blue Mesa Dam, Dixon Canyon Dam, Flatiron Dam, Granby Dam, Olympus Dam, Rifle Gap Dam, Sugar Loaf Dam

11. Dams on the Colorado: Nevada  Hoover Dam (the largest dam in the United States)

12. Dams on the Colorado: New Mexico  Navajo Dam

13. Dams on the Colorado: Utah  Deer Creek Dam, Flaming Gorge Dam, Moon Lake Dam

14. So what do we do?  We are going to map out the Colorado River and its tributaries. Using the map and colored pencils I pass out, follow these directions: 1. Use one color to trace the Colorado River from source to map 2. Use a second color to highlight tributaries that flow into the Colorado River. 3. Consulting state maps and the list of dams in this presentation, use a third color to mark the location of dams along the Colorado. 4. Use a fourth color to outline regions drained by the Colorado River. 5. Label large cities in the Colorado River watershed. 6. Put this map in your geography portfolio!

15. Part 2 of your assignment  Working with a partner, you will choose a state to research (it can be a state mentioned in this presentation).  Using the Internet for research, you will find out how many dams are in your state of choice (if you are researching a state from this presentation, you must research all dams, not just those on the Colorado River).  You will then research what communities in your state of choice depend on the dams for irrigation, drinking water, or electricity.  You’ll then use Microsoft Word to compile your information. Make a copy for both partners, then put it in your Geography portfolio along with your map.  Questions? Ask me or consult the example I handed out with your map.