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Rivers: Top 10 Questions

April 2017

Thanks to James McNamara, professor and chair of the department of geosciences, Boise State University and Elowyn Yager, associate professor, department of civil engineering, Center for Ecohydraulics Research, University of Idaho for the answers.

1: How do you make rivers?

You can make a river by creating a depression in the ground and having the water that you pour into that depression move from an area of high elevation to an area of low elevation. That is essentially what is driving the flow in a river. (From Brock at Amity Elementary School in Boise)

2: How did rivers get their water?

Rivers get their water from rain and snow. The water from the precipitation goes over the whole watershed, and eventually that water flows through the landscape and into the river. (From Amanda at Dalton Elementary School in Dalton Gardens)

3: How do rivers move?

Rivers move by eroding sediment or rocks within them. They will pick up rocks from of their bed, or from their banks, and transport them from one place to another. By transporting rocks from the banks of the river, they can erode one side of the river and deposit sediment on the other side thereby having a river literally migrate back and forth across its floodplain. (From Cayden at McDonald Elementary School in Moscow)

4: What is the deepest river in Idaho?

The deepest river in Idaho is the Snake River as it goes through Hells Canyon. At that point, it can be between seven and 8,000 feet deep. That depth is the depth of the river canyon, and not the flow depth of the river. This canyon is the deepest canyon in North America. (From Bryn at Russell Elementary School in Moscow)

5: How do dams affect the river and its environment?

Dams block the flow of water, and this creates lakes behind the dam. This is very useful for using the water later in the summer. (From Landen at Trail Wind Elementary School in Boise)

6: Why are rivers different colors?

The color of a river is dependent on where the sediment, or dirt, in the river comes from and how much there is. (From Trinity at Whittier Elementary School in Boise)

7: Why do rivers flow?

Rivers flow because of gravity. Although rivers may look flat, they actually slope like a hill. Gravity makes the water flow downhill. (From Genevieve at Garfield Elementary School in Boise)

8: How much drinking water comes from rivers?

Almost 70 percent of municipalities within the United States take drinking water from surface sources. That is either lakes or rivers, but how much is just from rivers is questionable. In Boise, we get a significant amount of our drinking water from groundwater rather than from rivers, but the rivers here do contribute some to our drinking water. (From Daxton at Trail Wind Elementary School in Boise)

9: Can you actually find gold in rivers?

Yes, you can! You can go to rivers and pan for gold. The gold that you find in rivers eroded from rocks in the landscape. In Idaho, we used to have many people searching for gold. You can find little bits of it in the rivers now but probably not much as in the past, because most of it has been removed already. (From Ruby at Trail Wind School in Boise)

10: How are deltas made?

A delta is the location where a river enters a larger body of water that is moving more slowly, if at all. We have the Mississippi River Delta where the Mississippi River enters the ocean. A delta forms when the fast moving river has to slow down as it enters the slower moving body of water. When it slows down, it deposits all of the rocks that it was carrying, building up sediment. This buildup makes the delta. The river will migrate back and forth over the delta, causing the lobe-like shape. (From Bella at Trail Wind Elementary School in Boise)


May 2010

Thanks to Jan Boll, Professor of Biological and Agricultural Engineering, University of Idaho; and Cindy Busche, Environmental Education Coordinator, Boise Watershed Project for the answers.

1: Why do we need rivers?

There are many reasons why we need rivers. Rivers are a lifeline, connecting the landscape to the oceans. They provide a transportation corridor for people. We also rely on them economically. The list goes on and on. (From Leah in Mrs. Hunt's class at Cynthia Mann Elementary School in Boise)

2: Does the river that a fish grows in affect it as in weight or health?

Yes, the chemistry of the river really can affect the way a fish can thrive within its environment. If the chemistry or water quality is poor, then the fish may have less of a chance of survival. If there are really nice, cold water temperatures like sometimes here in Idaho, and there are great habitats for fish to spawn and lay eggs, then there is a greater chance the fish will survive and become large healthy fish. (From Ancell in Gris' class at Horizon Elementary School in Boise)

3: How big of an issue is pollution?

The Boise River has been relatively cleaner than in the past; however, it's still listed as an impaired river by the U.S. EPA. This is because there are a lot of sediments as well as nutrients. Also, issues with temperature in parts of the river (temperatures that are not cold enough for the cold water fish and other aquatic habitat) lead us to know that some improvements still need to be made. (From Kelli in Mrs. Schweitzer's class at Riverside Elementary School in Boise)

4: Do all rivers lead to the ocean?

No, not all rivers lead to the ocean, but most rivers do. (From Parker in Mrs. Drainsfield's class at Mary McPherson Elementary School in Meridian)

5: Is there a difference between a brook and a stream?

Typically, I would say that a brook and a stream are smaller than a river, but by all definitions, they're really both rivers. Some of the terminology used may be determined by the part of the country it's in. For example, people like to talk about creeks in the West, but they may be referred to as streams, or brooks, in the East. (From Adam in Mrs. Bowe's class at McDonald Elementary School in Moscow)

6: What kind of force makes rivers flow?

Water is going to follow the path of least resistance, either across the land or where it flows underground. Gravity has a big impact on it, as well as the elevation or slope of the land. So, the geology is really important to the flow of a river. (From Kate in Mrs. Gris' class at Horizon Elementary School in Boise)

7: Is it true that three-quarters of our earth is covered by water?

That is true. However, if you look at just surface water, that would be rivers, lakes, and streams, it adds up to only .01% of all of our earth's water resources. It is a very small fraction of all of earth's water. (From Tucker in Mrs. McCoy's class at Donnelly Elementary School in Donnelly)

8: How long is the longest river in Idaho? Do the rivers in Idaho connect with other rivers, and can we get to the ocean starting with an Idaho river?

The Snake River is Idaho's longest river. It is approximately 1,040 miles long with many tributaries. Many smaller rivers feed into the Snake River. So, there is a large network of rivers all connecting each other. Yes, we can get to the ocean from the Snake River. The Snake River flows into the Columbia River, which flows into the Pacific Ocean. (From Brenna in Mrs. Chaffee's class at Valley View Elementary School in Boise)

9: How many rivers are there in Idaho?

There are eight major rivers in Idaho, and then there are hundreds, possibly thousands, that lead to those main rivers. (From William in Ms. Johnson's class at Cloverdale Elementary School in Idaho Falls)

10: Is there any salt in rivers?

The amount of minerals in the river really depends on what kinds of rocks the water is flowing over. I'm sure there is a small amount of salt, but most rivers are fresh water. (From Karina in Mrs. Mantooth's class at Riverside Elementary in Boise)


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