Algae grow in pools along the banks of the river, north of Los Feliz. Fertilizers in the runoff from a nearby golf course might encourage the growth of this algae. Phosphates in runoff from lawns and farms are major sources of water pollution around the country. This is an example of nonpoint source pollution, because it does not originate from a single source such as a factory or processing plant.

The problem with fertilizers is that they encourage too many algae to grow. When the algae die, their decomposition by aeorbic bacteria takes oxygen out of the water, thus killing many fish or other life that relies on disolved oxygen in the water. The amount of dissolved oxygen is an important indicator of water quality.

The presence of algae such as Navicula (left) and Cocconeis (right) indicates clean water. 12 On the other hand, algae such as Euglena, Spirogyra, and Nitzschia indicates polluted water. 13

If you use a microscope to study fresh water algae, you can use thesephotos from Bowling Green State University to help identify your samples.

Not all fresh water microoganisms are algae. Other organisms such as paramecia and rotifers are protozoans. Zooplankton such as fish and crayfish larvae also inhabit fresh water.

Certain microoganisms such as giardia and E. coli are health hazards and can be contracted from polluted water. Don't collect, test, or come in contact with water or unknown quality unless you know what you are doing.

Continue the tour here. So batten down your hard drives and cover your keyboards. The adventures of the urban river awaits you. Good Luck and remember, don't drink the water!

Yes! I like the Los Angeles River Virtual Tour, but my socks are wet and my feet are cold, so I would like to learn more about . . .

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