Remember when we learned about the water cycle back in grade school? Water evaporates off the surface of the earth, condenses into a cloud and eventually falls back to the ground through precipitation. The circle is complete, with water returning to its original liquid form in a river, stream, lake or ocean.

But this simplified model is only part of the story. As we look deeper, we can see that once that water molecule leaves a cloud, either as rain or snow, it can be subject to a host of possible pollutants. Any substance that binds itself to that molecule before it enters a larger water body can have potentially devastating effects.

Pollution that cannot be traced to one specific location, but rather results from runoff over a large area, is referred to as nonpoint source (NPS) pollution. The U.S. Environmental Protection Agency defines NPS pollution as “pollution that is not released through pipes, but rather originates from multiple sources over a relatively large area. Nonpoint sources include failing septic tanks, improper animal-keeping practices, forestry practices, and urban and rural runoff.” It can come from anywhere; our streets, yards, parks and fields all can be sources of pollutants that may enter our waterways.

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The EPA reports that nonpoint source pollution is the leading cause of water quality problems in the United States. The effects of NPS pollutants on specific waters vary greatly, and data needs to be collected to fully assess how severe these water quality problems really are. However, we do know that these pollutants can have harmful effects on drinking water supplies, recreation, fisheries and wildlife.

NPS pollution may include:

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• Fertilizers, herbicides and insecticides from farmlands and residences.

• Chemicals from urban runoff and energy production.

• Sediment from improperly managed construction sites, crop and forest lands, and eroding stream banks.

• Salt from irrigation practices and acid drainage from abandoned mines.

• Bacteria and nutrients from livestock, pet wastes and faulty septic systems.

• Deposition from air pollution.

• Stream channelization.

In Colorado, NPS pollution is monitored by the Colorado Department of Public Health and the Environment. Every two years, CDPHE compiles a list of impaired waterways, otherwise known as the state’s 303(d) list. There are currently hundreds of water body segments recognized as impaired by the state.

Even though a segment is listed, that does not necessarily impose a death sentence. In fact, much can be done to restore a river, stream or lake once it has been added to the list. A listing can be thought of as an alarm, notifying responsible parties that there is work to be done.

For example, back in 1998, Coal Creek, just west of Redstone, was added to the 303(d) list for failing to adequately support its aquatic life due to high levels of iron associated with excessive sediment loadings.

Many years of coal mining created unstable, steep slopes that caused debris to enter the creek after precipitation events. A project team led by the Colorado Division of Reclamation, Mining and Safety implemented several best management practices in order to reduce the sediment load into the creek. By 2004, sediment loading was reduced by 50 percent, and water quality in the Coal Creek Basin improved greatly, which resulted in CDPHE removing the segment from the 303(d) list.

An even easier approach is to prevent the chance of pollution ever entering a water body. By understanding what causes NPS pollution, it is far less costly and time-consuming to take immediate action and keep our streams free of materials that may cause impairment. Ways to prevent pollution can be as simple as picking up after your pets, using less fertilizer or disposing of motor oil properly. A comprehensive pollution reduction goal should be included in all community planning efforts, with citizens taking ownership to ensure their water resources are as clean as possible.

Dan Ben-Horin writes a monthly column for the Middle Colorado Watershed Council, which works to evaluate, protect and enhance the health of the Middle Colorado River Watershed through the cooperative effort of watershed stakeholders. To learn more, go to http://www.midcowatershed.org. You can also find the council on Facebook at http://facebook.com/midcowatershed.