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pH is a measure of the relative amount of hydrogen and hydroxide ions in water. The values for pH range from 0 to 14 on a log scale, meaning that a difference of 1 is actually a monumental difference. Values from 0 to 7 are considered acidic, while those greater than 7 are alkaline. Naturally, the pH of surface water can vary from 6.5 to 8 without any repercussions to aquatic ecosystems.

The pH of surface or groundwater can change for a variety of reasons, both natural and anthropogenic. Organisms that release CO 2 when they respirate can contribute to acidification of the water, as CO 2 and water combine to form an acid. However, the more common reasons are acid runoff from abandoned mine sites or acid rain from nitrates and sulfates in the atmosphere. The type of bedrock present can greatly impact the pH of surface water in an area. For instance, if limestone is the most common rock in a region, such as in Tennessee, waters are more prone to be neutral or alkaline, as limestone is basic. Some other types of rocks can further decrease the pH of acidic liquids.

A low pH is a more common cause of issues than a high pH, although both occur. Acidic conditions can prevent fish from reproducing, or kill adult fish themselves. Additionally, metals are more toxic when conditions are acidic, and sediments are more prone to release toxic materials. In alkaline conditions, ammonia is more dangerous to organisms.


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  • Adopt

    Are you a member of a group or organization in your community that would be interested in adopting this waterway? Contact us if you’re interested in learning more about stream adoption.

    Learn more about adopting a stream

  • Contact the EPA.

    Report any acid mine drainage, extremely polluted sites, or suspected environmental violations to the EPA.

    Resources include:

    • Report Abandoned Mine Drainage – EPA
  • Allow for natural growth near waterways

    If you live or work next to a waterway, leave a 35′ to 100′ no mow zone on its banks. Allow natural and native plant growth in this buffer area or plant native trees, bushes, and groundcover. This vegetation can filter pollutants before they reach your waterway and provide other water quality benefits that far exceed those of a mowed lawn. Native plants and grasses require less watering and fertilizer and also provide important habitat for native species of wildlife.

    Resources include:

  • Reduce paved, impervious surfaces

    Impervious or impermeable surfaces, like pavement, contribute significantly to polluted stormwater runoff and alter stream flow habitat. If you’ve got excess pavement you’d like removed, consider a de-paving project with the Compact. Elsewhere, ensure that your downspouts drain to vegetation, gravel, or rainbarrels, rather than impervious surfaces. If you constructing or repairing your driveway, pervious pavement allows stormwater to infiltrate and filter through the ground. If you can’t do the whole drive, consider making only the portion closest to the street pervious.

    Resources include:
    1) De-paving Work – Cumberland River Compact (Call 615-837-1151)
    2) Rain Barrel Sales – Cumberland River Compact
    3) Rain Barrels Make Good Sense – UT Extension

  • Organize with others in your community. Make your voices heard and your votes count.

    Participate in community planning efforts and advocate for relevant measures that improve or protect water quality. Write to your elected official and let them know this is concern or invite them to speak about the impairment with your home-owners association. When elections come up, vote for candidates who will address the problem and hold them accountable to their promises. Support local watershed / environmental associations.

    Resources include:

  • Spread the word.

    Do your neighbors, family, or roommates know about the problem? Now that you know how to be an effective steward, enlist the help of others in your neighborhood. Share iCreek or resources within it with your neighbors and encourage them to join the effort to protect your creek.