Data Delivery/Interpretation, cont.
pH measures hydrogen concentration in water and is presented on a scale from 0 to 14. A solution with a pH value of 7 is neutral; a solution with a pH value less than 7 is acidic; a solution with a pH value greater than 7 is basic. Natural waters usually have a pH between 6 and 9. The scale is negatively logarithmic, so each whole number (reading downward) is ten times the preceding one (for example, pH 5.5 is 100 times as acidic as pH 7.5). The pH of natural waters can be made acidic or basic by human activities such as acid mine drainage and emissions from coal-burning power plants and heavy automobile traffic.
Water Quality Standards and Other Criteria Regarding pH
The U.S. Environmental Protection Agency (U.S. EPA) sets a secondary standard for pH levels in drinking water: the water should be between pH 6.5 and 8.5. Secondary standards are unenforceable, but recommended, guidelines.
Colorado Department of Public Health and Environment Water Quality Control Division (CDPHE-WQCD) regulations (5 CCR 1002-31) state that waters to be used for domestic water supply should have pH values between 5.0 and 9.0.
CDPHE-WQCD regulations state that waters used for primary recreation (including such activities as swimming, rafting, and kayaking) should have pH values between 6.5 and 9.0.
CDPHE-WQCD regulations state that waters classified as “Class 1 Cold Water
Aquatic Life” or “Class 1 Warm Water Aquatic Life” should have pH values
More information about pH is available at www.basin.org/data/COBWQ/info/pH.html