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DNR Beach Policy


State Standard

  • The bacteria standard for Iowa’s recreational waters consists of two components. 
    • A geometric mean standard based on 5 samples in a 30-day period (126 colony forming units of E. coli bacteria per 100 mL of water).
    • A one-time maximum standard based on a single sample (235 colony forming units of E. coli bacteria per 100 mL of water).   

Beach Classes

  • Beaches are placed on “vulnerable” list after two years of high geometric means in the most recent 5 year period and removed from “vulnerable” list when this condition no longer applies.  One beach, Lake Darling, is being removed from “vulnerable” list; while one new beach, Pine Lake, has been added to the list.
  • A new beach class called “transitional” beaches is being added this year.  This class includes beaches where bacteria problems influencing the beaches have been fixed or no longer pose a threat.   Beaches on this list include Lake Darling, Nine Eagles and Emerson Bay beaches.  However, many more beaches could be moved from the “vulnerable” list into this category when problems are resolved.  Furthermore, beaches in this transitional class will be eligible to be removed from this list if they do not exceed the geometric mean standard for one year.
  • “Non-vulnerable” beaches are all beaches that do not fall into the above categories.

o       Beaches that have had two or fewer one-time standard (samples over 235 cfu/100 ml) exceedances of the state standard during a running five years will be monitored less frequently.  These beaches will be monitored on a weekly basis from the week before Memorial Day through Labor Day.  All other state-owned beaches will be monitored from April 15th through October 31st.

Posting of Signs/Advisories

  • All beaches will be posted with signs that provide general information regarding ways to reduce the health risk associated with swimming at public beaches.  These signs will also inform the public of current monitoring efforts and ways to obtain the data. 

  • Beaches that exceed Iowa’s geometric mean water quality standard for bacteria (the geometric mean of 5 samples in a 30-day period exceeds 126 colony forming units of E. coli bacteria per 100 ml of water) will be posted with signs that state, “Swimming is Not Recommended”.  Posting will only occur between Memorial Day and Labor Day.