The report finds that increasing human populations will create serious and growing water quality problems unless prompt action is taken in these areas at the mouths of rivers where currents meet the ocean tides. The study indicates that by the year 2020, conditions may worsen in the majority of the 138 estuaries examined, if population growth and development in the coastal zone are not managed properly. The most common cause of eutrophication is an increase in the amount of nutrients being discharged into the water body.
Nutrients can come from industry, fertilizer runoff, factory farms and other sources.
Nutrient related water quality problems have become worse in 48 estuaries since 1970 while in 14 estuaries conditions have improved, the report shows. Scientists predict that conditions will become even worse in 86 estuaries by the year 2020 as population growth and development in the coastal zone increases. Conditions are predicted to improve in only eight estuaries. The NOAA study indicates that for the majority of estuaries with serious problems, human related nutrient inputs are an important influence on development of those problems. However, many of these estuaries are also naturally sensitive to nutrient inputs.