Analyzing water quality trends helps managers identify deteriorating conditions so they can design effective corrective actions or confirm that actions already taken are having a positive effect on the resource. The Maryland Coastal Bays are lagoonal estuaries located behind the barrier islands of Fenwick and Assateague. They are relatively shallow and have high salinity and low flushing rates. Nutrient loads to the bays are dominated by nonpoint sources.
Nitrogen, phosphorus, and chlorophyll a data collected from 18 stations for the years from 1987 to 2005 were analyzed to detect trends in water quality. That research revealed a general shift throughout the Coastal Bays from a gradual reduction of nutrients and chlorophyll a to either an increase or a no significant change condition. Critical inflection points for those trends ranged between 1995 and 2000. Also documented was a leveling off of submerged aquatic vegetation abundance around the time of the inflection period of nutrient and chlorophyll a trend reversals.
The trend reversal throughout the bays might be due to a large-scale nonpoint source. Ground water inputs from agriculture, increased septic inputs, and atmospheric deposition are sources that should be investigated (Bricker et al. 2007).
Reference:
Bricker, S., B. Longstaff, W. Dennison, A. Jones, K. Boicourt, C. Wicks, and J. Woerner. 2007. Effects of Nutrient Enrichment In the Nation’s Estuaries: A Decade of Change. NOAA Coastal Ocean Program Decision Analysis Series No. 26. National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science, Silver Spring, MD. Accessed October 2016. https://yosemite.epa.gov/oa/EAB_Web_Docket.nsf/(Filings)/3BE82A42C7ED8C3585257B120059CB8A/$File/Opposition%20to%20Petition%20for%20Review%20–%20Ex.%2010%20Part1…23.53.pdf.