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Development and Analysis of Coastal Water Quality Indicators


PIs: Joan Sheldon and Merryl Alber (Dept of Marine Sciences, Univ of Georgia, Athens, GA, USA)

Support: Georgia Coastal Management Program

Timeframe: Oct 2007 - Mar 2010

Project Overview:

Objective 1. Compile coastal water quality data collected by GA DNR CRD into an integrated database and analyze it for long-term and seasonal trends.

Objective 2. Choose an appropriate framework for classifying water quality status with respect to public and living resource health.

Objective 3. Identify an appropriate suite of indicator variables and use them to evaluate Georgia coastal waters.

Objective 4. Write a report on the status and trends of water quality using environmental indicators developed for Georgia coastal waters.

Objective 5. Work with CRD to develop recommendations for efficient continued monitoring of Georgia coastal waters.

Accomplishments:     

        We obtained data from CRD for four monitoring programs (river nutrients, sound nutrients, shellfish water quality, and beach water quality) and compiled all the data into a common SQL Server database. 185 sites are represented, with some measurements spanning the years 1998-2009 but most, including nutrient observations, spanning 2000-2006.  For 76 sites with continuous data from 2000-2006, we found that temporal patterns have been fairly uniform across the spatial domain, and these patterns appear to be linked to patterns of freshwater input: a drought in 1998-2002 was followed by a wet 2003, then more moderate rainfall and another drought from 2006-2009. Nutrient (ammonia, nitrite, nitrate, phosphate, total dissolved phosphorus (TDP)) concentrations generally rose in late 2002 as the drought broke, then fell in 2003, when there was a pronounced decline in dissolved oxygen (DO) to <4 mg L-1 for many sites.

     We proposed a suite of seven indicators and recommended criteria intended to help classify and understand the causes of water quality degradation in Georgia. These included both “immediate” indicators of poor water quality (pH, DO) as well as “early warning” indicators of potentially poor water quality (total dissolved nitrogen (TDN), TDP, chlorophyll a, transparency, biochemical oxygen demand (BOD)). Specific recommendations for the criteria to be used to classify each of these seven indicators as “good”, “fair”, or “poor” are summarized in Chapter 5 of the technical report.

        We used the CRD data to assess the status of Georgia estuaries and coastal waters in terms of pH, DO, and nutrients, according to our recommended criteria. (At the present time we do not have data to assess chlorophyll a and BOD, and the turbidity data collected by CRD are not directly relatable to the recommended transparency criteria.) CRD measured TDP but only the inorganic fraction (DIN: nitrate, nitrite, ammonia) of TDN, so interim DIN criteria are expressed as a fraction of TDN criteria. Annual minimum pH was poor in blackwater streams in 2004 but improved in 2006. Annual minimum DO was low and median DO was fair coastwide in 2003, but conditions improved by 2006. Annual median DIN was mostly fair coastwide each year, with poor sites concentrated in Altamaha River estuary, and annual median TDP was fair at all sites throughout the study period.
     
     The report includes a series of recommendations regarding CRD’s water quality programs, including continued monthly monitoring of the parameters outlined in the indicators suite. Our primary recommendations are as follows: CRD should add chlorophyll a and BOD5  to the core monitoring programs; switch its nutrient monitoring from a focus on inorganic nutrients to total dissolved (TDN and TDP), with the particulate fraction (PN and PP) included to be able to be in compliance with expected national directives; switch from turbidity measurements to a measure of transparency, such as % light transmission or Secchi depth; and continue measurements of dissolved oxygen, pH, and ancillary data (salinity, specific conductance and water temperature).

Publications:

The Condition of Georgia's Coastal Waters: Development and Analysis of Water Quality Indicators (the full technical report submitted to the GaCMP) is available as individual chapters:

Front Matter

Executive Summary

1. Introduction

2. Data Description

3a. Trends

3b. Trend Maps

4. Correlations

5. Indicators

6. Status

7. Recommendations

8. References

Appendix A: Sampling Sites

Appendix B: Status Tables

Georgia Coastal Water Quality 2000-2006 is a brochure which summarizes the GA DNR CRD data to assess the status of Georgia estuaries and coastal waters for 2000-2006 according to the criteria recommended for dissolved oxygen, nitrogen, phosphorus, and pH - the only indicators for which information was available. The data is organized regionally around nine major sounds and nearby coastal areas.

Project Update:

Georgia Coastal Water Quality 2000–2010 This 2013 report is an update to the brochure, Georgia Coastal Water Quality 2000-2006, and incorporates data collected through mid-2010.

 


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This page was updated September 23, 2015