GCRC Reports

The GCRC writes technical reports and papers that address specific coastal management issues including marsh dieback, offshore wind, and water quality assessment. Clicking on the links below will take you to the full document.

TITLEDescriptionDATE
Use of Pulverized Glass for Beach Nourishment: A ReviewThis paper reviews geotechnical, biological, and abiotic analyses conducted on the experimental placement of recycled glass on beaches in Florida. It will also describe the experiences local governments have had when considering the use of recycled glass as an alternative material for beach nourishment.2018
Use of Thin Layer Placement of Dredged Material for Salt Marsh RestorationThis report reviews the use of TLP of fine sediments (i.e. silt and clay) in salt marshes. Part I describes TLP and how it is being used for the nourishment and restoration of salt marshes. Part 2 examines how TLP projects are planned and designed. Part 3 discusses the importance of monitoring TLP projects before, during, and after construction. Physical, biological, and chemical parameters that are commonly part of successful monitoring plans are described and results from case studies are discussed with a focus on the parameters useful for Georgia projects. Part 4 provides a discussion of factors that make up a successful TLP project. Summary information on the 26 TLP projects we reviewed for this report is included in Appendix A. 2017
Living Shorelines in the Southeast: Research and Data GapsThe purpose of this report is to synthesize scientific information relevant to living shorelines in the states of North Carolina, South Carolina, Georgia, and Florida. Part One of the report provides a brief overview of the types of approaches that have been used in the region. Parts Two, Three and Four describe research on the physical, biological, and chemical characteristics, respectively, of living shorelines in salt marshes. Part Five summarizes what little information is available regarding living shoreline projects in Florida mangroves. Part Six is a summary and a discussion of data gaps. Details about 441 living shoreline projects are included in Appendix A. Appendix B is an annotated bibliography of material relevant to living shoreline research in the southeast region.2016
Effects of Climate Signals on Shrimp and Crab Trawl Surveys in Ossabaw, St. Andrew, and Cumberland Sounds: Phase 2We obtained fishery data from the Atlantic Coastal Cooperative Statistics Program and compared trawl catch rates with statewide catch per unit effort (CPUE) for four catch species. For available observations between 1986 and 2011, we found that the relationships between climate signal (Bermuda High Index, El Niño/Southern Oscillation Index, Atlantic Multidecadal Oscillation) patterns, precipitation, and river discharge that were revealed in the first phase of this analysis extended to salinity as well. We also found limited correlations of water temperature with climate signals, including correlations with the North Atlantic Oscillation, which did not show correlations with salinity or flow variables. Correlations between trawl catch and river discharge and salinity were limited and weak.2015
Disposal of Dredged Material from the Atlantic Intracoastal WaterwayIn March 2014, the USACE released a draft Environmental Assessment and DMMP for the Savannah District AIWW, proposing to use a combination of new and existing dredged material disposal sites, open water placement of sandy dredged material, and Ocean Dredged Material Disposal Sites for disposal of AIWW dredged material over the next 20 years. In order to assist the Coastal Resources Division of the Georgia Department of Natural Resources in reviewing this document, this report provides general background on dredged material disposal (Part One) and describes the specific dredged material disposal policies and activities in North Carolina and South Carolina, and the northeastern portion of Florida (Part Two).2015
Vegetated Buffers in the Coastal ZoneThis updated report contains a summary of recent research on wetland buffers that is relevant to estuarine ecosystems. Part One describes the functions of vegetated buffers adjacent to wetlands. Part Two provides updated information on studies conducted on vegetated buffers (primarily riparian buffers) related to water quality maintenance and habitat protection. These areas are relevant to this report because the manner in which buffers protect and maintain these functions is similar whether the buffers are adjacent to streams or wetlands. Part Two also presents recent research about marsh migration and the role wetland buffers could play in protecting marsh functions. Part Three summarizes new research on the effect of upland land use on coastal systems, which suggests that intertidal marshes alone are not necessarily sufficient to protect water quality. Part Four discusses examples of the application of wetland buffers in other states. At the end of the document are conclusions and a bibliography.2014
Effects of Climate Signals on River Discharge to Ossabaw, St. Andrew, and Cumberland Sounds: Phase 1Variability in precipitation and river discharge to the Ogeechee, Satilla, and St. Marys River estuaries (Georgia, USA) was examined in relation to indices for several climate signals and compared to earlier results for the Altamaha River estuary. Precipitation patterns in the watersheds were described using empirical orthogonal functions (EOFs) and were consistent across watersheds. We compared the time series (principal components, PCs) associated with these EOFs, monthly standardized anomalies of river discharge, and four climate indices: an index of the Bermuda High position (BHI), the Southern Oscillation Index (SOI, an index of El Niño and La Niña, also referred to as ENSO), the Atlantic Multidecadal Oscillation (AMO), and the North Atlantic Oscillation (NAO). The complex, seasonally alternating patterns that emerged were very similar across all watersheds.2014
Georgia Coastal Water Quality: 2000-2010The Coastal Resources Division (CRD) of the Georgia Department of Natural Resources (GA DNR) collects water quality data in support of a variety of programs. The Georgia Coastal Research Council recently compiled these observations into an integrated database and analyzed it for long-term and seasonal trends. As a part of that effort, we proposed a suite of indicators and recommended evaluation criteria intended to help classify and understand the causes of water quality degradation in Georgia. In this report, we use the GA DNR CRD data to assess the status of Georgia estuaries and coastal waters according to the criteria recommended for the first four of these indicators: dissolved oxygen, nitrogen, phosphorus, and pH.2013
Factsheet: 2013 Update on Coastal Marsh Dieback in Georgia This update provides a summary of the ongoing research activities that are currently underway to address salt marsh dieback in Georgia and South Carolina.2013
A Survey of State Regulation of Offshore Wind FacilitiesThis report outlined the federal leasing process for offshore wind developments and also reviewed the regulations of nine East Coast states and the Gulf States of Texas and Louisiana. The report contains matrixes of federal and state statutes that affect offshore wind permitting as well as a general discussion of state regulatory policy, Coastal Zone Management Act consistency review, permitting requirements for underwater cables and transmission lines, and local government permitting. The report also includes individual state discussions of offshore wind development, and of offshore project and research activities. 2013
2013 Update on Coastal Marsh Dieback in GeorgiaThe best documented incidence of salt marsh dieback occurred in 2001-2002 when reports of marsh areas with little or no live above-ground vegetation were received from six of Georgia’s coastal counties. New dieback sightings were reported in 2007; however, this event was not as widespread as the previous dieback episode. In September 2011, new areas of marsh dieback along the Jerico River began to be reported. As of spring 2013, salt marsh dieback had been reported in areas along the Jerico River, the St. Simon’s Island causeway, and in Camden and Chatham Counties. This update provides a summary of current and recent research activities that have been undertaken to evaluate salt marsh dieback in Georgia and South Carolina.2013
Water Quality Metadatabase for the South Atlantic Landscape Conservation CooperativeThe Georgia Coastal Research Council developed a metadata-level database of existing water quality monitoring programs across the South Atlantic Landscape Conservation Cooperative (SALCC) geographic range. This report describes the updates that were made to the system and the website since the original project, summarizes the results of each project objective, and includes a discussion of challenges faced in meeting those objectives.2012
Executive Summary for Offshore Wind Energy: Considerations for GeorgiaThis is a two-page summary of the report, Offshore Wind Energy: Considerations for Georgia".2011
Offshore Wind Energy: Considerations for GeorgiaThis document provides background information about offshore wind energy, with a specific focus on potential development in Georgia coastal waters. Part I is an introduction to the use of offshore wind as a renewable energy source; Part II provides an overview of the components of a wind installation; Part III discusses factors that are considered in siting a wind facility; Part IV describes the environmental considerations associated with such a project; and Part V describes planning tools and ongoing offshore wind energy initiatives, along with some concluding notes. 2011
A Coastal Water Quality Metadata Data Base for the Southeast USAThis paper describes the development and initial implementation of a Coastal Water Quality Monitoring Metadata Database for the Southeast region (from NC to FL). The database was designed to store detailed information on water quality monitoring programs operated by federal, state and municipal agencies, as well as by research institutions, including monitoring station locations, measured parameters, program contacts, and links to program web pages and data downloads. 2011
Recommended Indicators of Estuarine Water Quality for GeorgiaWe propose a suite of seven indicators, as well as basic ancillary data (water temperature, salinity, specific conductance), that are intended to help classify and understand the causes of water quality degradation in Georgia. We recommend two immediate indicators of poor water quality (pH and dissolved oxygen) that may indicate that a stressful and potentially lethal condition is already in progress. The remaining five (nitrogen, phosphorus, chlorophyll a, transparency, and biochemical oxygen demand (BOD)) are “early warning” indicators of potentially poor water quality that should be measured in order to anticipate problems and make appropriate management decisions. We present the rationale for choosing these indicators and the considerations for developing evaluation criteria.2011
Water Quality Status of Georgia Estuaries and Coastal Waters Using Recommended IndicatorsWe have proposed a suite of seven indicators that are intended to help classify and understand the causes of water quality degradation in Georgia by covering the progression of eutrophication from nutrient over-enrichment to algal overgrowth (if present) to enhanced microbial respiration and hypoxia. Of these, we are able to assess four indicators coastwide using data collected by GA DNR CRD during 2003-2006. pH status was assessed using ΔpH, the deviation from the expected pH according to the sample salinity and estuary type (alluvial/tidewater, blackwater, alkaline blackwater). Annual median pH deviations were classified as good at almost all sites in all years, whereas annual minimum pH deviations often ranged into the fair and poor categories. pH status generally improved from 2004 to 2006. Annual median dissolved oxygen (DO) was mainly good to fair, while annual minimum DO was mainly fair to poor, with sites classified as poor occurring sporadically along the coast. DO status generally improved from 2003 to 2006. Annual median dissolved inorganic nitrogen status was mostly fair coastwide in all years, with the few sites classified as poor concentrated in the Altamaha River estuary. Annual median total dissolved phosphorus was fair coastwide during the study period. The generally poorer water quality in 2003 compared to later years may have been due to conditions related to high rainfall after a severe drought.2011
South Atlantic Regional Research Plan: Development and Application of Coastal Regional PrioritiesThe South Atlantic Regional Research Project is a regional, multi-agency project to develop a coordinated coastal and ocean research plan for the southeastern United States (from NC to FL). The South Atlantic effort was funded by National Sea Grant-NOAA and was conducted in concert with similar projects in other Sea Grant regions across the US and Insular Pacific. The project’s primary goals are to identify priority coastal and ocean research needs for the region and to foster productive cooperation among regional partners. The SARRP plan was released in April 2010 after a three-year process that involved federal, regional, state and academic partners from throughout the region. The plan identifies 27 research priorities, which were aligned with the four themes that are also being used by the South Atlantic Governor’s Alliance: Healthy Ecosystems, Working Waterfronts, Clean Coastal and Ocean Waters, and Disaster-Resilient Communities. We are currently collecting information describing ongoing or planned activities that are relevant to each priority, as well as identifying areas specifically aligned with the missions of particular agencies and organizations. This paper will describe the process by which the plan was developed, highlighting the key research priorities identified in the research plan and presenting an update on synergy with other regional initiatives.2011
Herbicide Use near the Coastal Marshlands: Companion DocumentFour years ago, in response to a request by the Coastal Resources Division, we produced a short paper concerning herbicide use near the coastal marshlands. The present document, which serves as a companion to our original summary, is focused on four specific herbicides (Plateau, Roundup, Garlon 3A, and Habitat) and how each might interact with Spartina alterniflora, the predominant plant species in the marsh. Rather than address a particular formulation of these herbicides, we present information on their active ingredients: Roundup® (glyphosate), Plateau® (imazapic), Habitat® (imazapyr) and Garlon 3A® (triclopyr). Information is provided on each herbicide, including a general description, information on its usage, environmental characteristics, and its effects on plants. 2009
Southeast Coastal Water Quality Monitoring Metadata Tools: Database and Web ApplicationsThis report describes the development of the SE Coastal Water Quality Monitoring Metadata Database and its initial application. Our goal for the database was to develop a tool for storing critical information about water quality monitoring programs, their sponsoring organizations, monitoring locations, and measured parameters. We wanted a flexible design that could accommodate variable types and amounts of information for each resource and support changing the types of metadata stored in the database without changing the underlying database structure and web interfaces. We also wanted to support direct links to data for monitoring stations whenever possible. The geographic scope of the project includes the Coastal Zones of NC, SC, GA and the east coast of FL. However, the geographic scope of the database is not rigidly defined, and may be expanded in the future based on NPS and user feedback. The database was designed to include information on water quality data collected by federal, state, and municipal agencies as well as by research institutions.2009
Marsh Dieback Update 2008Salt marsh dieback continues to be an issue of interest on the Georgia coast. We are still recovering from the widespread event of 2001-2002, and new dieback areas were reported this past year (2007). This paper provides the following information: (a) a description of the 2001-2002 dieback event, (b) a summary of the various research activities that are underway to address the issue, (c) a brief description of the current dieback event, and d) a list of recent newspaper articles on the subject. 2008
SE Coastal Water Quality Monitoring Metadata Workshop: SummaryAs part of a project compiling a database of long-term monitoring program metadata and summarizing long-term monitoring efforts in the region, the GCRC organized a workshop was organized in order to bring together representatives from various agencies and institutions involved in coastal water quality monitoring in the southeast. This report describes the workshop, which was held on June 5, 2008 at Hollings Marine Laboratory in Charleston, SC.2008
Coastal Watershed Condition Assessment of Fort Pulaski National MonumentWe recently completed an assessment of Fort Pulaski National Monument for the Water Resources Division of the National Park Service. The report provides information on park resources, water quality and impairments, and other issues of concern. Although there are no real sources of pollutants at Fort Pulaski itself, both point and nonpoint sources of pollutants can be found nearby that have the potential to affect its water resources. We identified nutrients and contaminants as currently existing problems. A majority of nutrient samples were classified as either fair or poor, and there is evidence for elevated contaminants (primarily arsenic and PAHs) in sediment and animal tissue taken from both tidal creeks and the main channel of the Savannah River. Dissolved oxygen was identified as a potential problem due to the amount of organic material and nutrients associated with industrial activity. Fecal bacteria concentrations are low and not considered a problem. Continued water quality monitoring at the Park is particularly important in order to note any change occurring with the Savannah Harbor Expansion Project. The report provides a list of recommendations for additional observations that would allow us to better evaluate coastal water resources. 2007
Research Summary: On the Shoulders of Giant PlantsThe paper compared the Georgia results with those from studies in marshes throughout the U.S., and found that most patterns were general. Increases in elevation were related to freshwater input in all areas, as was soil nitrogen. These results are especially interesting in the face of sea level rise, as increased upstream salinities can be expected to affect numerous soil properties in tidal marshes, as well as their elevation.2007
Stormwater Treatment in Coastal AreasFor this report, we have compiled brief descriptions of different stormwater treatment strategies. Although stormwater treatment has not been as well-studied in coastal areas as in other environments, there are several recent projects that are relevant to this issue. This document provides information from technical studies that have evaluated stormwater treatment via filtration (buffers), wetlands, and stormwater ponds.2007
Impervious Surfaces: Review of Recent LiteratureThe studies described in this paper demonstrate that increases in impervious surface and concomitant surface runoff routinely lead to impairments in water quality and biological communities in both freshwater and estuarine systems.2006
Assessment of Coastal Water Resources and Watershed Conditions at Fort Pulaski National Monument, Georgia This report provides information on the water quality and biological resources of Fort Pulaski National Monument as well as regional potential pollution sources. Although there are no pollutant sources at Fort Pulaski itself, both point and nonpoint pollutant sources can be found nearby that have the potential to affect the park’s water resources.

The report summarizes the potential for impairment to the various water resources associated with the park. Indicators considered include contaminants and other indicators of poor water quality; population effects in terms of harvest and invasive species; and habitat disruption. The largest water quality problem identified was low dissolved oxygen in the Savannah River Estuary due to the large amount of organic material released into the water, coupled with stratification. The report also lists a number of recommendations, which are described in detail.
2005
Marinas: Best Management Practices & Water QualityThis document provides an introduction to the Best Management Practices associated with the development of marinas. Part A is focused specifically on water quality and describes the types of measurements EPA recommends for marinas. Part B is an overview of the EPA Best Management Practices for all aspects of marina construction and management. Part C provides information on some of the criteria that other states use with regard to marinas. At the end of the document is a list of Resource documents and websites with useful information on marinas, and an Appendix with information on volunteer water quality monitoring programs in marinas.2005
Assessment of Coastal Water Resources and Watershed Conditions at Cumberland Island National Seashore, GeorgiaThis report provides information on the water quality and biological resources of Cumberland Island National Seashore as well as regional potential pollution sources. Although there are no pollutant sources at Cumberland Island itself, both point and nonpoint pollutant sources can be found nearby that have the potential to affect the island’s water resources. The report summarizes the potential for impairment to the various water resources associated with the island. Indicators considered include contaminants and other indicators of poor water quality; population effects in terms of fish harvest and invasive species; and habitat disruption. The largest potential water quality problem identified was low dissolved oxygen in Cumberland Sound, but there are also potential problems associated with nutrients and contaminants. 2005
Water Quality Conditions near Cumberland Island, GeorgiaThis paper describes water quality information compiled as part of a report to the National Park Service on the water resources and habitat conditions of Cumberland Island National Seashore. Observations of nutrients, bacteria, dissolved oxygen, and contaminants in Cumberland Sound were obtained from state and federal agencies (particularly data collected by the Coastal Resources Division (CRD) of the Georgia Dept. of Natural Resources) and from the literature. Dissolved nutrient concentrations (orthophosphate, total dissolved phosphorus, nitrate plus nitrite) were considered fair to good according to the U. S. Environmental Protection Agency (EPA) National Coastal Condition Report II criteria. Bacterial concentrations (fecal coliform) did not show evidence of problems. Dissolved oxygen levels were sometimes critically low, particularly during summer: measurements made by CRD at 20 stations between 2000 and 2004 were less than 4 mg/L 18% of the time. Although it is not clear the extent to which this is a natural phenomenon, these low values warrant continued observation. This review also suggests potential problems in terms of mercury and several pesticides (i.e. dieldrin, lindane, 4,4′-DDD), which may be due to legacy contamination of the sediment or to continued input from both point and non-point sources. Continued monitoring of water conditions (particularly dissolved oxygen) and forthcoming observations of contaminant concentrations in organisms and sediment taken as part of the EPA National Coastal Assessment Program will enable better evaluation of coastal water resources in the region.2005
Environmental Effects of Docks and Marinas, June 2005This document provides an introduction to the environmental effects of docks and marinas, with an emphasis on intertidal salt marshes such as those found in the Southeastern U.S. Below we describe studies undertaken to determine how docks and associated boating activity may affect coastal marsh vegetation, water quality, and the physical environment (i.e. water flow, changes in the sediment). The effects of upstream development on these environmental factors are also briefly discussed, because it can be difficult to separate the specific effects of docks from the more general effects of development. This is followed by a conceptual diagram that shows the relationships among the various factors described in the text and highlights those interactions that appear to be most important. At the end of the document there is a bibliography, a list of other resource information, and an Appendix with information on environmental mitigation strategies for docks. 2005
Herbicide Use near the Coastal MarshlandsHerbicides represent a potential risk for non-target plants and animals living in adjacent environments. Where herbicides are used near coastal marshes, there is a concern that they may have direct effects not only on marsh grasses but on other primary producers such as benthic algae and phytoplankton, as well as various animals living in the marsh (i.e. insects, larval fish, shrimp, crabs) which may also be sensitive to specific chemicals. Herbicides may have additional indirect effects on marshes which stem from reductions in plant growth, as plants are at the bottom of the marsh food web and also provide protection from storms and prevent erosion. The effects of herbicides on marsh health can be minimized by using herbicides that do not persist in the environment. This document provides information on seven common aquatic herbicides that was mainly drawn from the Plant Management in Florida Waters website. A list of other useful resources is also included. 2005
Comparing Transport Times through Salinity Zones in the Ogeechee and Altamaha River Estuaries Using SqueezeboxThis study explored differences in the transit times of dissolved substances through salinity zones in the Altamaha and Ogeechee River estuaries under a range of flow conditions. Salinity distributions and transit times were estimated from box models generated using the SqueezeBox modeling framework. The estuaries were compared in spite of the large difference in their river flow ranges by using flow rates ranging from the 10th-90th percentile within each range. In each case, zone lengths and transit times were calculated for the tidal freshwater, oligo-mesohaline, and polyhaline zones. Although the two estuaries have similar lengths, the slower-flowing Ogeechee grades from a zone of tidal freshwater (except at very low flows) through oligo-mesohaline zones to a polyhaline zone inside the mouth whereas the Altamaha always has a fairly long (>25 km) extent of tidal freshwater but only a short (or non-existent) polyhaline zone. Transit times through the whole Ogeechee estuary are 3.3-4.7 times longer than those in the Altamaha, but the lengths of time water spends in the tidal freshwater reaches of the estuaries are comparable whereas there are large differences in the times spent in oligo-mesohaline and polyhaline reaches. These types of predictions may be useful in interpreting nutrient and pollutant dynamics in estuaries as well as in studies that compare the relative susceptibility of estuaries to perturbations.2005
Vegetative Buffers in the Coastal ZoneThis document is divided into three sections. Part One provides a brief overview of the functions of vegetated buffers and the various factors that influence their effectiveness. Part Two describes some of the research that has been done to evaluate loading into coastal areas. Part Three lists some of the considerations that are relevant for buffers in tidal areas. An annotated bibliography and other resource information are also included. 2004
Marsh Dieback Fact SheetThis is a two-page fact sheet describing the state of marsh dieback knowledge in 2004. 2004
Simulating Material Movement through the Lower Altamaha Estuary Using a 1-D Box Model1-D optimum-boundary box models were used to simulate the movement of dissolved pollutants or other conservatively mixing constituents through the Altamaha River estuary. Tracers were introduced into the models as point sources at various locations within the estuary and as a non-point input to the entire system. In each case, models were run at four different river flow rates and were used to simulate both the movement of tracer within the estuary and its rate of removal. When tracer was introduced at head of tide, it moved rapidly (from 1-2 d, depending on flow) to the head of the mixing zone 30 km downstream. Tracer released anywhere in the estuary, including farther downstream at 2 km, moved toward an area 4-6 km upstream of the mouth, where it remained centered as overall removal continued. Movement toward this zone was observed regardless of flow rate. Introduction of tracer as a non-point source also resulted in distributions centered at 4-6 km, suggesting that this area is a potential convergence zone in the Altamaha River estuary. Maximum exposure to tracer, measured as the amount of time that concentration exceeds a given threshold, depends on where in the estuary tracer is released. When released at head of tide, maximum exposure is experienced at 6-10 km. Simulations of the type presented here are useful for evaluating the conservative movements of both point- and non-point-source constituents in the estuary. 2003
Spartina Species Zonation along the Altamaha River EstuaryChanges in freshwater inflow can cause changes in the distribution and diversity of marsh vegetation in estuarine habitats. In the fall of 2002 bankside vegetation was surveyed along the 24 km length of the Altamaha River estuary (n= 14 sites). Sites were quantified for multiple plant and edaphic parameters, including plant density, height, and tiller diameter. In this paper we present the characteristics of the bankside marsh vegetation as they change along the estuarine salinity gradient, and evaluate the use of a proportional relationship between two marsh grasses, Spartina cynosuroides and S. alterniflora, as a way to identify a transition line between salt and brackish marsh communities. S. alterniflora densities were greatest at the mouth of the estuary and decreased upstream and S. cynosuroides densities showed the opposite pattern, but there was not a well defined transition between these two plant communities. The percent S. cynosuroides cover along the estuary is a potentially useful way to document the response of the estuary to changing amounts of freshwater inflow. 2003
The Effects of Changing Freshwater Inflow to Estuaries: A Georgia PerspectiveThis is a white paper written by the staff of the Georgia Coastal Research Council to summarize information regarding the effects of changing freshwater inflow to estuaries. It is divided into three parts. Part One provides an overview of the scientific information available regarding the connections between freshwater inflow, estuarine conditions, and resources. Part Two presents a conceptual model for inflow management in terms of the types of regulation available and the societal values that must be considered. In this section we categorize management as inflow-based, condition-based, or resource-based, and use this structure as the basis to explore the differing approaches to estuarine inflow management that have been taken in various parts of the country. In Part Three we apply this perspective to Georgia. We describe the inflow policy currently in place in Georgia's rivers and summarize the scientific efforts being undertaken to understand the impact of changing freshwater flow to Georgia's estuaries.2002
Freshwater Inflow: Science, Policy, ManagementThe papers in this special issue were presented in a special session during the 2001 biennial conference of the Estuaries Research Federation held in St. Pete Beach, Florida. This session, “Freshwater inflow: Science, policy and management,” was focused on issues related to reduced freshwater inflow to estuaries. The session brought together scientists, managers, and regulators, and included presentations on the estimation of freshwater input to estuaries, development of ecological indicators to assess changes in inflow, management strategies used to set freshwater requirements, and experiences with the reintroduction of freshwater to restore inflow. 2002
A Comparison of Residence Time Calculations Using Simple Compartment Models of the Altamaha River Estuary, GeorgiaWe explored residence and flushing time scales in the context of the Altamaha River estuary, Georgia, and present a comparison of techniques for their calculation (fraction of freshwater models and variations of box models). Freshwater transit time estimates from simple steady-state box models were virtually identical to flushing times for four river-flow cases, as long as boxes were scaled appropriately to river flow, and residence time estimates from different box models were also in good agreement. Mixing time estimates from box models were incorrect when boxes were improperly scaled. Mixing time scales vary nonlinearly with river flow, so characterizing the range as well as the mean or median is important for a thorough understanding of the potential for within-estuary processing. 2002
Dead Marsh Information (2002)This document provides background information about marsh dieback as well as potential causes, summaries of regrowth and transplant studies, and responses to the problem in other states (e.g., LA, SC, FL). Georgia's initial responses to marsh dieback are also described and various contacts and other sources of information are listed. Two appendices, The Louisiana Brown Marsh Response Effort and the Georgia Coastal Ecosystems Dead Marsh BIOBLAST Overview are provided. 2002
Water Use Patterns in the Watersheds of the Georgia Riverine EstuariesWe examined water use patterns in the hydrologic units that comprise the watersheds of the 5 major coastal rivers in Georgia (Savannah, Ogeechee, Altamaha, Satilla, St. Marys). The data for this analysis were obtained from the Georgia Water Use Program, which regularly surveys both water sources (groundwater and surface water) and water uses (domestic, commercial, industrial, mining, irrigation, livestock, thermoelectric, and hydroelectric) as part of the USGS National Water Use Synthesis. Total water withdrawal in the study area totaled 5749 million gallons per day (mgd) in 1995, with no large changes in either water withdrawal or water use patterns for the last 3 reporting years (1985, 1990, and 1995). Surface water accounted for 91% of the water withdrawal in the region, and much of this was for thermoelectric use in the watersheds of the Savannah and Altamaha Rivers. However, most of the groundwater that was withdrawn was withdrawn in the Coastal Plain. Only 10% of the water withdrawn was actually consumed, with the remainder returned to the surface water. Irrigation represented the largest consumptive use, and much of this occurred in the Coastal Plain.2001
Salinity Response of the Satilla River Estuary to Seasonal Changes in Freshwater DischargeGeorgia's vast brackish water landscape is maintained, to a large extent, by the hydrostatic pressure of freshwater discharges which keep the sea out of these areas. The salinity regime throughout this landscape responds to fluctuations in discharge. We describe the salinity regime in the Satilla River Estuary based on two intensive field campaigns in 1999 (20 Jan - 20 Mar and 9 Sept - 19 Oct). River discharge varied from almost 150 m3s-1 in February (twice the average) due to a single rain event in late January, to below 10 m3s-1 in May and June, after which it remained relatively low. The single discharge event resulted in large decreases in salinity throughout the estuary that lasted for about one week. (Salinity in Crows Harbor Reach was between 12-14 practical salinity units (PSU) on 20 Jan but fell to less than 2 PSU by 5 Feb) After early February, salinity slowly increased and had returned to near January levels by mid-April. Thus, during the ramp-up of river discharge in late January, the estuary flushed out much of its salt within about 20 days, and it took more than 2 months (70 days) to return to the salinity levels observed in January. The events analyzed here are described within the context of a series of salinity surveys over the course of 1999 and 2000, which should enable managers to gain insight into the interactions between river discharge, salinity structure, and flushing times in this system. 2001
Linking Shifts in Historic Estuarine Vegetation to Salinity Changes Using a GISThere are anecdotal reports that upstream water withdrawals over the past 50 years have altered the salinity structure of coastal Georgia estuaries. Since few consistent salinity records exist, it may be possible to use shifts in vegetation to document salinity change. The purpose of this study was to use aerial photographs and GIS analysis to determine if the location of the brackish water interface in two Georgia estuaries has changed. Current vegetation maps of the Satilla and Altamaha estuaries were constructed from 1993 USGS DOQQs. Vegetation was outlined and classified as Juncus roemerianus, brackish marsh, fresh marsh, salt marsh, or other. Historic vegetation maps were similarly constructed from 1:77000-scale color infrared photographs taken in 1974 and 1:24000-scale black and white photographs taken in 1953. Change maps between all years were constructed for each river. In the Altamaha River, 6,786 hectares of marsh area were mapped, of which 77% did not change between 1953 and 1993. Of the 10,205 hectares of marsh area mapped in the Satilla, 87% did not change between 1953 and 1993. Shifts in Juncus constituted the primary vegetation change in both estuaries (95% in the Satilla and 87% in the Altamaha). However, these changes in Juncus do not necessarily reflect changes in estuarine salinity, indicating a need for further investigation of Juncus interactions in these systems. 2001
Trends in Salinities and Flushing Times of Georgia EstuariesFrom 1973-1992, the Georgia EPD sponsored a monitoring program in which surface salinities were sampled regularly at fixed stations in many of Georgia’s estuaries. We used these data to examine changes in the salinities and flushing times of the Savannah, Ogeechee, Altamaha, Satilla, and St. Marys estuaries over the period of record. Water-year average salinities increased slightly over time in four of the five estuaries. When data were smoothed with a three-year moving average (based on fast Fourier analysis of river discharge), the increases in salinity were statistically significant in the Satilla and Savannah River estuaries. We used the measured salinity values to estimate flushing times (average transit time of river water through an estuary) over the period of record. Flushing times averaged 28 d in the Ogeechee, 7 d in the Altamaha, 63 d in the Satilla, and 65 d in the St. Marys, although there was considerable inter-annual variability in these estimates. These results are discussed in light of current proposals to increase surface water withdrawal from the Georgia rivers.1999