V..JSX tT'tl* ^->>/ ^^>>Y>%^ S?\ty/ ^^^^ 1^.4 'uispg 1N3WSS3SSV A 3H1 3O

3H1 3O ADO1OD3 QNV ADOIO^QAHCOVER PHOTOGRAPH:

The Landsat image on the covershows the extent ofthe floodplain in the Apalachicola Riverbasin, Florida. The dark colorofthe floodplain is causedbylow reflectance from floodwaters. The river (600 feet wide) is barely visible in the centerofthe floodplain (1-6 miles wide). TheApalachicola Riverflows from Lake Seminole (at the top), 106 miles south, to Apalachicola Bay (near the bottom ofthe scene). The numerous white squares near the top of the scene are agricultural fields in Florida andAlabama. The large redarea east ofthe riveris a pine forest (Apalachicola National Forest). The faintbrown color
on the bird's-foot delta at the rivermouth depicts marsh grass. The lightblue colors nearthe beaches at the bottom ofthe scene represent a combination ofshallow waterand ocean currents that carryhigh suspended sediment loads. The false-colorcomposite was obtainedon February6,1977, bya Landsat multispectralscannerand includes bands 4,5, and 7. The scene ID is 2746-15190, andmore information on this andothersatellite images is available through the U.S. Geological Survey, EROS Data Center, Sioux Falls, SD 57101.

### Chapter D 

# HYDROLOGY AND ECOLOGY OF THE APALACHICOLA RIVER, FLORIDA: A SUMMARY OF THE RIVER QUALITY ASSESSMENT

By JOHN F. ELDER, SHERRON D. FLAGG, and HAROLD C. MATTRAW, JR.

U.S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 2196

Apalachicola River Quality Assessment

### DEPARTMENT OF THE INTERIOR

DONALD PAUL MODEL, Secretary

U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director

UNITED STATES GOVERNMENT PRINTING OFFICE: 1988
For sate by the Books and Open-File Reports Section, U.S. Geological Survey Federal Center, Box 25425, Denver, CO 80225

Library of Congress Cataloging in Publication Data Elder, John F. Hydrology and ecology of the Apalachicola River, Florida. (U.S. Geological Survey water-supply paper; 2196-D) Bibliography: p. Supt. of Docs, no.: I 19.13:2196-0 1. Hydrology Florida Apalachicola River Watershed. 2. Water qualityFlorida Apalachicola River Watershed. 3. Ecology Florida Apalachicola River Watershed. I. Flagg, Sherron D. II. Mattraw, H.C. III. Title. IV. Series. GB705.F5E44 1987 363.7'3942'0975992 86-600332

# PREFACE

The Apalachicola River Quality Assessment was part of a national river quality assessment program of the U.S. Geological Survey. The authors would like to thank the members of the Subcommittee on River Quality Assessment of the Advisory Committee on Water Data for Public Use for their interest and support.

Robert A. Canham, Executive Director Water Pollution Control Federation Washington, D.C.

Dr. E. J. Cleary1 Professor Emeritus Department of Environmental Health and Engineering The University of Cincinnati Cincinnati, Ohio

James B. Coulter, Secretary2 Maryland Department of Natural Resources Annapolis, Maryland

Ival V. Goslin Engineering Consultant Water Resources Western Engineers Grand Junction, Colorado

Dr. Laurence R. Jahn Vice President Wildlife Management Institute Washington, D.C. John E. Kinney Sanitary Engineer Ann Arbor, Michigan

Walter A. Lyon Deputy Secretary for Planning Pennsylvania Department of Environmental Resources Harrisburg, Pennsylvania

John A. Roller, Superintendent Water Division Department of Public Utilities Tacoma, Washington

Dr. Lois K. Sharpe Environmental Consultant Falls Church, Virginia

Dr. Clarence J. Velz Professor Emeritus Public Health Engineering The University of Michigan Ann Arbor, Michigan

1 Chairman 2Vice Chairman III

# CONTENTS

Preface Hi Abstract Dl 1.0 Background D2 1.1 Basin characteristics D2 1.2 Basin history D4 1.3 Basin management and environmental concerns D6 1.4 Information needs D8 2.0 Apalachicola River Quality Assessment D10 2.1 Activities D10 2.2 Objectives D12 2.3 Flood-plain forest D14 2.4 Leaf-litter production and decomposition D16 2.5 Flooding hydrology D18 2.6 Water budget D20 2.7 Total and dissolved carbon transport D22 2.8 Particulate carbon transport D24 2.9 Nitrogen transport D26 2.10 Phosphorus transport D28 3.0 Overview and implications D30 3.1 Flood-plain role in nutrient transport D30 3.2 Impact of river and wetland on Apalachicola Bay D32 3.3 Trace substances D34 3.4 Influence of dams D36 3.5 Effects of channel modifications D38 4.0 Conclusions of the Apalachicola River Quality Assessment D40 5.0 Summary D42 6.0 Scenes of the Apalachicola River D42 Selected references D44 Conversion factors D46

# HYDROLOGY AND ECOLOGY OF THE

APALACHICOLA RIVER, FLORIDA: A SUMMARY OF THE RIVER QUALITY ASSESSMENT

By John F. Elder, Sherron D. Flagg, and Harold C. Mattraw, Jr.

ABSTRACT

During 1979-81, the U.S. Geological Survey conducted
a large-scale study of the Apalachicola River in northwest Florida, the largest and one of the most economically important rivers in the State. Termed the Apalachicola River Quality Assessment, the study emphasized interrelations among hydrodynamics, the flood-plain forest, and the nutrient-detritus flow through the river system to the estuary. This report summarizes major findings of the study. Data on accumulation of toxic substances in sediments and benthic organisms in the river were also collected.

Because of the multiple uses of the Apalachicola River system, there are many difficult management decisions. The river is a waterway for shipping; hence there is an economic incentive for modification to facilitate movement of barge traffic. Such modifications include the proposed construction of dams, levees, bend easings, and training dikes; ditching and draining in the flood plain; and dredging and snagging in the river channel. The river is also recognized as an important supplier of detritus, nutrients, and freshwater to the Apalachicola Bay, which maintains an economically important shellfish industry. The importance of this input to the bay creates an incentive to keep the river basin in a natural state. Other values, such as timber harvesting, recreation, sport hunting, nature appreciation, and wildlife habitat, add even more to the difficulty of selecting management strategies. Water and nutrient budgets based on data collected during the river assessment study indicate the relative importance of various inputs and outflows in the system. Waterflow is controlled primarily by rainfall in upstream watersheds and is not greatly affected by local precipitation, ground-water exchanges, or evapotranspiration in the basin. On an annual basis, the total nutrient inflow to the system is nearly equal in quantity to total outflow, but there is a difference between inflow and outflow in the chemical and physical forms in which the nutrients are carried. The flood plain tends to be a net importer of soluble inorganic nutrients and a net exporter of paniculate organic material. Analysis of long-term records shows that dam construction in the upstream watersheds and at the Apalachicola headwaters has had little effect on the total annual waterflow but has probably suppressed low-flow extremes. Other effects include riverbed degradation and channelization which have to do with alteration of the habitat for aquatic biota and changes in flood-plain vegetation. Whatever management decisions are made should take into account the impact on the natural flooding cycle. Flooding is crucial to the presentflood-plain plant community and to the production, decomposition, and transport of organic material from that community. Permanent, substantial changes in the natural flooding cycle would be likely to induce concomitant changes in the flood-plain environment and in the nutrient and detritus yield to the estuary.

D11.0 BACKGROUND

7.7 Basin Characteristics

The Apalachicola River, the largest river in Florida, flows 106 miles through the northwest Florida Panhandle and empties into the Apalachicola Bay in the Gulf of Mexico (fig. 1.1). Its upstream limit is the Jim Woodruff Dam, 1 mile downstream of the confluence of the Chattahoochee and Flint Rivers. Lake Seminole, the 37,600-acre reservoirimpoundedbythe dam, provides the headwater inflow to the Apalachicola River, but there are
no other dams on the river. The Chattahoochee flows about 430 miles from its source in north Georgia to Lake Seminole at the Florida-Georgia State line. The Flint River originates south of Atlanta, Ga., and flows about 370 miles before itjoins the Chattahoochee River. The major tributary to the Apalachicola is the Chipola River. At the time of the Apalachicola River Quality Assessment, the Chipola River was constrained by a weir near Wewahitchka, Fla., to form a pool called Dead Lake. The control gates were removed in 1984 (although the weir remains), allowing the pool to drain to preweir levels. Immediately downstream of the weir, the Chipola is joined by water from the Apalachicola River flowing through the Chipola Cutoff distributary. These waters rejoin the main stem of the Apalachicola 13 miles downstream. The Brickyard Cutoff, a distributary channel, is located near Sumatra, Fla., at Brickyard Landing and conveys waterfrom the Apalachicola River to the Brothers River. The Brothers Riverrejoins the Apalachicola 8 miles south of the Brickyard Cutoff. The Apalachicola River then flows 6 miles south, where it connects to the Jackson River and flows southeast into Apalachicola Bay, one of the most productive shellfish areas in the United States. The entire Apalachicola-Chattahooch.ee-Flint River drainagebasinis 19,600mi2in area and encompasses parts of Georgia, Alabama, and Florida. The part below the dam, which drains directly into the Apalachicola River, has an area of2,400 mi2, halfofwhich is the Chipola River subbasin. Each winter and spring the rising waters of the Apalachicola flood the adjacent wetlands for 3-5 months. The flood plain occupies 175 mi2 and broadens downstream from 1/2-mile widejust below Lake Seminole to
more than 7 miles wide near the mouth. It is heavily forested with cypress, tupelo, and mixed hardwood trees, which thrive on the periodic inundation. The mean annual flow ofthe Apalachicola River at its headwaters near Chattahoochee is 22,300 ft3/s (1928- 82). Low flows are generally about 10,000 ft3/s, and high flows may exceed 100,000 ft3/s. The flow increases by about 25 percent over the course ofthe river. A geologic description ofthe area by Schnable and Goodell (1968) indicates that the river basin consists primarily of sediments of Holocene age with some late Pleistocene sediments near the mouth of the river. The riverbed is composed primarily of Pleistocene deposits consisting ofsand and coarse gravel. Sands and clays have been deposited constantly overtime and add to the natural high turbidity of the river. Flood-plain soil has a wide range of textures and colors because it is made up of a variety of sediments deposited under highly variable flow conditions. Near Blountstown and Wewahitchka, Fla., Leitman (1978)foundflood-plain soils tobepredominantly clay with some silty clay and occasionally clay loam. Sands on point bars were predominantlyfine and veryfine sands and were of the micaceous type, whereas most Florida sands are siliceous. Cation exchange capacity of flood-plain soils generally ranged from 20 to 50 meq/ L, and organic concentration ranged from 1 to 20 percent (higher nearthe surface). These levels arehigherthanmost Florida soils except peats and mucks. The pH of Apalachicola flood-plain soils ranges from 5.0 to 5.7 (Wharton and others, 1982). Average annual rainfall in the Apalachicola River basin in Florida is 58 in (1941-70), and mean annual potential evapotranspiration is between 39 and 45 in (U.S. Department ofCommerce, 1973). Average annual rainfall in the basin of the Chattahoochee and Flint Rivers in Georgia is 52in. Georgia rainfallhas agreaterinfluence on Apalachicola River flows than does Florida rainfall because only 11 percent ofthe basin ofthe Apalachicola, Chattahoochee, and Flint Rivers is in Florida. However, flows in the lower river can be substantially increased by Florida rainfall. Mean annual air temperature in the Apalachicola River basin in Florida is 66° F. Mean January air temperature is 52 ° F, and mean July air temperature is 81 °F (U.S. Department of Commerce, 1973).

D285°30' 85°15' 85°00' 84°45' 84°30'

32°

30°

28° 86° 84° 82° 80°

Apalachicola River drainage system

100 200 KILOMETERS 31°00'

30°45'

30°30'

30°15'

30°00'

29°45' WOODRUFF DAM _GEORGIA CHATTAHOQCHEE FLORIDA

100 river miles 'SWEETWATER CREEK 80 river miles

EXPLANATION
Flood plain CHIPOLA\ CUTOFF WEWAHITCHKA V 

### (\
20 river miles Apalachicola River basin boundary Drainage divide foi gaging stations



### B Figure 1.1. The drainage basins of (A) the Apalachicola, Chattahoochee, and Flint Rivers in Florida, Georgia, and Alabama and of (B) the Apalachicola and Chipola Rivers in Florida.

D31.0 BACKGROUND Continued

1.2 Basin History

The Jim WoodruffDam (fig. 1.2/1)was constructed bythe U.S. Army Corps ofEngineers. Constructionbegan in 1950, and filling ofthe reservoir was accomplished in several stages from May 1954 to February 1957. The primaryuse ofthe dam isto improve navigationforbarge traffic, with power generation as a secondary benefit. The U.S. Army Corps ofEngineers is authorized tomaintaina channel 100 ft wide and 9 ft deep. Dredging for the 9-ft depth began in 1956 in preparation ofthe completion of the Jim Woodruff Dam (Harry Peterson, U.S. Army Corps of Engineers, oral commun., 1980). Including the Jim Woodruff Dam, 16 dams are on the Apalachicola, Chattahoochee, and Flint Rivers (fig. 1.25). Most ofthe dams were built by local or private organizations for power generation. The oldest dam, the Eagle and Phenix,
was built in 1834. Most ofthe remaining small dams were built near the turn ofthe century. The U.S. Army Corps of Engineers made four cutoffs (fig. 1.2C)in 1956-57 and threemore in 1968-69to straightenbendsintheriverthatwereparticularlydifficult for barges to navigate. Groins (dikes perpendicular to banks) were installed to improve navigability by creating
scourinthe channel area ofthe river (fig. 1.2D). There are 29 sets ofgroins, mostlyintheupperriver. Constructed of wooden pilings or stone, the groins were installed from 1963 to 1970 (Harry Peterson, U.S. Army Corps of Engineers, oral commun., 1980). The major land use in the flood plain is forestry. Most areas were firstcutbetween 1870 and 1925 (Clewell, 1977, p. 11) and have been logged once or twice since that time. Otherextensiveusesarebeekeepingfortupelo honey production, commercial and sportfishing, and hunting. A few areas on the flood plain have been cleared for agriculture and residential developments. However, there
are no large urban centers, and there is very little industrialization. With the exception of a cattle ranch south of Wewahitchka, Fla., most ofthe flood plain in the lower reach ofthe river (south ofrivermile 20)ispublicly owned. The State ofFlorida Environmentally Endangered Lands Program purchased 44 mi2 of flood plain in 1977-78. According to Florida Statutes, land below the "ordinary high waterline" of the river is owned by the State. In addition, as ofOctober 1984, the Apalachicola River was designated by the Florida Department ofEnvironmental Regulation as an "Outstanding Florida Water" (OFW). This designation prohibits development which would significantly degrade water quality and applies to the entire river exceptfortwo reaches (nearmile 103 and mile 77).

D4DISTANCE. IN MILES B

Figure 1.2. Controls on the Apalachicola River: (A) Jim Woodruff Lock and Dam, (B) altitudes of the 16 dams on the Apalachicola, Chattahoochee, and Flint Rivers, (C) cutoff of a meander on the Apalachicola River above its confluence with the Chipola River, and (D) river training dikes at mile 100 on the Apalachicola River.

D51.0 BACKGROUND Continued

7.3 Basin Management and Environmental Concerns Questions about the most beneficial management strategies for the Apalachicola River result from the diverse values and possible uses ofthe system. Figure 1.3 shows separate uses and the likely management strategy employed for each use. Some uses call for mechanical or physical alteration of the natural system to maximize utility ofthe system forcommercialbenefit. Othersbenefit bylimited intervention in the natural system. Examples of engineered controls are dredging, dam construction, channelization, clearcutting, and road construction. Examples of water utilization are irrigation, water consumption by industry, and discharge of municipal or industrial wastes to the river. Shellfish harvesting in Apalachicola Bay is a multimillion-dollar industry that provides a major source of income and a way of life for residents of Franklin County, Fla. (Livingston and others, 1974; Prochaska and Mulkey, 1983). This resource could be threatened by disruption of the natural flow of river water and its constituents in the river system (Livingston and others, 1974). The other major use ofthe system which yields a high economic return is its use as a waterway for freight transport by barges. Barging is the most fuel-efficient

means offreight transport (Eastman, 1980), but it requires continual maintenance and navigational improvements in the river channel. Multiple use creates the possibility ofa dilemma in developing management strategy: how to enhance the function of the system as a resource of one type without damaging it as a resource ofanother type. Besides shipping, uses which may result in some alterations in the natural system include agriculture, timber harvesting, and urban development of the basin. To date, such activities have occurred only on a very limited scale, and most ofthe basin remains in a relatively natural state. One purpose ofthe OFW designation is to maintain the natural state ofthe water system. Benefits whichcould resultfrom active utilization of the river basin resources include the possibility of a stimulus to the local economy due to income from agriculture and industry, increased employment, and recreational use ofreservoirs which would be impounded by new dam construction. There would also be a probability of increased flood control and decreased impediment to mobility ofbarges and other large vessels. On the other hand, new problems would also be likely. Altered flooding patterns would probably eliminate large

areas of the flood-plain forest and, in general, would decrease itsproductivity (Leitmanand others, 1983). This would in turn have the probable effect of altering the nutrient, detritus, and sedimentflows to the bay, resulting in structural changes in the estuarine community and impacting the shellfish industry. There would also be a likely decrease in the diversity ofaquatic organisms in the freshwater system after channelization, scouring, and reservoir construction (Smalley and Novak, 1978). New reservoirs would inevitably bring new problems (such as algal blooms and aquatic weeds) that would require costly maintenance. Finally, there is the possibility of contaminationbyhazardous wastesthatcould resultfromthe development ofagriculture or industry in the basin. The tradeoffs involved in management decisions may be synthesized in the following general statements:

Itis unlikelythathumans, through accident ordesign, will produce altered systems that behave as efficiently as natural ones which represent the culmination ofover 200 million years of evolution and at least 10,000 years of biological acclimatization. Muchofthe activity ofthe next decade will be spent attempting to undo environmental damage ofthe last century and, hopefully, implementing wise protection and management strategies for existing quality environments (Cummins and Spengler, 1978).

There exists no reasontobelievethatthe currentecological situation represents an unfortunate state that is incapable of improvement through conscientious, intelligent management.

... Sound planning should be able to assure that the benefits derived from technology will continue to outweigh its disadvantages (Cairns, 1978).

D6

## PREDOMINANT BASIN MANAGEMENT STRATEGIES Engineered controls and water utilization

Shipping: barge traffic

Timber harvesting

Urbanization

Agriculture Natural controls and limited intervention in natural cycles

Shellfish industry, Apalachicola Bay

Harvest of natural resources other than timber

Wetland Preserve: Wildlife habitat Recreation Esthetic values Figure 1.3. Basin uses and associated type of management in the Apalachicola River basin.

D71.0 BACKGROUND Continued

1.4 Information Needs
At the time of the initiation of the Apalachicola River Quality Assessment, relatively little was known about the processes controlling the flow of water, sediments, nutrients, or detritus in this large river-wetland system. These types ofsystems had notbeen amajorfocus of ecological study, partly because ofthe complexities of dealingwithtwo interacting subsystems (riverand wetland) and poor documentation ofmethods. Interms ofavailable information, the Apalachicola Riverwas akind ofmissing link between the upstream and the downstream environments, both of which had been under study for several years. Upstream, heavy metals and pesticides were monitored in water, organisms, and sediments of Lake Seminole by the U.S. Army Corps of Engineers (1980). The study also included general hydrologic data aboutthe reservoir and the Chattahoochee and Flint Rivers. Downstream, Apalachicola Bay had been the site of intensive investigation for many years by Livingston and others (1974). Some of the important information needs for the Apalachicola River basin are outlined in figure 1.4. Information from the three main physiographic units of the basin the upland areas, the flood plain, and the river were all needed to understand functions of the system as a whole. Any type of budget estimates would also require informationaboutflows into the Apalachicola system from the upstream watersheds and out of the system to the estuary.

The Apalachicola River Quality Assessment filled

some of the information gap about the river basin. In particular, the study produced estimates for water and nutrient budgets, descriptions of hydrologic features of the river and wetland, an assessment ofrelations between hydrology of the wetland and the forest community, and the measurement of the extent of accumulation of potentially toxic substances in benthic organisms and bottom sediments. It also included some methods development for the collection ofdata from large rivers and forested wetlands. There is still much to be learned about the system, however, particularly with respect to the variability of water and nutrient budgets from year to year. Furthermore, very little work has been done to describe chemical and biologicalprocesses withinthe river water, flood-plain soils, and vegetation which affect the nutrient and toxicant chemistry of the river water and sediments. Continued fieldwork, supported bylaboratory experiments, would be valuable in adding information important for understanding the contribution from the river and the wetlands to estuarine productivity.

D8-*

> 

### UPSTREAM SYSTEM

OUTPUT TO APALACHICOLA RIVER 

# V

JLAK LAKE SEMINOLE



# «/«* tt RIVER FLOOD PLAIN

HYDROLOGIC FEATURES HYDROLOGIC FEATURES EFFECTS WATER BUDGET NUTRIENTS. DETRITUS FLOW METHODS OF STUDY ON VEGETATION
WATER QUALITY CHANGES EFFECTS ON WETLAND METHODS OF STUDY 

### UPLAND

LAND USE IMPACTS



### ESTUARY

OUTPUT FROM APALACHICOLA RIVER-EFFECTS ON ESTUARINE PRODUCTIVITY

APALACHICOLA BAY Figure 1.4. Information needs by basin unit.

D92.0 APALACHICOLA RIVER QUALITY ASSESSMENT

2.1 Activities In February 1979, theU.S. Geological Surveybegan data collection for a 2-year intensive investigation ofthe Apalachicola River and its associated wetland, a vast flood plain covered with a dense bottom-land hardwood forest. Data collection for the investigation, called the Apalachicola River Quality Assessment, continued until December 1980. Dataanalysis and interpretationfollowed, and a series ofreports, each addressing a major objective ofthe study, was published. These reports were "Production and Decomposition of Forest Litter Fall on the Apalachicola River Flood Plain, Florida" (Elder and Cairns, 1982); "Wetland Hydrology andTree Distribution ofthe Apalachicola River Flood Plain, Florida"(Leitman and others, 1983); and "Nutrient and Detritus Transport in the Apalachicola River, Florida" (Mattraw and Elder, 1984).In addition to this report series, other publications focused on specific questionsaddressedintheinvestigation. These publications, listed in order of publication date,
were "Nutrient Yield of the Apalachicola River Flood Plain, Florida: River-Quality Assessment Plan"(Mattraw and Elder, 1980); "Riverine Transport of Nutrients and Detritus to the Apalachicola Bay Estuary, Florida"(Elder and Mattraw, 1982); "Riverine Transport of Nutrients and Detritus to Apalachicola Bay" (Elder, 1983); "Accumulation of Trace Elements, Pesticides, and Polychlorinated Biphenyls in Sediments and the Clam Corbicula manilensis ofthe Apalachicola River, Florida" (Elder and Mattraw, 1984); "Forest Map and Hydrologic Conditions, Apalachicola River Flood Plain, Florida" (Leitman, 1984); and "Nitrogen and Phosphorus Speciation and Flux in a Large Florida River-Wetland System" (Elder, 1985). A workshop in Tallahassee, Fla., in April 1982, provided an additionalmode ofinformationtransferfrom the Apalachicola River QualityAssessment. Theworkshop
was cosponsored by the Northwest Florida Water Management District and the U.S. Geological Survey. It included participation by personnel from various local, State, and Federalagencies, localuniversities and colleges, and private organizations. Information presented at the workshop was collated in a workbook entitled "Apalachicola River Flood-Plain Processes in Nutrient Transport" and distributed to all participants.
This final Apalachicola River Quality Assessment report summarizes theprincipalresults and conclusions of all of the elements of the investigation. The primary purpose ofthis report is to provide information that will aid those who areinvolved, eitherdirectly orindirectly, in implementing best management practices for the Apalachicola River basin. The rationale for selecting certain management practices may have transfer value to other similar systems in the Southeastern United States. Inview of the many values and uses of the Apalachicola River system, some of which are illustrated in figure 2.1, it is clear that management decisions are not easy ones. The
more they can be based on scientific knowledge, the more likely suchdecisionswillbebeneficialtothestabilityofthe system and to users ofthis valuable natural resource.

D10Figure 2.1. Examples of the different uses and values of the Apalachicola River system: (A) Oystering in Apalachicola Bay, (B) barging on the river, (O beekeeping on the river bank, and (D) flood-plain vegetation: swamp lily and (f) flood plain forest: Ogeechee tupelos.

D112.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.2 Objectives
The Apalachicola River Quality Assessment was onepart ofanationalriver-qualityassessmentprogramof the U.S. Geological Survey. The broad objectives ofthe national program were (1) to define the character, interrelations, and apparent causes of existing river-quality problems and (2) to devise anddemonstratethe analytical approaches andthetools and methodsthatwouldprovide
a sound technical basis for planners and managers to use in assessing river-quality problems and evaluating management alternatives (Greeson, 1978). The specific goals ofthe Apalachicola RiverQuality Assessment conformed to thesebroad program objectives with the modification that the investigation was process oriented rather than problem oriented. The Apalachicola River system supports largely undisturbed forested wetlands onthefloodplain andhighlyproductive estuaries at its mouth, the Apalachicola Bay. The overall purpose of this assessment was to investigate river-wetland relations and controllingfactorsthat influencetheyield ofnutrients and detritus to the bay. Specific objectives ofthe study are listed below.
1. To describe howtree distribution onthe floodplainis related to the pattern ofinundation (duration, level, and frequency). 2. To assess the importance of leaf production and decomposition on the flood plain to detritus and nutrient yields.
3. To identify major sources of nutrients to the river system and to quantify transport of nutrients and organic detritus in various parts ofthe system. 4. To determine the extent to which potentially toxic trace elements and organic substances accumulate in benthic organisms and sediments.

Figure 2.2 shows diagrammatically the interaction ofbasin characteristics and processes to produce nutrient and detritus outflow. The relations addressed by the first three objectives of the study are highlighted in red (objective 1), green (objective 2), and blue (objective 3). The fourth objective was quite distinct from the others in that it was not involved with processes that affect the export ofnutrients and detritus tothe bay. Unlike the rest of the study, this part was oriented more toward monitoring a particular problem or potential problem, and there was little focus on methods development.

D12OTHER NUTRIENT SOURCES

C Stage J

» (inundation)-

1 V /


# c Soils

FLOOD-PLAIN DYNAMICS t f 

### /

1
// 

# A

# Y

//^Decc
4

M 

# ( Tree species distribution Nutrient-detritus transport

NUTRIENT AND DETRITUS SOURCES NUTRIENT BUDGET Figure 2.2. The interaction of basin characteristics and processes to produce nutrient and detritus outflow.

D132.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.3 Flood-Plain Forest

The forested flood plain ofthe Apalachicola River, with an area of 175 mi2, isthelargestinFlorida. Ofthe 211 different species oftreesgrowinginthenorthFloridaarea, about 60 are found onthe ApalachicolaRiverfloodplain. It is dominated by the general forest type, oak-gumcypress, defined bytheU.S. Forest Service asbottom-land forest in which 50 percent or more ofthe stand is tupelo, blackgum, sweetgum, oak, and cypress, singly or in combination (U.S. Forest Service, 1969, p. 9). The oakgum-cypress type is very common on the flood plains of southeastern alluvial rivers; however, this general forest type has been divided into numerous specific types that various authors define differently from river to river. Leitman and others (1983) identified 47 tree species in the Apalachicola flood plain. Baldcypress and two species of tupelo (water and Ogeechee) dominate the swamp areas ofthe flood plain. Togetherthey accountfor
over halfofthe relative basal area (percentage ofthe total cross-sectional stem area) of the entire flood-plain tree community. Other common species are Carolina ash, swamp tupelo, sweetgum, overcup oak, planertree, green ash, water hickory, sugarberry, diamond-leafoak, American elm, and American hornbeam. The nomenclature follows Kurz and Godfrey (1962). Leitman and others (1983) also defined five major forest types in the Apalachicola River flood plain and listed the composition of each in terms of relative basal
area and density for each species. The types were defined
on the basis of sampling results from eight transverse transectscrossingthefloodplainatapproximatelyequally spacedintervalsfromJimWoodruffDamtoApalachicola Bay. The five types defined were type A (sweetgumsugarberry-water oak); type B (water hickory-green ashovercup oak-diamond-leaf oak); type C (water tupeloOgeechee tupelo-baldcypress); type D (water tupeloswamp tupelo); and type E (water tupelo-baldcypress). Biomass increased downstream and was greatest with forest types C, D, and E. Forest types A and B were lumped together (type AB) for mapping (Leitman, 1984) because their color infrared signatureswereindistinguishable. Similarly,types D and E were lumped into a singletype (DE). Inaddition, there were three minor forest types that were not sampled by Leitman and others (1983). These were pine (loblolly pine with scattered sweetgum, water oak, American hornbeam, and possumhaw); A/pine (sweetgum, sugarberry, water oak, and loblolly pine); and P (pioneer, dominated by black willow, in sandy soil along river margins). Type M is salt-marsh vegetation found only
near the estuary, and type U is unidentified due to alteration by clearing, cultivation, or construction. Water in the flood plain influences the distribution of trees because the availability of oxygen is severely restrictedin saturated and inundated soils. Water-logging tolerance varies with species, environmental conditions, and season (Whitlow and Harris, 1979). Flooding during the dormant season has little or no effect because the oxygenrequirements ofplantsareverylow, but as littleas 3 days of flooding during the growing season can affect seedlings of certain intolerant species such as yellow poplar (Southeastern Forest Experiment Station, 1958). Seedlings of many species can survive soil saturation without standing waterformuchlongerperiodsthanthey
can survive complete inundation (Hosner, 1960; Hosner and Boyce, 1962). Flooding can also influence the many otherfactors that affect tree distribution, such as seed dispersal and germination, seed consumption by animals, type of soil, availabilityofnutrients,competition,temperature, salinity, fire, and man's activities. Ingeneral, types C, D, and E are commonly found in permanently saturated soils, whereas types A and B are not (Leitman and others, 1983). Figure 2.3 shows how the relative proportion of
covertypes changes fromupperto lowerriver. Type ABis the majortype inthe upperandmiddle riverand decreases in importance downstream of Wewahitchka, nearly disappearinginthetidal reaches oftheriverfrom Sumatra to the mouth. The tupelo-dominated types, Cand DE, are significantbut minorintheupperandmiddleriverand are dominant in the lower river. Marshes dominate the flood plain inthelower 10miles oftheriverandare insignificant in the other 97 miles.

D14REACHES OF APALACHICOLA RIVER

100

Upper Middle Lower river * river river

EXPLANATION

^^ WATER HICKORY-SWEETGUM-OVERCUP ^^H OAK-GREEN ASH-SUGARBERRY

DE TUPELO-CYPRESS WITH

MIXED HARDWOODS

TUPELO-CYPRESS

PIONEER

MARSH

SWEETGUM-SUGARBERRY-WATER OAKLOBLOLLY PINE

UNIDENTIFIED B

5 MILI J I 5 KILOMETERS Figure2.3. Relative proportion of covertype changes from upperto lower river (from Leitman, 1984): (A)Area, in percent, of each mapping category, excluding open water, for five reaches of the Apalachicola River. (B) Upper river flood-plain segment showing distribution offorest covertypes. (C) Lower river flood-plain segment showing distribution offorest cover types.

D152.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.4 Leaf-Litter Production and Decomposition
Litter-fallmeasurementswere madefrom September 1979 through August 1980inthe Apalachicola Riverflood plain of northwest Florida. Litter fall was collected monthly from nets located in 16 study plots (fig. 2.4/1). The plots represented the five forest types in the swamp and levee areas ofthe Apalachicola Riverflood plain. The measurements showed that 43 species oftrees, vines, and other plants contributed to the total litter fall. Average annual litter fall was determined to be 7,100 Ib/acre and resulted in an annual deposition of4 X 105tons oforganic material in the 175-mi2 flood plain. Figure 2AB shows that about half of the litter production was distributed among the major tree types. Slightly less than halfwas composed ofnonleafmaterial. Tupeloand baldcypress areboth swamp species; hencethe swamp community accounts for 31 percent of the litter production as leafmaterial. Decomposition rates of leaves from five common flood-plain tree species were measured using a standard leaf-bagtechnique. Leafdecompositionwas highly species dependent. Tupelo (Nyssa spp.) and sweetgum (Liquidambar styraciflud) leaves decomposed completely in 6 months whenfloodedbyriverwater. Leaves ofbaldcypress (Taxodium distichum) and diamond-leaf oak (Quercus laurifolid) were much more resistant. Water hickory (Carya aquaticd) leaves showed intermediate decomposition rates. Decomposition of all species was greatly reduced in dry environments. Carbon and biomass loss rates from the leaves were nearly linear over a 6-month period, but nitrogen and phosphorus leaching was nearly complete within 1 month. Why is litter fall and decomposition important? It has been estimated (Cummins and Spengler, 1978) thatas much as 60 percent ofthe particulate organic matter in a stream may originate as leaflitter. This materialis rapidly colonizedby streammicro-organisms fungiand bacteria. These organisms accelerate the decomposition of the material and release nutrients which are important to the primary productivity ofthe system. The micro-organismleafassociation also serves as afood supplyforconsumers inthe riverandestuary. Micro-organisms and leafparticles

areingested together like "peanutbutter oncrackers."The "peanut butter" provides most of the nutrition, but the "crackers" are necessary as a substrate (Cummins and Spengler, 1978, p. 4). Ifthe annual litter production of4 X 105 tons were totally flushed into the channels, it could produce a mean concentration increase of7 mg/L oforganic carbon. This is not likely to be the case, of course, because of natural recycling within the flood-plain communities. It is nevertheless a major potential source ofnutrients and detritus to the river and estuary. The transport oforganic litter from the flood plain to the river depends on flooding. Extensive floods with high flow velocities in the interior ofthe flood plain can mobilize large amounts of material. The timing of the flood is important. The major annual flood normally

occurs several months afterthe peak litter-fallperiod. Ifit

occurs earlier, there couldbe more litterdeposited directly

on the water surface, but there is less opportunity for decomposition prior to transport. In comparison with other systems worldwide, the Apalachicola forest annual litter-fall production rate of 7,100 Ib/acre is high. It is greater than those of many tropical systems and almost all warm temperate systems. Because most other systems thathavebeen studied are not wetland systems, this comparison adds credence to the suggestion (Odum, 1979) that wetlands are more productive than uplands in comparable latitudes. Leaf decompositionrates in the Apalachicolaenvironmentappear tobe similarto those found in comparable studies ofother systems.

D16Nonleaf material
42%

Major levee species 19% Other

major swamp species 11%

7100 (pounds/acre)/year B

Figure 2.4. Litter fall in the Apalachicola River flood plain: (A) Leaf-litter collection net and (8) annual litter fall in the Apalachicola River flood plain.

D172.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.5 Flooding Hydrology
Ifany single characteristic ofthe Apalachicola River system can be said to be the most critical to its character and function, it is the flooding cycle. In any riverine system, floods are important reset mechanisms, scouring old deposits and growth and redistributing stored organic matter and dried soils. In the Apalachicola, where the forested flood plain occupies 15 percent oftheentirebasin area, itisespeciallyimportant. Theflood-plaincommunity structure is controlled largelyby the annualfloodingcycle (Leitman and others, 1983). This community does not exist in its present form in nonflooded areas, and it would not exist ifthe flooding cycle were to change significantly and permanently. Discharge inthe Apalachicola Rivergenerallyranges
over about an order ofmagnitudeeach year from 10,000 to 100,000 ft3/ s. High flow periods nearly always occur in late winter or early spring. Hydrographs for 1979-80 at two sites (fig. 2.5/1) illustrate the flow variability. They also show the discharge above which flooding occurs at both sites. The flooding threshold at the upper site (Chattahoochee) is higher because of more relief and greaterchannelization. Atthe downstream site (Sumatra), flooding is evident for several months ofthe year. A series of water-level and current-meter discharge measurements at medium and highflood stagesweremade

across two transects during the spring of 1980. One transect was near Sweetwater Creek, 6 miles upstream from Bristol, and the other was at Brickyard Landing, 6 miles south of Sumatra. The distribution of water level, flow, andvelocity measured attwo stagesforeachtransect
are shown in figures 2.55 and 2.5C. An analysis ofthe flow patterns at the Sweetwater intensive transect on March 11 and 18, 1980, shows that instantaneous water levels vary considerably across the flood plain at moderate flood stage (fig. 2.55). The flood plain carried 10 percent ofthe flow on March 11 and 26.6 percent of the flow at a higher stage on March 18. Velocities increased in the main channel and theeastflood plain but decreased in the west flood plain with higher stage. Flowpatterns atthe Brickyard transect on March 14 and 19, 1980, show that instantaneous water levels are fairly uniform across the flow corridor at both medium and high flood stages (fig. 2.5C). The flood plain at this site has two major channels, Brickyard Cutoff and Brothers River, which convey a high percentage of flow during flooding, especially at lower flood levels. Those two flood-plain channels carried 27.7 and 24.1 percent of the total flow on March 14 and 19, respectively. The remainder ofthe flood plain, excluding Brickyard Cutoff and Brothers River, carried 35.0 and 44.3 percent ofthe total flow during medium and high flood stages, respectively. Velocities were higher in most sections of the flood plain at the higher stage.

D182000 FEET

600 METERS

VERTICAL SCALE GREATLY EXAGGERATED (0 U. Chattahoochee

I I I 200.000 O 100.000 Sj § 60.000
0 g 20.000

- m 10,000 g"5 200

.000 Sumatra

* K- 100.000 O u 60.000

20.000 10.000 I I I I \ \ I I I I I I

I I I

^ A» A» 040 

### « £ o /f /
1979 T
1980

EAST WEST EAST WEST

FEET

FEET

20 i 31.6%

SEA LEVEL FEET

^-APALACHICOLA RIVER 14% of Q V=0.56 feet per second BROTHERS - RIVER 9% of Q V=0.36 feet per second 23.3% of Q V=2.27 feet per second SEA

LEVEL

EXPLANATION Q MEAN DAILY DISCHARGE. V MEAN DAILY VELOCITY. WATER LEVEL ON MARCH 16. 1960. TOTAL Q 87.900 CUBIC FEET/SECOND. WATER LEVEL ON MARCH 11. 1980. TOTAL Q 67.600 CUBIC FEET/SECOND. EXPLANATION MEAN DAILY DISCHARGE. MEAN DAILY VELOCITY. WATER LEVEL ON MARCH 19. 1960. TOTAL Q 103.000 CUBIC FEET/SECOND. WATER LEVEL ON MARCH 14. 1980. TOTAL Q 70.000 CUBIC FEET/SECOND. B C Figure 2.5. Flooding on the Apalachicola River: (A) Discharge for Chattahoochee and Sumatra gages, Apalachicola River, February 1979toJune 1980; dashed lines show flooding thresholds. (B) flow and velocity distribution at medium and high flood stages at the Sweetwater transect, and (C) flow and velocity distribution at medium and high flood stages at the Brickyard transect.

D192.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.6 Water Budget
A water budget for the Apalachicola basin during the 1-year period from June 3, 1979, to June 2, 1980, was described by Mattraw and Elder (1984). Continuous discharge records from gages at each of seven sampling sites on the river and its tributaries, plus rainfall and ground-water-levelmeasurements and evapotranspiration estimates, provided the basis for the calculations. Anequationwhichexpressesthewaterbudgetofthe Apalachicola River system is

WO- WI+ P, Pdp +GW+CR-Ret ±r where allterms representvolumes ofwaterand aredefined
as follows:
WO = outflow at the downstream limit; WI = inflow at the upstream limit; Pro - precipitation runoff; Pd - direct precipitation in river and flood plain; G W - ground-water discharge; CR = input from the mouth ofChipola River; Ret = evapotranspiration ofriver-derived water; and

r - residual the amount required to balance the equation (equivalent to an error term and not associated with any known component of the budget). The water budget described by this equation is depicted diagrammatically in figure 2.6. The numbers shown with each component give overallestimates forthe 1979-80 study year; their derivations and seasonal breakdowns are detailed by an earlier report (Mattraw and Elder, 1984). Several ofthe major components, shown by large circles, can be subdivided into more specific categories. Onlythecomponents or subcomponents which provide direct input to or outflow from the river-wetland system are included in the equation. Inputs exceeded losses, resulting in a 25-percent gain in waterflow from Chattahoochee to Sumatra. More than half of the input was contributed by the Chipola River. The water budget of the Apalachicola basin is heavily streamflowdominated; watervolumes involved in precipitation, ground-water flow, surface-water runoff, and evapotranspiration are relatively minor compared to channelized inputs ( WIand CR).

D20

### APALACHICOLA RIVER

-FLOOD-PLAIN BOUNDARY

BASIN BOUNDARY

EXPLANATION
Wl = Inflow at upstream limit. WO = Outflow at downstream limit. CR = Inflow from Chipola River. GW = Ground water. GWO = Ground-water flow

out of basin. ET = Evapotranspiration (total). P = Precipitation. Pgw ~ Precipitation which recharges ground water. Pro = Precipitation which enters river as surface-water runoff. P<jp = Direct precipitation to river and tributaries. <et = Evapotranspiration from riverine and flood-plain storage. et = Precipitation which exits as evapotranspiration. Values in cubic miles. Figure 2.6. Apalachicola water budget.

D212.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.7 Total and Dissolved Carbon Transport
As in any river system, nutrients are transported by theflowingwatersintotheestuaryinenormous quantities. Thousands of tons of organic carbon, nitrogen, and phosphorus aretransported annuallyintotheestuary and supply a critical base for the highly productive estuarine food web. There aretwoimportantquestionswithrespect to nutrient transport in the Apalachicola system. How much does flooding and the flood-plain community contributeto orremove fromthe riverine nutrientflow? If there were no flooding, would the nutrient yield to the estuary be different? Organic carbon was one of three major nutrients whosetransportwas studiedintensivelyinthe Apalachicola River Quality Assessment. Samples for analysis of both dissolved organic carbon (DOC) and particulate organic carbon (POC) were collected in 1979-80 at the seven sites shownin figure 2.7A. The firstfour sites were onthemain river channel; the fifth site was a transect across the lower flood plain, including Brickyard Cutoff and Brothers River; the sixth site was in Little Sweetwater Creek, a smallground-water-fedtributary; andthe seventh sitewas in the Chipola River. Samples were collected monthly duringlow-flow periodsandmuchmorefrequentlyduring the flood of March and April 1980. Organiccarbontransportestimatesforfoursampling dates representing different flow and growth conditions
are shown in figure 2.7B. The transport rate, in tons per hour, was calculated as the product ofconcentration and dischargeforthedayindicated. Thedataweretakenat site 4, the most downstream main-stem site. Some similarities and some differences in the data for the four dates are immediately obvious. The dissolved fraction predominated over the particulate fraction at all times. Such predominance ofDOC over POC is common to many river systems (Naiman and Sibert, 1978). The amount of POC was almost constant on the first three dates, although the total carbon transport dropped substantially in November. Both dissolved and particulate fractions increased in March, during the spring flood. Factors which may explain the observations shown in figure 2.1B include flow variability coupled with biological(photosynthetic)activitywhichproduces organic material. In June 1979, riverflow was quite low, but photosynthetic activity was high; the relatively high carbon transport was primarily a reflection ofhigh DOC concentrations due to the high autotrophic production rate. In November, this production rate was much lower, causing the decrease in DOC. However, litter fall was high, and the flow rate had increased slightly since June, maintainingPOCatnearlythesamelevel. Inlate February, productivity wasjust beginning to increase, and the flow rate was also higher; a significant increase in DOC flow had occurred. Finally, in March, the very high flow ofthe spring flood produced a major increase in both POC and DOC transport. Flooding in March caused an increase in organic carbon transport, but the data indicate that the total increase was notnearlyas high asmightbe expected from the increase in flow. DOC concentrations were lower on March 19than on February28in spite oftheflowincrease. POC outflow, however, did increase substantially in March and became a much larger fraction of the total load over 10 percent as opposed to about 5 percent in February. This effect of flooding on POC is examined further in the next section.

D2285°00' 84°45' 84°30'

30°45'

-

30°30'

-

30°15'

-

30°00'

-

29°45'

-

29°30'

-

3



## gffi

B 17,700

(6/18/79)

23,600 (11/20/79)

30,000 (2/28/80)

109,000 (3/19/80) ORGANIC CARBON I I Dissolved | J Participate

20 40 60 TRANSPORT, IN TONS PER HOUR 80 Figure 2.7. (A) The ApalachicolaChipola River subbasin, showing sampling sites, and (6) organiccarbon transport near Sumatra on four specific dates in 1979 and 1980. D232.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.8 Paniculate Carbon Transport
The particulate organic carbon (POC) fractions shown in figure 2.7B are expanded in figure 2.8A. The total POC load is divided into four fractions according to particle size and mode oftransport. The suspended load, sampled by pumping water through nested sieves and a filter, was separated into (1) the very fine (VF) fraction, with a particle-size range of0.0000018-0.0024 in; (2) the fine (F) fraction, with a particle-size range of0.0024-0.04 in; and (3) the coarse (C) fraction, with a particle size greater than 0.04 in. The bottom-load (B) samples were collected with a net of 0.04-in-mesh size held on the bottom at midchannel. As in nearly all streams and rivers (Naiman and Sedell, 1979), the concentrations of organic carbon decrease as particle size increases. On all of the days represented infigure 2.8,4,the VFPOCfractionamounted to considerably more than the sum ofthe otherfractions. Thisfeatureprobablyenhancesthevalueoftheparticulate material as a nutrient source because of the greater surface:volume ratio in finer particles.
The floodingeffect on POC, as shownbythe data of March 19, was very different than its effect on DOC (fig. 2.1B). Total POCtransportincreasedby almostfivetimes from February 28 to March 19, more than the increase in waterflow. Otherdatacollectedinthe study suggestedthat this concentration increase in POC during flooding was due to flushing of particles out of the flood plain. Although the flood plain seems to produce very little net increase in dissolved carbon transport, there can be little doubt that it does serve as a source for POC. The POC transport capacity of the Apalachicola floods is further illustrated by figure 2.85. This graph compares the cumulative transport of all fractions of carbon at Sumatrawiththetransportcurvesthatwouldbe observed ifthe rates were constant during the entire year (using January 4, 1980, as the date for determining constant rate). Observed datainthe springmonths of 1980
were offsetconsiderablyfromtheconstantratecurves. On close inspection, the most critical "flushing periods" appear to be quite distinguishable for the different fractions. Forexample, theprincipal CPOC surge occurred in April, while the FPOC was released somewhat earlier and had a slower transport rate in April. Bottom-load material (BPOC) showed one of its greatest surges in November, coinciding with the period of heaviest litter fall, and thenincreased againin winterand springperiods
as greater areas became inundated.

D246/18/79

11/20/79

2/28/80

3/19/80 PARTICULATE ORGANIC CARBON
I I Very fine
I | Fine [££] Coarse
IH Bottom load

0 234567

TRANSPORT, IN TONS PER HOUR

CO z1oo.ooo F



### cc o O. CO z < 10.000 

### cc

o m cc o 

### o 1000 z CD 

### cc o lil Sc
100 

### o

### Icc < Q. 

### lil

10 JJASONDJFMAMJ

1979 1980 

### o

Figure 2.8. Paniculate organic carbon transport near Sumatra: (A) Paniculate organic carbon transport near Sumatra on four specific dates in 1979 and 1980, and (B) paniculate organic carbon transport for June 1979 to June 1980 (logarithmic vertical scale).

D252.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.9 Nitrogen Transport
ThemassofnitrogentransportedbytheApalachicola River to its estuary is approximately 10 percent of the
mass oforganic carbon. Thetotalyield duringa 12-month period in 1979-80 was over 23,000 tons. Graphical representations of nitrogen transport on the same four samplingdates that were previously shownforcarbon are given in figure 2.9A. Nitrogen in aquatic systems is measurable in four principal fractions: (1) oxidized inorganic nitrogen, consisting ofdissolved nitrate (NO3.) and nitrite (NO2.) ions; (2) reduced inorganic nitrogen, consisting of dissolved ammonia (NH3); (3) dissolved organic nitrogen (DON) associated with various soluble organic compounds; and (4) particulate organic nitrogen (PON) associated with suspended organic material (detritus) such as leafparticles and micro-organisms. Nitrate and DON tend to predominate in the Apalachicolawaters, although PONcan occasionallybea major fraction ofthe total. The November sampling date represents a condition in which the particulate species formalargefraction;the totalnitrogenload was relatively low, but litter deposition was occurring at a very fast rate at the time, contributing high amounts ofPON. The March flood coincided with increases in nitrate and DON concentrations, causing an increase in the total nitrogentransportratewhichexceededtherelativeincrease inwaterflow. Theseincreasesinconcentrationareprobably attributable to two primary causes. The nitrate increase
was quite gradual during the winter; this is normal in aquatic systems during nongrowing seasons when biological uptake ofnitrate is diminished. The examination ofall nitrate data from the study (Elder, 1985) indicated that nitrate concentrations followed a definite seasonal pattern low in late summerand increasing to maximum levels inlate winter. Thelargeincreasein DONduringthe flood (March 19) probably was attributable to flushing of soluble organics fromflooded areasthroughouttheupper basins (Chattahoochee and Flint) as well as from the Apalachicola flood plain. One oftheimportantcharacteristics oftheinorganic nitrogen data is illustrated in figure 2.95. The data points representmeans ofall samples collected ata siteduringthe study, and the plots show variation over the course ofthe river. Ammonia concentrationsdecreased considerablyin

adownstreamdirection, whilenitrateconcentrationswere nearly the same at sites 1 and 4. (Sites 2 and 3 had higher means, but because of the time variability shown by standard error bars, the differences are probably not significant.) As a result, the ratio of ammonia: total inorganic nitrogen decreased in a downstream direction from 0.14 at site 1 to 0.08 at site 4. Mass balance calculations (Elder, 1985) showed that ammonia loss duringtransport was quite consistent,theresultbeingthat the 12-month ammonia export was over 50 percent less than the sum ofits imports. The system was clearly a net
consumer ofammonia, although it was a net exporter of organicnitrogenand somecarbonandphosphorus species.

D266/18/79



### 11/20/79

2/28/80

3/19/80 \ i i i i i i r

NITRATE PLUS NITRITE
AMMONIA
DISSOLVED ORGANIC NITROGEN
PARTICULATE ORGANIC NITROGEN

2468 TRANSPORT, IN TONS PER HOUR 10

DC LUIDC LU 0_ CO

DC O _J



### z O

DCIZ LU 

### o z O o 0.4

0.3

0.2

0.1 

### Nitrate

10 20 30 40 50 60 70 80 100 90 I SITE 1 SITE 2 SITE 3 SITE 4 B MILES DOWNSTREAM FROM LAKE SEMINOLE Figure 2.9. (A) Nitrogen transport on four specific dates in 1979 and 1980 and (B) changes in inorganic nitrogen concentrations with stream location.

D272.0 APALACHICOLA RIVER QUALITY ASSESSMENT Continued

2.70 Phosphorus Transport Primary productivity in Apalachicola Bay is phosphorus limited during summer and autumn each year (Livingston and Loucks, 1979). The ratio of soluble reactivephosphorus (SRP)todissolved inorganicnitrogen in the Apalachicola River generally ranges from about 1:20 near the headwaters to about 1:40 near the mouth. This suggests an imbalance which can lead to the phosphorus limitation in Apalachicola Bay. It also indicates net consumption of SRP in the flood plain. Justas ammonianitrogenbecame a smallerfraction of dissolved inorganic nitrogen from upstream sites to downstream sites, SRP also became a smaller fraction of total phosphorus (fig. 2.10). At the headwaters, dissolved phosphorus was composed entirely of SRP. Farther downstream, SRP decreased while the total dissolved phosphorus concentration increased slightly, reflecting a downstreamincrease indissolved organicphosphorus. At site 4, SRP comprised only about 50 percent of the dissolved phosphorus concentration. There was a small overall downstream increase in total phosphorus concentration, maintained by slightly increasing concentrations ofboth particulate and dissolved phosphorus. On an annual time scale, the phosphorus mass balance for the entire river system shows a mixed result similar to that for nitrogen. There was net import ofSRP and net export of other dissolved phosphorus and particulate phosphorus.
Unlike nitrogen, phosphorus is relatively insoluble in neutral or alkaline pH conditions. Particulate forms tend to predominate, as is indicated by the difference between total and dissolved phosphorus shown in figure 2.10. Muchparticulatephosphorusis associated withiron, calcium, and other metals and can sorb to sediments and detritus suspended in the river water. Hence, the pulses of detritus flow during floods, which became evident by analysis of POC, tend to be accompanied by pulses of particulate phosphorus transport. As shown in table 2.10, more thantwo-thirds ofthephosphorustransportin 1979-80 was in particulate form.

Table 2.10-1. Amounts and percentages of phosphorus load at Sumatra (site 4) during 12-month period of 6/3/79-6/2/80.

Phosphorus fraction Load (tons) Percent of total
Particulate Soluble nonreactive Soluble reactive 1,230 310 250 69 17 14

Total 1,790

D28O.O7 Z 

## o _J _J 0.06

QC 

# a 0.05

CO 1-

< 0.04 Q. Z

- 0.03 O H

< 0.02 1- Z III O 0.01 O O



### c I I I

- 

## _j_J°i2i-;

-

-



### T Dissolved

I I I ) | 10 20 30 I I I I I



### us T -I

-

_Phosph2IiiSJ J

-


# ~~*^ii^ *Ph555h7?

U8
~ i i i i i

40 50 60 |?0 80 90 100 

### SITE 1 SITE 2 SITE 3 SITE 4

MILES DOWNSTREAM FROM LAKE SEMINOLE Figure 2.10. Changes of phosphorus concentrations with stream location. Data represent means from 20-41 samples with standard errors as shown by error bars.

D293.0 OVERVIEW AND IMPLICATIONS

3.1 Flood-Plain Role in Nutrient Transport Having examined some ofthe characteristics ofthe
occurrence and transport of various species of organic carbon, nitrogen, and phosphorus, it becomes quite evident that the flood plain does have an influence on nutrient yield. However, the influence is not as simple as might be implied byviewing wetlands as either sources or sinks for nutrients. The Apalachicola wetland fluctuates between being an importer and being an exporter, depending on numerousvariables. Aswas suggestedbyde la Cruz (1979), itismore appropriateto depictthe wetland
as a transformer than either as a source or as a sink. The transformer role ofthe flood plain is diagrammatically illustrated in figure 3.1. An amount (X) of a given mix of nutrients (A) is transported into the flood plain. After some processing within the flood plain (incorporation of processes including biological uptake, complexation, oxidation, reduction, sorption, and precipitation), a different mix (5) is outputin an amount( Y). Over an annual cycle, the quantities ofinput and output
are not greatly different, hence Xis approximately equal to Y. In qualitative terms, however, the output may be very different from the input, henceA is unequal to B. By affecting nutrient chemistry more than total nutrient loads, the river-wetland system plays a critical role in supporting estuarine productivity. The forms ofnutrients exported to estuaries are probably of equal or greater importance than are the total amounts (Nixon, 1980).

In the Apalachicola River-wetland system, one effect ofthe wetland is to transform the nutrient load to
one which favors secondary productivity and a detritusbased food web in the estuary. Primary productivity in estuarine systems is likely to be limited by bioavailable species of either nitrogen (Ryther and Dunstan, 1971) or phosphorus (Taft and Taylor, 1976). Aswas noted earlier, phosphorus would seemto be the more criticalnutrientin the Apalachicola River-wetland system because of the shortage of soluble reactive phosphorus relative to inorganic nitrogen. No matter which nutrient is more critical, the inorganic forms of both nitrogen and phosphorus are only sparingly supplied to the estuary by riverineinflow. However, therivertransports an abundant supply of detritus from the flood plain (Elder and Mattraw, 1982). The detritus provides an excellent substrate for bacterial growth (Fenchel, 1970) and a base for support of a thriving population of detrital feeders (Darnell, 1961), including many of the economically valuable shellfish species.

D30

### FLOOD-PLAIN FUNCTION


# 0 X tons 

## Flood plain Y tons 

# 0

X=Y Figure 3.1. Flood-plain function.

D313.0 OVERVIEW AND IMPLICATIONS Continued

3.2 Impact of River and Wetland on Apalachicola Bay
Research conducted for several years by scientists from Florida State University (Livingston, 1983) has shown conclusively that the productivity and general vitalityoftheApalachicolaBayestuaryishighlydependent
on inflow from the river (fig. 3.2). Not only the nutrient and detritus inputs but also the salinity controls by the seasonal fluctuations of riverine input are crucial in maintaining the estuarine community, including the extremely valuable shellfish population. Ifthere were major changes in the present flooding cycle of the river or if large areas of the flood-plain community were removed, would the river still be able to maintain the estuary the way it does today? Information from the studies of this river basin, as well as others, suggests that there would be at least some appreciable changes in the estuarine community if the river were subject to such major alterations. The importance ofthe flood plain in propagating nutrient transformations has already been noted. The importance of salinity controls has been extensively described by Livingston (1983). The fluctuating inflows of the river are important in maintaining a community ofspecies that are either euryhaline (tolerant to a wide salinity range) or migratory. Without such pulsations, species with a lower tolerance to salinity variation couldimmigrate,producing aninevitable change in the community structure. In addition to the control of nutrient quality by flood-plain processes and to the effects of pulsating riverflow on estuarine salinity, there are other impacts of the river-wetland system on the estuary. One wetland function which may become ofgreater importance in the Apalachicola basin in future years is the filtration of potentiallytoxic substances. This processhasbeen shown to be of such efficiency that wetlands can be utilized for wastewater purification (Sloey and others, 1978; Tilton and Kadlec, 1979). Otherwetlandfunctions which are less directly related to the estuary are flood detention, aquifer recharge, and utilization as a fish and wildlife habitat.

D32

## DETRITUS 

# RIVER FLOW
FRESHWATER



# ( MICROBIAL VCOLONIZATION

( DETRITIVORES ) FILTER FEEDERS 

# &
(CONSUMERS)

Figure 3.2. Riverflow controls on the estuarine food web. 

## PRIMARY A PRODUCERS J



# GRAZERS)

D333.0 OVERVIEW AND IMPLICATIONS Continued

3.3 Trace Substances
The fourth objective of the Apalachicola River Quality Assessment, to determine the accumulation of potentially toxic elements and organic substances in benthic organisms and sediments, was addressed by conductinga survey oftraceelementand syntheticorganic compounds in bottom materials. Data were collected from five sites, all on the main river channel. Four ofthe sites were the same as sites 1-4 identified earlier, and the fifth site was 6 miles from the river mouth.
Substances analyzed included trace elements (predominantly heavy metals), organochlorine insecticides, organophosphorusinsecticides, chlorinated phenoxy-acid herbicides, and polychlorinatedbiphenyls. Three kinds of materials were surveyed: fine-grained sediments, wholebody tissue ofthe Asiatic clam Corbicula manilensis, and bottom-load organic detritus.
Some ofthe results ofthe survey are showninfigure 3.3. The predominant metals and organic compounds are included, although a large number of other substances
were analyzed. More details ofthe study are available in the report by Elder and Mattraw (1984). The concentrations shown in figure 3.3 do not signify hazardous levels for any ofthe substances. Concentrations in the fine-grained sediments and clams were generally at least 10 times lower than maximum limits considered safe for biota of aquatic systems (National Academy ofSciences and NationalAcademy ofEngineering, 1972; Walshand others, 1977). Further data analysis did not identify any trends, either with time or from upstream to downstream reaches ofthe river. A comparison of trace-substance data from the Apalachicola River with data from Lake Seminole (upstream) and Apalachicola Bay (downstream) showed lower concentrations in riverine clams. Sediment concentrations in all parts ofthe system were comparable. The principal use ofthe results ofthis survey is as a baseline for comparison with future water quality. At present, there are no major point discharges of these substances in the Apalachicola basin (although there are such sources in the Chattahoochee and Flint basins). If future development were to create additional sources, the impacts ofthose sources might be assessed on the basis of predevelopment conditions.

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METALS ORGANICS Figure 3.3. Concentration ranges and medians of metals and organic substances in fine-grained sediments and Corb/cu/a manilensis in the Apalachicola River, August 1979 through May 1980. Where no median is shown, it was at or below detection limit. Dieldrin in sediments was below detection limit in all samples.

D353.0 OVERVIEW AND IMPLICATIONS Continued

3.4 Influence of Dams
Atpresent, theApalachicolaRiverflowsunimpeded by dams. At the headwaters of the river, however, Jim Woodruff Lock and Dam (fig. 3.44) impounds Lake Seminole, and further upstream, 15 additional dams regulate the flow ofthe Chattahoochee and Flint Rivers. Leitman and others (1983) conducted an analysis of long-term stage and dischargerecordsforthe Apalachicola River at Chattahoochee. The records represented the period 1929-79. Althoughthe 16dams ontheApalachicola, Chattahoochee, and Flint Rivers were constructed at various times from 1834to 1975, filling ofboththe largest reservoir, Lake SidneyLanier, andthe reservoirclosest to the area ofinvestigation, Lake Seminole, was completed in 1957. The second and third largest reservoirswerefilled in 1975 and 1963, respectively. Thus, 1929-57 and 1958-79
were the periods ofrecord chosen for comparison. Figure 3.45 shows that the predam and postdam periods were very similar in terms of the distribution of flow through the annual cycle. The principal difference
was that the flow of the more recent period was higher. Examination ofrecords from otherrivers innorthFlorida for the same periods showed that the mean annual discharge in all ofthem was higherfrom 1958 to 1979than in the 20 years priorto 1958. This was attributed tohigher rainfall over the three-State area during the later period. A more subtle difference between the two periods is shown in figure 3.4C. This graph shows flow duration, or thepercentage oftimethatdischargeexceedsanyparticular level. The curve is somewhat flatterfortheperiod 1958-79 than for 1929-57, indicating that the dams may have had
an effect of dampening fluctuations or reducing the amount oftime that the flow was at low extremes. In short, the effect of dams on riverflow is to decrease expection ofextreme low flow. There has been very little effect on either the amount or the seasonal distribution ofdischarge over an annual cycle. Ecological changes are probably the most notable effects of dam construction. Most ecological changes result from the development of reservoirs in former terrestrial or wetland environments. A system which contains dams and theirassociated reservoirs is obviously very different than the system before the construction of the dams. Reservoirs, whatever their benefits, bring an entirely new set of management problems, as was previously discussed. Flood-plain area is diminished, and wildlife habitat is altered. Erosion downstream ofa dam can result from the channelized, turbulentflow ofrelativelyclearwaterbelow the dam (Taylor, 1978). This could be manifested by degradation ofthe channel and erosion ofstreambanksin
somereaches, withconcomitant aggradation ofthechannel in others. In the Apalachicola River, scouringjust below Jim WoodruffDam has left the river bottom quite rocky and relativelyfree ofsediments. Ingeneral,bankerosionis retarded by the heavy growth ofrooted vegetation on the banks. Proposals for the construction of dams on the Apalachicola River to facilitate navigation have been rejected inthepastbecauseitwas the generalconsensus of policymakers that the benefits of such dams would be outweighed by losses ofexisting resources due to alterations to the system. These kinds ofdecisions are based on the perceived value ofthe existing conditions; the greater the value ofthe status quo, the greater the deterrence to introduced changes.

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Figure 3.4. (A) Jim Woodruff Lock and Dam and Lake Seminole, (B) average monthly flows at Chattahoochee, 1929-57 and 1958-79, and (C) cumulative discharge curve at Chattahoochee, 1929-57 and 1958-79. «oog_ .512 5 W 90 95 »8 99 PERCENT OF TIME INDICATED DISCHARGE IS EQUALED OR EXCEEDED

D373.0 OVERVIEW AND IMPLICATIONS Continued

3.5 Effects of Channel Modifications
The amended River and Harbor Act of 1946 authorizes the U.S. Army Corps ofEngineerstomaintain
a channel in the Apalachicola River 100 ft wide and 9 ft deep that is navigable 95 percent of the time from the mouth ofthe Apalachicola River to Bainbridge, Ga., on the Flint River and to Columbus, Ga., on the Chattahoochee River. The main purpose ofthe Jim Woodruff Lock and Dam was to help sustainthis channel. However, the dam alone is not enough, and channel maintenance requires a considerable amountofdredging(fig. 3.5/1) and snagging each year. The average annual volume of dredging since 1956 has been 350,000 yd3/yr. In the past, dredged material was placed at 131 locations along the river (fig. 3.55), many ofwhich were undiked flood-plain disposal sites used on a one-time basis. Most ofthe 151 disposal sites currentlyinuse arebetweenthebanks ofthe river rather than on the flood plain (Harry Peterson, U.S. Army Corps ofEngineers, oral commun., 1980). In a study of 11 dredged materialdisposal sites from mile 6.5 to mile 42.5, Eichholz and others (1979) found that deposition on the flood-plain forest averaged 4 acres per disposal area. Dredged material was deposited most often in the mixed bottom-land hardwood forest of the riverbankleveeand frequentlyblocked flood-plainsloughs and creeks. In only one instance was dredged material placed in the tupelo-cypress forest behind the riverbank levee. The depth ofdeposition ranged fromlessthan 3 ftto
over 30 ft. Clewell and McAninch (1977) found that tree vigor was reduced when only 1.5-5 in offill was deposited
on Apalachicola River flood-plain trees. Most trees were killed by 2.5 ft or more offill. Dredging of the river might be expected to have
some effect on the trace-substance concentrations in bottom materials. Disturbance ofbottom sediments due to dredging is likely to cause some resuspension of fine materials, resulting in altered rates of adsorption or release of associated metals and organic substances. It is also likely to change the benthic community and physical environmentwhichis involvedinuptakeandrelease ofthe substances. Other effects of dredging and snagging have been pointed out by Livingston (1978). The disturbance ofthe natural habitatforbenthic organisms and fish is included among these. Ifspoils are disposed on banks, destruction ofsome wildlife habitat will also occur. Channelization may entail construction of levees which could have a long-term effect of decreasing the extent of the flood plain. The loss of flood-plain area would very likely have an impact on the composition of nutrient and detritus yield to the estuary, as was previously described. A significant amount of channel modification, includingconstruction oflevees and cutoffs, ditching, draining, or filling wetlands, could also change theinflux offreshwatertothe system andthereforechange the natural salinity distribution in the estuary.

D38Figure 3.5. (A) Dredging operation and (B) dredge spoil site.

D394.0 CONCLUSIONS OF THE APALACHICOLA RIVER QUALITY ASSESSMENT

The essence of the findings of the Apalachicola River Quality Assessment is diagrammatically shown in figure 4.0. The Apalachicola River Quality Assessment dealtwith interrelations amonghydrodynamics,thefloodplain community and nutrient and detritus flow in the system, and the overall yield to the estuary (fig. 4.0). Important conclusions ofthe study are as follows: Flooding plays a critical role in the combined set of processes which support the existing estuarine productivity. The extent and duration of floods have major influence on the species composition and productivity ofthe flood-plainplant community. The extent and velocity of floods are important in determining the amount of detritus which can be moved throughthe system. Leaf-litterdecomposition, whichproducesmostofthedetritus, is alsoaccelerated by flooding. The Apalachicola water budget is heavily streamflow dominated; water volumes involved in precipitation within the basin, ground-water flow, surface-water runoff, and evapotranspirationarerelativelyminorin comparison with main-stem flow. As is indicated in figure 4.0, however, rainfall inthe upperbasins ofthe Chattahoocheeand Flint Riversistheprimarycontrol
on waterflow in the Apalachicola, especially in the winter when rainfall input is not rapidly taken up by vegetation. The flood-plain community is very productive, more so than most warm temperate systems and even more thanmanytropical systems. Forest-litterfall amounts to about 7,100 Ib/acre annually. The fraction ofthis material that is transported each year to the estuary depends on flooding. In addition to the extent, duration, and velocity of the flood, timing is also important. If the flood occurs very early, more material may be deposited directly on the water surface,butthereislessopportunityfordecomposition before transport. The role of the flood plain in nutrient transport through the system should not be considered as a source or as a sink but more as a transformer. On an annual basis, the quantities of nutrients which enter the headwaters of the Apalachicola are not greatly different from the amounts that exit to the estuary. However, there is a tendency for soluble inorganic nutrients to undergo substantial net import to the flood plain, while there is a net export ofparticulate organic material. This is important in sustaining a detritivore-based estuarine community. Because of the dependence of the forest-community structure onflood characteristics,it shouldbeexpected that ifthe normal flooding cycle is significantly and permanently altered, the flood-plain forest will graduallychangein structure and character. Thismay or may not affect productivity and yield to the estuary, depending on the nature ofthe change. Because of the high litter production of the floodplain community and the mobilization of littergenerated detritusbyinundation,it shouldbeexpected that substantial reductions in flood-plain area will result in decreased detritus yield to the estuary. Dam construction and other channel modifications

cause moderate to severe changes in the aquatic and wetland environments. Analysis oflong-term hydrologicrecords, includingperiodspriorto and following construction oftheJimWoodruffDam, indicatesthat dams donot significantly alterthetotalannualflowor the monthly distribution offlow. However, dams do have an effect of dampening the low-flow extremes. Channelization practices such as dredging and snagging may have a significant effect on benthic organisms and fish by destroying habitats. Ifdredge spoils are deposited in the flood plain, they will also alter the habitat in that environment. Dredging also
causesincreased mobilization ofsubstancesassociated with bottom sediments. Toxic substances are present in Apalachicola sediments and benthic organisms, buttheirconcentrations
are well below hazardous levels. Future development of industry or agriculture in the basin should be accompanied bymonitoringoftoxic substances which could be introduced from the new sources.

D40

# RAINFALL

FLOOD-PLAIN ^EXTENT^^^ TREE INUNDATION DURATION COMMUNITIES



## DETRITUS LEAFLITTER S1TION PRODUCTION

NUTRIENT AND ESTUARINE DETRITUS ^^^^M» E5TUAKINE UtlKIIUS ^^^^^^ PROniirTIVITY 

## TRANSPORT PRODUCTIVITY

Figure 4.0. Flood-plain processes.

D415.0 SUMMARY

During 1979-81, the U.S. Geological Survey conducted a large-scale study of the Apalachicola River in northwest Florida. The Apalachicola River Quality Assessment emphasized the interrelations among hydrodynamics, the flood-plainforest, andthenutrient-detritus flow through the river system to the estuary. The Apalachicola River is a waterway for shipping; hence, there is an economic incentive for modification to facilitate movement of barge traffic. The river is also recognized as animportant supplierofdetritus, nutrients, and freshwater to the Apalachicola Bay. The importance of this input to the bay creates an incentive to keep the river basin in a natural state. Questions about the most beneficial management strategies for the Apalachicola Riverresult fromthese diversevalues andpossibleuses of the system. Some uses call for mechanical or physical alteration ofthe natural system to maximize utility ofthe system for commercial benefit. Other uses need limited interventioninthenatural system. Thebenefits arelargely controlled by physical, chemical, and biological features ofthe system, andtheycanbestbemaintainedby scientific understanding ofthose features.

The primary purpose of this report is to provide information that will aid those who are involved, either directly or indirectly, in implementing best management practices for the Apalachicola River basin. The more management decisions can be based on scientific knowledge, the more likely such decisions will be beneficial to the stability of the system and to users of this valuable natural resource. The authors hope that the information in this report will help to maximize the possibility that decisions can be made which suit the needs ofall users of the river basin.

6.0 SCENES OF THE APALACHICOLA RIVER "Apalachicola Doin' Time"

When she leaves the dam at Chattahoochee, Winding in a southern flow, Easy on her way, another night and day, She'll finally reach the GulfofMexico.
Apalachicola, let her wind; Apalachicola, flowing fine; Apalachicola, strong in mind; Apalachicola, doin' time.

Crider and Crider (1981)

D42SELECTED REFERENCES

Cairns, J.,Jr., 1978, Waterwayrecovery: Water Spectrum, v. 10,
no. 4, p. 26-32. Clewell, A. F., 1977, Geobotany of the Apalachicola River region: Conference on the Apalachicola drainage system, Gainesville, Florida, April 1976, Proceedings, p. 6-15. Clewell, A. F., and McAninch, Helen, 1977, Effects of a fill operation on tree vitality in the Apalachicola River floodplain, Florida: Conference on the Apalachicola drainage system, Gainesville, Florida, April 1976, Proceedings, p. 16-19. Crider, Dale, and Crider, Linda, 1981, Apalachicola doin1time, in Crider, Linda, ed., The water song book: Gainesville, Anhinga Roost Music Company, p. 51. Cummins, K. W., and Spengler, G. L., 1978, Streamecosystems: Water Spectrum, v. 10, no. 4, p. 1-9. Darnell, R. M., 1961, Trophic spectrum of an estuarine community based on studies ofLake Pontchartrain, Louisiana: Ecology, v. 43, no. 3, p. 553-568. de la Cruz, A. A., 1979, Production and transport ofdetritus in wetlands, in Greeson, P.E., Clark, J.R., and Clark, J.E., eds., Wetland functions and values The state of our understanding: National Symposium on Wetlands, Lake Buena Vista, Florida, 1978, Proceedings, p. 162-174. Eastman, S. E., 1980, Fuel efficiency in freight transportation: The American Waterways Operators, Inc., Arlington, Va., 17 p. Eichholz, N. F., Bailey, D. B., and McGehee, A. V., 1979, An investigation ofdredged materialdisposal sites onthe lower Apalachicola River: Tallahassee, Fla., Florida Game and Freshwater Fish Commission, Office of Environmental Services, 115 p. Elder, J. F., 1983, Riverinetransport ofnutrients and detritus to Apalachicola Bay, in Andree, Scott, ed., Apalachicola Oyster Industry Conference: Apalachicola, Fla., October 6-7, 1982, Proceedings, Report No. 57, Florida Sea Grant College, p. 28-30. 1985, Nitrogen and phosphorus speciation and flux in a large Florida river-wetland system: Water Resources Research, v. 21, no. 5, p. 724-732. Elder, J. F., and Cairns, D. J., 1982, Production and decomposition offorest litter fall on the Apalachicola River flood plain, Florida: U.S. Geological SurveyWater-Supply Paper 2196-B, 42 p. Elder, J. F., and Mattraw, H. C.,Jr., 1982, Riverinetransport of nutrients and detritus to the Apalachicola Bay estuary, Florida: Water Resources Bulletin, v. 18, no. 5, p. 849-855. 1984, Accumulation of trace elements, pesticides, and polychlorinated biphenyls in sediments and the clam Corbicula manilensis of the Apalachicola River, Florida: Archives ofEnvironmentalContaminationandToxicology,

v. 13, no. 5, p. 453-469. Fenchel, Tom, 1970, Studies on the decomposition of organic detritus derived fromtheturtle grass Thallassia testudinum: Limnology and Oceanography, v. 15, no. 1, p. 14-20. Greeson, P. E., ed., 1978, River-quality assessments: American Water Resources Association Symposium, Tucson, 1977, Proceedings, 191 p. Hosner,J. F., 1960, Relativetoleranceto complete inundation of fourteenbottomland tree species: Forest Science, v. 6, no. 3, p. 246-251. Hosner, J. F., and Boyce, S. G., 1962, Tolerance to water saturated soil of various bottomland hardwoods: Forest Science, v. 8, no. 2, p. 180-186. Kurz, Herman, and Godfrey, R. K., 1962, Trees of northern Florida: Gainesville, University ofFlorida Press, 311 p. Leitman, H. M., 1978, Correlation ofApalachicola Riverfloodplain tree communities with water levels, elevation, and soils: Florida State University Master's Thesis, 57 p. 1984, Forest map and hydrologic conditions, Apalachicola River flood plain, Florida: U.S. Geological Survey Hydrologic Investigations Atlas HA-672, 1 sheet. Leitman, H. M., Sohm, J. E., and Franklin, M. A., 1983, Wetlandhydrology andtreedistribution oftheApalachicola River flood plain, Florida: U.S. Geological Survey WaterSupply Paper 2196-A, 52 p. Livingston, R. J., 1978, The Apalachicola dilemma: Wetlands priorities, developmental stress, and managementinitiatives, in U.S. Fish and Wildlife Service, Proceedings of the National Wetland Protection Symposium, Reston, Va., June 6-8, 1977: Biological Services Program FWS/OBS78/97, p. 163-177. 1983, Resource atlas of the Apalachicola Estuary: Florida Sea Grant Report No. 55, 64 p. Livingston, R. J., and Loucks, O. L., 1979, Productivity, trophic interactions, and food-web relationships in wetlands and associated systems, in Greeson, P.E., Clark, J.R., and Clark, J.E., eds., Wetland functions and values The state of our understanding: National Symposium on Wetlands, Lake Buena Vista, Florida, 1978, Proceedings, p. 101-119. Livingston, R. J., Iverson, R. L., Estabrook, R. H., Keys, V. E., and Taylor, John, Jr., 1974, Major features of the Apalachicola Bay system Physiography, biota, and resource management: Florida Scientist, v. 37, no. 4, p. 245-271. Mattraw, H. C., Jr., and Elder, J. F., 1980, Nutrient yield ofthe Apalachicola River flood plain, Florida: River-quality assessment plan: U.S. Geological Survey Water-Resources Investigations 80-51, 21 p. 1984, Nutrient and detritustransportinthe Apalachicola River, Florida: U.S. Geological SurveyWater-Supply Paper 2196-C, 62 p. Naiman, R. J., and Sedell, J. R., 1979, Characterization of particulate organic matter transported by some Cascade Mountain streams: Journal ofthe Fisheries ResearchBoard of Canada, v. 36, no. 1, p. 17-31. Naiman, R. J., and Sibert, J. R., 1978, Transport of nutrients and carbon from the Nanaimo River to its estuary: Limnology and Oceanography, v. 23, no. 6, p. 1183-1193. National Academy of Sciences and National Academy of Engineering, 1972, Section III Freshwateraquaticlife and wildlife, water quality criteria: Ecology Research Service Environmental Protection Agency EPA-R3-73-033, Washington, D.C., p. 106-213.

D44Nixon, S. W., 1980, Between coastal marshes and coastal waters A review of twenty years of speculation and research ontherole ofsalt marshesinestuarineproductivity and water chemistry, in Hamilton, P., and MacDonald, K. B., eds., Estuarine and wetland processes: New York, Plenum Press, p. 437-525. Odum, E. P., 1979, The value of wetlands: A hierarchical approach, in Greeson, P.E., Clark, J.R., and Clark, J.E., eds., Wetlands functions and values The state of our understanding: National Symposium on Wetlands, Lake Buena Vista, Florida, 1978, Proceedings, p. 16-25. Prochaska, F. J., and Mulkey, David, 1983, The Apalachicola Bay oyster industry: Some economic considerations, in Andree, Scott, ed., Apalachicola Oyster Industry Conference: Apalachicola, Fla., October 6-7,1982, Proceedings, Report No. 57, Florida Sea Grant College, p. 18-20. Ryther, J. H., and Dunstan, W. M., 1971,Nitrogen, phosphorus, and eutrophication in the coastal marine environment: Science, v. 171, p. 1008-1013. Schnable, J. E., and Goodell, H. G., 1968, Pleistocene-Recent stratigraphy, evolution, and development of the Apalachicola Coast, Florida: Geological Society of America Special Paper No. 112, 72 p. Sloey, W. E., Spangler, F. L., and Fetter, C. W., Jr., 1978, Management offreshwater wetlands for nutrient assimilation, in Good, R. E., Whigham, D. F., and Simpson, R. L., eds., Freshwater wetlands, ecological processes and management potential: New York, Academic Press, p. 321-340. Smalley, D. H., and Novak, J. K., 1978, Natural thermal phenomena associated withreservoirs, in Chadwick, W. L., and others, eds., Environmental effects oflarge dams: New York, American Society ofCivil Engineers, p. 29-49. Southeastern Forest Experiment Station, 1958, Annual report 1957: U.S. Department of Agriculture, Forest Service, Asheville, N.C., 75 p. Taft, J. L., and Taylor, W. R., 1976, Phosphorus dynamics in
somecoastalplainestuaries, in Wiley, M. L., ed., Estuarine processes, v. 1: New York, Academic Press, p. 507-522. Taylor, K. V., 1978, Erosion downstream ofdams, in Chadwick, W. L., and others, eds., Environmental effects of large dams: New York, American Society ofCivil Engineers, p. 165-186. Tilton, D. L., and Kadlec, R. H., 1979, The utilization of a fresh-water wetland for nutrient removal from secondarily treated waste water effluent: Journal of Environmental Quality, v. 8, no. 3, p. 328-334. U.S. Army Corps of Engineers, Mobile District, 1980, 1979 Project maps: Mobile, Ala., 154 maps. U.S. Department of Commerce, 1973, Monthly normals of temperature, precipitation, and heating and cooling degree days 1941-70 Florida: Climatography oftheUnited States No. 81 (Florida), National Oceanic and Atmospheric Administration, Environmental Data Service, National Climatic Center, Asheville, N.C., 8 p. U.S. Forest Service, 1969, A forest atlas of the South: Forest Service, 27 p. Walsh, D. F., Berger, B. L., and Bean, J. R., 1977, Mercury, arsenic, lead, cadmium, and seleniumresidues infish, 1971- 73, National Pesticide Monitoring Program: Pesticide Monitoring Journal, v. 11, no. 1, p. 5-34. Wharton, C. H., Kitchens, W. M., Pendleton, E. C., and Sipe, T. W., 1982, The ecology ofbottomland hardwood swamps of the southeast A community profile: U.S. Fish and Wildlife Services FWS/OBS-81/37, Washington, D.C., 133 p. Whitlow, T. H., and Harris, R. W., 1979, Flood tolerance in plants: A state-of-the-art review: Department of Environmental Horticulture, University of California, Davis, Environmental and water quality operational studies, Technical ReportE-79-2,161 p. plus appendixes andtables.

045CONVERSION FACTORS

For those readerswho may prefer to use International System (SI) units rather than inch-pound units, the conversion factors for the terms used in this report are listed as follows:

Multiply inch-pound unit By To obtain SI unit
inch (in) foot (ft) square foot (ft2) mile (mi) square mile (mi2)

acre
acre cubic mile (mi3) ton pound (Ib)
ounce (oz)

parts per million (ppm) foot per second (ft/s) cubic foot per second (ft3/s) pound per acre per year (Ib/acre/yr) pound per acre (Ib/acre) ton per hour (ton/hr) parts per billion (ppb) cubic yard per year (yd3/yr) 0C (degree Celsius) 25,4 millimeter (mm) 0.3048 meter (m) 0.09294 square meter (m2) 1.609 kilometer (km) 2.590 square kilometer (km2) 4,047 square meter (m2) 0.4047 hectare (ha) 4.168 cubic kilometer (km3) 0.9072 metric ton 453.6 gram (g) 28.35 gram (g) 0.0000353 milligram (mg) 1.0 milligram per liter (mg/L) 0.3048 meter per second (m/s) 0.283 cubic meter per second (m3/ s) 0.1122 gram per square meter per year

(g/m 2/yr) 1.1208 kilogram per hectare

(kg/ha) 907.2 kilogram per hour (kg/hr) 1.0 microgram per kilogram (ug/kg) 0.7646 cubic meter per year

(m 3/yr) 1.81(+ 32) °F (degree Fahrenheit)

D46