# F INAL REPORT

Southwest Florida Water Managem e nt District Contract Num b er 06C00000079 Project B678 

## Water quality characteristics of the ne arshore Gulf coast waters adjacent to Citrus, Hernando and Levy Counties Project COAST 1997–2008

Prepared by Charles A. Jacoby, Thom as K. Fraz er and Darlene D. Saindon
Program in Fisheries and Aquatic Sciences School of Forest Resources and Conservation University of Florida 7922 NW 71 st

### Street Gainesville, Florida 32653

Submitted to Southwest Florida Water Managem e nt District 2379 Broad Street Brooksville, Florida 34604–6899

August 2009Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties 

### E X E CUTIVE SUMMARY 

### Further exam ination of data revealed spatial patterns in exposure to fresh water, as indicated by salinity and concentrations of total nitrogen, total phosphorus and chlorophy ll. In com b ination, these results guided pooling of data from stations within sy stem s before analy ses of trends. Florida’ s coastal waters have becom e vulnerable to problem s associated with increased organic m a tter. These increases arise from higher nutrient loads created by a larger hum an population and changes in land use. Im pacts from such eutrophication could include algal bloom s; lowered oxy gen levels; da m a ge to habitats; and loss of scallops, shrim p s, blue crabs, my riad fishes and other ecologically and econom ically im portant anim als. In recognition of this threat, broad-scale sam pling of water quality along the coast of Citrus, Hernando and Levy Counties began in 1997 (Project COAST, see Frazer et al. 1998). This report summ arizes key results from sam pling through 2008. Trends were exam ined by correlating indicators with tim e. Total nitrogen concentrations increased significantly in the Withlacoochee, Cry s tal and Hom o sassa sy stem s, especially during wet m onths. Significant increases in total phosphorus concentrations were not as widespread. As expected, chlorophy ll concentrations in these sy stem s increased in response to increased nutrients. In contrast, decreases in nutrient and chlorophy ll concentrations were prevalent in the Chassahowitzka and Weeki Wachee sy stem s. Further insights into causal relationships await collation of data on hum an activities and com p letion of diagnostic studies of key biological and biogeochem i cal processes. In sam ples taken off Citrus, Hernando and Levy Counties, chlorophy ll concentrations increased as concentrations of total nitrogen and total phosphorus increased, with a stronger relationship to total phosphorus. Thus, concentrations of total nitrogen, total phosphorus and chlorophy ll represent three valuable indicators of eutrophication. Overall, baseline sam pling has established patterns in water quality off the coasts of Citrus, Hernando and Levy Counties. Indications of increasing nutrient concentrations raise concerns about eutrophication. Effective and efficient m anagem e nt of this threat will arise from additional analy ses and data that enhance insights into spatial and tem poral changes and trends. For exam ple, an understanding of the direction, m a gnitude and variability of links am ong water quality param e ters and key forcing factors can guide the choice of targets for m anagem e nt actions designed to protect or restore coastal sy stem s. Furtherm ore, an understanding of spatial coherence can foster optim al allocation of sam pling effort in m onitoring program s. In som e cases, the necessary level of understanding will require investm e nt in collection of data that com p lem e nts the existing baseline. Ultim ately , long-term baseline data com b ined with targeted diagnostic studies will guide the design of m onitoring that continually evaluates and adapts m anagem e nt actions to ensure healthy coastal sy stem s that deliver value to Citrus, Hernando and Levy Counties. Increased rainfall during the 1998 El Niño event created short-term changes in total nitrogen, total phosphorus, chlorophy ll, and water clarity across all sy stem s. However, the sy stem s recovered from this natural disturbance within 6–8 m onths. Another set of analy ses indicated that rainfall also affected concentrations of nitrogen, phosphorus and chlorophy ll at the level of m onths. Concentrations differed am ong wet m onths and dry m onths in the Hom o sassa and Chassahowitzka sy stem s. This pattern was m o st likely related to increased rainfall during wet m onths, which resulted in an increased delivery of fresh water containing nutrients. Less obvious wet–dry tem poral patterns in the Withlacoochee, Cry s tal and Weeki Wachee sy stem s probably reflected differences in hy drological characteristics. Analy s is of total rainfall data identified groups of m onths with relatively consistent rainfall, whic h generated coherent tim e periods for use in detecting trends.

1Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### I NTRODUCTION 

### In addition to using nutrients m o re efficiently , both epiphy tic m i croalgae and phy toplankton require less light than slow-growing, benthic m acrophy tes, like seagrasses (Duarte 1995). Studies from around the world indicate that increased nutrient loading to estuarine sy stem s fosters replacem ent of seagrasses with bloom s of fast-growing m acroalgae and phy toplankton (Duarte 1995, Valiela et al. 1997). Moreover, available inform ation suggests that dam a ged seagrass beds require y ears to centuries to recover (Duarte 1995). In several springs and rivers along Florida’s Springs Coast, nutrient concentrations have increased due to agricultural practices and urban developm ent within the relevant watersheds (Jones et al. 1997, Southwest Florida Water Managem e nt District 2001). When loads to these riverine sy stem s exceed internal rates of assim ilation or transform a tion, the rivers discharge surplus nutrients, especially nitrate, into the Gulf of Mexico (Frazer et al. 1998, Frazer et al. 2001a). This anthropogenic nutrient enrichm e nt can fuel increased plant production resulting in an accum u lation of organic m a tter, or eutrophication. Florida’ s coastal sy stem s, including Apalachee Bay , Tam p a Bay and Florida Bay , have suffered substantial losses of seagrass, with declines often attributed to changes driven by increased nutrient loads (Hale et al. 2004, Handley et al. 2007). Along Florida’s Gulf coast, Hale et al. (2004) reported large-scale shifts in the depth distribution of turtle grass ( Thalassia testudinum ) and shoal grass ( Halodule wrightii ), as well as areas of seagrass loss near the m ouths of rivers. They suggested that increased nutrient loading to coastal rivers could underlie these changes. In m o st nearshore waters, detrim ental effects follow nutrient enrichm e nt and eutrophication (Duarte 1995, Valiela et al. 1997). Seagrass beds, like those found off the Springs Coast, are particularly vulnerable to such effects. Dam a ge to seagrasses raises broader concerns about the overall health and ecological integrity of Florida’ s estuarine and nearshore sy stem s (Frazer and Hale 2001, Mattson et al. 2007). For exam ple, seagrass beds provide refuge and a habitat for foraging to ecologically and econom ically im portant anim als, such as scallops, shrim p s, blue crabs, my riad fishes, m a natees and sea turtles (Killam et al. 1992). The potential negative consequences from increased nutrient delivery to estuarine and coastal waters along Florida’s Springs Coast are recognized. In response, broad-scale sam pling of water quality began in 1997 (Project COAST). The planned, long-term baseline will help water resource m a nagers i) differentiate natural variation in water quality from persistent declines that arise from hum an activities and threaten to degrade coastal sy stem s, ii) identify targets for diagnostic studies that optim ize m a nagem e nt actions, and iii) design effective and efficient long-term m onitoring to docum ent the success of m a nagem e nt and guide responses to unforeseen circum stances. Consistent with these objectives, we provide updated results that illustrate changes and trends in water quality and point to analy ses and data required to m a nage the risk of eutrophication effectively

. In this report, we focus on links to rainfall, a driver of coastal water quality and an influence to address in efforts to differentiate natural variation and anthropogenic im pacts. Seagrasses and other plants require nutrients, especially nitrogen and phosphorus, to support their growth. However, nutrient enrichm e nt often results in dam a ge to seagrasses. For exam ple, seagrasses die if phy toplankton, epiphy tic m i croalgae and/or benthic m acroalgae shade them too m u ch. These fast-growing algae generally take up nutrients m o re efficiently , especially in nutrient enriched environm ents (Duarte 1995). Although seagrasses, phy toplankton, epiphy tic m i croalgae and m acroalgae assim ilate nutrients from the water column , the various ty pes of algae can outcom p ete seagrasses for several reasons. For exam ple, phy toplankton and epiphy tes take up nutrients m o re rapidly , and they have greater contact with water and the nutrients it contains because they are located inthe water columnor on a host plant (William s and Ruckelhaus 1993).

2Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties 

### M ETHODS 

### Earlier reports detailed sam pling protocols, analy tical procedures and characteristics of the five coastal rivers and their associated estuaries, the Weeki Wachee, Chassahowitzka, Hom o sassa, Cry s tal and Withlacoochee below the Inglis Dam (Frazer et al. 1998, 2001b, 2002, 2003, 2004 and 2006; Jacoby et al. 2008). In general, m onthly sam ples were collected at 10 fixed stations array e d in each of five sy stem s along the Springs Coast since 1997 (Figure 1, Appendix 1). Water tem p eratures, salinities, dissolved oxy gen concentrations and Secchi depths were recorded at each sam pling station during each sam pling event. Light attenuation was m easured from May 1999. In addition, water sam ples were analy zed according to procedures docum ented in the program ’s Quality Assurance Plan (Com pQAP#91-01-57G) to y i eld concentrations of total nitrogen, total phosphorus, chlorophy ll, and from May 1999, m easurem e nts of color. The Southwest Florida Water Managem e nt District has received all data in electronic form at com p rising: sy stem nam es; station ty pes (riverine or estuarine); station num bers; y ears, m onths, day s , and seasons of sam pling; bottom depths; Secchi depths; tem p eratures; salinities; concentrations of dissolved oxy gen, total nitrogen, total phosphorus, and chlorophy ll; m easures of color; and average light attenuation coefficients. This report focuses on estuarine and coastal stations. This report elucidates broad-scale patterns related to the project’ s goals. Analy ses involved annual or m onthly m eans, standard statistical procedures, and in som e cases, transform a tions to im prove norm a lity and hom ogeneity of variance.

Fi gure 1. St udyarea and sam p l i ng st at i ons.

3Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### K EY CHANGES AND TRENDS 

### Ongoing m onitoring should detect short-term changes in water quality , or events, and distinguish these changes from long-term trends. Across all stations in all sy stem s, m ean concentrations of total nitrogen, total phosphorus and chlorophy ll increased in response to an El Niño event, which generated significant rainfall during 1998 (Figures 4–6). These changes decreased water clarity as shown by a reduction in the proportion of tim es a Secchi disc rem a ined visible throughout the water column(Figure 7). The sy stem s recovered, with “ty p ical” values recorded after 6–8 m onths. Overall, these results illustrated how natural variation can confound identification of anthropogenic im pacts, and they pointed to the value of sustained sam pling. Chlorophy ll concentrations, proxies for increased phy toplankton biom ass, represent valuable indicators of increased organic m a tter or eutrophication. Chlorophy ll concentrations rem a in correlated with concentrations of total phosphorus and total nitr ogen (Figures 2 and 3). The stronger em pirical relationship between chlorophy ll and total phosphorus pointed to phosphorus as a m a jor driver of changes in chlorophy ll. In com b ination, the relationships supported a focus on these three param e ters.

C o r r e l atio n c o ef fic i ent = 0.84 p < 0.001 -1

. 0 0.0 1.0 2.0

0.0 0 .5 1

. 0 1

. 5 2.0 2 .5log10[Chlorophyll(μgL-1)]

Log 10 [ T ot a l p hos ph or u s ( μ gL -1 )]

0 200 400 600 800

1996 1997 19 98 1999 2000 2001 2002 20 03 2004 2005 2006 2 007 2008 Cal endar y earMeantotal nitrogen (μg L-1)

Fi gure 2. R e l a t i onshi p betw een l o g 10 -transform ed

m onthl ym ean chl o rophy l l and t o t a l phosphorus concentrations from a ll estuarine system s. Fi gure 4. Annual m ean t o t a l ni tr ogen concentr at i ons across the five estuarine system s.

C o r r el ation c oeffic i ent = 0.46 p < 0. 0 0 1 -1

. 0 0.0 1.0 2.0

2.0 2 .5 3.0 3 .5log10[Chlorophyll(μgL-1)]

Lo g 10 [ T o t al ni tr og en ( μ g L -1 )]

0 5 10 15 20 25 30 35

1996 1997 19 98 1999 20 00 2001 20 02 2003 2004 2005 2006 2007 2008 Cale ndar y earMean total phosphorus (μg L-1)

Fi gure 3. R e l a t i onshi p betw een l o g 10 -transform ed m onthl ym ean chl o rophy l l and t o t a l ni tr ogen

concentrations from a ll estuarine system s. Fi gure 5. Annual m ean t o t a l phosphorus concentrations across the five estuarine system s.

4Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties

-1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5

-1 .5

- 1 .0 -0

. 5 0

. 0 0 .5 1

. 0 1

. 5 Jan Fe b Ma r Ap r Ma y Ju n Ju l Au g Se p Oc t No v De c

S t r e s s = 0. 1 670

0 2 4 6 8 10

1996 1997 19 98 1999 20 00 2001 20 02 2003 2004 2005 2006 2007 2008 Cale ndar y earMean chlorophyll (μgL-1)

Fi gure 8. Ordi nat i on for th e W i th l acoochee com p rehensi v e wat e rshed m a nagem e nt basi n. bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er) Fi gure 6. Annual m ean chl o rophy l l concentrations across the five estuarine system s.

0. 0 0. 2 0. 4 0. 6 0. 8 1. 0

1996 199 7 1998 1999 200 0 2001 2002 2003 200 4 2005 2 006 2007 2008 C a lend ar y e arSecchi readingsrecorded as Bottom(proportion)

-1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5

-1 .5

- 1 .0 -0

. 5 0

. 0 0 .5 1

. 0 1

. 5 Jan Fe b Ma r Ap r Ma y Ju n Ju l Au g Se p Oc t No v De c
S t r e s s = 0

. 15 31

Fi gure 7. Annual m eans for th e proport i on of sam p ling events where the Secchi disk was visible at th e b o tto m acro ss th e fiv e estuarine system s. Fi gure 9. Ordi nat i on for th e Spri ngs C o ast com p rehensi v e wat e rshed m a nagem e nt basi n. bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er) 

### Less dram atic variation in rainfall occurs am ong m onths, y e t such variation could obscure trends. Two-dim e nsional ordinations based on total m onthly rainfall between 1997 and 2008 for the Withlacoochee and Springs Coast com p rehensive watershed m a nagem e nt basins confirm e d wellknown patterns in rainfall (Figures 8 and 9). Higher rainfall characterized June, July , August and Septem ber, wet m onths. The least rain fell in April, May , October and Novem b er, dry m onths. The transitional m onths, January , February and March had variable rainfall. Decem ber differed from other m onths, probably due to high rainfall in 1997 and 2002 (Withlacoochee 11.92 and 9.81 inches and Springs Coast 11.04 and 10.19 inches). In further analy ses, Decem ber was considered a transitional m onth. Multivariate ordinations provided evidence that variation in rainfall influenced concentrations of total nitrogen, total phosphorus and chlorophy ll in a m anner that will affect evaluations of trends (Figures 10–14). Stress values indicated reasonable representations in three dim e nsions, with axes 1 and 2 shown. Sam p ling events with sim ilar concentrations of total nitrogen, total phosphorus and chlorophy ll y i elded clusters of points in the ordinations. Black sy m bols representing wet m onths (June–Septem b er) tended to separate from other m onths in ordinations for the Hom o sassa and

5Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### Chassahowitzka sy stem s. This clustering suggested consistency in responses to higher rainfall. Weaker clustering in ordinations for the other three sy stem s probably reflected controlled flow past the Inglis Dam on the Withlacoochee River and differences in sizes, hy droperiods, and other hy drological characteristics of watersheds. Given these results, separate analy ses exam ined trends for wet, transitional and dry m onths.

-3 -2 -1 0 1 2 3

- 3

- 2

- 1 0123 We t mo n t h s T r an si t i on m o n t hs Dr y m o n t h s
St ress = 0

. 16 07 -3 -2 -1 0 1 2 3

- 3

- 2

- 1 0123 We t mo n t h s T r an si t i on m o n t hs Dr y m o n t h s
St ress = 0

. 16 10

Fi gure 12. Ordination for the W eeki W achee system

. bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er)

Fi gure 10. Ordination for the Hom o sassa system

. bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er)

-3 -2 -1 0 1 2 3

- 3

- 2

- 1 0123 We t mo n t h s T r an si t i on m o n t hs Dr y m o n t h s
Stre s s = 0. 1514 -3 -2 -1 0 1 2 3

- 3

- 2

- 1 0123 We t mo n t h s T r an si t i on m o n t hs Dr y m o n t h s
St ress = 0

. 16 12

Fi gure 13. Ord i n a tio n fo r th e Crystal system

. bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er)

-3 -2 -1 0 1 2 3

- 3

- 2

- 1 0123 We t mo n t h s T r an si t i on m o n t hs Dr y m o n t h s
St ress = 0

. 15 07

Fi gure 11. Ordi nat i on for th e C h assahowi t z ka sy st em . bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er)
Fi gure 14. Ordi nat i on for th e W i th l acoochee sy st em . bl ack sy m bol s = wet m onths (June–Sept e m b er); gray sy m bol s = m onths of vari abl e rai n fal l (January , February, March and Decem be r); white sym bols = dry m onths (Apri l , M a y , Oct ober and Novem b er)
6Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties 

### Given the influence of rainfall, water quality can be expected to vary according to the spatial relationships between sta tions and the m ouths of the five rivers, with the stations spanning gradients of freshwater influence that will affect evaluations of trends. Salinity represents a conservative m a rker of riverine influence, and m

u ltivariate ordinations based on salinity m easurem e nts from 1999 onward highlighted one or m o re stations in each sy stem that were m o st strongly affected by river flow, except in the Cry s tal sy stem where the stations form ed three groups corresponding to distance offshore (Figures 15–19). In analy ses to identify trends, riverine influence, as characterized by salinity , should highlight groups of stations that exhibit coherent patterns. -2.5 -2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5

-2 .5 -2

. 0 -1 .5 -1 .0 -0. 5 0

. 0 0 .5 1

. 0 1 .5 2. 0 2 .5 St n 1 St n 2 St n 3 St n 4 St n 6 St n 7 St n 8 St n 9 S t n 10
St ress = 0

. 03 41

Fi gure 17. Ordination for the Hom o sassa system b a sedo n salin ities.

-2.5 -2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5

-2 .5 -2

. 0 -1 .5 -1 .0 -0. 5 0

. 0 0 .5 1

. 0 1 .5 2. 0 2 .5 St n 3 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 1 0
St r e ss = 0. 016 7

-2.5 -2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5

-2 .5 -2

. 0 -1 .5 -1 .0 -0. 5 0

. 0 0 .5 1

. 0 1 .5 2. 0 2 .5 St n 1 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 10

St ress = 0.0 385

Fi gure 18. Ordi nat i on for th e C h assahowi t z ka sy st em b a sedo n salin ities.

-2.5 -2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5

-2 .5 -2

. 0 -1 .5 -1 .0 -0. 5 0

. 0 0 .5 1

. 0 1 .5 2. 0 2 .5 St n 3 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 1 0

St ress = 0.0 220

Fi gure 19. Ordination for the W eeki W achee system b a sedo n salin ities. Fi gure 15. Ordi nat i on for th e W i th l acoochee sy st em b a sedo n salin ities.

-2.5 -2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5

-2 .5 -2

. 0 -1 .5 -1 .0 -0. 5 0

. 0 0 .5 1

. 0 1 .5 2. 0 2 .5 Stn 1 Stn 2 Stn 5 Stn 6 Stn 7 Stn 8 Stn 9 St n 1 0

St ress = 0

. 06 52

Fi gure 16. Ordi nat i on for th e C ry s t a l sy st em based on salin ities.

7Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### Concentrations of n itrogen, phosphorus and chlorophy ll can vary independently of riverine influence due to inputs from other sources and biological and biogeochem i cal processing. Therefore, a series of m u ltivariate ordinations assessed consistent differences am ong stations that m i ght affect detection of trends. Ordinations based on range-standardized data [ ( value – m i nim u m value)/range] y i elded suitable representations in three dim e nsions as indicated by stress values (Figures 20–24). Plots showing the first two axes highlighted spatial patterns that augm ent the results derived from variations in salinity . As expected when using three param e ters instead of one, the results are m o re com p lex than those based on salinity alone. Therefore, a com b ination of the two sets of data was used in a third set of ordinations. -2

. 0 -1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5 2. 0

- 2 .0

- 1 .5

- 1 .0

- 0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 1 St n 2 St n 3 St n 4 St n 6 St n 7 St n 8 St n 9 S t n 10

S t r e s s = 0

. 493

Fi gure 22. Ordination for the Hom o sassa system

based on concentr at i ons of t o t a l ni tr ogen, t o t a l phosphorus and chl o rophy l l

.

-2

. 0 -1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5 2. 0

- 2 .0

- 1 .5

- 1 .0

- 0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 3 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 1 0

S t r e ss = 0. 10 70

-2

. 0 -1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5 2. 0

- 2 .0

- 1 .5

- 1 .0

- 0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 1 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 1 0

S t r e s s = 0. 1 106

Fi gure 23. Ordi nat i on for th e C h assahowi t z ka sy st em based on concentr at i ons of t o t a l ni tr ogen, t o t a l phosphorus and chl o rophy l l

.

-2

. 0 -1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5 2. 0

- 2 .0

- 1 .5

- 1 .0

- 0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 3 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 1 0

S t r e s s = 0

. 156 0 Fi gure 20. Ordi nat i on for th e W i th l acoochee sy st em based on concentr at i ons of t o t a l ni tr ogen, t o t a l phosphorus and chl o rophy l l

.

-2

. 0 -1

. 5 -1

. 0 -0

. 5 0. 0 0. 5 1. 0 1. 5 2. 0

- 2 .0

- 1 .5

- 1 .0

- 0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 1 St n 2 St n 5 St n 6 St n 7 St n 8 St n 9 St n 1 0

S t r e ss = 0. 09 97

Fi gure 24. Ordination for the W eeki W achee system based on concentr at i ons of t o t a l ni tr ogen, t o t a l phosphorus and chl o rophy l l

.
Fi gure 21. Ordi nat i on for th e C ry s t a l sy st em based on concentr at i ons of t o t a l ni tr ogen, t o t a l phosphorus and chl o rophy l l

.

8Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties 

### Stations were grouped according to results of hierarchical classification, which provided m

u ltivariate “distances” m easuring the sim ilarity am ong the data for each station (Table 1). Plots showing two of the three axes in ordinations highlighted spatial patterns (Figures 25–29).

-2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0

-2 .0 -1 .5 -1

. 0 -0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 1 St n 2 St n 3 St n 4 St n 6 St n 7 St n 8 St n 9 St n 10

S t ress = 0. 0899

Gro up 4 Gro up 3

Group 2 Group 1

Ta ble 1 . Maxim u m m u ltivariate distances am ong est u ari n e st at i ons i n groups. W i = W i th l acoochee system ; Cr = Crystal system ; Ho = Hom o sassa system ; Ch = Chassahowitzka system ; W W = W eeki W achee system Fi gure 27. Ordination for the Hom o sassa system b a sedo n salin ities an dco n cen tratio n s o f to tal ni tr ogen, t o t a l phosphorus and chl o rophy l l

. G r o u p W i C r H o C h W W 1 0

. 6 9 0

. 4 5 0

. 4 9 0

. 3 0 0

. 7 9 2 0

. 3 1 0

. 4 9 0

. 2 7 0

. 2 3 0

. 3 9 3 0

. 3 1 0

. 3 7 0

. 3 5 0

. 3 0 0

. 2 6 4 0

. 4 4 0

. 3 8 0

. 2 6

-2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0

-2 .0 -1 .5 -1

. 0 -0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 3 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 10

S t ress = 0. 0683

Grou p 3 Grou p 2 Group 1

-2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0

-2 .0 -1 .5 -1

. 0 -0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 1 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 10

S t ress = 0. 0690

Gro up 1 Group 3 G r oup 2

Fi gure 28. Ordi nat i on for th e C h assahowi t z ka sy st em b a sedo n salin ities an dco n cen tratio n s o f to tal ni tr ogen, t o t a l phosphorus and chl o rophy l l

. Fi gure 25. Ordi nat i on for th e W i th l acoochee sy st em b a sedo n salin ities an dco n cen tratio n s o f to tal ni tr ogen, t o t a l phosphorus and chl o rophy l l

.

-2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0

-2.0 -1. 5 -1.0 -0

. 5 0.0 0 .5 1.0 1

. 5 2.0 St n 3 St n 4 St n 5 St n 6 St n 7 St n 8 St n 9 St n 10

Group 4

Group 3 Grou p 2

Grou p 1 S t ress = 0. 0933

-2.0 -1.5 -1.0 -0.5 0. 0 0. 5 1. 0 1. 5 2. 0

-2 .0 -1 .5 -1

. 0 -0 .5 0

. 0 0 .5 1

. 0 1 .5 2

. 0 St n 1 St n 2 St n 5 St n 6 St n 7 St n 8 St n 9 St n 10

S t ress = 0. 0791

Grou p 3

Group 4 Gro up 2

Group 1

Fi gure 29. Ordination for the W eeki W achee system b a sedo n salin ities an dco n cen tratio n s o f to tal ni tr ogen, t o t a l phosphorus and chl o rophy l l

. Fi gure 26. Ordi nat i on for th e C ry s t a l sy st em based on salin ities an dco n cen tratio n s o f to tal n itro g e n , to tal phosphorus and chl o rophy l l

.

9Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### Correlations assessed trends in concentrations of total nitrogen, total phosphorus and chlorophy ll between 1999 and 2008 for estuarine stations in the five coastal sy stem s. Wet m onths (June, July , August and Septem ber), transitional m onths (January , February , March and Decem ber), and dry m onths (April, May , October and Novem b er) form ed the basis for three sets of correlations. A further three sets com p rised wet, transitional and dry “y ears” with m onths treated as replicates. Individual correlations in each of the six sets evaluated data from stations or groups of stations differentiated by hierarchical classification and ordination based on salinities and concentrations of the three water quality param e ters (Table 2). This approach y i elded 162 correlations for both m onths and y ears or 324 correlations in total. The patterns for correlations with m onths and y ears were sim ilar, so correlations with m onths are presented. During wet m onths, concentrations of total nitrogen, total phosphorus and chlorophy ll increased through tim e, especially at stations in the Withlacoochee, Cry s tal and Hom o sassa sy stem s (Figures 30–32). These trends suggest increased transport of nutrients and stim ulation of phy toplankton production. In fact, widespread increases in total nitrogen concentrations would be expected because highly soluble nitrate is a comm on form of nitrogen in these sy stem s. The distribution of trends probably relates to hum an activities and the hy drology of watersheds, as determ ined by their sizes, contributions from surface water and groundwater, hy droperiods, and other characteristics. Concentrations of total phosphorus decreased through tim e in the Chassahowitzka and Weeki Wachee sy stem s. These decreases m a y be related to uptake by phy toplankton, an explanation that is supported by an increase in chlorophy ll at an inshore station near the m outh of the Weeki Wachee but not by decreases in chlorophy ll concentrations in the Chassahowitzka sy stem

. Ta ble 2 . Groups of est u ari n e st at i ons for correl a t i ons. W i = W ith laco o c h ee system ; Cr = Crystal system ; Ho = Hom o sassa system ; Ch = Chassahowitzka system ; W W = W eeki W achee system Wi C r H o C h W W 6 8 4 3 , 4 3 1, 4, 5, 8, 9 9 1, 2, 6 5, 6 4

4, 7, 10 1, 5, 6 1. 2. 6 7, 8, 9, 10 5, 7, 8 2, 7, 10 3, 7, 9 6 6, 9, 10



### Out of 162 correlations, 49 were statistically significant (p < 0.05), with 27 correlations indicating significant increases through tim e and the rem a ining 22 correlations indicating significant decreases through tim e. The largest, significant positive and negative correlation coefficients were 0.511 and –0.523, which m eant that no correlation explained m o re than 27% of the variation in the appropr iate data. Thus, spatial and tem poral variation inconcentrations of key param e ters rem a ins a challenge when seeking to identify trends. Discussion is lim ited to broad patterns and potential causal links until com p lem e ntary data have been collected or collated. Fi gure 30. Sig n i fican t co rrelatio n s b e tween to tal ni tr ogen and wet m onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

10Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties 

### In com p arison to results for wet m onths, a greater proportion of significant correlations were negative for transitional m onths (Figures 33–35). Significant positive correlations indicated that concentrations of total nitrogen and/or chlorophy ll increased at a few stations in the Withlacoochee, Cry s tal and Hom o sassa sy stem s, whereas concentrations of total phosphorus rem a ined unchanged in those sy stem s. In com b ination with results for wet m onths, this pattern suggests increased transport of nitrogen resulting in stim ulation of phy toplankton production. In general, concentrations of total nitrogen, total phosphorus and/or chlorophy ll decreased through tim e at stations in the Chassahowitzka and Weeki Wachee sy stem s. Further insights into causal relationships await auxiliary data on water m anagem e nt activities, changes in land use, and other potential influences on nutrient loads, as well as diagnostic studies to elucidate biological influences such as uptake and recy cling of nutrients or grazing pressures on phy toplankton. Fi gure 31. Sig n i fican t co rrelatio n s b e tween to tal phosphorus and wet m onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

Fi gure 33. Sig n i fican t co rrelatio n s b e tween to tal ni tr ogen and tr ansi t i onal m onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on Fi gure 32. Si gni fi cant correl a t i ons betw een chl o rophy l l and wet m onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

11Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### Results for dry m onths resem bled results for transitional m onths (Figures 36–38). Significant positive correlations indicated increasing concentrations of total nitrogen and/or total phosphorus in the Withlacoochee, Cry s tal, Hom o sassa and Chassahowitzka sy stem s, but there was no evidence of a corresponding increase in phy toplankton production, as indicated by chlorophy ll concentrations. In contrast, concentrations of total nitrogen or total phosphorus decreased significantly through tim e at stations in the Hom o sassa, Chassahowitzka and Weeki Wachee sy stem s. Auxiliary data on factors that could influence nutrient loads and diagnostic studies of biological and biogeochem i cal processing should y i eld further insights into the causes of these trends.

Fi gure 34. Sig n i fican t co rrelatio n s b e tween to tal phosphorus and transitional m onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

Fi gure 36. Sig n i fican t co rrelatio n s b e tween to tal ni tr ogen and drym onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

Fi gure 35. Si gni fi cant correl a t i ons betw een chlorophyll and transitional m onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

12Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties 

### C ONCLUDING REMARKS 

### The results in this report bear on issues related to sustainable m a nagem e nt of Gulf coast waters adjacent to Citrus, Hernando and Levy Counties. Three of the param e ters m easured in the baseline study are correlated, with increasing concentrations of total nitrogen and total phosphorus linked to increasing concentrations of chlorophy ll, a m e tric related to eutrophication. In addition, the afterm ath of an El Niño event highlighted how increased chlorophy ll concentrations negatively affect light penetration, as m easured with a Secchi disk. Prolonged decreases in light penetration can lead to loss of seagrasses and a variety of undesirable flow-on effects through these valuable coastal sy stem s. Efforts to differentiate trends from short-term changes and variation inwater quality benefited from evaluating both the influence of rainfall and the extent of spatial and tem poral coherence am ong sam pling stations. Results for the Withlacoochee, Cry s tal and Hom o sassa sy stem s y i elded evidence of increasing nutrient loads and consequent increases in phy toplankton. In contrast, results for the Chassahowitzka and Weeki Wachee sy stem s indicated decreases in loads of total nitrogen and total phosphorus. Further insights require collation of data on anthropogenic factors that could alter nutrient loads, such as changes in land use or im proved m a nagem e nt of stormw ater, along with diagnostic studies to elucidate transform a tion of nutrients, grazing pressure on phy toplankton, and other biological and biogeochem i cal processes. For exam ple, data on local weather conditions and m

u ltiple m easurem e nts of water quality within day s would y i eld an im proved understanding of key interactions and, ultim ately , im proved m a nagem e nt of the threat of eutrophication. Fi gure 37. Sig n i fican t co rrelatio n s b e tween to tal phosphorus and drym onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on



### The understanding generated by efforts to elucidate spatial and tem poral coherence also will contribute to the design of effective and efficient m onitoring. Identify i ng, differentiating and sourcing the effects of long-term , anthropogenic loading and short-term responses to clim ate and weather will require a com b ination of highfrequency sam pling at characteristic s t a t i o n s Fi gure 38. Sig n i fican t co rrelatio n s b e tween to tal chl o rophy l l and drym onths. g r een circle = sig n i fican t p o s itiv e co rrelatio n ; red square = si gni fi cant negat i v e correl a t i on

13Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties 

### L ITERATURE CITED 

### and less frequent sam pling across an a rr ay of stations over decades (Enfield et al. 2001, Sutton and Hodson 2005). Such m onitoring will docum ent the success of m anagem e nt and guide responses to unforeseen circum stances. Thus, the baseline study and this report are delivering the desired results by identify i ng im portant patterns in water quality , providing data for m o re in-depth analy ses of trends, pointing to the need for key diagnostic studies, and lay i ng the foundation for the design of long-term m onitoring. Duart e, C

. M. 1991. Seagrass dept h l i m i t s . Aquat i c Botany 40: 363-377. Duart e, C

. M. 1995. Submerged aquat i c vegetat i on i n rela tio n to differen t n u t rien t reg i mes. Op h e lia 41: 87-112. Enf i e l

d

, D.B., A.M. Mesta s–N unez and P.J. Tri m bl e. 2001. The Atlantic multidecadal oscillation and its rela t i on to rai n f

a l l and ri ver f l o w s i n t h e cont i n enta l U.S. Geophysi cal Research Let t e rs 28: 2077-2080. Frazer, T.K

. and J.A. Hal e . 2001. C hanges i n t h e abundance and di st

ri but i on of submersed aquat i c vegetat i on al ong Fl ori da’s Spri ngs C oast : 1992– 1999. Fi nal Report

. Sout hw est Fl ori da Wat e r Management Di st

ri ct ( S WFWMD C ont ract N o
. 99C ON 000041)

. 

### Inform ation in the scientific literature com b ined with this report reinforces m a nagers’ concerns regarding the potential im pacts of increased chlorophy ll and decreased light availability on seagrasses and their associated fauna. High chlorophy ll concentrations and resultant shading can cause loss of seagrasses (Duarte 1991). Seagrasses represent a valuable habitat that integrates the effects of water quality over tim e; therefore, data on seagrass distribution and abundance would com p lem e nt sam pling of water quality param e ters. The absence of such data can com p rom i se inferences about the effects of deteriorating water quality at the ecosy stem level and design of effective m anagem e nt responses. Frazer, T.K., M.V. Hoyer, S.K. Notestein, D.E. Canfield, F.E. Vose, W

. R

. L e a v e n s , S.B. Blitch and J. Conti. 1998. Nitrogen, phosphorus and chl o rophyl l rela t i ons i n sel ect ed ri vers and nearshore coasta l w a t e rs al ong t h e Bi g Bend regi on of Fl ori da. Fi nal Report

. Suw annee Ri ver Wat e r Management Di st

ri ct ( S

RWMD C

ont ract N o
. 96/ 97-156) and t h e Sout hw est Fl ori da Wat e r Management Di st

ri ct (

S WFWMD C

ont ract N

o . 96/ 97/ 157R)

. Frazer, T.K., M.V. Hoyer, S.K. Notestein, J.A. Hale and D.E. C anf i e l

d

, Jr. 2001a. Physi c al , chemi c al and vegetat i ve charact e ri st i c s of f

i ve Gul f

coast ri vers. Fi nal Report

. Sout hw est Fl ori da W a t e r Management Di st

ri ct (

S WFWMD C ont ract N

o . 98C ON 000077)

. 

### This report inform s water resource m anagers of em erging patterns and potentially im portant issues that can affect decisions about auxiliary diagnostic work and m a nagem e nt actions. Clearly , there is a need for a quantitative understanding of nutrient loads within the region. The robust em pirical relationship between chlorophy ll and total phos phorus concentrations and results of nutrient addition assay s point to phosphorus as a lim iting n u t r i e n t a c r o s s m u c h o f t h e r e g i o n (Frazer et al. 1998, 2001b, 2002, 2003, 2004 and 2006, Hoy e r et al. 2002; Jacoby et al. 2008). However, estim ates of all nutrient loads rem a in essential for quantify i ng responses and attributing causal links at the appropriate spatiotem poral scales. Data on nutrient loads and m odels of ecosy stem responses will never obviate the need for sustained m onitoring of water quality in a program designed to detect unforeseen changes and determ ine ongoing success of m anagem e nt actions. Frazer, T.K., M.V. Hoyer, S.K. Notestein, J.A. Hale, D.E. Canfield, Jr. and S.B. Blitch. 2001b. Water q u a lity ch a r a c teristics o f

th e n e a rsh o r e Gu lf co a s t waters adjacent to Citrus, Hernando and Levy count i es. Fi nal Report

. Sout hw est Fl ori da Wat e r Management District, Brooksville, Florida. Frazer, T.K., S.K. Notestein, J.A. Hale, M.V. Hoyer, D.E. Canfield, Jr., S.B. Blitch and C. Bedee. 2003. Wa ter q u a lity ch a r a c teristics o f

th e n e a rsh o r e Gu lf coast w a t e rs adj acent to Ci t r us, Hernando and Levy Counties – Project COAST 2002. Final Report

. Sout hw est Fl ori da Wat e r Management District, Bro o k sville, Flo r id a
. Frazer, T.K ., S.K

. N o t e st ei n, C

. A. Jacoby and J

. A

. H a l e
. 2004. Water quality characteristics of t h e nearshore Gul f

coast w a t e rs adj acent to Citrus, Hernando and Levy Counties – Project C O AST 1997 t h rough 2003. Annual Report

. Sout hw est Fl ori da Wat e r Management Di st

ri ct , Bro o k sville, Flo r id a
.

14Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Ci trus, Hernando and Levy Counties

15 Frazer, T.K. S.K. Notestein, S.R. Keller and C.A. Jacoby. 2006. Water Quality Characteristics of the Nearshore Gulf Coast Waters Adjacent to Citrus, Hernando and Levy Counties – Project COAST 1997 – 2005. Final Report. Southwest Florida Water Management District, Brooksville, Florida. 54 pp. Frazer, T.K., E.J. Phlips, S.K. Notestein and C. Jett. 2002. Nutrient limiting stat us of phytoplankton in five Gulf coast rivers and their associated estuaries. Final Report. Southwest Florida Water Management District (SWFWMD Contract No. 00CON000038). Hale, J.A., T.K. Frazer, D.A. Tomasko and M.O. Hall. 2004. Changes in the distribution of seagrass species along Florida’s central Gulf coast: Iverson and Bittaker revisited. Estuaries 27: 36-43. Handley, L., D. Altsman and R. DeMay (eds.). 2007. Seagrass status and trends in the northern Gulf of Mexico: 1940–2002. U.S. Geological Survey Scientific Investiga tions Report 2006–5287. 267 pp. Hoyer, M.V, T.K. Frazer, S.K. Notestein and D.E. Canfield, Jr. 2002. Nutrient, chlorophyll, and water clarity relationships in Florida’s nearshore coastal waters with comparisons to freshwater lakes. Canadian Journal of Fisheries and Aquatic Sciences 59: 1024-1031. Jacoby, C.A., T.K. Frazer, D.D. Saindon, S.R. Keller and D.C. Behringer, Jr. 2008. Water quality characteristics of the nearshore Gulf coast waters adjacent to Citrus, Hernando and Levy Counties. Annual Report. Southwest Florida Water Management District (SWFWMD Contract No. 06C00000079). Jones, G.W., S.B. Upchurch, K.M. Champion and D.J. Dewitt. 1997. Water-quality and hydrology of the Homosassa, Chass ahowitzka, Weeki Wachee, and Aripeka spring complexes, Citrus and Hernando Counties, Florida: origin of increasing nitrate concentrations. Technical Report prepared by the Ambient Ground-Water Quality Monitoring Program, Southwest Florida Water Management District. Killam, K.A., R.J. Hochberg and E.C. Rzemien. 1992. Synthesis of basic life histories of Tampa Bay species. Technical publication #10–92. Tampa Bay National Estuary Program, St. Petersburg, Florida. Mattson, R.A., T.K. Frazer, J. Hale, S. Blitch and L. Ahijevych. 2007. Florida Big Bend. pp. 171–188. In Handley, L., D. Altsman and R. DeMay (eds.), Seagrass status and trends in the northern Gulf of Mexico: 1940–2002. U.S. Geological Survey Scientific Investigations Report 2006–5287. 267 pp. Southwest Florida Water Management District. 2001. Springs Coast comprehensive watershed management plan. Southwest Florida Water Management District, Brooksville, Florida. Sutton, R.T. and D.L.R. Hodson. 2005. Atlantic Ocean forcing of North American and European summer climate. Science 309: 115-118. Valiela, I., J. McClelland, J. Hauxwell, P.J. Behr, D. Hersh and K. Foreman. 1997. Macroalgal blooms in shallow estuaries: controls and ecophysiological and ecosystem consequences. Limnology and Oceanography 42: 1105-1118. Williams, S.L. and M.H. Ruckelshaus. 1993. Effects of nitrogen availability and herbivory on eelgrass (Zostera marina) and epiphytes. Ecology 74: 904-918.Final Report: Contract Number 06C00000079 Project B678 Water Quality Characteristics of the Nearshore Gulf C oast Waters Adjacent to Citrus, Hernando and Levy Counties

16 

# Appendix 1 – Sampling coordinates
System Station Latitude (N) Longitude (W) decimal minutes decimal minutes Withlacoochee 1 29°02.500 82°47.500 2 29°01.500 82°43.300 3 29°01.500 82°40.500 4 29°00.500 82°49.500 5 29°00.500 82°47.500 6 29°00.500 82°45.500 7 28°58.500 82°49.500 8 28°58.500 82°47.500 9 28°58.500 82°45.500 10 28°56.500 82°47.500 Crystal River 1 28°55.500 82°44.500 2 28°55.500 82°42.500 3 28°55.500 82°40.500 4 28°54.300 82°37.100 5 28°53.500 82°44.500 6 28°53.500 82°42.500 7 28°53.500 82°40.500 8 28°51.500 82°44.500 9 28°51.500 82°42.500 10 28°50.500 82°39.500 Homosassa1 28°49.500 82°44.500 2 28°47.500 82°44.500 3 28°47.500 82°42.500 4 28°47.700 82°39.500 5 28°47.300 82°37.100 6 28°45.500 82°44.500 7 28°45.500 82°42.500 8 28°45.500 82°40.500 9 28°43.500 82°42.500 10 28°43.500 82°40.500 Chassahowitzka 1 28°42.960 82°34.660 2 28°42.880 82°36.480 3 28°42.310 82°37.210 4 28°41.500 82°38.500 5 28°40.500 82°39.500 6 28°41.150 82°39.900 7 28°41.500 82°40.500 8 28°39.800 82°40.400 9 28°40.500 82°41.500 10 28°42.500 82°41.500 Weeki Wachee 1 28°31.087 82°34.416 2 28°31.886 82°37.316 3 28°32.069 82°38.246 4 28°32.500 82°39.500 5 28°34.500 82°39.500 6 28°33.500 82°40.500 7 28°31.500 82°40.500 8 28°30.530 82°41.500 9 28°32.500 82°41.500 10 28°34.500 82°41.500