Technical Support Document for U.S. EPA’s Final Rule for

Numeric Criteria for Nitrogen/Phosphorus Pollution in Florida’s Inland Surface Fresh Waters

B1-1 

Appendix B1. Data Supporting EPA’s Approach for Deriving Numeric 

Nutrient Criteria for Florida Lakes

Appendix B1 contains the data EPA used to derive numeric nutrient criteria for Florida lakes. It 

is being provided in electronic form on CD. A copy of the CD can be obtained by contacting 

EPA’s docket office. The docket identification number is EPA-HQ-OW-2009-0596. 

The Office of Water (OW) Docket Center is open from 8:30 a.m. to 4:30 p.m., Monday through 

Friday, excluding legal holidays. The OW Docket Center telephone number is 202-566-1744 

and the Docket address is OW Docket, EPA West, Room 3334, 1301 Constitution Ave., NW, 

Washington, DC 20004. 
Technical Support Document for U.S. EPA’s Final Rule for

Numeric Criteria for Nitrogen/Phosphorus Pollution in Florida’s Inland Surface Fresh Waters

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Appendix B2. Analysis of Paleolimnological Data

Although naturally eutrophic lakes occur in Florida, and may be common, just because a lake is 

naturally eutrophic does not necessarily mean that it has not eutrophied further as a result of 

human activities. Nutrient criteria for naturally eutrophic lakes (most probably developed as sitespecific alternative criteria, or SSAC) should protect the natural state of the lakes and prevent 

further eutrophication. Hyper-eutrophication of Florida lakes can be manifested as increased 

dominance of blue-green algae (Riedinger-Whitmore et al. 2005) or as an ecosystem shift from 

submerged vegetation dominance (transparent water) to extreme phytoplankton dominance (loss 

of transparency; see, Bachmann et al. 1999, 2002; Lowe et al. 1999, 2001; Scheffer et al. 1993, 

2001). EPA examined evidence whether Florida lakes have increased in trophic state since early 

settlement or development.

EPA reanalyzed the paleolimnological findings reported by Whitmore and Brenner (2002), and 

Whitmore-Riedinger et al. (2005). Analysis was restricted to the WACALIB inferred TP for 32 

lakes reported (Whitmore and Brenner 2002, Whitmore-Riedinger et al. 2005). Total phosphorus 

concentration of the lakes was inferred from the diatom species composition from surface and 1 

m deep samples of sediment cores, from 1 to 4 cores for each lake (Whitmore and Brenner 

2002). EPA only used data from the top and bottom of the cores reported in an appendix table of 

Whitmore and Brenner (2002), plus two additional cores from Whitmore-Riedinger et al. (2005). 

Intermediate samples between the sediment surface and 1 m depth have also been analyzed by 

Whitmore and colleagues for a subset of the 32 lakes. 

Inferred TP concentrations were log-transformed (common logarithm). An appropriate statistical 

test is the paired t-test of the inferred top and bottom TP concentrations, which is equivalent to a 

t-test of the differences, where the null hypothesis is zero difference. To avoid artificially 

inflating the sample size with multiple cores, the t-test was performed on lake-average 

differences (N = 32). The results were highly significant—on average, the inferred limnetic TP is 

higher in surface sediments than in pre-industrial sediments in these lakes. The average 

difference was 0.132 (common log units), which is equivalent to a 35% increase in TP. There 

was less than 1% probability of these results being due to chance alone (p = 0.00167; t31 = 3.44). 

Although a 35% increase in TP might not seem particularly large, it is important to remember 

that 35% is the average estimated increase over all 32 lakes. Several lakes had almost no 

inferred difference (no change); a small number of lakes actually decreased in inferred TP 

(apparent oligotrophication); and in more than half of the lakes the inferred TP increased, some 

more than doubling. Table B2-1 shows the breakdown of the magnitudes of apparent TP change. 

In summary, inferred TP increased by more than 25% in 59% of the lakes examined, and the 

inferred TP more than doubled in 19% of lakes. Inferred TP decreased by more than 20% 

(oligotrophication) in 13% of lakes. 
Technical Support Document for U.S. EPA’s Final Rule for

Numeric Criteria for Nitrogen/Phosphorus Pollution in Florida’s Inland Surface Fresh Waters

B2-2 

Table B2-1. Decrease or increase of inferred TP in 32 lakes.

Magnitude of Inferred Change, 1m Sediment vs. 

Surficial Sediment

N of

Lakes

% of 

Lakes Notes

Lakes with decreased TP 4 13% Total oligtrophication

Decrease by more than 33% 2 6.2% Apparent oligotrophication

Decrease by 20–33% 2 6.2% Probable oligotrophication 

Decrease less than 20% and increase less than 25% 9 28% No apparent change in TP

Increase by 25–50% 6 19% Probable eutrophication

Increase by 50–100% 7 22% Apparent eutrophication

Increase more than 100% ( more than double) 6 13% Severe eutrophication

Lakes with increased TP 19 59% Total eutrophication

Source: data analyzed from Whitmore and Brenner (2002) and Whitmore-Riedinger et al. (2005).

References

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relation to alternative stable states. Hydrobiologia 394:219–232. 

Bachmann, R.W., C.A. Horsburgh, M.V. Hoyer, L.K. Mataraza, and D.E. Canfield, Jr. 2002. 

Relations between trophic state indicators and plant biomass in Florida lakes. 

Hydrobiologia 470:219–234. 

Lowe, E.F., L.E. Battoe, M. Coveney, and D. Stites. 1999. Setting water quality goals for 

restoration of Lake Apopka. Lake and Reservoir Management 15(2):103–120. 

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alternative view to that of Bachmann et al. (1999). Hydrobiologia 448:11–18. 

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many Florida lakes: a paleolimnological assessment. Lake and Reservoir Management 

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Scheffer, M.S., S. Hosper, M.L. Meijer, B. Moss, and E. Jeppesen. 1993. Alternative equilibria 

in shallow lakes. Trends in Ecology and Evolution 8:275–279. 

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Whitmore, T. and M. Brenner. 2002. Paleologic Characterization of Pre-disturbance Water 

Quality Conditions in EPA Defined Florida Lake Regions. University of Florida, 

Department of Fisheries and Aquatic Sciences, Gainesville, FL.