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Do EPA’s Water Quality Standards Work for Lakes? - Developing Water Quality Targets for Lakes In Central Florida David A. Tomasko, Ph.D. Emily Keenan,

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Presentation on theme: "Do EPA’s Water Quality Standards Work for Lakes? - Developing Water Quality Targets for Lakes In Central Florida David A. Tomasko, Ph.D. Emily Keenan,"— Presentation transcript:

1 Do EPA’s Water Quality Standards Work for Lakes? - Developing Water Quality Targets for Lakes In Central Florida David A. Tomasko, Ph.D. Emily Keenan, M.S. Kathy Anamisis, M.A. Mike Britt, P.E. City of Winter Haven

2 Main topics covered 2 ● Why do we have EPA’s Numeric Nutrient Criteria (NNC)? ● What existed prior to EPA’s NNC? ● Who developed the EPA’s NNC? ● Is the NNC an improvement over its predecessor? ● What are implications of utilizing it for managing lakes in Florida? ● Importance of factors other than nutrients

3 Why do we have EPA’s NNC? 3 ● Plaintiffs sued EPA (CWA) claiming State of Florida was not making sufficient progress dealing with non-point sources of pollution – FDEP’s water quality standards (i.e., dissolved oxygen) make situation look worse than it is ● Key argument was that FDEP had only narrative standards (i.e., “shall not cause an imbalance in flora and fauna”) for nutrients ● Plaintiffs argued that numeric nutrient concentration criteria were needed ● EPA officials (under prior administration) concurred ● Timeline laid out for development of NNC ● Today, let’s focus on lakes alone

4 What did we have prior to EPA’s NNC? 4 ● Contrary to plaintiff’s arguments (and EPA’s concurrence) lakes in Florida already had existing numeric nutrient concentrations in their standards and TMDLs ● Low color lake – 40 PCU ● High color lake – 60 PCU ● Not known likely because not familiar with Trophic State Index

5 Who developed EPA’s NNC for lakes? ● Perception seems to be bureaucrat in Washington, D.C – true? ● Reality – EPA’s version almost identical to numbers generated by FDEP’s scientists ● One relatively minor modification ● As in spring’s nitrate levels, EPA NNC is basically FDEP’s numbers ● Bigger controversy for streams – Disagreement among experts ● Biggest controversy for estuaries – Consensus that EPA’s first numbers (independent of FDEP) were not reasonable

6 Is NNC an improvement over its predecessor? 6 TSINNC Types of lakes26 Chlorophyll-a targets22 Nitrogen targets26 Range of nitrogen targets0.45 to to 2.25 Phosphorus targets26 Range of phosphorus targets0.02 to to If anything, NNC is more “lenient” for lake nutrient levels (higher highs) But, is it more appropriate?

7 NNC is certainly not as simplistic – Low color lakes 7

8 High color lakes 8

9 Important considerations with NNC 9 ● EPA’s guidance on data requirements is very thorough – Seasonality of data – Multiple years of data ● In the absence of sufficient data on chlorophyll-a, default to TN and TP targets for system that exceeds chlorophyll- a threshold – If you don’t have enough chlorophyll-a data, you are presumed to have an excess, and stricter nutrient targets are set ● Example where more data is a good thing

10 Is NNC better than what it replaced? 10

11 In Winter Haven, TMDL program based on TSI has been pursued to completion. Projects constructed to meet required load reductions (kg TP/yr) for TSI goal of 60 (from Table 5.2 in FDEP TMDL report for WHCOL)

12 Lake Howard Stormwater Retrofit and Alum Injection Alum Injection completed 2000 Stormwater Retrofit completed 2001

13 Reality Check- Lake Howard Secchi p=0.43 Pre: Post:

14 Reality Check- Lake Howard Chlorophyll a p=0.13 TSI CHLA 60 goal Pre: Post:

15 Reality Check- Lake Howard TP p=0.013 TP target for TSI CHLA 60 goal (TSI TP goal of 60 is 0.07 mg / liter) Pre: Post:

16 Lake May Stormwater Retrofit and Alum Injection Completed 2005

17 Reality Check- Lake May Secchi p=0.60 Pre: Post:

18 Reality Check- Lake May Chlorophyll a p= TSI CHLA 60 goal Pre: Post:

19 Reality Check- Lake May TP p=0.19 TP target for TSI CHLA 60 goal Pre: Post:

20 Lake Lulu Stormwater Retrofit and Alum Injection Completed 2005

21 Reality Check- Lake Lulu Secchi p=0.40Pre: Post:

22 Reality Check- Lake Lulu Chlorophyll a p=0.023 TSI CHLA 60 goal Pre: Post:

23 Reality Check- Lake Lulu TP p=0.38 TP target for TSI CHLA 60 goal Pre: Post:

24 What happened? 24 ● Projects constructed as designed ● Designs met or exceeded TMDL load reductions ● TMDL load reductions met water quality model expectations ● But, did we take time to figure out if model algorithms and water quality targets made sense? – Most models use TSI equations for setting goals – Most models are “calibrated” by modifying a rate coefficient never measured in the lake in question (or even in Florida)

25 TSI vs. locally-developed TP goal 25 Locally-derived TP goal of Chl-a of 50 expected using TSI-60 TP goal of 0.07

26 Why didn’t lakes become “unimpaired”? 26 ● TP targets from TSI are too high ● Locally-derived targets are more difficult to reach ● NNC matches up much better than TSI for target TP for chl-a of 20 µg / liter TSI-60 targetLocally-derived targetEPA NNC 0.07 mg TP / liter0.029 mg TP / liter0.030 mg TP / liter

27 Is NNC an improvement for managing Florida lakes? 27 ● Absolutely, with some limitations – 3 times as many lake types – But still only two chlorophyll-a targets – 3 times as many TP targets ● Much broader range – 3 times as many TN targets ● Much broader range ● But can it accommodate different types of lake restoration projects?

28 For lakes with swampy shorelines, reducing Chl-a levels might have more to do with tannins than nutrients 20 PCU 225 PCU Low TP, high Chl-a High TP, low Chl-a

29 How to “restore” Lake Lulu 29 ● TMDL already been met (exceeded) – Water quality didn’t improve ● Maybe the key is to reconnect the swamp on the southern shoreline with the lake – Increase tannin loads – Increase TP, most likely – But decrease chl-a ● Raise the lake? ● Bring lake water to swamp? ● Lower the swamp? ● These projects are not compatible with TSI ● These projects could occur with EPA NNC as guidance

30 EPA NNC 30 ● More appropriate targets than TSI ● Will work with locally-appropriate restoration projects ● But will it save money? ● How does impairment status match up with TSI?

31 NNC vs. TSI – comparison from Winter Haven Interior Lakes. Which list would you prefer to see? 31 LakeImpaired by FDEP? TMDL required?Impaired with NNC? BuckeyeYes – nutrientsYesInsufficient data DaisyYes – nutrientsYesInsufficient data ElbertYes – nutrientsYesUnimpaired MarthaYes – nutrientsYesUnimpaired MaudeYes – nutrientsYesUnimpaired PansyYes – nutrientsYesImpaired* SilverYes – nutrientsYesUnimpaired * Pansy unimpaired if color was 40 PCU (vs. current 39)

32 Comparisn of two systems: WHCOL vs. WHIL (at different scales) 32

33 WHCOL vs. WHIL 33 ● Similarities – Both have highly developed watersheds (up to 80% or more) – Both have lakes with history of point source discharges ● Differences include – WHCOL are connected by canals ● Canals are connected to regional drainage features (Peace and Saddle Creeks) ● Most lakes in WHCOL are ca. 5 feet lower than historical levels – WHIL are not (for the most part) connected by canals ● Less data, but no evidence yet that WHIL lakes are lower than historical levels

34 WHCOL vs. WHIL 34 WHCOLWHIL Number of Lakes 2529 Lakes declared impaired by FDEP 197 Lakes with sufficient data for NNC (using EPA guidance) 255 Lakes with sufficient data that would be impaired with NNC 18 (72%)0 (0%)

35 Why the difference in percent impaired with NNC? 35 ● Roughly similar levels of urbanization ● Some of WHIL are substantially deeper than WHCOL ● But, main difference could be WHIL do not appear to have been lowered as much as WHCOL – For Ridge lakes, WHCOL closer to mucky bottom – For Swale lakes, WHCOL more likely to have become disconnected from adjacent swamps ● For lakes in Florida, hydrology can be more important than nutrients

36 Findings consistent with literature 36 ● Terrell et al. (2000) – Examined data from 127 Florida lakes – Trends examined for 1967 to 1997 ● Overall increases in chlorophyll-a ● No overall trend in nitrogen ● Overall decrease in phosphorus – Did NOT conclude that nutrients were unimportant – Did conclude that factors such as altered hydrology and control of Hydrilla could be more important than nutrients

37 NNC is an improvement over TSI, but focusing on nutrients alone (i.e., TMDLs, NNC, MS4 permits, stormwater retrofits, etc.) is overly simplistic, and not likely to be successful for lake management 37

38 Questions? 38


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