Florida s Small Lakes Cycle One Jan 2000 Dec 2003

Transcription

1 Florida s Small Lakes Cycle One Jan 2000 Dec 2003 Florida Department of Environmental Protection Watershed Monitoring and Data Management Presented by Margaret Murray March 2005

2 Florida s Small Lakes Cycle One DEP Status Network Types of Lakes Sample Analytes and Median Results

3 Status Network Objective To provide scientifically defensible, statewide and watershed (basin) information on important chemical, physical and pertinent biological characteristics from surface waters and major aquifer systems in Florida.

4 Northwest Florida WMD Suwannee River WMD St. Johns River WMD Status Network Rotating Basin Sampling Units Southwest Florida WMD South Florida WMD

5 Status Network Small Lake Sample Sites

6 Status Network What makes the Status Network different from other sampling programs? Sampling Design Trained Samplers Field Quality Assurance/Quality Control DEP Lab analyzes all samples Lab QA/QC Data Review

7 Types of Florida Lakes Sinkhole lakes (solution, cover-collapse, cover-subsidence) Depressions in ancient seabed River lakes Coastal dune lakes Extraterrestrial origin Artificial lakes

8 Sinkhole Lakes Lake Eustis, Lake County

9 Sinkhole lakes Cover-collapse Most common type in Florida Solution cavity develops in limestone can t support overlying weight, abrupt collapse Water table rises forms lake f

10 Sinkhole Lakes - Solution Occurs where limestone exposed at surface or covered by thin layer of soil Solution along surface, cracks, fractures Soil subsides, bowl shape Clay forms impermeable seal Collects surface runoff and forms lake or pond

11 Sinkholes Cover-subsidence Noncohesive and permeable sand and clay (former coastal sediments and beach deposits) over limestone Grains move down and replace grains moving into limestone cavity Very small if sand cover is feet thick

12 Depression Lakes Natural depressions in ancient limestone bedrock Formed by wave action or water currents as sea levels rose and fell Shallow, bowl-shaped Generally elongated, or appear threaded together, along the coast or near rivers Lake Helen Blazes, Brevard County, Large Lake

13 Fluvial Lakes Develop as river carries and deposits sediments along the river bank River can enlarge existing water bodies, create natural levies that form a new waterbody, or leave a remnant oxbow waterbody Appear elongated and occur in linear chains or as U- shaped oxbow lakes. Lake Harney along St. John s River

14 Coastal Dune Lakes Long shore currents deposit sediments, cut off water from bay Landlocked lake becomes fresh Intermittently high salinity (hurricanes) Draper and Big Redfish Lakes, Walton County

15 Extraterrestrial Influenced Lakes Meteor impact makes crater, fills with water

16 Artificial Lakes Reservoir Lakes Retention Ponds Real Estate Lakes, Borrow Pits Agriculture Ponds Aquaculture Ponds Mining Ponds Lake Ella, Tallahassee

17 Lake Hydrology Seepage Lakes Dominated by rainfall, evaporation and groundwater No surface water outflow Longer residence time Lake level reflects water table altitude Drainage Lakes Dominated by surface water outflow Shorter residence time Lake level reflects altitude of surface water outlet

18 Small Lake Analytes, Cycle One Field Dissolved Oxygen, ph, Specific Conductance, Temperature, Secchi Depth Biology Fecal Coliform, Enterococci, Chlorophyll, Algal Growth Potential, Phytoplankton ID Chemistry Calcium, Magnesium, Alkalinity, Sulfate, Fluoride, Sodium, Chloride, Potassium, Nitrate-Nitrite, Total Kjeldahl Nitrogen, Ammonia, Orthophosphate Total Phosphorous,

19 10,630 small lakes 6,930 sampleable lakes We sampled 564 lakes

20 Sampled Lakes Lower 5% 4.47 Median 7.21 Upper 5% 8.82 State-wide Sampleable Lakes Wt. Avg Criteria % meet criteria

21 Sampled Lakes Lower 5% 0.65 (MDL) Median 32 Upper 5% 161 State-wide Sampleable Lakes Wt. Avg. 59 Criteria > 20 62% meet criteria

22 Sampled Lakes Lower 5% 5 Median 50 Upper 5% 250 State-wide Sampleable Lakes Wt. Avg. 67 Clear 20 38% clear

23 Trophic States

24 Trophic State Categories Visible Depth (feet) Total Phosphorous (µg/l) Total Nitrogen (mg/l) Chlorophyll (ug/l) Oligotrophic > 13 < 15 < 0.4 < 3 Mesotrophic Eutrophic Hypereutrophic < 3 > 100 > 1.5 > 40 http //lakewatch.ifas.ufl.edu/circpdffolder/trophic2.pdf from Forsberg and Ryding, 1980

25 Phosphorus 15% 29% Trophic State of Sampleable Lakes Phosphorus Oligotrophic < 15 µg/l Mesotrophic µg/l 35% Eutrophic µg/l 21% Hypereutrophic > 100 µg/l Total Nitrogen Chlorophyll Secchi 21% 8% 18% 13% 5% 31% 18% 27% 46% 53% 14% 46%

26 Sampled Lakes Lower 5% Median Upper 5% 0.51 State-wide Sampleable Lakes Wt. Avg

27 Sampled Sites Lower 5% 0.29 Median 0.87 Upper 5% 2.9 State-wide Sampleable Lakes Wt. Avg. 1.16

28 Sampled Lakes Lower 5% 0.85 (MDL) Median 2.6 Upper 5% 82 State-wide Sampleable Lakes Wt. Avg. 18.5

29 Sampled Lakes Lower 5% 0.1 (MDL) Median Upper 5% 13.9 State-wide Sampleable Lakes Wt. Avg Productivity Low 22% Mod. 29% ModHi 33% High 16%

30 Sampled Lakes Lower 5% 1.96 Median 7.13 Upper 5% State-wide Sampleable Lakes Wt. Avg Criteria 5 78% meet criteria

31 Sampled Lakes Lower 5% 1 (MDL) Median 8 Upper 5% 390 State-wide Sampleable Lakes Wt. Avg. 114

32 Sampled Lakes Lower 5% 1 (MDL) Median 2 Upper 5% 240 State-wide Sampleable Lakes Wt. Avg. 50

33 Cycle Two 5 years, 29 basins, 30 samples per basin Exclude artificial lakes Revised analyte list Less water chemistry Added sediments Lake Vegetative Index

34 The End