NUTRIENT CONCENTRATION, DISTRIBUTION AND TRANSPORT FROM THE EAST COAST CANALS TO BISCAYNE BAY AND WATER-QUALITY TRENDS AT SELECTED SITES IN SOUTH FLORIDA

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NUTRIENT CONCENTRATION, DISTRIBUTION AND
TRANSPORT FROM THE EAST COAST CANALS TO BISCAYNE
BAY AND WATER-QUALITY TRENDS AT SELECTED SITES IN
SOUTH FLORIDA

• South Florida Ecosystem Program

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INTRODUCTION

• Biscayne Bay Is An Oligotrophic Subtropical
  Estuary Which Provides Habitat To A Variety Of
  Plant And Animal Life
• Nutrient-laden Discharges From East Coast Canals
  Threaten Ecological Health Of Bay (Biscayne Bay
  SWIM Plan)
• Ecosystem Restoration Plans Diversion Of
  Discharges To Biscayne Bay To Re-establish
  Natural Flow To Everglades National Park

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INTRODUCTION(CONTINUED)

• Anthropogenic Activities Are Major Source Of
  Nutrients And May Result From Urban And
  Agricultural Runoff
• Adverse Effects Of Excessive Nutrients
• Eutrophication
• Algal Blooms
• Phytoplankton Growth
• Decreased Light Penetration Harmful To Submerged
  Aquatic Vegetation
• Hypoxia/anoxia

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PROJECT OBJECTIVES

• Determine Method For Estimating Loads From Canals
  To Bay
• Characterize Nutrient Concentration And
  Distribution In The East Coast Canals
• Evaluate Sampling Methods In Order To Document
  Most Representative Manner Of Sample Collection
• Determine Long-term Trends at Selected Sites in
  South Florida

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DESCRIPTION OF PROJECT

• Samples Collected Upstream Of Gated Control
  Structures At East Coast Canals During Periods Of
  Flow
• Depth-integrated And Point Or Grab Samples
  Collected
• Depth-integrated Samples Collected By
  Equal-Width-Increment (EWI) Using Weighted Bottle
  Since Velocities lt 2.0 Ft/sec
• Instantaneous Discharge Determined for Each
  Sampling Event

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DESCRIPTION OF PROJECT (CONTINUED)

• Samples Analyzed For
• Total Organic Nitrogen
• Total Ammonia
• Total Nitrite And Nitrate
• Total Phosphorus
• Total Orthophosphate
• Kjeldahl Nitrogen (Calculated)
• Total Nitrogen (Calculated)

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LOCATION OF SAMPLING SITES
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DESCRIPTION OF PROJECT(CONTINUED)

• Depth-integrated Samples Collected By
  Equal-Width-Increment (EWI) Method
• Stream Width Subdivided Into Equal Width
  Intervals With Sampling Vertical Associated With
  Each Interval
• Vertical With Highest Velocity Is Selected And
  Sampler Is Raised And Lowered At Constant Rate So
  Bottle Is Not Overfilled When Returned To Surface
  

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DESCRIPTION OF PROJECT(CONTINUED)

• Depth-integrated Samples (Continued)
• Same Transit Rate Used In All Verticals But
  Sample Volume May Be Different
• Samples Composited In Churn Splitter
• Samples Collected In Amber Polyethylene Bottles
  And Chilled To 4 Degrees Centigrade And Sent To
  Lab

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FIGURE SHOWING EWI SAMPLING
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DESCRIPTION OF PROJECT(CONTINUED)

• Point Or Grab Samples
• Collected At 0.5 Or 1.0 Meter Below Water Surface
  in Middle of Stream
• Niskin Bottle Or Van Dorn Sampler

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SNAPPER CREEK AT S-22 LOOKING UPSTREAM
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SNAPPER CREEK AT S-22 DOWNSTREAM
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SAMPLES COMPOSITED IN CHURN AT BRIDGE UPSTREAM OF
S-22
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SAMPLES COLLECTED WITH VAN DORN SAMPLER AT
SNAPPER CREEK S-22
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DESCRIPTION OF PROJECT(CONTINUED)

• Nutrient Concentrations In East Coast Canals
• Total Organic Nitrogen Ranged From 0.20 To 1.7
  Mg/l And Median Was 0.75 Mg/l
• Ammonia Ranged From 0.01 To 1.5 Mg/l And Median
  Was 0.10 Mg/l
• Nitrate Ranged From .001 To 4.38 Mg/l And Median
  Was 0.18 Mg/l

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DESCRIPTION OF PROJECT(CONTINUED)

• Nutrient Concentrations (Continued)
• Total Nitrogen Ranged From 0.31 To 4.7 Mg/l And
  Median Was 1.47 Mg/l
• Total Phosphorus Ranged From .004 To 0.31 Mg/l
  And Median Was 0.02 Mg/l
• Orthophosphate Ranged From lt.001 To 0.26 Mg/l And
  Median Was .005 Mg/l

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DESCRIPTION OF PROJECT(CONTINUED)

• Five Sites (G58, G93, S-26, S-27, And S-123) Had
  Ammonia Concentrations That Exceeded The
  Miami-Dade DERM Standard Of 0.5 Mg/l
• Maximum Total Phosphorus Concentration Of 0.31
  Mg/l At G58 (Arch Creek) Was Above Recommended
  EPA Upper Limit Of 0.10 Mg/l To Control
  Eutrophication

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DESCRIPTION OF PROJECT(CONTINUED)

• Nutrient Distribution In East Coast Canals Based
  On Land Use Categories
• Agricultural (S-20f, S-20g, S021, S21a)
• Urban (G-58, G-93, S-22, S-25, S-25b, S-26, S-27,
  S-28, S-29, S-123)
• Wetland (S-20)

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MEDIAN TOTAL ORGANIC NITROGEN CONCENTRATIONS WERE
HIGHEST IN WETLAND AND URBAN AREAS
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MEDIAN CONCENTRATIONS OF TOTAL AMMONIAWERE
HIGHEST IN URBAN AREAS
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MEDIAN NITRATE CONCENTRATIONS WERE HIGHEST IN
AGRICULTURAL AREAS
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MEDIAN TOTAL PHOSPHORUS CONCENTRATIONS WERE
HIGHEST IN URBAN AREAS
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DESCRIPTION OF PROJECT(CONTINUED)

• Comparison Of Grab With Depth-integrated Samples
  For Total Nitrogen And Total Phosphorus
• Wilcoxon Signed Rank Test Exact Form Of The
  Test Statistic
• Comparison Between Grab Samples At 0.5 Meter
  Depth And EWI Samples
• Comparison Of Grab Samples At 1.0 Meter Depth And
  EWI Samples
• Comparison Of Grabs At 0.5 Meter Depth And 1.0
  Meter Depth

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DESCRIPTION OF THE PROJECT(CONTINUED)

• Statistical Interpretation Of Differences Between
  Grab Samples And Depth-integrated Samples
• Total Nitrogen
• No Significant Differences Between Grabs And
  Depth-integrated Samples (Plt.025)

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DESCRIPTION OF PROJECT(CONTINUED)

• Statistical Interpretation Of Differences
  (Continued)
• Total Phosphorus
• Three Sites (25) Showed Significant Differences
  Between Grabs At 1.0 Meter Depth And
  Depth-integrated Samples
• One Site (33) Showed Differences Between Grabs
  At 0.5 Meter Depth And Depth-integrated Samples

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DESCRIPTION OF PROJECT(CONTINUED)

• Water-Quality Cross-section Surveys
• Document Water-Quality Homogeneity In The East
  Coast Canal System
• At Several Sites Temperature, Dissolved Oxygen,
  pH, And Specific Conductance Measured Beneath
  Surface And At 2-foot Intervals To Streambed
• Dissolved Oxygen Was Only Parameter Showing
  Variation In Cross-section

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DESCRIPTION OF PROJECT(CONTINUED)

• Water-Quality Cross-section Survey At Snapper
  Creek At S-22
• Temperature, Dissolved Oxygen, pH, Specific
  Conductance Measured From 1.0 Foot Below Surface
  Every 2 Feet To Streambed
• Total Nitrogen And Total Phosphorus Samples
  Collected Every 2 Feet To Above Streambed

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DESCRIPTION OF PROJECT(CONTINUED)

• Water-Quality Cross-section Survey (Continued)
• Discharge Of 414 Cfs During Measurements
• Suspended Sediment Sample Collected By EWI And By
  Grab

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DISSOLVEDOXYGENDECREASEDWITHDEPTH
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TOTALNITROGENAND TOTALPHOSPHORUSINCREASED
WITH DEPTH
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DESCRIPTION OF PROJECT(CONTINUED)

• Suspended Sediment Sample Collected By EWI Method
  Was 3.0 Mg/l And By Grab Method Was 1.0 Mg/l
• Depth-integrated Samples Collected By EWI
  Probably More Accurately Reflect Phosphorus
  Concentration Than Those Collected As Grabs

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DESCRIPTION OF PROJECT(CONTINUED)

• Relation Between Grab And Depth-integrated
  Samples
• Line Of Organic Correlation (LOC) Describes
  Relation Between Two Variables. No Reduction in
  Variance of Estimated Values

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DESCRIPTION OF PROJECT(CONTINUED)

• Grab Samples Underestimate Phosphorus
  Concentration Compared To EWI Samples
• S-21 (0.5) Grab 0.25EWI .00625
• S-21 (1.0) Grab 0.2973EWI .0057
• S-25b (1.0) Grab 0.8255EWI - .0018
• S-28 (1.0) Grab 1.093EWI - .008

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DESCRIPTION OF PROJECT(CONTINUED)

• Determination Of Constituent Loads

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DESCRIPTION OF PROJECT(CONTINUED)

• Discharge Computed Corresponding to Each Sampling
  Event
• Fundamental Equations

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DESCRIPTION OF PROJECT(CONTINUED)

• Linear Regression Analysis To Develop Predictive
  Models
• Load Was Dependent Variable
• Discharge Was Explanatory Or Predictor Variable
• Best Model Based On Highest R-squared And Lowest
  Predicted Error Sum Of Squares (PRESS)
• R-squared Averaged 0.87 For Nitrogen Models And
  0.76 For Phosphorus Models

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DESCRIPTION OF PROJECT(CONTINUED)

• Log-linear Model Called Estimator Used At Miami
  Canal S-26
• Used For Load Estimation By NAWQA
• Continuous Discharge Data
• Minimum Of 50 Samples For Period Of At Least 2
  Years
• Minimum Variance Unbiased Estimator (MVUE) For
  Elimination Of Bias From Log Space To Real Space
  And Adjusted Maximum Likelihood Estimator (AMLE)
  For Censored Data

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DESCRIPTION OF PROJECT(CONTINUED)ESTIMATOR
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DESCRIPTION OF PROJECT(CONTINUED)

• Water-Quality Trends At Two Long-term Discharge
  Sites In South Florida
• Miami Canal At S-26 (1966 To 1994). Represents
  Flow Through Agricultural, Conservation and Urban
  Areas.
• Tamiami Canal 40-mile Bend To Monroe (1967 T0
  1993). Represents Overland Sheet flow From Big
  Cypress National Preserve.

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DESCRIPTION OF PROJECT(CONTINUED)

• Constituents Analyzed For
• Major Inorganics And Physical Characteristics
• Field Parameters Specific Conductance, pH,
  Dissolved Oxygen
• Suspended Sediment
• Nitrogen And Phosphorus Species
• Total Organic Carbon
• Trace Metals
• Fecal Coliform And Fecal Streptococcus
• Phytoplankton

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LOCATION OF SAMPLING SITES
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TAMIAMI CANAL OUTLETS
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OUTLET ON TAMIAMI CANAL IN BIG CYPRESS NATIONAL
PRESERVE
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MIAMI CANAL AT S-26
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DESCRIPTION OF PROJECT(CONTINUED)

• Extraneous Variation in Water-Quality Must Be
  Removed in Order to Ascertain Anthropogenic
  Changes on Water-Quality
• Extraneous Variation in Water-Quality Caused by
• Seasonality
• Discharge

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DESCRIPTION OF PROJECT(CONTINUED)

• ESTREND A Program For Determining Monotonic
  Trends In Water-Quality
• Non-parametric Seasonal Kendall Trend (SKT) Test
  To Remove Extraneous Variation
• SKT Applied To Time Series Of Flow-adjusted
  Concentrations (Residuals) From Regression Of
  Concentration With Discharge
• Time Series Of Non-adjusted Concentrations

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DESCRIPTION OF PROJECT(CONTINUED)

• Form Of Linear Models
• Conservative Constituents (Dissolved Solids,
  Cations And Anions)

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DESCRIPTION OF PROJECT(CONTINUED)

• Form Of Linear Models (Continued)
• Non-conservative Constituents (Nitrogen And
  Phosphorus Species, Suspended Sediment, Organic
  Carbon, Bacteria And Phytoplankton)
• Non-linear Method Fitting Concentration/discharg
  e Or Log Concentration/log Discharge Relation By
  LOWESS

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SUMMARY

• Nutrient Concentrations Vary In The East Coast
  Canals Based On Land Use Categories
• No Statistical Differences Between EWI And Grab
  Samples For Total Nitrogen But 25 Of Sites
  Showed Differences For Total Phosphorus
• Coefficients Of Determination (R2) For Nitrogen
  Models Averaged 0.87 And 0.76 For Phosphorus
  Models
• Long-term Trends At Miami Canal At S-26 And
  Tamiami Canal Showed Both Improvement And
  Deterioration In Water-Quality With Time

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WHERE DO WE GO FROM HERE?

• Continued Water-quality Monitoring At Tamiami
  Canal And Miami Canal At S-26
• Continued Water-quality Monitoring At East Coast
  Canal Sites

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ACKNOWLEDGEMENTS

• South Florida Water Management District Employees
• George Hwa, Control Room
• Ron Dempsey, Supervisor, Homestead Field Office
• Dawn Browning, Supervisor, Miami Field Office