Lake Okeechobee: Current and Future Management ChallengesLake Okeechobee: Current and Future Management ChallengesPaul V. McCormick, R. Thomas James, & Susan GrayWatershed Management Department, South Florida Water Management District

Paul V. McCormick, R. Thomas James, & Susan GrayWatershed Management Department, South Florida Water Management District

22

Lake Okeechobee – A RegionalMultipurpose Water ResourceLake Okeechobee – A RegionalMultipurpose Water Resource

Lake Uses:

Water SupplyFlood ProtectionNavigationFishingRecreationWildlife

33

Lake Okeechobee – The PastLake Okeechobee – The Past

44

Lake Okeechobee – The PresentLake Okeechobee – The Present

55

Rehabilitation, NOT RestorationRehabilitation, NOT Restoration

Extent of landscape change precludes true restorationRehabilitate lake to:• prevent water-quality impairments• improve in-lake biological conditions

• submerged and emergent vegetation • fisheries• wading birds• endangered species

Lake improvements benefit downstream ecosystems

66

Three Critical IssuesThree Critical Issues

Extreme Water Levels

Excessive Phosphorus Loads

Exotic Species

77

Year1970 1980 1990 2000

Lake

Sta

ge (f

t. N

GVD

)

8

10

12

14

16

18

20

Historic vs. Desirable Lake StagesHistoric vs. Desirable Lake Stages

88

Impacts of Extreme High Water LevelsImpacts of Extreme High Water Levels

Poor nearshore water qualityLoss of submerged vegetation (SAV)Stressed emergent vegetationAccumulation of organic bermAlgal blooms

Pelagic

Near-shore

Littoral

99

1010

Impacts of Extreme Low Water LevelsImpacts of Extreme Low Water Levels

Negative Impacts:Loss of littoral zone habitatLoss of key fauna Increased spread of exotic plants

Positive Impacts:Regeneration of emergent plant speciesOxidation, burning, and removal of accumulated detritusImproved control of exotic plants

1111

Water Level Extremes – SolutionWater Level Extremes – Solution

Options:Surface-water reservoirsAquifer Storage and Recovery (ASR)Private lands

Alternative storage for ~ 1 million acre-ft of water

1212

Phosphorus Loads and Concentrations:Historical TrendsPhosphorus Loads and Concentrations:Historical Trends

1970 1980 1990 2000 2010

Ann

ual T

P Lo

ad (m

t)

0

200

400

600

800

1000

1200

1400

TMDL

1970 1980 1990 2000 2010Cum

ulat

ive

Sedi

men

t Loa

d (m

t)

0

2000

4000

6000

8000

10000

12000

1970 1980 1990 2000 2010

Prop

ortio

n of

Lak

e M

ass

to S

edim

ents

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1970 1980 1990 2000 2010

In-L

ake

TP (p

pb)

0

50

100

150

200

250

Target

1313

Phosphorus ImpactsPhosphorus Impacts

Increased in-Lake P concentrations and lower N:P ratiosIncreased frequency of cyanobacterial bloomsLoss of benthic invertebrate biodiversityExpansion of cattail in the lake’s wetlandIncreased P export downstream

1414

Phosphorus ControlPhosphorus Control

Lake Okeechobee TMDL• in-lake TP = 40 ppb• algal bloom frequency < 5%• External load = 140 mt P/yr

Watershed P Control ProgramsChallenges:• Legacy P

• 176,000 mt• ~50% potentially mobile

• Internal P Loading• 35,000 mt sediment P• Internal P load ~ external load

1515

Exotic Species – Success StoriesExotic Species – Success Stories

1616

Exotic Species – Success StoriesExotic Species – Success Stories

1717

Exotic Species – New InvadersExotic Species – New Invaders

The South American watergrass, Luziola subintegra

Welcome to south Florida!

1818

Exotic Animals – A Source of Concern?Exotic Animals – A Source of Concern?

Exotic fishes in Lake Okeechobee

Blue tilapia(Oreochromis aurus)Peacock bass (Cichla ocellaris)Callichtyid catfish (Hoplosternum littorale)Common carp (Cyprinus carpio)Convict cichlid (Cichlasoma nigrofasciatum)Grass carp (Ctenopharyngodon idella)Green sunfish (Lepomis cyanellus)Jack Dempsey (Cichlasoma octofasciatum)Jewelfish (Hemichromis bimaculatus)Sailfin catfish (Liposarcus multiradiatus)Mayan cichlid (Cichlasoma urophthalmus)Oscar (Astronotus ocellatus)Pacu (Colossoma sp.)Spotted tilapia (Tilapia mariae)Suckermouth catfish (Hypostomus plecostomus)Walking catfish (Clarias batrachus)

1919

Progress to dateProgress to date

Development and implementation of watershed P-reduction programs• Dairy buy-outs and remediation• BMPs• Dairy BATs

Critical construction projects (STAs)Control of exotic vegetationImprovements to Lake Regulation Schedule

2020

Performance Measures – A “Report Card”Performance Measures – A “Report Card”

25,602 acres>40,000 acresSAV cover

Not consistentlyattained

~15.5’ in Jan to~12.5’ in June

Spring recession

4.8% of samples<5% of samplesAlgal Bloom Frequency

114 ppb40 ppbNearshore TP

184 ppb40 ppbPelagic TP

558 mt/yr140 mt/yr(by 2015)

TP Load

WY’04-’08 AverageGoal

Performance Measure

2121

Future ChallengesFuture Challenges

Alternatives for water storage Achieve TMDL by 2015Sediment managementPopulation growth and urbanizationMaintaining a long-term commitment Confronting uncertainty and surprise

2222

Questions?Questions?