Ed Dunne, Ph.D, Division of Environmental Sciences, SJRWMD P.O. Box 1429, Palatka, FL 32178; ph: A Case Study in Lake Management Issues

 Issues in lake management  Approach to lake restoration/enhancement  Lake Apopka and historical sketch  Time series of:  basin changes and nutrient loading  Nutrient budgets and water quality trends  Total P, Chl a, Transparency, TSS  Management practices  Within watershed, within lake  Lake Improvements  Accessing lake data  Water levels and water quality Overview

Water Management Districts in Florida

18 Counties in the Districts

Ten Major Watersheds

Source: Florida 2010 Lakes, Reservoirs, and Ponds 2010

Lakes, Reservoirs, and Ponds 2010: Causes of impairment Source:

Multipronged approach to deal with impairment Restoration/Enhancement   Reduce nutrient load to the lake   Cost effective nutrient program to:   Remove   Reduce Source Control Within Watershed Mitigate Loss Within Lake

Controlling and Mitigating Eutrophication Reduce P loading Lower P concentration & plankton Increase water transparency Increase SAV Increase game fish Time Improved Ecosystem Health

Multipronged approach to lake improvement Lake water quality Water levels Restoring Wetlands Storm water Acquiring land TMDL Control of Hydrilla Planting littoral zone Marsh Flow-Way Shad Harvest Within Watershed Within Lake

Lake Apopka

A lake and it’s watershed

Lake Apopka Historical timeline: 1880s-2010s   1880s Land around the lake $0.25/acre   1890s Apopka Beauclair Canal   1920s Sewage, wastewater, hurricanes (6-8ft)   1940s Muck farms on NS, lake levee, hurricanes, blooms, < SAV   1950s Water control structures on ABC   1960s Fish kills, pesticide use by agriculture   1970s State/federal restoration, bacterial disease, bass failing, 4 fish camps   1980s Tower Chemical, fish kill, Apopka and SWIM Acts, no fish camps, pilot projects initiated, $15 million land purchase   1990s FOLA, MFW pilot project, shad harvest, Act ’96 (P criterion), $100 million land purchase, bird die off   2000s TMDL, MOU, MFW, reflooded 5,000 acres of NSRA   2010s Bird list = 346 sp., MFW, shad, BMAP projects, reflooded 10,000 acres, > SAV

Time series: Basin changes, P loading, and water quality

Sources: Lake Apopka External Nutrient Budget ; Schelske et al., Basin Land Use Changes

Major Former Farm Areas Source: Lake Apopka External Nutrient Budget

Basin Land Use Changes

Phosphorus Loading to Lake Apopka Measured Estimated from literature Loading g m -2 yr -1

Phosphorus Loading to Lake Apopka

Total Phosphorus (P) (mg/L)

Total P (metric tons) and Stage

Relationship between chl. a and total P

Chlorophyll a (µg/L)

Relationship between TSS and chl. a

Total Suspended Solids (mg/L)

Secchi depth (meters)

Some management practices to help improve the lake Within lake Within watershed

Reflooding Ag. lands back to Wetlands RESULTS  2000 Initial flooding of Duda Sub-East 680 acres  2011 Flooding to date about 10,000 acres Phased Approach  Environmental Site Assessments, Risk Assessment  BA, BO, biota monitoring during flooding  Prior to flooding:  Field prep., which included soil amendment (3,000 ha; $2.5 m)  Remediation to reduce OCP - deep ploughing (1,620 ha; $9.6 m)

2000 Phased Approach to Flooding Maps produced by P. Bowen

2005 Phased Approach to Flooding Maps produced by P. Bowen

2010 Phased Approach to Flooding Maps produced by P. Bowen

2011 Phased Approach to Flooding 9,870 acres flooded Maps produced by P. Bowen

Gizzard Shad Harvest on Lake Apopka RESULTS  mT/yr of fish harvested  P removal in fish = 2-3 mT/yr GOALS  Remove P in fish bodies  Reduce recycling of P caused by bottom feeding  Reduce turbidity caused by bottom disturbance

Gizzard Shad Harvest on Lake Apopka

Marsh Flow-way REMOVAL RESULTS  TP: 2 mT, 28%, 0.8 g m -2 yr -1  TSS: 4,000 mT, 91%, 1,300 g m -2 yr -1  TN: 80 mT, 22%, 26 g m -2 yr -1 GOALS  Maximize P removal from the lake  Provide wetland habitat

Total Phosphorus

Total Suspended Solids

Total Nitrogen

Evidence for Lake Improvement

PrePost Pre = period used to measure baseline loading for TMDL development (Magley, 2003) Post = period to include years with both normal and low lake stages Total Phosphorus (P) (mg/L)

Changes in Lake Apopka Concentrations & Loads ParameterUnitsComparison period Pre (‘89-’94) Post (‘03-’10) Change TP loading mT/yr % TP mg/L % Chl a µg/L % Secchi m % TSS mg/L % TP mT % TSS mT17,53310,927-38% TN mT1, %

YearArea (acres) Changes in areal coverage of Vallisneria americana along Lake Apopka shoreline

Accessing lake data