1.1 Project Background

With a surface area of approximately four square miles, Lake Tarpon is the largest freshwater lake in Pinellas County. Because of its historic excellent water quality and rich fish and wildlife resources, the lake has served as a regionally important recreational resource for many decades. In recent years, however, Lake Tarpon and its associated natural resources have begun to exhibit signs of ecological stress.

While it is likely that increasing urban development in the watershed has increased pollutant loadings to Lake Tarpon, a series of major public works projects begun in 1967 probably simultaneously affected the natural assimilative capacities of the lake. An outfall canal with an earthen dam to separate the lake from Tampa Bay was completed in July of 1967 by the U.S. Army Corps of Engineers as a measure to control periodic flooding around the lake. This canal was to augment the only outfall existing at the time which was via a natural sinkhole. The sinkhole, located halfway down the western shoreline was, until May, l969, connected through the Floridan aquifer to Spring Bayou in Tarpon Springs. In 1969, the Southwest Florida Water Management District (SWFWMD) constructed an earthen dike around the sink preventing any flow between the lake and the sink, cutting off the lake's primary source of saline water, and making the outfall canal the only point of discharge. In July, 1969, part of the dam in the south canal was removed for high water discharge, and by 1971 the dam was replaced with gated culverts. In 1972, SWFWMD adopted and implemented a controlled lake level fluctuation schedule.

In the summer of 1987, Lake Tarpon suffered a major bloom of blue-green algae (Anabaena circinalis) that covered 80% of the lake. The bloom persisted for much of the summer and severely impacted recreational and aesthetic use of the lake during the prime recreational season. Extremely low dissolved oxygen concentrations were noted in several residential canals and minor fish kills were reported. The lake's surface was blanketed by a characteristic scum of algal cells and pigments from lysed algal cells, and a typical "geosmin" odor was associated with the bloom. As a result of the perceived ecological degradation, Pinellas County, responding to concerned local citizens, petitioned the SWFWMD to place Lake Tarpon on the list of priority water bodies to be remediated under the newly enacted Surface Water Improvement and Management (SWIM) program. In late 1987 Lake Tarpon was subsequently designated by the SWFWMD as the seventh ranked SWIM priority water body.

In addition to the actions of the SWFWMD, the Pinellas County Board of County Commissioners passed a Special Resolution in July of 1987 creating the Lake Tarpon Management Committee (LTMC). The intent of the Resolution was to create a multi-agency committee to formulate a "Plan of Action" whereby a long term lake management plan would be developed and implemented for Lake Tarpon. The plan was to specifically address the causes and potential remediation measures for the 1987 algae bloom; however, long term effective lake management was stressed as the primary mission. The originally intended tenure of the LTMC was not defined by the Resolution. The original members of the LTMC included representatives of the following:

Since its inception, the LTMC has continued to meet on a more or less monthly basis, and has served as a very effective forum for the discussion of lake management issues. By virtue of its representation by key state environmental regulatory and management agencies, the committee has generally functioned efficiently as a vehicle for developing technical consensus on decisions related to research, funding, and resource management. The primary responsibilities and accomplishments of the LTMC during its first decade of existence have included the:

In May of 1989, the SWFWMD completed the Lake Tarpon SWIM Plan. Since relatively little was known about the hydrology and ecology of Lake Tarpon, this initial plan focused primarily on the design of diagnostic studies aimed at identifying lake management problems and determining possible causes for those problems. An inter-local Agreement between Pinellas County and the SWFWMD was subsequently executed whereby the SWFWMD was to provide matching funds to Pinellas County to support a variety of diagnostic/feasibility studies. Pinellas County was to be responsible for providing in-kind funding for the studies, and for selecting and managing a consultant to perform the work. The Lake Tarpon Diagnostic/Feasibility Study project was subsequently initiated in March of 1990, and completed in April of 1992.

The primary objective of the diagnostic/feasibility project was to generate much of the scientific data necessary to advance the Lake Tarpon SWIM Plan beyond the study phase. Specifically, the multi-faceted project included investigations on: ambient water quality; nutrient loadings from atmospheric fallout, stormwater runoff, and groundwater; sediment quality, accumulation rates, and nutrient release; phytoplankton community characterization; and temporal and spatial trends in emergent vegetation. The biotic, physical and chemical data obtained from the study were utilized to qualitatively characterize the current hydrological and ecological conditions, and to develop quantitative water and nutrient budgets for the lake. In addition, the diagnostic/feasibility project established the scientific basis for setting a number management goals for the lake and its watershed.

Another objective of the diagnostic/feasibility study was to develop a linked watershed/waterbody model on a PC/GIS platform. The model was completed as a deliverable of the project, and is known as the Lake Tarpon Management Model. The ultimate goal and application of this predictive mathematical model was to aid in the development and evaluation of various management options and Best Management Practices (BMPs) aimed at reducing non-point source nutrient loads to the lake. Although various preliminary management options were proposed for consideration in the diagnostic/feasibility study, the development of a comprehensive management plan was not part of the scope of work.

Policy 3.1.4 of the Conservation Element of the Pinellas County Comprehensive Plan calls for the systematic development of watershed/waterbody-specific management plans for all major drainage basins in the County on a priority basis. With regard to the Lake Tarpon watershed, separate plans were to be developed for the Lake Tarpon, Brooker Creek, and South Creek drainage basins. Although water quality conditions in Lake Tarpon stabilized somewhat after the major algal bloom of 1987, monthly monitoring data indicated that water quality began to decline again in 1993 (Leasure, 1995). This trend prompted the County to expedite the watershed planning process, and initiate the development of a comprehensive management plan specifically for the Lake Tarpon drainage basin. In September of 1994, Pinellas County entered into an agreement with Coastal Environmental, Inc. to prepare the Lake Tarpon Drainage Basin Management Plan (the Plan). Building upon the work of the diagnostic/feasibility study, the Plan is to be composed of management policies and best management practices - both structural and non-structural - aimed at restoring and/or maintaining the hydrological and ecological integrity of the lake and its immediate watershed. As such, the Plan should specifically include recommended management options and BMPs addressing priority lake and watershed management issues identified by the LTMC.

This document - The Lake Tarpon Drainage Basin Management Plan - represents the culmination of a decade of resource planning activity undertaken by numerous governmental agencies and key individuals. The management actions recommended herein are based on the extensive knowledge gained from the scientific/engineering studies and monitoring programs conducted to date, and represent the most cost-effective means of attaining the adopted goals of the LTMC.

1.2 Purpose and Objectives of the Plan

The primary purpose of the Lake Tarpon Drainage Basin Management Plan is to provide implementation guidance for the Pinellas County Growth Management Plan with respect to lake, wetland, and upland management issues in the Lake Tarpon basin. As such, the Plan is to provide specific recommended management options addressing the following management objectives:

Because concern over declining water quality was the original driving force behind the planning process, the primary focus of the Plan was the development and evaluation of various BMPs and other structural and non-structural remediative measures to reduce external and/or internal pollutant loadings to Lake Tarpon, while maintaining effective public flood protection. The reach of the Plan, however, extends well beyond water quality and flood control issues. Using the evolving "ecosystem management" approach, the Plan addresses the interactions between water quality and quantity, and dependent living resources such as fish, wildlife and natural habitats.

Furthermore, the Plan acknowledges that people are key components of the Lake Tarpon ecosystem. As such, the above listed management objectives need to be met while allowing for reasonable and prudent growth and redevelopment within the Lake Tarpon basin. Therefore, the Plan recognizes the socioeconomic benefits of the lake to the County and affected homeowners and businesses, and accommodates the multiple uses of this precious resource in a balanced manner. In this regard, it will serve to improve the effectiveness of existing resource management activities, and reduce the impact of future growth and redevelopment in the watershed.

In addressing the above listed management objectives, the Plan presents the development and prioritization of a wide range of recommended management options in an integrated manner. In addition to the evaluation of structural BMPs in the watershed, and in-lake remediative measures, the Plan further addresses the project objectives through a variety of regulatory, management, and policy components. The Plan is broken down into the following nine primary components.

1. Structural Components.

2. Management Components.

3. Legal Components.

4. Compliance and Enforcement Components.

5. Policy Components.

6. Social and Recreational Components.

7. Operation and Maintenance Components.

8. Public Education Components.

9. Monitoring Components.

In summary, the primary purpose of the Plan is to serve as a comprehensive, multi-use natural resource improvement and management guide for Lake Tarpon and its immediate watershed. The ultimate goal of the Plan is the optimization of all beneficial uses of the lake and its watershed such that these uses are sustained for future generations without compromising the integrity and functions of the Lake Tarpon ecosystem.

1.3 Plan Organization

This document, the final Lake Tarpon Drainage Basin Management Plan, presents a synthesis of the various management recommendations developed and considered during the diagnostic/feasibility and planning processes, and provides an integrated summary of the preferred alternatives. The Plan document has been prepared to provide a succinct description of the various recommended management options and components. An attempt has been made to provide sufficient background information regarding the rationale and justification for each of the management recommendations, however, the reader is encouraged to review the individual Interim Task Reports prepared during the planning process if more detailed information is desired. In addition to the detailed information provided in each of the Interim Task Reports, other ancillary project deliverables generated in the development of this Plan, including maps and survey data, are available from the Pinellas County Department of Environmental Management.

This document is organized as follows:

Section 2.0 presents a discussion of the identified lake and watershed management issues, and summary of existing conditions.

Section 3.0 presents a discussion of the planning and alternatives analysis process for nutrient load reduction, the primary goal of the Plan. In addition, a technical justification for the full implementation of the Plan is presented.

Section 4.0 presents the recommended Plan, including a summary of the adopted lake and watershed management goals and level-of-service targets, and a detailed description of the various components and elements of the Plan.

Section 5.0 presents a summary of the recommended monitoring and success evaluation program.

Section 6.0 presents the recommended capital improvement and Plan implementation schedule.

Section 7.0 presents a summary of the financing requirements of the Plan as well as various financing options.

Section 8.0 provide a listing of the references cited in this document.

Section 9.0 contains a compendium of public comments on the draft Plan as well as written responses to each indicating revisions made to the final Plan, as appropriate.