LAKE TARPON MANAGEMENT STRATEGIES

LAKE TARPON MANAGEMENT STRATEGIES

The focus of the Lake Tarpon DBMP (PBS&J 1998) was the development and evaluation of various strategies to reduce external and/or internal nutrient loadings to improve and maintain good water quality. Staff from the District participated in the development of the DBMP (PBS&J, 1998) through their membership on the LTMC. Strategies included in this update of the Lake Tarpon SWIM Plan are those identified in the DBMP (PBS&J, 1998) that are consistent with the legislative directive of SWIM, which is to protect or restore water quality and natural systems. Analysis of the management issues and development of the management strategies are briefly discussed in Appendix A. For more detail the reader is directed to the Lake Tarpon Drainage Basin Management Plan developed for Pinellas County (PBS&J 1998).

Management Strategies for Water Quality

As previously discussed in the Management Issues section and in more detail in Appendix A, the primary concern with regard to water quality in Lake Tarpon is increasing productivity as measured by the amount of algae (chlorophyll-a) in the water. This condition results from an increase in nutrients entering the lake and from the recycling of these nutrients once they have entered the lake. Management strategies to control nutrients may focus on external and/or internal sources.

Based on the water and nutrient budgets shown in Appendix A (PBS&J 1998), external nutrient loading sources to Lake Tarpon include atmospheric deposition, direct runoff (modeled), Brooker Creek, septic tanks, and seepage from the surficial and Floridan aquifers. Internal nutrient sources include sediment resuspension, movement of nutrients from the sediment into the overlying water and decomposition of organic matter. Outflows of nutrients occur by discharge through the Lake Tarpon Outfall Canal, fish harvest, sedimentation and uptake by aquatic plants.

External Nutrient Loading: Stormwater runoff and septic tank leachate were identified as the only external sources of nutrients to Lake Tarpon that could be realistically managed. Nutrients from atmospheric deposition, precipitation and groundwater inflows are not considered to be manageable from a practical standpoint.

Based on the work done by PBS&J (1998), loads of total nitrogen (TN) and total phosphorus (TP) from modeled sub-basins in the Lake Tarpon watershed equals to 6.32 and 0.73 tons per year, respectively. This equates to 11.2 percent and 12.5 percent of the total loading of the two nutrients. Stormwater retrofit projects are designed to provide treatment for stormwater from previously untreated urban areas. The most common stormwater retrofit design includes the construction of wet detention ponds. However, stormwater treatment may be enhanced by the addition of alum treatment systems to remove phosphorus. The DBMP (PBS&J, 1998) identified enhanced stormwater treatment as a management strategy to control nutrients entering the lake from runoff and this SWIM Plan has recommended stormwater retrofit projects in the priority projects section.

The Lake Tarpon Ground-water Nutrient Study (ERM 1998), determined that inputs of TN and TP from the surficial and Floridan aquifers are 2.13 and 0.2 tons per year, respectively. This equates to 3.7 percent of the TN and 4.4 percent of the TP loadings in the nutrient budget for the lake (PBS&J 1998) and these loads are relatively low compared to the inputs from surface water inflows. However, based on modeling results, PBS&J (1998) concluded that TN and TP inputs from septic tank leachate comprised 11.5 and 14.0 percent of the nitrogen and phosphorus budgets. Unlike groundwater seepage, which is difficult to control, the conversion of septic tanks to central sewer facilities would effectively remove the nutrient inputs contributed by the septic tanks. However, based on groundwater monitoring conducted by ERM (1998), the impact of septic tank leachate on the lake is not conclusive. Therefore, this SWIM plan recommends the collection of additional groundwater data in the vicinity of the area served by septic tanks to better understand the relationship between septic tank leachate and water quality degradation. This additional data will also be useful in refining the nutrient budget for the lake.

Internal Nutrient Loading: The annual nutrient budget for Lake Tarpon indicates that approximately 36.5 percent of the TN and 72.2 percent of the TP inputs are retained within the lake and this is likely through sediment deposition and/or plant assimilation. Quantifying the actual nutrient loading potential from these sources is difficult, but water quality monitoring data have shown that this loading may be significant following large scale chemical treatment of hydrilla. Therefore, these internal nutrient stores represent a potentially major source of nutrient loadings to the water column under certain conditions. Various strategies for managing internal nutrient cycling were reviewed and increased lake flushing/dilution and mechanical harvesting of nuisance aquatic plants were recommended to lower in-lake nutrient concentrations. Additionally, these strategies should aid in attaining goals related to maintaining submerged and emergent plant species diversity and improving fisheries habitat.

Management Strategies for Aquatic Vegetation

Aquatic plant (macrophyte) dominated lakes tend to have better perceived water quality than phytoplankton dominated lakes. Based on the observed increase in TSI in 1993 following the large scale chemical treatment of hydrilla, if Lake Tarpon could be converted from a phytoplankton dominated lake to one dominated by desirable macrophytes then this could help to achieve water quality goals for the lake. Additionally, aquatic vegetation is important as fish and wildlife habitat. However, emergent vegetation can cause recreational and aesthetic problems, as a dominance of cattails has been the focus of complaints related to impeded views of the lake. Periodic mapping and monitoring of aquatic vegetation are recommended to assess status and trends in the macrophyte community and to evaluate attainment of aquatic plant goals.

Management Strategies for Fisheries

Historically, Lake Tarpon has supported an excellent sport fishery (Champeau 1992). However, 1995 data indicate that fish standing crop (biomass) increased by approximately 500 percent (Champeau 1996). The FFWCC considers this observed increase in fish biomass an indicator of increasing eutrophication that, if left unchecked, could threaten the future quality of sport fishing in the lake.

At this time no specific management strategies are proposed to manipulate the fish community structure in Lake Tarpon. Management strategies to maintain or improve fisheries in Lake Tarpon focus on strategies to reduce internal and external nutrient loading thus slowing or reversing the increasing trophic state of the lake. These strategies will result in improved water quality and a more stable trophic state. Additionally, the management strategies for aquatic vegetation will be aimed at optimizing fisheries habitat. Monitoring of fish biomass and species composition is recommended to evaluate the success of these management strategies and to determine whether other management strategies should be proposed.

Management Strategies for Hydrologic and Habitat Restoration

Wetlands within the Lake Tarpon and Brooker Creek watersheds have been impacted to varying degrees by anthropogenic activities. Hydrologic restoration of these wetlands to restore historic surface water flow patterns (i.e., ditch blocks and rehydration) would provide multiple benefits. Initially, the restored wetlands would provide habitat for wetland dependant animals and plants. Hydrologic restoration could result in increased flows through the historic channels of Brooker Creek and other unnamed tributaries to Lake Tarpon. Ultimately, increased surface inflows to Lake Tarpon could lead to increased flushing and dilution of the lake, which could lead to improved water quality. Hydrologic and habitat restoration projects should be pursued where opportunities exist to improve or enhance water quality, water quantity or wetland and aquatic habitat.

Management Strategies for Public Education

The LTMC was first established in July 1987 by a special Resolution of the Pinellas County Board of County Commissioners. 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. Following the implementation of the Lake Tarpon Drainage Basin Management Plan, the focus of the LTMC will likely shift more towards the monitoring and evaluation of the implemented DBMP (PBS&J, 1998) components. Other than the LTMC, no formal community involvement or public outreach program exists to further the adopted Lake Tarpon management goals.

LINKAGE TO OTHER WATER RESOURCE MANAGEMENT ACTIVITIES

In addition to the projects that are implemented through SWIM, the SWIM Program is able to accomplish its objectives more effectively and efficiently by coordinating internally with other District programs and externally through partnerships with local governments and other state and federal agencies.

Internal Linkages

The District has many tools available to implement the legislative intent of the SWIM Program, including but not limited to, integrated planning and coordination, regulatory authority, land acquisition programs and the SWIM program itself. Each of these areas provides opportunities to assist in the management of Lake Tarpon, one of the more prominent lakes within the District.

The District’s Water Management Plan - As required in Chapter 373, Florida Statutes, the District prepared its Water Management Plan (DWMP) in 1995. Within this plan the District organized its mission into four areas of responsibilities; water supply, flood protection, water quality management and natural systems management. The DWMP recognizes that the integration of all these areas is essential to effective planning and management of the resource. The DWMP supports the SWIM Program and has policies that relate to the restoration, protection and management of Lake Tarpon.

Comprehensive Watershed Management - The District has recognized the need to take a more aggressive and unified approach to surface water management and has created an initiative which would prioritize resource management needs by watershed throughout the District. It is intended to combine water quantity (i.e., flood) management with water quality and natural systems objectives, as well as water supply when applicable. Ultimately regulation, land acquisition, facilities and land use controls would be combined into a comprehensive surface water management strategy including appropriate policies, on a watershed specific basis. This effort is the District’s embodiment of the EPA’s watershed planning approach and the FDEP’s Ecosystem Management Initiative.

Local governments, as the parties responsible for land planning and development and service provision, will be key players in this integrated management approach. Similarly, the State’s Ecosystem Management Initiative will provide an impetus to collective efforts as it implements an environmental strategy that encourages innovation, pollution prevention, incentive-based regulatory alternatives, public education and individual stewardship.

Regulation

Wetlands Protection Through Regulatory Programs - One way that the District achieves wetlands protection is through regulatory programs. Wetland protection is addressed under Chapters 40D-2, 40D-3, 40D-4, 40D-40 and 40D-45, F.A.C. The District’s surface water permitting rules (40D-4, 40 and 45, F.A.C.) require that any impact to wetlands not specifically exempted must either be avoided or compensated. Compensation varies depending upon the function and value of the impacted wetland. Different types of compensation may be utilized, including preservation of associated upland areas, alternate types of wetland creation, protection of exempt wetlands, and restoration for previously impacted wetlands. The intent is to ensure that the habitat necessary for the survival of fish and wildlife is maintained.

Minimum Flows and Levels - Another management tool available for water and related natural resource protection is through the District's minimum flows and levels (MFLs) program. Maintaining minimum flows and levels is a significant statutory charge for Florida's water management districts. SWFWMD programs for minimum flows and levels originate in Chapter 373.042, F.S., as well as from the District's desire to treat the environment as a rightful "user" of water. If water resources and associated natural systems are to be protected and maintained, the identification and establishment of water levels and flows are essential. Such activities will also serve to balance water withdrawals for human needs with protection of surface water levels for navigation, recreation and related functions.

Once established, MFLs are implemented through a variety of means. Most prevalent is the application of these flows and levels to the District's water use permitting program. As directed by Chapter 373.042, F.S., the District may restrict withdrawals of water which would cause flows and levels to drop below their established minimums and which would be significantly harmful to the water resources or ecology of an area. The District's water use permitting rules, which include criteria to prevent adverse impacts from occurring as a result of withdrawals, effectively establish MFLs for specific sources throughout the District.

Minimum levels have been set for several lakes in northwest Hillsborough which are part of the headwaters of Brooker Creek, the primary surface water flow to Lake Tarpon. Additionally, there are several other lakes in this area which are to have Minimum Levels set in the 1999. A Minimum Flow is anticipated to be established for Brooker Creek during the 2006-2010 time frame based on the 1998 MFL Priority List and Schedule approved by the District Governing Board in October 1998.

Mitigation Banking - Mitigation banking allows developers to compensate for wetland losses in one place by preserving, restoring or creating wetlands in the same basin to achieve a no net loss of wetlands. The rule allows mitigation banking in some instances, although it remains a controversial issue.

Land Acquisition - Land acquisition at the District is currently guided and funded by two major Statewide initiatives: The Water Management Lands Trust Fund (a.k.a. Save Our Rivers Program or SOR), and Preservation 2000 (P-2000). In 2000, the P-2000 Program for land acquisition will be "sunset." Funds for land acquisition and management will be available through the SOR Program through 2000, however, the SOR funds may not be used for land acquisition after 2001. The Florida Forever Act, passed by the Florida Legislature in 1999, will make funds available, beginning in 2001 to the water management districts for both land acquisition and restoration, including funding for SWIM projects.

The District’s land acquisition program targets the protection of natural resources at the regional level. Lands of importance to water resources and water management are acquired along with lands of unique environmental value that are endangered by development activities. The District owns more than 320,000 acres, the majority of which were purchased through the SOR and P2000 programs. Many recent land purchases have been a joint acquisition between the District and a partner such as Pinellas County in the case of Brooker Creek Preserve, or with other state agencies. Leveraging District land acquisition funds with those of local governments and other agencies can and has resulted in significant acquisitions that would otherwise not be made. These programs have been coordinated with SWIM Plans by focusing on critical habitats, such as wetlands and their interconnected upland communities that are part of Lake Tarpon’s ecosystem that should be acquired for preservation or for restoration.

Basin Board Activities - The District’s eight Basin Boards have specific functions and duties that are consistent with Chapter 373, F.S., and the programs of the Governing Board. Their purpose is to identify and evaluate key water resource management issues in order to develop and fund management strategies to address them. The Basin Boards are facilitators in the resolution of non-regulatory water management issues for a number of other governments. It is at the Basin Board level that intergovernmental water resource programs are implemented, monitored and evaluated for improvement. The Basin Boards serve as a sounding board for the District by obtaining feedback from local governments and citizens and as funding partners for local governments and others in addressing mutually beneficial water resource solutions. The Basin Boards also provide the District’s SWIM funding match for approved SWIM projects within their basins.

The District, through the eight basin boards, has an established Cooperative Funding Program which provides financial assistance on a cost-share basis primarily to local governments for regional water resource projects. Projects can also be funded through “Basin initiatives” where a Basin Board decides to provide the impetus for a water management solution, with or without a local partner. The Basin Boards presently have in place a five-year plan which outlines the types of activities it expects to undertake in the next five years and provides an estimate of the funding required to support these projects. The Basin plans were prepared in close coordination with local governments demonstrating another opportunity for integration with local governments and ensuring the most efficient and cost-effective approach to addressing the mutual water resource management goals and objectives.

Lake Tarpon is located within the boundaries of the Pinellas-Anclote River Basin Board (PABB). The Pinellas-Anclote River Basin Board Five-Year Basin Plan FY 2000-2004 identifies the water quality and natural systems areas of responsibility (AOR) as the PABB’s priorities, and as such, supports the Lake Tarpon SWIM Plan. The fisheries study and the habitat restoration and stormwater retrofit projects in the Lake Tarpon SWIM Plan are consistent with the AOR priorities of the PABB.

External Linkages

FDEP - Ecosystem Management Initiative - Ecosystem management is a process for managing environmental resources that originated at the State level. The FDEP is required by the Florida Environmental Protection Act of 1993 to develop and implement measures to “protect the functions of entire ecological systems through enhanced coordination or public land acquisition, regulatory and planning programs.”

FDEP has defined ecosystem management as an integrated, flexible approach to management of Florida’s biological and physical environments - conducted through the use of tools such as planning, land acquisition, environmental education, regulation and pollution prevention - designed to maintain, protect and improve the State’s natural, managed and human communities. The primary goal of this effort is to provide for the maintenance of a healthy, sustainable environment for the benefit of present and future generations.

The District has been an active participant in this evolving process in terms of statewide program development. A strong correlation is apparent between the District’s Comprehensive Watershed Management Initiative (CWM) and Surface Water Improvement and Management (SWIM) Program and FDEP’s Ecosystem Management Initiative.

FDOT - Mitigation Program - Pursuant to 373.4137, Florida Statutes, the FDOT, FDEP and water management districts (WMDs) are required to work together to develop long-range mitigation plans for environmental mitigation of impacts from transportation projects. It was the intent of the Legislature that mitigation to offset the impacts of transportation projects be funded by the FDOT and be carried out by the FDEP and WMDs, including the use of mitigation banks.

Through this process, the FDOT provides FDEP and WMDs with a copy of its adopted work program and an inventory of habitats which may be impacted by the projects on the work program. The FDEP, WMDs, other appropriate federal, state and local governments and other interested parties develop a plan to provide the mitigation required to compensate for the impacts identified by the FDOT. Pursuant to the statute, the "FDOT Mitigation Plan" is to be developed using sound ecosystem management practices to address significant water resource needs and to focus on the activities of the FDEP and WMDs, such as surface water improvement and management (SWIM) waterbodies and lands identified for potential acquisition for preservation, restoration, and enhancement.

Once the mitigation projects have been identified and included in the plan, the FDEP, WMD or other entity implements the mitigation project and bears the costs of design and construction. Upon completion of the project, whether it be wetland restoration or creation, the entity that constructed the project may then apply to the FDOT for reimbursement of the costs to complete the mitigation project.

Local Government Coordination and Partnering - Building on the relationships and partnerships that have been developed over the past decade of management activities for Lake Tarpon is central to the future of managing Lake Tarpon and is the core to this update of the SWIM Plan. Pinellas County and the City of Tarpon Springs are key to the implementation of any management activity that is proposed for the lake.

Pinellas County’s Comprehensive Plan calls for the systematic development of watershed/waterbody-specific management plans for all major drainage basins in the County. Subsequently, the County contracted with a consultant to prepare the Lake Tarpon Drainage Basin Management Plan (PBS&J 1994). This Plan built upon the work of the first SWIM Plan and other diagnostic studies to develop management policies and best management practices aimed at restoring and/or maintaining the hydrological and ecological integrity of the lake and its immediate watershed. The County’s Plan forms the basis of this revision of the Lake Tarpon SWIM Plan.

As part of the District Water Management Plan, the District is in the process of updating Integrated Plans for FY 2000 for every county whose boundaries lie largely within in the District. The purpose of an integrated plan is to identify and evaluate key water resource management issues within the local government’s jurisdiction and to develop common District and local government strategies to address these issues. The integrated plan is intended to serve as a tool to foster the integration of land use planning and growth management activities of local governments with the water use planning and management activities of the District. This effort will strengthen the local government’s comprehensive plan by linking local water resources planning to the best available data and other resources of the District. The development of the integrated plans is a cooperative effort of the District, local governments and citizens. This endeavor is best viewed as a process, however, since it is intended to promote continuing relations and mutual planning in the best interest of the resource. It is hoped the action strategies identified will end up back in the local government plan where local and District energies, and funding, can be directed toward them.