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Water: Nonpoint Source Success Stories

Florida: Renaissance for Lake Jackson - An Outstanding Florida Water

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Lake Jackson in northcentral Leon County, Florida, became known for its bass fishing in the late 1950s and was held in high esteem until the early 1970s when rapid urbanization of its watershed resulted in dramatic changes to the lake. The lake is a relatively closed system with no outlets other than several sinkholes. In fact, its renown followed a natural drawdown after the collapse of a solution sinkhole.

In addition to the stress of residential and other urban development, a major federal highway, Interstate I-10, was built through the Megginnis and Fords Arms subbasins in 1972. Above average rainfall during the highway's construction, coupled with inadequate sediment controls, created a large turbidity plume over the southern third of the lake. Subsequent efforts to protect the lake turned Megginnis and Fords Arms into sediment traps.

A clean lakes remedy

Many studies conducted between 1974 and 1976 indicated widespread problems, including increased sediment, nutrient loading, and contamination of the bottom sediments by heavy metals and other pollutants. The Northwest Florida Water Management District compiled and evaluated this research in a 1977 report. The report concluded that stormwater runoff was the primary cause of Lake Jackson's water quality degradation. It recommended that nutrient and sediment loads to the lake be reduced. In 1981, a partnership was established between the Florida Department of Environmental Regulation, the Northwest Florida Water Management District, and EPA. Using a section 314 Clean Lakes program grant, the partners built a detention pond, sand filter, and marsh system to reduce the flow of stormwater pollutants through Megginnis Arm.

This system, completed in 1984, was studied extensively for the next four years and eventually refined for optimal performance. No matter how efficiently the system operated, it was still undersized in relation to development within the watershed. Stormwater loadings were substantially reduced, but the lake and Megginnis Arm continued to deteriorate.

Removing sediment

In 1990, the Florida Department of Environmental Regulation committed section 319 funding to the Northwest Florida Water Management District to remove the troublesome sediments from Megginnis Arm. Analyses indicated that the sediments were well within the limits for land application.

The project broke ground October 11, 1990. The first tasks centered on the establishment of sediment controls and site barricades. Favorable weather and minimal equipment problems enabled rapid construction of the disposal area and a sheetpile dam to isolate Megginnis Arm from the main body of Lake Jackson.

Dredging started on December 3, 1990. Low water levels facilitated progress until they were too low to support the dredge. Groundwater provided by the city of Tallahassee was then used to augment the pool.

Concerned that the dredge slurry could not be effectively controlled in the disposal area, the project used a section of an adjacent constructed marsh as a polishing pond. To counter unusually heavy rains from January to March 1991, hay bales were placed between sections of the marsh to protect the main area, while increased alum treatments helped control turbidity.

Dredging in Megginnis Arm was completed by July 1991, followed by reconditioning of the marsh area, removal of the sheetpile dam, and consolidation of the disposal area. Remaining details such as grading and landscaping the containment area were completed by May 1992. All told, the project removed more than 100,000 cubic yards of contaminated sediment from Megginnis Arm.

Streambank stabilization

Following the dredging project, workers (again using section 319 funds) helped remove exotic or nuisance vegetation (primarily Chinese tallow and alligator weed) from the littoral area of Megginnis Arm and began to reestablish native species. The project originally called for planting 150,000 herbaceous wetland plants and 200 woody plants on 44 acres of the littoral zone. However, these plans were substantially revised because water levels remained unusually high and wild seed stock quickly stabilized the area. Ultimately, 40,000 herbaceous wetland plants and 700 trees were planted in Megginnis Arm to enhance the basin's natural biological communities.

Effects on Water quality

In general, sampling analyses indicate poorer water quality at the inflows to the lake (i.e., at Megginnis and Fords Arms) and better water quality in more open areas. Data trends from the northernmost part of Megginnis Arm show that the project to remove nonpoint source pollution from the watershed is achieving success. The values shown in Table 1 are means for the various periods.


Table 1.--Water quality measures in Lake Jackson, 1970 to 1990.

PERIOD NO3-NO2
mg/L
TN
mg/L
Orth. P.
mg/L
TP
mg/L
Chl a
µg/L
Cond.
µmho/cm
Turbidity
NTU
Sfc. DO
mg/L
Early 1970's .054 --- .015 .394 --- 61 55.07 5.81
Late 1970's .087 .882 .046 .464 16.10 87 14.10 9.64
Early 1980's .035 .559 .048 .131 26.40 82 21.91 10.10
Mid 1980's .038 .427 .012 .055 22.97 127 9.48 8.47
Early 1990's .010 .605 .042 .073 12.54 67 5.70 6.55
Mid 1990's .008 .670 .005 .037 --- 55 --- 9.10
Average .039 .629 .028 .192 19.50 80 --- 8.30

NO3-NO2 = nitrate-nitrite
TN = total nitrogen
Orth. P. = orthophosphorus
TP = total phosphorus
Chl. a = chlorophyl a
Cond. = conductivity
Sfc. DO = surface dissolved oxygen

Nitrate-nitrite, orthophosphorus, total phosphorus, turbidity, conductivity and chlorophyl a are at their lowest levels in over 20 years. Dissolved oxygen concentrations at the surface are near all-time highs and, even more important, were above 8 milligrams per liter at mid-depth and bottom during sampling in April and July 1996.

The Lake Jackson project exemplifies section 319's contribution to successful nonpoint source management. This program financed the restoration of impaired areas and provided for better management of Lake Jackson in the future. The lake has been designated an "Outstanding Florida Water" and is included in the state's aquatic preserve program. Consequently, it will continue to merit attention, protection, and restoration. The partnerships formed on behalf of Lake Jackson will continue to achieve remarkable results.


CONTACT: Eric Livingston
Florida Department of Environmental Protection
(904) 921-9915



Florida's Silviculture Best Management Practices-
Test Sites Rated "Excellent"



Florida's silviculture NPS management program was cooperatively developed by the Florida Department of Environmental Regulation, the Florida Division of Forestry, the U.S. Forest Service, and the forest industry, acting in response to requirements set forth in Section 208 of the Clean Water Act. In 1976, responsibility for the program passed to a newly formed Silviculture Technical Advisory Committee. The major goal of this committee whose members included 12 paper companies, the relevant state and federal agencies, a consulting forester, the University of Florida School of Forest Resources and Conservation, and the Florida Forestry Association was to develop a workable set of best management practices (BMPs) to minimize water quality impacts associated with forestry activities.

Early developments get results

Between 1977 and 1979, the technical advisory committee, together with the Department of Forestry, developed a set of practices, including streamside management zones, minimum bare ground exposure, culvert and cross ditches, water turnouts, broad-based dips, and a variety of nonstructural BMPs to minimize stream crossings and other potential nonpoint sources of pollution created by forestry activities. In 1979, these practices were published as the Silviculture Best Management Practices Manual. The practices are intended for use with forestry activities in discretionary zones adjacent to waterbodies. The width of these zones and the specific BMPs to be used within them are recommended, depending on a "site sensitivity classification" (SSC), an index that identifies sedimentation potential. The SSC is based on soil erodibility, slope, and proximity to a waterbody.

Initial implementation of the program was voluntary. In 1982, as part of the state's stormwater regulation, forestry activities conducted in accordance with the BMP manual were exempt from stormwater permitting. When the Department of Environmental Regulation delegated the stormwater program to the regional water management districts, the silviculture exemption became a noticed general permit. Its only requirement was to identify the location and timing of planned forestry activities.

New issues prompt review

In November 1991, the Department of Forestry held a public meeting to review the silviculture NPS management program. Participants at this meeting identified 12 major BMP issues, and a 22-member Technical Advisory Committee was formed to conduct a comprehensive review of the BMP manual. This committee, like its prototype, had broad stakeholder representation this time also including nonindustrial private land owners and conservation organizations. The review was undertaken in expectation that a revised updated manual would result. This revision occurred between January 1992 and March 1993, with funding provided by a 1992 section 319 grant.

The revised Silviculture Best Management Practices greatly increases the water quality protection associated with forestry activities. Though many of the original BMPs were retained, their use has been expanded to address other water resources such as sinkholes, small lakes (less than 10 acres), canals, and wetlands. Streamside Management Zones were renamed Special Management Zones (SMZ). The width of the primary zone of the SMZ was expanded from 35 feet to up to 200 feet, depending on stream width and waterbody classification. In addition, general ecological considerations and wildlife habitat values were added as specific BMP objectives. An entirely new set of BMPs were developed for forestry activities conducted in wetlands or during wet weather.

Training

Once the new manual was published, distribution and training began. In July 1994, the Department of Forestry asked the community to identify individuals who could serve as BMP trainers within their respective companies, agencies, or area; and in September, 28 prospective trainers 18 from the forest industry and 10 from state and federal agencies attended a "train the trainers" session in Tallahassee.

Following that initial training session, the Department of Forestry conducted BMP workshops throughout the state, beginning in northwest Florida and working toward the south. By May 1994, 47 BMP workshops had been conducted with over 1,500 participants, primarily loggers, foresters, forest landowners, and regulatory agencies' staff. These workshops and distribution of the manual continue to be a key component of Florida's silviculture program.

Effectiveness assessments

In addition to reviewing the BMP manual, the 1991 Silviculture Technical Advisory Committee was also charged to evaluate the environmental effectiveness of the practices. To lead this effort, a BMP Effectiveness subcommittee was created. Working with the Departments of Forestry and Environmental Protection, the BMP Effectiveness subcommittee has also designed a monitoring program that will use recently developed bioassessment protocols to evaluate the impacts of forestry activities on aquatic ecosystems. This assessment is unrelated to compliance, since in every case the forestry activities are already in compliance. The effectiveness study is to determine whether the BMPs actually protect the water resources as planned.

The effectiveness evaluation, which began in the fall of 1995, includes two components: long-term BMP effectiveness monitoring and project-duration monitoring for BMP effectiveness under select, controlled conditions including before and after disturbance. An example of this second component is the nearly completed "319 Biological Assessment of the Effectiveness of Forestry Best Management Practices in Protecting Stream Biota." This project used a before and after control impact design to sample sites up- and downstream of forestry activities. The sampling parameters included benthic macroinvertebrates (resident biota), habitat assessment, and standard physical and chemical measurements.

Four streams in north Florida were chosen for this project. Then, in February 1996, on each of these streams, three stations upstream and three stations downstream of a proposed clear-cutting operation were monitored to determine the streams before treatment condition. In February 1997, investigators went back to the identical stations to sample for the after treatment condition.


At three of the test streams, the reference and test sites were rated "excellent"; at the other stream, they were "good".

Next, the data were used to calculate the Stream Condition Index (SCI) for each stream segment studied. The Stream Condition Index (a composite of seven invertebrate parameters) has been calibrated to reflect the regional conditions in undisturbed streams. Its final result supports the effectiveness of the silviculture BMPs.

Based on the SCI, no statistically significant changes were observed between the reference and test sites after silviculture activities in which the BMPs are strictly adhered to during all aspects of the operation. At three of the test streams, the reference and test sites were rated "excellent"; at the other stream, they were "good." Results from habitat assessment showed no major adverse habitat changes from the forestry operations. The project analysts also found the precision (that is, the repeatability) of the SCI measures very satisfactory.

The development of forestry BMPs is thus shown to be an effective solution to a nonpoint source environmental problem.


CONTACT: Eric Livingston
Florida Department of Environmental Protection
(904) 921-9915


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