Florida Taylor Creek - Nubbin Slough (RCWP 14)

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Okeechobee & Martin Counties
MLRA: U-156A
HUC: 030901-02




4.1 Project Synopsis

The Taylor Creek - Nubbin Slough (TCNS) Basin is located in southern Florida, directly north of Lake Okeechobee. The watershed covers 120,000 acres of a typically flat landscape with generally poorly drained, coarse textured soils (Spodosols) that have a low phosphorus retention capacity. Water flow from the basin tributaries enters Lake Okeechobee through a flow control structure (S-191).

Lake Okeechobee provides drinking and irrigation water, supports commercial and sport fishing, and is a habitat for many migratory as well as endemic bird species. High phosphorus (P) concentrations in Lake Okeechobee promote eutrophic conditions that impair all water uses.

Agricultural nonpoint source (NPS) pollution has been documented as a significant water quality problem in the TCNS watershed (Allen et al., 1982). The TCNS Basin contributes 27% of the external P load but only 4% of inflowing water to the lake (Federico et al., 1981).

Land use in the watershed is primarily agricultural, consisting of intensive dairy and beef cattle farms whose animals graze on improved pastures that are surface drained and fertilized. The main sources of high phosphorus loads in the watershed are thought to be runoff from dairy barns and holding areas, direct stream access by large numbers of dairy cattle, and runoff from improved pastures.

About 63,109 acres have been identified as critical areas needing treatment. This includes all dairy farms, all beef cattle pastures that have been extensively ditched for improved surface drainage, and all areas within one-quarter mile of a waterway. Land treatment and water quality goals were established to: 1) reduce phosphorus and nitrogen concentrations from the project area to Lake Okeechobee by at least 50%; 2) contract at least 75% of the critical area; and 3) contract with all dairy farms in the project area (Stanley et al., 1986).

The general treatment strategy was to install best management practices (BMPs) which exclude dairy cows and beef cattle from waterways and to control wastewater runoff from dairy barns. Principal BMPs used were stream protection systems, reduction of barn waste by improving water use efficiency and improving effluent disposal with spray irrigation, animal waste management systems, diversion systems, grazing land protection systems, permanent vegetative cover, sediment retention structures, and water control structures. Stream protection emphasized fencing to keep animals out of the water courses, along with providing shade and alternative water facilities. Dairy closures independent of Rural Clean Water Program (RCWP) activities may also have affected water quality within the basin. The Florida Department of Environmental Regulation (FDER) imposed a Dairy Rule requiring each dairy to collect the runoff from high intensity areas and treat the P through spray irrigation, so that the P in the effluent would be assimilated by plants or absorbed by the soil (nutrient mass balance).

This project has a high level of BMP implementation, most of which occurred in 1985 to 1987. This allowed for a baseline pre-BMP period of four to six years. Contracts were written for 54,709 acres or 87% of the critical area. All critical dairies are under contract. Ninety-nine percent of contracted practices were installed. The two most important reason farmers decided to participate was availability of cost share funds (federal and state) and concern about future pollution regulations. Increased farm production was given by producers as the second most important reason.

The primary objective of the water quality monitoring network was to evaluate the effectiveness of agricultural BMPs for reducing P concentrations to Lake Okeechobee, as measured by changes in water quality concentrations (particularly phosphorus) in the tributaries and basin outlet.

The TCNS project had extensive water quality monitoring. The monitoring design allowed for comparison of the pre-, during-, and post- BMP implementation periods. Upstream/downstream station pairs were established in a few tributaries to adjust for pollutant concentrations originating above the BMP implementation sites. Ground water table depth was also measured. Biweekly grab samples were taken biweekly at 23 tributary stations; some were monitored since 1978. In 1988, the network was modified to monitor site- specific BMP effectiveness on each dairy. This modification were a result of the FDER dairy rule.

Due to a high level of BMP implementation and dairy closures, the project exceeded its goal for reduction of phosphorus and nitrogen concentrations at the project outlet, despite substantial increases in the numbers of cows. Tracking of BMP implementation by practice and subwatershed allowed the project to link the water quality and land treatment data bases on subwatershed drainage area and annual basis. This contributed to the project's ability to document changes in water quality as a result of land treatment on both subwatershed and project levels. Subwatersheds with a large amount of BMP implementation such as Mosquito Creek and Nubbin Slough have shown significant decreases in phosphorus concentrations. In contrast, in northwest Taylor Creek and Lettuce Creek subwatersheds, increased cattle densities have had a negative effect on water quality. Adjustments of phosphorus concentrations for changing cow numbers, ground water table depth, and upstream concentrations increased the ability of the project to document water quality effects from the RCWP BMPs.

Fencing to keep animals out of the water courses, along with providing shade and water facilities, was effective in reducing the phosphorus concentrations from the project area. However, these BMPs alone were probably not sufficient to meet the water quality goal of a 50% reduction. BMPs that require more active management, such as dairy waste water utilization, reduction, and timing of nutrient applications on dairy and beef operations and controlling the release of high intensity area runoff, seemed to have the greatest impact on water quality.

This project is demonstrating that a large project can be successful, if it is well organized, tightly managed and sufficiently funded. One key to this project's success was the implementation of an administrative subcommittee. This subcommittee was made up of the Agricultural Stabilization Conservation Service (ASCS), Soil Conservation Service (SCS), Cooperative Extension Service (CES), and the South Florida Water Management District (SFWMD). The subcommittee met regularly to coordinate project activities and each member participated in all phases and activities of the project.

In 1988, the Taylor Creek-Nubbin Slough RCWP project was expanded to include dairies in the Lower Kissimmee River Basin. Please refer to the profile on the Lower Kissimmee River, Florida RCWP project for further detail.


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Figure 4.3: Taylor Creek - Nubbin Slough (Florida) RCWP project map, FL-1.




4.2 Project Findings, Recommendations, and Successes

4.2.1 Definition of Project Objectives and Goals

4.2.1.1 Findings and Successes

The Taylor Creek - Nubbin Slough (TCNS) RCWP project set realistic quantitative goals for both water quality and land treatment.

Specific goals for BMP implementation were set by the Local Coordinating Committee (LCC) on an annual basis.

Water quality modeling was used in setting quantifiable project land treatment goals. Based on a modification of the Vollenweider Model, the Lake Okeechobee Technical Advisor Committee (1986) recommended reducing all phosphorus loadings to the lake by 40% to protect long-term water quality. From a land treatment management perspective, phosphorus loadings from the TCNS basin would need to be reduced by 75 to 90% to achieve this objective. The original project goal was to reduce phosphorus concentrations from the watershed by 50%. Based on this watershed reduction goal, the project refined their land treatment objectives and goals by estimating the amount and location of land treatment that would be required to achieve this increased level of phosphorus reduction.

New state regulations changed the specific land treatment BMP goals. Due to the 1987 FDER Dairy Rule and the 1989 State of Florida Surface Water Improvement and Management (SWIM) Plan, the BMP emphasis for waste management, pasture and hayland management, and irrigation management increased.

The project set land treatment and water quality monitoring objectives and goals that guided the establishment and maintenance of effective monitoring designs. Monitoring provided valuable feedback on progress toward meeting land treatment and water quality goals.

4.2.1.2 Recommendations

Implementation strategy goals need to be flexible for adaptation to watershed conditions and relative BMP effectiveness, but still support the overall strategy of improving water quality. For example, BMP selection and emphasis should include all major sources of pollutants, such as animal and dairy barn waste.

4.2.2 Project Management and Administration

4.2.2.1 Findings and Successes

The local ASCS project administrator also served as the project coordinator. The project coordinator facilitated communication and inter-agency cooperation.

The key to success of the project was the implementation of an administrative subcommittee. This subcommittee was made up of the ASCS, SCS, CES, and the SFWMD. The subcommittee met regularly to coordinate project activities and each member participated in all phases and activities of the project.

Full-time water quality monitoring specialists were assigned to the project throughout its duration, from which the project benefited greatly.

The project was affected by local and state political and regulatory pressures. Regulations that came into effect mid-project forced changes in both land treatment and water quality goals.

4.2.2.2 Recommendations

A local project coordinator is essential to provide coordination among the agencies and keep the project on course to meet its goals.

A core project staff, with low turnover rates, is important to provide for a smooth transition as a project shifts from planning to installation, then to operation and maintenance.

4.2.3 Information and Education

4.2.3.1 Findings and Successes

Close cooperation among the four local key agencies (ASCS, SCS, CES, and SFWMD) was essential to the success of the information and education (I&E) program.

Field days, demonstration sites, and tours were the most effective methods for presenting the accomplishments of the project.

The level of funding for I&E was insufficient and restrictive to accomplish all the I&E goals.

Funding of a laboratory to conduct effluent, manure, tissue, water, and soil sample analysis would have been useful to producers to encourage proper nutrient management.

4.2.3.2 Recommendations

Demonstration projects should be encouraged.

Management booklets describing management of animal waste systems should have been developed.

Projects need sufficient and flexible funding for I&E.

4.2.4 Producer Participation

4.2.4.1 Findings and Successes

Technical assistance and increased cost share funds provided by the state increased program participation.

One-to-one consultation with producers improved BMP management and maintenance.

The threat of regulations increased participation.

4.2.4.2 Recommendations

One-to-one contact with potential participants should be emphasized because this is the most effective method in convincing landowners to participate in a water quality project. This technique also improves BMP management and maintenance.

4.2.5 Land Treatment Implementation, Tracking, and Evaluation

4.2.5.1 Findings and Successes

All land treatment goals were met or exceeded.

The project found that explicit guidance for animal waste management practices needed to be written into the contracts to ensure that both the management and structural components of these systems were operated and maintained according to specifications.

Fencing to keep animals out of the water courses, along with providing shade and water facilities, was effective in reducing the phosphorus concentrations from the project area. However, these BMPs alone were probably not sufficient to meet the water quality goal of a 50% reduction.

BMPs that require more active management, such as dairy waste water utilization, reduction, and timing of fertilizer applications on dairy and beef operations, and controlled release of high intensity area runoff, seemed to have the greatest impact on water quality.

Fencing cattle out of streams did not prevent runoff into the streams of excess waste from the adjacent lands.

Adoption of BMPs, such as improved fertilizer and feeding practices, was observed in surrounding areas.

State regulations, implemented in 1987 and 1989, changed the focus of the water quality goals and land treatment. Dairy farmers and others thought that the original BMPs would be insufficient to meet the requirements of these new regulations.

A holistic farm management approach is necessary which considers not only milk production, but also the handling of manure. Improving nutrient management and crop production techniques were essential for a total project success.

Continued improvements in the quality of water leaving the TCNS basin will require more nutrient management, efficient use of dairy waste water, and management of waste storage lagoons.

4.2.5.2 Recommendations

Due to the temptation of contractors to increase the cost of structural BMP installation when government cost share funds are involved, the project (ASCS) should set an average price for each BMP.

Local projects should have flexibility in selecting and modifying BMPs. This will help ensure that the water quality goals will be met, farmers will participate, and needed BMPs can be implemented in a timely fashion. However, oversight should be given from the state and national level to ensure that the BMPs selected are directed at the water quality goals.

Management plans are a key element in the operation and maintenance of BMPs.

All farms in the critical area should have a plan written and a contract signed to ensure the project's success.

Practices with the greatest water quality benefits should be prioritized and implemented first.

Participant involvement in plan preparation is critical in getting a plan suited to the needs of the participant and the project goals; this also increases the probability of successful implementation of the plan.

Sufficient time should be devoted to defining the critical area. The TCNS RCWP project initially designated the entire basin as critical. The critical area was redefined in 1983 based on the major sources of phosphorus to allow for effective targeting.

Close coordination between the project and regulatory agencies is needed in selecting and implementing BMPs.

Follow-up meetings with participants should be held to facilitate completion of BMP implementation.

Phosphorus imports into a watershed can be minimized by purchasing animal feed lower in phosphorus concentration and reducing phosphorus fertilization rates by animal waste management. Practices which encourage exporting of phosphorus should also be incorporated into the overall basin plan when phosphorus production in the basin exceeds phosphorus needs.

4.2.6 Water Quality Monitoring and Evaluation

4.2.6.1 Findings and Successes

The TCNS project had multiple years of baseline data collect by the Agricultural Research Service (ARS) and the SFWMD. The SFWMD continued to monitor and expand the sampling program. This allowed for a good pre- project assessment and several years of post-BMP monitoring.

The project exceeded its goal for reduction of phosphorus and nitrogen concentrations at the project outlet.

Trend analysis has shown that significant reductions in phosphorus and nitrogen concentrations have occurred in more than half of the subwatersheds.

There has been an overall decrease in total phosphorus (TP concentrations at the project's outlet to Lake Okeechobee (S-191)), despite an increase in cow numbers. This decrease is largely a function of the high number of BMPs installed in subwatersheds, especially the Mosquito Creek and Nubbin Slough subwatersheds, and dairy closures in the Otter Creek subwatershed (Ritter and Flaig, 1987; Stanley et al., 1988).

4.2.6.2 Recommendations

As demonstrated by the TCNS project, data management is crucial to the success of a monitoring program. All data should be reviewed frequently and should be stored in a central project file for efficient integration and subsequent evaluation of hydrologic and water quality variables.

Lab and field quality assurance and quality control programs that include data evaluation and verification for precision and accuracy are elements critical in a successful monitoring program.

Flow data should be collected to establish relationship between changes in nutrient concentrations and changes in flow. Some storm event monitoring may be useful to establish this relationship.

4.2.7 Linkage of Land Treatment and Water Quality

4.2.7.1 Findings and Successes

The TCNS project's tracking of BMP implementation by practice and subwatershed allowed the project to link the water quality and land treatment data bases on a drainage and annual basis. This contributed to the project's ability to document changes in water quality as a result of land treatment on both subwatershed and project levels.

The project achieved a high level of BMP implementation, primarily between 1985 and 1987. This allowed for a baseline or pre-BMP period of four to six years. Combined with a high level of land treatment, this type of monitoring increased the ability of documenting BMP effectiveness.

The fact that total phosphorus concentrations continue to decrease as the length of the post-BMP data base increases, supports the argument that the BMPs were effective in reducing TP concentrations. Consistent improving trends over time support the evidence that changes in water quality were attributed to BMPs.

Subwatersheds with a large amount of BMP implementation such as Mosquito Creek and Nubbin Slough have shown significant decreases in total phosphorus concentrations. In contrast, in northwest Taylor Creek and Lettuce Creek sub watersheds, increased cattle densities have had a negative effect on water quality (Ritter and Flaig, 1987; Flaig and Ritter, 1989). Detection of predicted water quality trends and patterns over multiple water quality monitoring stations and drainage areas improves the documentation that the changes in water quality were attributed to the BMPs.

Due to the high degree of variability in the water quality monitoring data and the limited number of monitoring stations, positive changes in water quality cannot be attributed to any one BMP, but can be attributed to a cumulative impact of BMPs implemented in a given watershed or subwatershed.

Fencing cows out of streams is an example of a passive BMP. External factors, such as increased cow numbers, changes in fertilizer applications, and nonpoint sources of runoff from high intensity grazing pastures, seem to mask the short-term effect of fencing.

Other factors that confound the interpretation of water quality trend results include variations in rainfall, water quality depth, pollutant concentrations upstream of BMP implementation, soil types, and cow numbers. Changes in ground water table depth and cow numbers were the most important non-RCWP factors affecting phosphorus concentrations. Ground water table depth is thought by the project to be a surrogate for the project area hydrology and season. In addition, a high water table contributes to increased phosphorus concentrations in the tributaries. Increases in cow numbers increases the potential source of phosphorus. Adjustments for these variables have allowed for valid interpretations regarding the observed trends, and have also increased the statistical significance of the decreasing trends (Spooner et al., 1990).

The project team believes that observed decreases on TP concentrations at the watershed outlet to Lake Okeechobee can be attributed to several BMPs such as fencing, water conservation/waste water recycling, drainage improvement, and fertilizer management.

The shutdown of dairy operations is a major factor contributing to significant downward water quality trends. These dairies were a high priority for needing improvements in waste management. Such closures have resulted in a masking effect, making it difficult to quantify the impacts of other BMPs located in the same subwatershed.

4.2.7.2 Recommendations

As this project has demonstrated, several years of pre- and post- BMP monitoring are required to document a consistent trend in water quality and quantify the impact of the BMPs.

Site specific monitoring can enhance the ability of a project to document BMP effectiveness.

Factors that could confound the interpretation of water quality trend results (such as rainfall, water quality depth, soil types, and changes in cow numbers) should be measured. These measurements should be matched on a temporal and spatial scale to water quality and land treatment data to ensure valid interpretations regarding trends in water quality.

BMP implementation and water quality monitoring need to be conducted on similar spatial (i.e., drainage) and temporal scales so that the two data bases can be linked.

Sophisticated data management and integration of all water quality and land treatment / land use variables into a GIS would be useful in future water quality projects.

4.3 Project Description

4.3.1 Project Type and Time Frame

General RCWP

1981 - 1991

4.3.2 Water Resource and Watershed Descriptions

4.3.2.1 Water Resource and Water Quality

4.3.2.1.1 Water Resource Type and Size

Streams, canals, Lake Okeechobee

4.3.2.1.2 Water Uses and Impairments

Lake Okeechobee is a class I water resource covering 480,000 acres. Lake Okeechobee is the primary source of public drinking water for five towns around the lake and the secondary source for the lower east coast of Florida from West Palm Beach to Miami. Water from the lake is also used to irrigate about 500,000 acres of vegetable crops, row crops, sugar cane, and pasture south of the lake. The lake is part of a water management system providing flood protection.

The lake supports commercial fishing, valued at $6.3 million annually; sport fishing, valued at $2.2 million annually (Bell, 1987); a significant tourist industry; and habitat for many migratory as well as endemic bird species.

High phosphorus (P) concentrations in Lake Okeechobee promote eutrophic conditions that promote algae blooms, with associated low dissolved oxygen levels, and impair all water uses.

4.3.2.1.3 Water Quality Problem Statement

The Taylor Creek - Nubbin Slough Basin contributes a disproportionate amount of phosphorus to Lake Okeechobee (~28% of the external P load in only 4% of inflowing water to the lake) (Federico et al., 1981).

Dairy and beef agricultural activities are the primary sources of P in the watershed (Allen et al., 1982). The main sources of high phosphorus loads are runoff from dairy barns and holding areas, cattle lounging in and around streams, and runoff from improved pastures (Allen et al., 1982; Stanley et al., 1986). Streambank erosion from animals lounging in the stream is also thought to be significant.

Phosphorus concentrations in the runoff is high because the soils are sandy Spodosols which have low phosphorus retention capacity and rainfall is in excess of evapotranspiration. The water table is usually high, and standing water occurs in low areas during the rainy season, June to October. Total phosphorus concentration in the tributaries are related to the water table depth and antecedent precipitation (Ritter and Flaig, 1987). Because the land is flat and poorly drained, most of the runoff occurs when the ground water table is close to the surface. Therefore, as suspected, total phosphorus concentrations in the tributaries increases as the water table depth rises to within two feet of the surface.

4.3.2.1.4 Water Quality Objectives and Goals

Objective: Measure the success of implementing the selected BMPs in the project area

Goals: Reduce phosphorus and nitrogen concentrations to Lake Okeechobee by at least 50% by 1992 measured at the watershed outlet, S-191

4.3.2.2 Watershed Characteristics

4.3.2.2.1

Watershed Area: 120,000 acres
Project Area: 120,000 acres
Critical Area: 63,109 acres

4.3.2.2.2 Relevant Hydrologic, Geologic, and Meteorologic Factors

Mean Annual Precipitation: 50.0 inches (70-80% occurs from June through October)

Geologic Factors: Topography is relatively flat with an elevation range of about 50 feet. Soils are coarse textured, mostly poorly drained with rapid surface permeability and moderate internal drainage. An organic hard pan underlies most of the area, typically within a depth of 30-50 inches from the surface.

Hydrologic Factors: The water table is very shallow. Seasonal ground water fluctuations are closely related to rainfall amount and intensity. Water flow from the basin tributaries enters Lake Okeechobee through a flow control structure, S-191.

4.3.2.2.3 Project Area Agriculture

Land use in the watershed is primarily agricultural. Major land use consists of intensive dairy farming, followed by beef cattle which graze on improved pastures that are surface drained (ditched) and fertilized to improve runoff during the wet season. Citrus groves occupy approximately 1,400 acres and require extensive drainage and irrigation.

4.3.2.2.4 Land Use

Use            %of Project Area  % of Critical Area
Cropland (primarily        2         1.8
      citrus groves)
 Pasture/range
   Dairy          30       50.5
   Beef              45       47.7
 Woodland (and wet prairies)     18            -
 Urban/roads            5          - 
 Other               -          -

4.3.2.2.5 Animal Operations

Operation      # Farms        Total #  Total Animal
            Animals     Units

Dairy       24*      37,166*           52,032*
Beef        56       25,000      25,000
* Numbers of cows in 1980. Cow numbers varied by year and subwatershed. The cow numbers generally increased during the project period (1980-90), except during 1983. For example, in 1988, there were 44,365 dairy cows (Stanley and Gunsalus, 1991, p. 52). By 1990 the number of dairies had decreased to 22. In 1991, four additional dairies took advantage of the State Buy-out Programs, with a resulting decrease in cow numbers.

4.3.3 Total Project Budget

  SOURCES  Federal     State    Farmer     Other

ACTIVITY SUM

Cost Share 957,440 310,119 448,920 0 1,716,479 Info. & Ed. 13,000 0 0 66,044* 79,044 Tech. Asst. 404,952 12,000 0 15,908** 432,860 Water Quality 0 0 0 400,000*** 400,000 Monitoring SUM 1,375,392 322,119 448,920 481,952 $2,628,383 * CES ** SCS, state of Florida funds ***SFWMD (probably a conservative estimate) Source: Stanley et al., 1991

4.3.4 Information and Education

4.3.4.1 Strategy

The Cooperative Extension Service (CES) took the lead role in information and education activities. ASCS, SCS, and the SFWMD also played key roles in the I&E effort.

4.3.4.2 Objectives and Goals

Goals: Inform all farmers located in the project area of their eligibility and obligations to receive federal assistance under the RCWP

Publicize the goals and benefits to be gained from the RCWP to the public

Keep farmers and public informed of the progress being made during the project towards meeting water quality benefits and goals

4.3.4.3 Program Components

Field days, tours, news articles and releases, TV coverage and material for handouts

A 1986 field day, with participation from many different agencies, landowners, public officials, and public groups

Field studies and develop management plans

4.3.5 Producer Participation

4.3.5.1 Level of Participation

This project has a high level of BMP implementation, most of which occurred in 1985 to 1987. Contracts were written for 54,709 acres or 87% of the critical area. All critical dairies are under contract. 99% of contracted practices are installed.

4.3.5.2 Incentives to Participation

Cost Share Rates: (federal) 75% for structural BMPs

Supplemental state funds for cost sharing BMPs in some areas to raise cost share to 100%

Payment Limitation: (federal RCWP) $50,000 per landowner

Assistance Programs: Technical assistance for all contracted BMPs

Regulations: A DER rule has been implemented which requires dairies whose drainage reach Lake Okeechobee to address areas of high cattle intensity on their farms. It has been estimated that on the larger farms it would cost up to $450,000 per barn to comply with this rule.

The two most important reason farmers decided to participate was availability of cost share funds (federal and state) and concern about future pollution regulations. Increased farm production was given by producers as the second most important reason.

4.3.5.3 Barriers to Participation

Some producers took advantage of the federal and state dairy buy-out programs

Lack of perception that the producer was causing a water quality problem

4.3.5.4 Chances of Continued Maintenance/Adoption of BMPs

Excellent for most BMPs

BMPs that were most likely to be discontinued after contract expired included: shade structures (BMP10), diversions, and fences.

BMPs that are most likely not to be maintained after contracts expire included: rotational grazing, shade structures, diversions, and fences.

4.3.6 Land Treatment

4.3.6.1 Strategy and Design

The nonpoint source management strategy was to decrease the contribution of phosphorus to the lake from pastures located on poorly drained, sandy flatwood (coastal) plain soils that are heavily grazed by dairy cows and beef cattle.

The general treatment strategy was to install BMPs that exclude dairy cows and beef cattle from waterways (such as fencing) and to control wastewater runoff from dairy barns. Fencing to keep animals out of water courses, along with providing shade and water facilities, was emphasized initially. Waste management (including reduction of commercial fertilizer), pasture and hayland management, and irrigation management BMPs were added in 1982.

Water quality modeling was used in setting quantifiable project land treatment goals. Based on a modification of the Vollenweider Model, the Lake Okeechobee Technical Advisor Committee (1986) recommended reducing all phosphorus loadings to the lake by 40% to protect long-term water quality. From a land treatment management perspective, phosphorus loadings from the TCNS basin would need to be reduced by 75 to 90% to achieve this objective. Based on this watershed reduction goal, the project refined their land treatment objectives and goals by estimating the amount, type, and location of land treatment that would be required to achieve this increased level of phosphorus reduction. Consistent with the goal of additional decreases in phosphorus export, the 1987 FDER Dairy Rule and the 1989 State of Florida Surface Water Improvement and Management (SWIM) Plan changed the focus of the water quality goals and the land treatment emphasis. The Regulation (FDER) Dairy Rule requiring each dairy to collect the runoff from high intensity areas and treat the P through spray irrigation, so that all the P in the effluent would be assimilated by plants or absorbed by the soil (mass balance concept).

4.3.6.2 Objectives and Goals

Contract at least 75% of the critical area (47,331 acres) for BMP implementation

Contract with all 24 dairy farms in the project area

4.3.6.3 Critical Area Criteria and Application

Criteria:

All dairy farms in the project area

All beef cattle pastures that have been fertilized and extensively ditched for improved drainage

All agricultural areas within one-quarter mile of major streams, ditches, and channels that hold water year-round

4.3.6.4 Best Management Practices Used

General Scheme: The emphasis of BMP contracts is on stream protection, reduction of barn waste by improving water use efficiency and improving effluent disposal with spray irrigation, animal waste management systems (at the holding areas near the milking barns), and grazing land protection (i.e., RCWP BMPs 1, 2, 6, and 10).

BMPs Utilized in the Project *:

Permanent vegetative cover (BMP 1)
Animal waste management system (BMP 2), added in 1982 Grazing land protection system (BMP 6)
Cropland Protection System (BMP 8)
Stream protection system (BMP 10)
Permanent vegetative cover on critical areas (BMP 11)
Sediment retention, erosion, or water control structures (BMP 12)
Improving irrigation system and / or water management system (BMP 13)
*Please refer to Appendix I for description/purpose of BMPs

4.3.6.5 Land Treatment and Use Monitoring & Tracking Program

4.3.6.5.1 Description

Cost shared BMPs were monitored in terms of units installed and acres served. A summary of acres served for each subwatershed and year, by each BMP component and by installed (structural) BMP systems and management BMP systems was calculated. This information was provided on a subwatershed and annual basis in each annual progress project. Cow numbers per subwatershed, per water quality monitoring station, and per year were also estimated by a joint effort between the SFWMD and ASCS.

Non-cost shared BMPs were also included in the contracts so they could be tracked for implementation and costs.

4.3.6.5.2 Data Management

ASCS maintained the land treatment records and prepared reports.

4.3.6.5.3 Data Analysis and Results

Quantified Project Achievements:
           Critical Area            Treatment  Goals
 Pollutant
 Source        Units     Total   % Implemented    Total      % Implemented
Cropland acres        63,109     86%            47,337             114%
Dairies  # farms       22*    100%               22           100%
Cattle      # farms       35     74%               31            84%
Hogs     # farms         2    50%                2            50%
Contracts   #        56    82%               51            90%
* The number of dairies decreased from 24 in 1980.

Source: Stanley and Gunsalus, 1991

Most land treatment goals were met or exceeded. Two beef cattle operations in the critical area declined to sign contracts.

Fencing to keep animals out of the water courses, along with providing shade and water facilities, was effective in reducing the phosphorus concentrations from the project area. However, these BMPs alone were probably not sufficient to meet the water quality goal of a 50% reduction.

BMPs that require more active management, such as dairy waste water utilization, reduction, and timing of fertilizer applications on dairy and beef operations and controlling the release of high intensity area runoff, seemed to have the greatest impact on water quality.

The project found that explicit guidance for animal waste management practices needed to be written into the contracts to ensure that both the management and structural components of these systems were operated and maintained according to specifications.

Adoption of BMPs, such as improved fertilizer and feeding practices, was observed in surrounding areas.

4.3.7 Water Quality Monitoring and Evaluation

4.3.7.1 Strategy and Design

The water quality monitoring network emphasis was to measure phosphorus reductions over time and associate these changes with BMP implementation. Monitoring was performed before, during, and after BMP implementation. Stations were located in tributaries downstream of BMP implementation and at the project area outlet to document improvements on a subwatershed and project level scale. "Upstream/downstream" station pairs were established in a few tributaries. In 1988, the network was enhanced with monitoring site-specific BMP effectiveness on each dairy. This modification was a result of the FDER Dairy Rule.

The monitoring was performed by the South Florida Water Management District (SFWMD), Okeechobee, Florida. From 1978 to 1981, ARS collected biweekly baseline data, increasing the length of the pre-BMP data base.

4.3.7.2 Objectives and Goals

Objectives:

Evaluate the effectiveness of agricultural BMPs for reducing P concentrations to Lake Okeechobee, as measured by changes in water quality concentrations in the tributaries and basin outlet

Goals:

Identify and quantify trends in pollutant concentrations that occurred due to changes in land use and/or implementation of BMPs

Identify differences in upstream and downstream nutrient concentrations within the major tributaries

Establish nutrient inputs from subtributaries and to Lake Okeechobee

Using the pre-RCWP water quality monitoring data base: 1) document the general water quality throughout the 9 major tributaries in the basin; 2) provide a means for identifying the sources and causes of high episodic P events; and 3) document the need for agricultural BMPs to control P runoff (Ritter, 1988)

Analyze waste water in anaerobic and aerobic lagoons to determine its value for use as a supplemental fertilizer and treatment efficiency

Monitor nutrient runoff from the holding areas around barns into existing ditches that eventually drain into the major tributaries

4.3.7.3 Time Frame

1981 to 1990. Most stations have been monitored for water quality since 1978 and some since the early 1970's. Monitoring is planned to continue after 1990 to support other watershed management programs.

4.3.7.4 Sampling Scheme

4.3.7.4.1 Monitoring Stations

Surface: 38 stations originally; 23 instream stations throughout the 9 major tributaries continued after 1984. 3 stations located at dairy waste lagoons. From August, 1988 the monitoring network was expanded to 53 instream grab sample stations including 34 automatic sites to meet non- RCWP regulatory requirements. "Upstream/downstream" station pairs were established in a few tributaries to adjust for pollutant concentrations originating above the BMP implementation sites.

4.3.7.4.2 Sample Type

> Grab and automatic sampler

4.3.7.4.3 Sampling Frequency

Surface grab sample sites: until Mid-1988 - biweekly; afterwards - weekly

Surface automatic sample sites: daily

Ground water table depth: weekly at 8 stations; hourly at 4 other stations

Lagoon systems: monthly

4.3.7.4.4 Variables Analyzed

Total phosphorus (TP), orthophosphate-P (OP), Nitrate- nitrogen (NO3), nitrite-N (NO2), ammonia-N (NH3-N), total Kjeldahl-N (TKN), lab pH, lab specific conductivity, chlorides, turbidity, and color

4.3.7.4.5 Flow Measurement

Staff heights for flow have been taken with grab samples at five stations since 1978 and at remaining stations since 1983.

4.3.7.4.6 Meteorologic Measurements

Precipitation and hourly ground water table levels were monitored at four sites in close proximity to stations 01, 03, 06, 09, 11, and 23. Four additional ground water and rainfall sites were installed in the late 1980's.

Temperature and evaporation were also measured.

4.3.7.4.7 Other Important Water Quality Monitoring and Evaluation Information

None

4.3.7.5 Data Management

All chemical data are stored locally by the SFWMD. In 1991, the PC-based lotus files were converted to a mainframe ORACLE data base.

The trend analyses for pollutant concentrations were summarized in Ritter and Flaig (1987) and Flaig and Ritter (1989).

The hourly ground water table depth and daily precipitation measurements are stored on a mainframe data base by the USDA-ARS Southeast Watershed Research Laboratory at Tifton, Georgia. A copy is also stored on the SFWMD ORACLE data base system at West Palm Beach, Florida.

4.3.7.6 Data Analysis and Results

Analysis:

Exploratory data analysis included: 1) tabular presentation of the annual means and standard deviations for water quality concentrations at each station and 2) time plots of the entire period of record with pre- , transitional-, and post-BMP periods indicated.

Water quality trend detection techniques include: 1) the nonparametric Seasonal Kendall Tau test to detect linear trends over time; 2) linear regression to detect linear trends over time; 3) double mass curves to compare phosphorus concentrations and cow numbers in each subwatershed over time to account for changes in P concentrations after accounting for changes in cow numbers; 4) linear regression with time series errors to detect trends and adjustments for explanatory variables such as upstream concentrations, precipitation, ground water table depth, and autocorrelation.

Examination of the measured variability in the water quality data is used to determine the amount of change in annual mean concentrations required to be statistically significant (minimum detectable change) (Spooner et al., 1990).

Water quality modeling is being used to develop a watershed phosphorus transport model.

4.3.7.6 Data Analysis and Results (continued)

Results:

Seven out of 14 water quality monitoring stations tested by Ritter and Flaig (1987) exhibited significant decreasing trends over the period of 1978 through October, 1986.

Subsequent trend analysis using the period of data between 1978 though 1989 (adding data from 1987-1989) indicates that an increased number of stations exhibit significant decrease in TP concentrations and that the magnitude of decreasing TP concentrations had increased (Flaig and Ritter, 1989).

There has been an overall decrease in TP concentrations at station S-191, despite a substantial increase in cow numbers. The project has exceeded its goal of a 50% reduction in TP concentrations. It is postulated that this decrease is largely a function of the dairy closures in Otter Creek and the high number of BMPs installed in the other subwatersheds such as the Mosquito Creek and Nubbin Slough subwatersheds (Ritter and Flaig, 1987; Stanley et al., 1988). The closed dairies were thought to have been poorly managed, explaining the significant impact of their closure.

The project team realizes that uncontrollable variables such as weather, changes in land use, and changes in management, greatly affect the water quality data and make it difficult to isolate the effects of BMPs. This fact increases the need for a long post-BMP implementation monitoring period (Stanley et al., 1988). Variations in rainfall, depth to ground water, and flow must be considered when evaluating changes in land use and BMPs and their impact on water quality (Ritter, 1988).

4.3.8 Linkage of Land Treatment and Water Quality

Heatwole et al. (1987) used the BASIN model to give an estimate of the expected long-term average annual response of the Taylor Creek - Nubbin Slough basin to a hypothetical "maximum" BMP scenario. They predicted reductions of about 50% in the annual phosphorus loads from this basin.

The TCNS project's tracking of BMP implementation by practice and subwatershed allowed the project to link the water quality and land treatment data bases on a drainage and annual basis. This contributed to the project's ability to document changes in water quality as a result of land treatment on both subwatershed and project levels.

Site-specific monitoring was found to enhance the ability to document BMP effectiveness.

The fact TP concentrations continue to decrease as the length of the post-BMP data base increases supports the argument that the BMPs were effective in reducing TP concentrations.

Subwatersheds with a large amount of BMP implementation such as Mosquito Creek and Nubbin Slough have shown significant decreases in TP concentrations. In contrast, in northwest Taylor Creek and Lettuce Creek subwatersheds, increased cattle densities have had a negative effect on water quality (Ritter and Flaig, 1987; Flaig and Ritter, 1989).

There is strong evidence that two dairy closures in the Otter Creek subwatershed (in 1980 and 1986) resulted in a decrease in TP concentrations in Otter Creek and at Station S-191 (the main discharge to Lake Okeechobee from the project area). The effect of these closures was so large in part because of their poor waste management. These dairy shutdowns resulted in a masking effect, making it difficult to evaluate impacts of BMP implemented along this tributary (Ritter, 1988).

Other factors that confound the interpretation of water quality trend results include variations in rainfall, water quality depth, pollutant concentrations upstream of BMP implementation, soil types, and cow numbers. Changes in ground water table depth and cow numbers were the most important, non-RCWP factors affecting phosphorus concentrations. Ground water table depth is thought by the project to be a surrogate for the project area hydrology and season. In addition, a high water table contributes to increased phosphorus concentrations in the tributaries. Increases in cow numbers increases the potential source of phosphorus. Adjustments for these variables have not only allowed for valid interpretations regarding the observed trends, but have also increased the statistical significance of the decreasing trends (Spooner et al., 1990).

The project team believes that observed decreases on TP concentrations at the watershed outlet to Lake Okeechobee can be attributed to several BMPs such as fencing, water conservation/waste water recycling, drainage improvement, and fertilizer management.

Documentation of water quality improvements in Lake Okeechobee may be difficult in the short term. Canfield and Hoyer (1988) suggests that a 40% reduction in phosphorus loadings to the lake may have only a minor impact on the short-term water quality (as reflected by the phosphorus concentration), because the lake has a substantial phosphorus reserve. However, although changes in Lake Okeechobee's phosphorus impairment may be undetectable over a short period, monitoring external concentrations and loadings provides valuable information to use to project long-term effects from land treatment in surrounding watersheds.

4.3.9 Impact of Other Federal and State Programs on the Project

One dairy in the Otter Creek subwatershed participated in the Dairy Termination Program in 1986. Several dairies reduced their cow numbers in 1984 and 1985 by participating in the Federal Milk Diversion Program. A reduction in cow numbers usually resulted in a decrease in P entering the adjacent tributary.

In 1989 and 1990, three dairies participated in the Florida state buy-out program and ceased operation.

The 1987 FDER Dairy Rule and the 1989 State of Florida Surface Water Improvement and Management (SWIM) Plan changed the focus of the water quality goals and the associated land treatment emphasis. The Regulation (FDER) Dairy Rule requiring each dairy perform nutrient management such that minimum phosphorus left the operation. In 1989, the South Florida Water Management District (SFWMD) set standards for P concentrations at tributary discharges and the basin outlet (at S-191) to meet the requirements of the SWIM Plan.

4.3.10 Other Pertinent Information

A new dairy opened in 1986 in the Otter Creek subwatershed.

4.3.11 References

A complete list of all project documents and other relevant publications may be found in Appendix IV.

Allen, L.H., Jr., J.M Ruddell, G.J. Ritter, F.E. Davis, and P. Yates. 1982. Land Use Effects on Taylor Creek Water Quality. p. 67-77. In: Proc. Specialty Conference on Environmentally Sound Water and Soil Management. American Society of Civil Engineers, New York, New York.

Bell, F.W. 1987. Economic Impact and Evaluation of the Recreation and Commercial Fishing Industries of Lake Okeechobee, Florida. Dept. Economics, Florida State University, Tallahassee.

Canfield, D.E., Jr. and M.V. Hoyer. 1988. The Eutrophication of Lake Okeechobee. Lake and Reservoir Management, 4(2):91-99.

Federico, A.C., K.G. Dickson, C.R. Kratzer, and F.E. Davis. 1981. Lake Okeechobee Water Quality Studies and Eutrophication Assessment. Tech. Pub. 81-2. South Florida Water Management District. West Palm Beach, Florida. 270p.

Flaig, E.G. and G. Ritter. 1989. Water Quality Monitoring of Agricultural Discharge to Lake Okeechobee. ASAE Paper No. 89-2525, American Society of Agricultural Engineers, St. Joseph, MI. 17p.

Heatwole, C.D., A.B. Bottcher, K.L. Campbell. 1987. Basin Scale Water Quality Model for Coastal Plain Flatwoods. Transactions of the ASAE, 30(4):1023-1030.

The Lake Okeechobee Technical Advisory Committee (LOTAC). 1986. The overall review of South Florida Water Management District Lake Okeechobee research, Final report to Florida Department of Environmental Regulation.

Ritter, G. 1988. Project Spotlight - Taylor Creek/Nubbin Slough RCWP. NWQEP NOTES, 3:2-3.

Ritter, G. and E.G. Flaig. 1987. 1986 Annual Report - Rural Clean Water Program. Technical Memorandum. South Florida Water Management district, West Palm Beach, Florida. 71p.

Spooner, J., D.A. Dickey, and J.W. Gilliam. 1990. Determining and Increasing the Statistical Sensitivity of Nonpoint Source Control Grab Sample Monitoring Programs. p. 119-135. In: Proceedings International Symposium on the Design of Water Quality Information Systems. Information Series No. 61, Colorado Water Resources Research Institute, Colorado State University, Fort Collins, Colorado. 473p.

Stanley, J., G. Ritter, V. Hoge, and L. Boggs. 1986. Taylor Creek-Nubbin Slough RCWP No. 14, November, 1986. Annual Progress Report. Okeechobee County, FL.

Stanley, J., V. Hoge, L. Boggs, G. Ritter. 1988. Taylor Creek- Nubbin Slough Project, Rural Clean Water Program Annual Progress Report. Okeechobee County, Okeechobee, FL.

Stanley, J. W. and B. Gunsalus. 1991. Taylor Creek Nubbin Slough Project, Rural Clean Water Program Okeechobee, Florida Ten Year Report 1981 - 1990. September, 1991. Cooperators: Okeechobee ASCS, Okeechobee CES, Okeechobee SCS, and the South Florida Water Management District. Taylor Creek-Nubbin Slough, Florida RCWP Local Coordinating Committee, Okeechobee, Florida. 231p.

4.3.12 Project Contacts

Administration

Diane N. Conway / Jack Stanley, USDA-ASCS
609 SW Park St.
Okeechobee, Florida 34972
(813) 763-3345

Water Quality

Greg Sawka / Joe Albers, South Florida Water Management District
1000 NE 40th Ave.
Okeechobee, Florida 34973
(813) 763- 3776

Land Treatment

District Conservationist, USDA-SCS
611 SW Park St.
Okeechobee, Florida 34972
(813) 763-3619

Information and Education

Vickie Hoge, Cooperative Extension Service
501 N.W. Fifth Ave.
Okeechobee, FL 34972
(813) 763-6469