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NCSU Water Quality Group |
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Okeechobee, Highlands, and Glades Counties
MLRA: U-156A
HUC:030901-02
Lake Okeechobee provides drinking and irrigation water, supports commercial and sport fishing, and is a habitat for many migratory and endemic bird species. High phosphorus (P) concentrations in Lake Okeechobee promote algal blooms and eutrophic conditions that impair all water uses.
The Lower Kissimmee River Basin is the second largest source of external phosphorus loading to Lake Okeechobee, delivering 20% of the total phosphorus (TP) and 25% of the total nitrogen in 31% of the inflow to the lake. The project seeks to reduce phosphorus loadings to Lake Okeechobee by 43%, as measured at the watershed outlets (S65E and S154).
Over 95% of the land use in the watershed is agricultural. Dairy and beef operations are the primary sources of phosphorus. Runoff from dairy holding areas and milking barns, direct stream access by large numbers of dairy cattle, and runoff from improved pastures are the main contributors. Most of the beef cattle pastures have been fertilized and surface drained to improve drainage during the wet season. The critical area covers 15,500 acres and includes all dairies in the project area. In 1988 there were 19 milking barns with approximately 12,655 milking cows in the project area. The number of milking barns decreased to 11 in 1992; however, the number of milking cows remained in excess of 10,000.
Regulation has played a major role in defining land treatment and water quality goals. The best management practices (BMPs) implemented through the Rural Clean Water Program (RCWP) project are directed toward recycling nutrients produced on the farm to comply with the 1987 Florida Department of Environmental Regulation (FDER) Dairy Rule. This rule requires dairies to collect and then dispose of runoff from milking barns and high animal intensity areas through spray irrigation, so that the phosphorus in the effluent is assimilated by plants or absorbed by soil. In addition, in 1989, the South Florida Water Management District (SFWMD) set standards for TP concentrations at tributary discharges and the basin outlet to meet the requirements of the 1987 Florida Surface Water Improvement Management Act (SWIM-Act).
The RCWP BMP emphasis includes animal waste management, diversion systems to capture effluent from milking barns, stream protection, fertilizer management, grazing land protection, permanent vegetative cover, and pesticide management.
The Lower Kissimmee River RCWP project has an extensive water quality monitoring program. Baseline water quality data have been collected since 1986. Since 1987, a combination of instream and BMP site-specific water quality monitoring stations have been employed to document long-term trends and the effectiveness of implementing a set of intensive animal waste management BMPs, combined with removing cows from the streams. Grab and time- weighted proportional samples were taken from major tributaries, water control structures, and at the major outflow of each dairy. The weekly grab samples are utilized to document long-term trends; the automated samples are utilized to quantify loads and determine the efficiency of individual management practices.
Beginning in October, 1991, the dairy monitoring program was streamlined to better support the FDER Dairy Rule. Monitoring of all dairy offsite discharges continues with grab samples taken two times per month.
By September, 1990, approximately 97% of the critical area was under contract and BMPs were 45% implemented. As of April, 1992, implementation of BMPs was complete on 100% of critical area, including all dairies. Cost share was available under RCWP and other federal and state programs.
The project did not start BMP implementation until 1988; therefore, changes in phosphorus loadings to Lake Okeechobee have not been quantified. However, BMPs appear to be improving water quality at individual dairies within a year after implementation. Preliminary results indicate that a reduction in TP has occurred on at least 80% of the dairies that have implemented BMPs.
Figure 4.4: Lower Kissimmee River (Florida) RCWP project map, FL-2.
State regulations were used to establish both the land treatment and the water quality goals. The 1987 Florida Department of Environmental Regulation Dairy Rule requires dairies to collect and dispose of runoff from high animal intensity areas through spray irrigation, so that most of the phosphorus in the effluent is assimilated by plants or absorbed by soil (nutrient mass balance concept). In addition, in 1989, the SFWMD set standards for TP concentrations at tributary discharges, the basin outlet, and various land uses, to meet the requirements of the SWIM-Act. The project calculated its goal to reduce phosphorus and nitrogen loadings by 43% at the LKR Basin outlet by applying the basin discharge concentration standard required by the SWIM-Act (0.18 milligram P per liter, mg P/l) concentration at the watershed outlet to Lake Okeechobee.
From the experience in the TCNS Basin, intensive waste management BMPs, along with fencing to remove cows from the stream, were thought to be required to meet the water quality goals.
The two most important reason farmers decided to participate is the availability of cost share funds (federal and state) and concern about meeting pollution regulations. Technical assistance was also important.
Regulation has played the major role in defining land treatment. The BMPs implemented through the RCWP project are directed toward recycling most of the nutrients produced on the farm to comply with the 1987 FDER Dairy Rule. This rule requires dairies to collect and dispose of runoff from high animal intensity areas through spray irrigation, so that phosphorus in the effluent is assimilated by plants or absorbed by soil (nutrient mass balance concept). In addition, in 1989, the SFWMD set standards for TP concentrations at tributary discharges and the basin outlet to meet the requirements of the SWIM-Act.
To meet the objective of substantial decreases in P loadings at the watershed outlet, the BMPs recommended by LOTAC (1986) were more intensive than those used in the Taylor Creek - Nubbin Slough Basin. The emphasis was on a set of expensive animal waste management BMPs to achieve nutrient mass balance, combined with removing cows from the streams.
Using the lessons learned from Taylor Creek - Nubbin Slough, priority of BMP components and implementation is based on expected water quality benefits.
Based on the Taylor Creek - Nubbin Slough portion of the project and other studies, the planned land treatment program, although costly, is thought to the be most cost effective method to achieve the desired P reduction. Alternatives for nutrient reduction, such as treatment plants, relocation of dairies, and total confinement operations are considered more costly.
Close coordination between the project and regulatory agencies is needed in selecting and implementing BMPs.
Animal waste management and fertilizer management should be used as a complementary set of BMPs.
Although monitoring the efficiency of individual BMPs was an original goal of the autosampling program, that goal was never realized, primarily due to the inter-relationships of the practices. For example, fencing to exclude cows from streams was implemented at the same time as fertilizer management, reduced phosphorus in the feed, and possibly portable shades or feed/water/shade in the high intensity areas around milking barns. Therefore, the monitoring program is not capable of separating the effects of the individual practices.
The project did not start BMP implementation until 1988; therefore, changes in phosphorus loadings to Lake Okeechobee have not been quantified. However, BMPs appear to be improving water quality at individual dairies within a year after implementation. Preliminary results indicate a reduction in TP has occurred on at least 80% of the dairies that have implemented BMPs.
The project is conducting a study to document the effectiveness of implementing an expensive nutrient mass balance set of animal waste and fertilizer management BMPs, combined with preventing animal access to a stream.
More efficient use of dairy waste water and effective management of waste storage lagoons has resulted in improvements at the individual dairy operations and downstream water quality.
The use of computer models is useful to predict the fate of nutrients on a field, subwatershed, and watershed scale as well as provide a mechanism for integration of multiple environmental variables such as rainfall, water table, soils, water quality, animal units, land area, topography, cow numbers, and flow.
1988 - 1995
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. A diverse wildlife habitat draws many tourists to the lake area.
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.
Over 95% of the land use in the watershed is agricultural. Dairy and beef operations are the primary sources of P. Runoff from dairy holding areas, milking barns, direct stream access by large numbers of dairy cattle, and runoff from improved pastures are the main contributors. Most of the beef cattle pastures have been fertilized and surface drained to improve drainage during the wet season.
Phosphorus concentrations in runoff are high because the soils are sandy Spodosols with low phosphorus retention capacity and rainfall is in excess of evapotranspiration. Most of the P loss occurs in the dissolved phase as orthophosphate phosphorus (OP). 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, total phosphorus concentrations in the tributaries increases as the water table depth rises to within two feet of the surface.
Geologic Factors: Topography is relatively flat with an elevation range of about 40 feet (17 to 58 feet above mean sea level). 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. In upland areas, the water table seasonally fluctuates from ground surface to three to five feet. In undrained flood plains and low-lying flood prone areas, the water table is above ground surface or very near the surface most of the year. Much of the watershed has been extensively drained for control of high water tables.
The Lower Kissimmee River is channelized (sometimes referred to as Canal 38) with flow control structures such as S-65C, S-65D, and S-65E. Water flow from the Lower Kissimmee River Basin and its tributaries enters Lake Okeechobee through flow control structures S-65E and S-154.
Use % of Project Area % of Critical Area Cropland (mostly citrus groves) 0.1 - Pasture/range
Dairy (milk barns/pasture) 7 100 Beef grazing 91 - Woodland (and wet prairies) 1 - Urban/roads 1 - Other - -
Operation # Farms Total # Total Animal
Animals Units
Dairy* 15 18,000 25,200
Beef 155 68,500 68,500
* 1988 numbers (12,655 of the dairy
animals were milking cows, the remaining were primarily dry
cows and springers). In 1988, there were 19 milking barns.
From May, 1989 to August, 1992, 7 milking barns chose to
take advantage of the State Buy-out and closed. In January,
1992, another milking barn removed its cows due to
participation in the Florida Save Our Rivers Program. In
May of 1992, there were an estimated 10,930 milking cows
(plus non-milking cows) and 11 milking barns in the LKR
Basin.
SOURCES Federal State Farmer Other ACTIVITY SUM Cost Share 835,840 2,570,000 601,030 0 4,006,870 Info. & Ed. 110,000 0 0 0 110,000 Tech. Asst. 504,000 113,000 0 0 617,000 Water Quality 0 1,167,422 0 0 1,167,422** Monitoring SUM 1,449,840* 3,850,422 601,030 0 $5,901,292* $1,249,840 of this is RCWP funds; $200,000 in ACP funds were available for cost share to the dairies under the LTA program.
** Water quality monitoring budget only reflects FY87 - FY91 expenditures.
Source: Stanley and Gunsalus (1991) and personal communication, SFWMD staff
Keep farmers and public informed of the progress being made during the project towards realizing water quality benefits and goals
Supplemental federal funds under the LTA and from state funds
RCWP payment limit of $50,000 per landowner
Technical assistance for all contracted BMPs
Regulations: A FDER rule has been implemented which requires dairies whose drainage reach Lake Okeechobee to address areas of high cattle intensity on their farms. It was estimated that the average cost will be $238,000 per barn to comply with this rule. The actual costs were as much as two to three times this estimate.
The two most important reason farmers decided to participate was availability of cost share funds (federal and state) and concern about pollution regulations.
The $50,000 per farm cost share limit under RCWP has been a constraint to addressing the waste disposal problems of these dairies.
Implementing the nutrient mass balance concept at the farm level required innovative management strategies on the dairies that were expensive and required major management changes.
Goals: Contract 100% of the critical area
Contract all 15 dairy farms with their 19 milking barns in the project area.
This objective was modified to include only the 11 milking barns in the project area that did not cease operation as a result of the buyout programs.
Implement BMPs over a three-year period
BMPs Utilized in the Project *:
Non-cost shared BMPs were also included in the contracts so they could be tracked for implementation and costs.
** As of 9/30/90, contracts had been made on 13 milking barns (9 under RCWP and 4 with the LTA or state programs). Implementation was in progress on 9 contracts and 1 contract was completely installed. By April, 1992, implementation was 100% complete on 11 milking barns.
Source: Stanley and Gunsalus (1991)
The monitoring is performed by the SFWMD, Okeechobee, Florida.
Assess water quality and provide baseline stream water quality data for support of FDER's Dairy Rule.
Evaluate the effectiveness of agricultural BMPs for reducing P loads to Lake Okeechobee, as measured by changes in water quality concentrations and loads at individual dairies, selected ditched pastures, in key tributaries and basin outlets
Identify episodic high P loads and locate source areas
Quantify P loadings at key dairies, tributaries and structures on the LKR.
Estimate P load reductions resulting from implementation of BMPs
Forecast the movement of phosphorus throughout the LKR Basin, specifically, investigate P movement and retention in soil by monitoring one or more dairies and modeling P-transport.
Determine the site-specific efficiency of specific BMPs (fencing, lagoons, spray irrigation systems) for P load attenuation.
Evaluate the efficiency and long-term effectiveness of individual BMP practices on typical soils and land drainage patterns
RCWP monitoring is from implementation date to 1995 for Level 3
Some baseline data has been collected since January 1986 at selected tributary sites
Monitoring is planned to continue after 1995 by the SFWMD
Flow control structure S-154 (on a tributary to LKR) has been monitored since 1973
Flow control structure S-65E has been monitored since 1982
Level 1 monitoring will continue to support the FDER after the RCWP project ends
Individual dairy and beef sites with automatic and weekly grab samplers
Ground water: Ground water levels are monitored two times per month at 11 sites
Dairies are monitored for TP and TKN only.
Temperature and evaporation is also measured.
Ground water level data are stored in a PC-based Lotus file by the SFWMD.
Exploratory data analysis includes: 1) tabular presentation of the annual means for water quality concentrations at each station and 2) time plots.
Water quality trend detection techniques includes: 1) nonparametric tests to detect linear trends over time and 2) the double mass curve method to correct the data for changes in hydrologic variation using rainfall and ground water stage data.
Water quality modeling is being used to develop a watershed phosphorus transport model.
Time series analysis will be used to examine trends (step and linear) over multiple years. Changes in ground water table depth and cow numbers will be incorporated to adjust for changes in water quality not directly related to the RCWP.
Load reductions will be estimated based on hydraulic model simulations.
Results:
The project did not start implementation until 1988; therefore, changes in phosphorus loadings to Lake Okeechobee from this watershed due to RCWP have not been quantified.
For most of the dairies, the quality of agricultural runoff from improved pastures and dairies is poor and well above the standards allowed for land uses (Flaig and Ritter, 1989).
BMPs appear to be improving water quality at individual dairies a year after implementation (Flaig and Ritter, 1989; Stanley and Gunsalus, 1991). BMPs appear to be improving water quality at individual dairies within a year after implementation. Preliminary results indicate a reduction in TP has occurred on at least 80% of the dairies that have implemented BMPs.
TP concentrations have decreased at flow control structure S- 65E during the 1980s, possibly from improvements prior to the RCWP project (Flaig and Ritter, 1989).
TP concentrations have increased dramatically over the last 15 years at flow control structure S-154, probably from increased dairy activity in the basin (Flaig and Ritter, 1989).
Phosphorus concentrations in discharges at the outlet from this project area may exceed 1.0 milligram/liter (mg/l). Baseline data are currently being evaluated.
Financial assistance for animal waste management systems is also available through the federal LTA and state cost share programs, in addition to the RCWP. These monies allow for a greater portion of the expensive systems to be cost shared than would be allowed under the RCWP.
State and federal dairy buy-out programs decreased the number of milking barns in the LKR Basin from 19 in 1988 to 11 in 1992. However, the number of milking cows decreased only by 14%.
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.
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.
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. and E.G. Flaig. 1987. 1986 Annual Report - Rural Clean Water Program. Technical Memorandum. South Florida Water Management district, West Palm Beach, Florida. 71p.
Stanley, J. W. and B. Gunsalus. 1991. Taylor Creek Nubbin Slough Project, Rural Clean Water Program Okeechobee, Florida Ten Year Report 1981 - 1990. Cooperators: Okeechobee ASCS, Okeechobee CES, Okeechobee SCS, and the South Florida Water Management District. Okeechobee RCWP Local Coordinating Committee, Okeechobee, Florida. 231p.
Stanley, J., V. Hoge, L. Boggs, G. Ritter. 1988. Lower Kissimmee River Project, Rural Clean Water Program Annual Progress Report. Okeechobee County, Okeechobee, FL.
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NCSU Water Quality Group |
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