WAM has been applied to the Lake Okeechobee Protection Plan (LOPP) area in numerous studies over the past several years. These previous studies have been related to either the Comprehensive Everglades Restoration Plan (CERP) performed for the SFWMD and the US Army Corps of Engineers (USACE), or phosphorus budget analysis conducted for SFWMD. The most recent project completed on the LOPP, was the WAM Enhancement and Application on Lake Okeechobee watershed (WAMEA). WAMEA (Phase III) was completed in March 2009. The goal of the WAMEA was to develop an assessment tool that will enable the evaluation of ongoing and proposed phosphorus control measures at the Lake Okeechobee Watershed scale.  The assessment tool will enable the District to refine prior Technical Plans for the Lake Okeechobee Construction Project and adapt it to better meet the Total Maximum Daily Load (TMDL) goal of 140 metric tons of phosphorus per year.

Baseline simulations for each basin in the WAM Enhancement study area were performed to represent existing conditions. The existing conditions were based on mapped land uses. Each land use was assigned parameters to represent current fertilization and water management practices that affect water quality.   Then "what-if" scenarios were run, where the land use was updated to included various BMP implementations, and the modeled results used to evaluate the most effect method to reduce the P loading in the watershed.

WAM has been used extensively in the Lake Okeechobee area, with varying goals and objectives.    Details of each of these projects are described in the relevant projects below.

On March 22, 1995 the Suwannee River Water Management District (SRWMD) authorized Soil and Water Engineering Technology, Inc. (SWET) to perform a watershed assessment with respect to water quality for the entire District by using a Geographic Information System (GIS).  The outcome of this project is the SRWMD Water Assessment Model (SR-WAM), which became known as WAMview as it was designed as an extension to ESRI ArcVIEW 3.2.

The watershed assessment approach for the SRWMD used the District's GIS databases (land use, soils, hydrography, etc.) in addition to known pollutant transport processes to locate the areas within the District that have potential adverse impacts on the environment. The goal is to locate the problem areas and to quantify the relative impact on different scales in the study area.

Nitrogen continues to be of concern in the Suwannee River Water Management District. In order to address these concerns, a partnership with the agricultural community was developed with the Florida Department of Agriculture (FDACS), the SRWMD, the USDA-Natural Resources Conservation Service (NRCS), the Florida Department of Environmental Protection (FDEP), the Soil and Water Conservation Districts and other partners within the watershed. This partnership has concluded that the creation and implementation of BMPs is the best approach to control nitrogen levels in the District‘s ground and surface water.

Both the partnership, in general, and FDEP, in particular, had a strong interest in determining the potential impacts of BMPs. In order to address this issue, FDACS contracted with SWET to use WAM to evaluate the impacts of key agricultural BMPs to be implemented in the basin by 2008.  The Lower Suwannee River Basin was chosen for these analyses because it contains a high density of agricultural land uses.

The Suwannee Basin was selected as a focus basin for a joint project with the NASA COAST Interface to develop an on-line tool to test BMP's.  This project is currently under development.

SWET contracted with the National Institute of Water & Atmospheric Research Ltd (NIWA) in New Zealand to do a comprehensive watershed assessment of a large basin targeted for development just north of Auckland. The purpose of the assessment was to develop a plan for acceptable levels of development that would not adversely impact the streams and downstream estuary. A variety of scenarios were run to evaluate impacts during both construction and post construction phases.

The study clearly showed that the amount of construction within the basin had to be regulated to prevent significant impacts; however, over time, the basin could be developed if done properly with critical areas protected.

The Florida Watershed Restoration Act and Federal TMDL program requires the development of TMDLs for pollutants that result in non-attainment of water quality standards, allocation of those loads among point and nonpoint sources, and implementation to achieve water quality standards. WAM has been applied by the St. Johns River Water Management District (WMD), Suwannee River WMD and South Florida WMD to assist in the development of pollutant load reduction goals (PLRGs). Also, the U.S. Environmental Protection Agency has used this model for a TMDL project in the Myakka River Basin, Florida.

For the Hillsborough River project WAM was linked to WASP to provide simulation data to develop additional TMDL's in the Florida.  Read the project section on this below.

In support of the FDEP TMDL program, SWET has calibrated WAM for use with WASP modeling to provide daily estimated flows, water levels, total suspended solids, nutrients (nitrogen and phosphorus species), BOD, chlorophyll a, and dissolved oxygen levels.   To develop the TMDL limits, SWET used the Watershed Assessment Model (WAM) to simulate the source loads of pollutants and water quantity originating on the land surrounding the three water bodies that drain to the WBIDs of concern.  WAM has been linked to the Water Quality Analysis Simulation Program (WASP).   The source load generated by WAM was used as the input parameters to WASP in order to accurately model the lake simulation processes present.

The purpose of this project is to simulate water quantity and quality discharges within the Lake Hancock Basin in support of the Florida Department of Environmental Protection’s (FDEP’s) TMDL Program. The basin is located in the Lakeland, FL area and drains into the Peace River.  The WAM model was used to simulate the hydrology and pollutant contributions to the entire stream system.  This basin is dominated with natural and manmade (phosphate mining pits) lakes, which have been listed for poor water quality by FDEP.  WAM simulated constituent movement throughout the stream system, however, to represent more detailed in-lake processses, it was linked to the BathTub lake model.  WAM produced all of the necessary inflow and outflow quantities and water qualities for the BathTub model.  The model was modified during this project to handle the significant lake leakage that occurs in this basin

In order to provide information to support the identification of planning targets for total phosphorus (TP) concentrations and loads in Fisheating Creek (FEC), a pre-drainage simulation was performed using WAM.  The pre-drainage hydrographic network was mapped using historical aerials.  The historic land use was mapped by an interpolation technique based on native landuse occurence on soil types in the basin.  The results of this analysis are shown below.

To determine the assimilative capacity of wetland and streams systems under native conditions,  a literature/data search was done to locate information that would be relevant to native TP concentrations in FEC.  Based on the data collected and discussions with the experts, it is our best professional judgment that the most probable annual average pre-drainage/native TP concentrations would have been around 70 to 80 ppb.  However, given the uncertainty in the estimates, there is a significant error range around this estimate that could range somewhere between 30 and 100 ppb.  Given these annual average values, it should be recognized that daily variations in TP concentrations could be expected to range between 20 and 250 ppb.The above ranges were used as targets for the re-calibration of WAM for the pre-drainage condition.

This technique was also used in the TMDL assessment done for the 3 lakes in the Upper Peace River.

WAM has been used to test the conceptual design of Reservoirs and Regional Storm Wastewater Treatment Systems.  The DMSTA submodel for STAs,developed by Bill Walker, was integrated into WAM for this project.  The project included the testing of different scenarios with the placement or design of the systems.  By simulating these different scenarios the expected nutrient reduction can be compared, allowing for a relative comparisons to be made before the expensive process of construction and implementation in considered.

WAM has been selected for Springshed assessment projects because of its capability to simulate surface and groundwater flow and water quality, including land source loads and appropriate attenuation processes along the flow path.  This includes its ability to handle closed (no surface outlet) sub-basins and their resulting groundwater flow and nutrients.  Below are two projects in which WAM has been effectively used in this capacity:

Rainbows Springs

The purpose of this project was to develop and utilize a GIS-based computer model to simulate water and non-point source pollution discharges from Rainbow Springs and to spatially quantify sources of nitrogen; the pollution of greatest concern. Located several miles north of the City of Dunnellon in western Marion County, Florida, Rainbow Springs is one of the largest spring systems in the state, and is the dominant source of water in the Rainbow River, which flows into the Withlacoochee River near the southern edge of Dunnellon.

There were three land use scenarios developed and simulated using the Watershed Assessment Model (WAM). The first is the “base” or “existing condition” run that is based on the 2007 land use coverage. The 2007 land use is primarily based on 2005 land use data updated to reflect 2007 tax assessment data and aerial verification. The next two scenarios use the “2025” and “2055” future land use coverages. The future land use scenarios required the development of a future condition utility zone (central sewer).

The figure below provides the predicted trends that are anticipated to occur as the springshed develops. The red trend line shows the current nitrogen trend in the springs based on measured data, while the blue trend line indicates what would happen if 2007 land use within the springshed were never altered. The green trend line shows the anticipated nitrogen increases in the springs based on predicted future land use. The nitrogen levels in the springs are likely to reach about 5 to 6 ppm by 2055, as compared to about 1.7 ppm currently observed in the Rainbow River.

Coastal Springs

The purpose of this project is to simulate water quantity and quality discharges for the coastal springs along the west coast of Florida from Pasco County up to Crystal River.  This project was completed for the Southwest Florida Water Management District to determine the regional growth impacts on the numerous springs along the coast. The Springs Coast watershed encompasses approximately 800 square miles of coastal Citrus, Hernando, and Pasco counties in west-central Florida. The watershed includes four major spring groups, discharging an estimated 900 million gallons per day from the Floridan aquifer into the Crystal, Homosassa, Chassahowitzka, and Weeki Wachee rivers (Figure 1). Additionally, there are numerous second and third magnitude springs within the study area. Most of these springs lie west of the U.S. Highway 19 corridor. This area has undergone, and continues to undergo, considerable development. This development has impacted and will continue to impact, the springs in the Springs Coast Basin. Nitrate is the primary constituent of concern.  The model was used to assess three scenarios including predevelopment, existing condition, and complete buildout.

This involved the compilation of existing data on the locations, and groundwater basins of the springs in the Coastal Rivers Basin, and the development of new information on the spatial extent of the surface water contributing area of each spring(s) complex. This effort produced: maps of the locations of springs and surface and ground water contributing areas, a Geographic Information System (GIS) database, and pollutant loading estimates and predictions linked to land use within the surface water contributing areas.

WAM was developed by SWET and has been in use by both private and public sectors for over 15 years.  The first WAM GIS based interface was developed before commercially available GIS software was even available, which resulted in SWET developing its own version of a GIS.  Since then WAM has been upgraded to work as an extension in the ESRI software platform.  This extension was originally built into the ArcVIEW 3.2 environment, and was recently upgraded to a fully compatible .NET framework that operates as an series of "dockable" windows and tools inside of the ArcGIS platform.

WAM has been linked to other hydrologic and constituent transport models to provide additional capabilities and specificities.  These linkages have been used in various projects, espacially for the development of TMDL's in Florida.  Please review the WAM projects pages for specific details.

SWET’s Watershed Assessment Model is being integrated into NASA’s Coastal On-line Assessment and Synthesis Tool (COAST). By merging these tools the end user will be able to implement BMP’s to hydrology and water quality responses on water being discharged into coastal waters within the COAST Interface. SWET is working with NASA to create a conceptual design report for the “area of interest” tool and the COAST/WAM Tool.   The tools created will provide data transfer and operational protocols for the COAST environment.

The Everglades Agricultural Area (EAA) is a an important agricultural region that covers about 500,000 ac to the southeast of Lake Okeechobee and to the north of the Everglades system.  The area has primarily flat organic soils with naturally high water tables (Histosols).  When these Histosols are drained for agriculture, aerobic mineralization releases both phosphorus (P) and nitrogen (N) from the organic matter.  The nutrient loss from these soils is of concern to the downstream Everglades ecosystem, since it can cause vegetation changes through eutrophication, especially in an oligotrophic system like the Everglades.

EAAMOD was developed to test the effectiveness of BMPs for reducing the P losses from EAA farms, and to evaluate the long-term effects of various BMPs at the field and farm scale.

In the EAA, an organic topsoil covers the marl bedrock, and is often separated by an impeding layer.  Water content and redox potential change with depth, affecting phosphorus mineralization and partitioning.  The marl layer has a high affinity for P as indicated by the low P concentration of drainage water from ditches penetrating this layer.  Lateral drainage is sometimes to two different ditches (field and regional).  This level of physical complexity steered the model design to a two-dimensional multi-layered approach.

The EAAMOD-FIELD model is a two-dimensional model that predicts flow and P losses from a field.  The hydraulic flow model divides the field into four vertical layers within the soil profile and numerous horizontal cells across the field.  These zones can vary in both hydraulic conductivity and aerobic state.  Any one of the cells can be a ditch and an impeding layer can be implemented.

The P model tracks the size of the mineral P pools (adsorbed and soluble/labile P).  Because the soil organic matter pool is dominant in size, it is the only organic matter pool considered, and it is assumed to be infinite.  Modeled P processes include mineralization and sorption-desorption while inputs of P can be from fertilizer, rainfall, and irrigation water.

Recently, a user-friendly Windows-based interface was developed for the EAAMOD-FIELD model.  The interface is designed to make the model useable by farmers, agricultural technical advisors, and governmental personnel.  It provides access to pre-defined EAA farming scenarios and the ability to manipulate the soils, phosphorus, and management parameters.  Farming scenarios include a number of soils, crops, water management options, and a large record of weather data.  Output is presented graphically or in tables and extensive on-line help is available.  Examples of some of the interface screens are given below.

EAAMOD modules/objects for the South Florida Water Management District’s (SFWMD’s) RSM model have been developed.  These modules will specifically handle the soil and cropping conditions found in the Everglades Agricultural Area south of Lake Okeechobee.  Two modules called EAAMod-Field and EAAMOD-Farm were developed and coded using the SFWMD’s Hydrologic Process Module (HPM) format to simulate the high water table / flatwood and histosol soil conditions for the SFWMD’s Regional Simulation Model’s (RSM) Hydrologic Simulation Engine (HSE).  The EAAMod-Field HPM was developed as a subclass to the PseudoCell class that defines the attributes and methods for simulating HPMs.

SWET in association with Breedlove, Dennis & Assoc. and Hazen and Sawyer performed a major update of the Lake Okeechobee Agricultural Decision Support System (LOADSS).   LOADSS is a GIS-based tool for evaluating the environmental and economic impacts of different agricultural management practices on reducing phosphorus loads from the Lake Okeechobee watershed.  LOADSS stores and retrieves data; edits modeling scenarios; and generates reports and maps.  Within LOADSS, a land use and phosphorus management plan can be developed using a menu-driven user interface.  LOADSS was originally developed with data collected from 1973 to 1987 and was updated by SWET to take into account the substantial changes in dairy land use and phosphorus management practices that occurred since 1987.  The updated LOADSS model also provides a better estimate of in-stream phosphorus assimilation.  In the previous version of LOADSS, the in-stream phosphorus assimilation was estimated using an exponential decay function based on flow travel distance.  However, the assimilation of phosphorus is influenced by many other factors.  In this study, an improved phosphorus assimilation algorithm was developed.  The algorithm is based on a second-order exponential relationship among flow rate, concentration, travel distance, and background concentration.  The updated LOADSS model was re-calibrated using observed tributary phosphorus loads from 1991 to 1995.  The updated model was used by Dr. Joyce Zhang with the SFWMD to evaluate alternative land use and phosphorus management strategies for reducing phosphorus loads to Lake Okeechobee.

SWET has worked with over twenty animal feeding operations, primarily dairies, in Florida and Georgia, to develop NPDES, Groundwater, and Surface Water (ERP) permit applications and renewals.  Assistance includes Nutrient Management Plan and permit application development, groundwater monitoring plans, renewal applications, and addressing compliance issues as they develop.  One of the more recent activities was working with a dairy and a bio-tech company to evaluate a bioprocessing plant on the dairy to utilize100% of the barn waste.

SWET has gotten six rotationally grazed (RG) dairy facilities permitted including Piedmont, Southpoint, V&W, HW Rucks, Zolfo Springs, and Ten Mile Grade dairies.  The dairy facilities consisted of lactating cow paddocks, a dry cow/sprayfield, a milk/feed barn and lagoon system, and a solids application area that are designed to made the dairies very neighbor and environmental friendly.

SWET assisted Suwannee Farms with the design and permitting of the 5000 head cattle feeding operation which includes a large methane digester with a gen-set for electricity productions.  This was the first animal methane system in the state of Florida.

The overall objective of this project is to identify and rank sites within the Northern Everglades Watershed that would be most suitable for the implementation of chemical treatment technologies. The P reduction potential and costs for the chemical treatment systems will be used to determine the relative cost effectiveness of the identified systems. A combination of cost effectiveness and net P load reductions to Lake Okeechobee will then be used to establish rankings.

The Watershed Assessment Model (WAM) has been used to simulate all the basins within the project area except for those in the St. Lucie, Indian River Lagoon and the Northern Coastal Caloosahatchee River. For those basins simulated by WAM, an estimated flow weighted concentration for each of the source cells in the model was calculated. These outputs were used to develop an Event Mean Concentration (EMC) for each of the Land Use and Soil combinations simulated. This EMC was used to produce an estimated TP concentration for that portion of the project area not simulated by WAM, based on the land use or soils combinations.

The WAM calculated flow weighted concentrations and monitoring data sourced from DBHydro and STORET were used to identify the TP loading hotspots using GIS analysis and visual spatial correlation techniques. This resulted in the selection of 60 potential chemical treatment sites.

These 60 sites were entered into a priority ranking matrix which compared sites to each other by assigning a numerical score to each and ranking them based on their cost effectiveness of P removal. The ranking matrix used the following information to calculate a score for each site: TP concentrations, flow, adjusted treatment cost, and possible physical constraints such as the presence of wetlands, other P control projects, and multiple landowners, as well as upstream land use. The TP concentration and flow data were obtained from either monitoring data or from the WAM simulations that have been done for the watershed. It was assumed that each chemical treatment facility would reduce the TP load at that site by 80%, which is an estimate of an achievable reduction that could be expected for an alum based system.

The overall objective of this conservation plan is to provide guidance for water quality and conservation management of the Lykes Bros. Inc. property in the Okeechobee Basin that will protect, conserve, and enhance natural resources (soil, water, air, plants and animals) within their related social and economic interests for a site-specific enterprise. The plan identifies existing and future conservation practices or Best Management Practices (BMPs) that are to be maintained and implemented to meet the above objective as well as serving to meet obligations under State water quality rules and regulations.

This is the first time WAM has been used for conservation planning and was found to be extremely useful, particularly for evaluating the various retention alternatives within the very complex hydrography on such a large land parcel.

Dr. Del Bottcher has been an expert witness in a number of cases.   In Georgia, Dr. Bottcher has provided expert evaluation and testimony in three flood damage cases with one including a damn failure evaluation and one weather related accident case.  In Florida, Dr. Bottcher served as one of two IFAS experts for the 1988 Federal Lawsuit against the State of Florida (SFWMD) for not protecting the Everglades.   He has also provided expert evaluation and testimony in three flood damage cases, one urban contaminate transport case, and four administrative hearings on dairy permits in Florida.

Dr. Del Bottcher has designed new dairies and upgraded waste management systems for existing dairies.  All of the new dairies have been rotationally grazed dairies, but major confinement dairy upgrade designs have also been done.  Assistance includes development of Nutrient Management Plan and permit application development, groundwater monitoring plans, renewal applications, and addressing compliance issues as they develop.

Dr. Bottcher with SWET has been actively involved in Animal Waste Management design and research for over thirty years.  Recent projects include:

1.  Design of two new rotationally grazed dairies in northern Florida.

2.  Waste water lagoon and spray field design for several dairies.

3.  Research project for determining manure deposition distribution throughout a dairy.

4.  Determination of nitrate leaching potential from under dairy spray fields for various management and cropping treatments.  Project uses underground solution-cup lysimeters to capture leaching water.

5.  Designed a irrigation scheduler program for a multiple pivot spray field.

6.  Redesigned several existing dairy HIA and waste management systems to meet current regulations.

7.  Provided expert testimony for dairy rulemaking and for several administrative hearings for dairy permits

SWET completed a comprehensive study on renewable energy alternatives for dairies in Florida for the Sunbelt Milk Producers.  The study evaluated methane and gasification systems.

SWET assisted Suwannee Farms with the design and permitting of the 5000 head cattle feeding operation which included a large methane digester with a 600 KW gen-set for electricity productions.  This was the first animal methane system in the state of Florida.  SWET has also been active in promoting and obtaining grants for solar energy systems on dairies.