Technical reports

The report is a review of published scientific literature related to the Upper Floridan aquifer and entire Floridan aquifer system. Reviewed documents covered the time period from the mid-1930s to the present day in order to assimilate sufficient information related to trends in the potentiometric surface.

This report documents an expanded effort beyond a 2013 report in which work was conducted to generate consumption estimates for the U.S. Geological Survey (USGS) Peninsular Florida Model (MEGA Model) domain. Monthly water-use estimates were generated from January 2000 to December 2012 for 242 counties across Florida, Georgia, Alabama, and South Carolina.

This report describes the development of a three-layer analytical drawdown model by modifying and enhancing the capabilities of the district’s existing two-layer analytical drawdown model.

This report documents a study to determine the mechanisms and magnitudes of nitrogen removal in spring-fed rivers, using a variety of methods and across springs spanning a gradient of concentrations and size.

The objective of this study was to monitor the composition and abundance of phytoplankton in the Indian River Lagoon, with special emphasis on potentially harmful species. The long-term goal is to provide a baseline of information with which future trends in algal blooms can be evaluated and the overall integrity of the Indian River Lagoon ecosystem can be preserved through sound management practices.

The information reported in this report validates historic contaminant information and enhances understanding of the river ecology.

This report documents creation of a database to allow parcel-level evaluation of water use to determine the success of water conservation.

The purpose of the industrial end use guide is to supply users with best management practices in each industrial sector in order to evaluate water conservation potential. Each BMP structure has several elements that describe the efficiency measures, implementation techniques, schedule of implementation, scope, water savings estimating procedures and estimates, cost effectiveness considerations, and references to assist end-users in implementation.

This study reflects data collected to develop base assumptions of irrigation efficiencies, with cost factors for various irrigation systems and crops grown in the study area, and to develop an irrigation land geodatabase and associated farm-level irrigation estimates for 1995 and 2010.

This report is a literature review of water shortage determination methodologies and an analysis of St. Johns River Water Management District data. The focus of the literature review was to identify methodologies to select water shortage indicators, develop and analyze thresholds for each indicator; and to identify water shortage conditions based on indicators and thresholds.

Collaborative research by the St. Johns River Water Management District, Florida Fish and Wildlife Conservation Commission, and the University of Florida suggests that spawning habitat use of migrating shad could be influenced by variation in water levels.

This report from U. S. Geological Survey, Florida Cooperative Fish and Wildlife Research Unit, and the University of Florida presents data on snail kite usage and reproduction within the Blue Cypress Marsh Complex during 2008, 2009 and 2010. Developing a thorough understanding of the kite’s ability to move between wetlands as well as their resistance and resilience to disturbances such as drought or change in habitat is essential for optimizing the management of the ecosystems inhabited by the snail kite in Florida.

This project seeks to identify dominant groundwater pathways and travel times between specific locations and the Silver Springs spring group, and the potential sources of groundwater nutrient contamination that appear to be directly connected to spring discharge vents.

Specific macrofaunal bioindicators of changes in salinity and freshwater inflows are discussed and speculations are presented about the possible implications of decreasing volumes of freshwater inflows into the St. Johns Estuary.

This expanded executive summary documents the development process, cooperative procedures, work products, and results of the Regional Aquifer Storage and Recovery Demonstration Project implemented in the city of DeLand.

This expanded executive summary summarizes the work accomplished for the city of Sanford Aquifer Storage and Recovery (ASR) Project at the city’s auxiliary no. 2 water treatment plant. The ASR system consists of an ASR well, two storage zone monitoring wells, one confining zone monitoring well, and a pretreatment system.

This overall summary covers all phases of the aquifer storage recovery (ASR) system implemented in Orange County for Orange County Utilities, including work products and deliverables previously submitted.

Work is summarized for the Seminole County Aquifer Storage and Recovery (ASR) Project, consisting of an ASR well, two storage zone monitoring wells, and one confining zone monitoring well, plus a pretreatment system

This report describes modifications to the U.S. Geological Survey Peninsular Florida Model to assist SJRWMD in water supply planning activities, with modeling reflecting data through 2030.

This report documents two models — a saltwater upconing model and a pumping impact model that are based on solutions by Motz (1992) and Denis and Motz (1998). The report includes documentation on the use of the models and modified computer codes.

This report includes a review of the literature for recovery strategies used in addressing concerns about the loss of revenue from conservation. Cost recovery strategies that are available to water utilities are outlined, including the mechanisms that Florida utilities can use to finance water conservation program costs. The descriptions serve as a menu of options for utilities and local governments.

The current and future potential for reducing potable water demand for five counties within the St. Johns River Water Management District are examined, using account-level billing information provided by the participating utilities, parcel geodatabases from county property appraisers, and population projections. While the data are variable and complex, the study shows that several spatial databases could be joined to leverage water consumption information and estimate conservation potential.

A baseline is presented for the improved understanding of nitrogen (N) fixation within these shallow, often hypereutrophic, subtropical lakes. The authors discuss physicochemical and biological influences on cyanobacterial N₂-fixations; estimations of annual, within-lake TN loading as a result of N-fixation; seasonal and other variations in N₂-fixation; other variables; and the molecular characterizations of (algal) organisms and levels of gene expression responsible for N₂-fixation — the knowledge of which may be useful in refining lake management scenarios.

Data collected at each of 40 surface water sites sampled March 2000 through August 2003, with supplemental data, are evaluated and described in this report. Sampling locations were within freshwater and estuarine rivers and streams of the Lower St. Johns River Basin in northeast Florida. Sampling sites were selected for their known or suspected sediment contamination.

Provides a detailed description of the methods and techniques developed by GIS Associates and applied by the St. Johns River Water Management District to project future water demand to a 2030 planning horizon. Takes into account annual historic water use, annual variations in water use with respect to climatic variations, as well as the methodologies consistent with the recommendations of a water demand protection subcommittee.

Summary report findings are two-fold: Evaluates the potential for capturing excess water currently discharged to the Indian River Lagoon, for beneficial uses; and evaluates the reconnection of the C-25 and C-52 basins, potentially to convey available water supplies across the jurisdictional boundaries of the St. Johns River and South Florida water management districts.

Repeated herbicide use to control the proliferation of hydrilla can be costly over time, conflict with various uses and functions of water bodies, and result in increasing chemical resistance. The authors discuss the goal of surveillance-based management to identify and treat hydrilla before it expands to whole-lake coverage, thus avoiding expensive, large-scale herbicide applications.

Provides cost definitions/cost estimating and economic criteria to be used in the development of regional planning level water supply facilities’ cost estimates for the draft District Water Supply Plan 2010. Provides a consistent set of definitions and criteria for the development of comparable planning level life cycle cost estimates for all water supply alternatives.

Multiple consultants present first-year findings of a 25-year monitoring action plan for Blue Spring and Blue Spring Run, the site of a popular state park and a warm-water manatee refuge. Year one (October 2007–September 2008) summarizes the data analysis for water quality, in-stream recreation, algal thickness, stream condition index, two genera of snails, a diversity of fish and turtles, and manatee use. A few ecological parameters found to be most sensitive to flows are recommended to be added to the yearly, ongoing monitoring.

Planned wetlands restoration is an important component of the restoration of Lake Apopka. This study summarizes the nature and extent of pesticides and evaluates the remedial alternatives under a range of targets that would allow wetlands reestablishment on a large portion of the lands that had been drained for agricultural use from 1941 to 1985.

A steady-state groundwater model was developed to predict drawdown impacts in the confined surficial and Upper Floridan aquifers, as well as the unconfined surficial. A sensitivity analysis was performed for the model, and parameters were described based on hydrologic conditions existing in 1995. The steady-state groundwater model presented here could be utilized as the basis for other models to assess the impact of future groundwater withdrawals in the area.

Final report concludes that post-fasting organochlorine pesticide (OCP) concentrations in alligator blood can be a reliable indicator of environmental OCP levels. The authors recommend additional monitoring of alligator populations to provide further insight on the bioavailability of OCPs to piscivorous birds and other wildlife. Research of 408 alligators was conducted in 2008–2009 as a follow-up to a 2007 pilot study of the North Shore Restoration Area.

This report describes the methods used to recompute daily discharge of Silver Springs, near Ocala. Recomputed daily discharge values for the period 1948–2005 are compared with the historical (USGS) record. Hydrographs and summary tables are presented. Daily discharges are specific to a single reference station, located about 3,900 feet downstream from the main spring boils. Recomputation considers the effects of measurement location on rating-curve development. Also, new discharge rating curves based on head difference between the spring pool and the aquifer were used to recompute discharge values for the period 1948–2002.

Available hydrologic data including rainfall records, stream discharge records, and individual spring discharge measurements were compiled, reviewed, and compared, for the purpose of identifying long-term trends or underlying causes of changes in discharge. Stream discharge locations in the lower basin were consistent in data except for Riverside Landing, which showed a very large increase in measured flow relative to upstream measurements. Further investigation would be required for realistic hydrologic modeling to be developed.

Statistical trend analyses were performed to characterize the annual time series of the available historic hydrologic and groundwater withdrawal data on a calendar year basis. S-plus software was used for the analyses, and a software package provided by SJRWMD was used to run the S-plus scripts in a batch. A cluster analysis was conducted on all groundwater level time series.

In this supplement report to SJ2010-SP11, the entire period of record for historic groundwater levels (Upper Floridan) data in the Suwannee River Basin and northeast Florida were analyzed for long-term trends and cluster analysis. In the final report under the original contract, groundwater level data available prior to 1980 was neglected, since other time series of interest (principally groundwater withdrawal estimates) were not consistently available before then.

A comprehensive statistical analysis was performed on 120 hydrologic data stations throughout the Central Florida Coordination Area. The analysis included rainfall stations, surficial wells, intermediate wells, Upper and Lower Floridan wells, lakes and springs. A total of 48 stations exhibited statistically significant decreasing trends for their respective periods of record, while 15 stations exhibited statistically significant increasing trends in the data.

The report documents the investigation of the Upper Ocklawaha River Basin as a potential water supply source, using annual streamflow records and historical records for the 38-year period from 1969 to 2007 from the Moss Bluff U.S. Geological Survey gage.

The report presents an estimate of the potential additional water supply yield, in addition to existing withdrawals, available from the St. Johns River at or above State Road 50.

The report compiles hydrogeologic and water quality data from the surficial aquifer system of Flagler, Brevard and Indian River counties to assess the feasibility of shallow Class V well concentrate disposal.

The report documents the work toward the goal to determine the estimated amount of potable-quality water offset that occurs when reclaimed water is used in place of potable water for irrigation.

This report documents the results of a feeding study to determine the potential for bioaccumulation of organochlorine pesticides in great egrets, to determine the potential for toxicosis and to evaluate the effects of fasting on tissue from these birds.

This report gives details about the health of aquatic vegetation in the St. Johns River’s lower basin and discusses changes in the vegetation.

The report describes the methodologies used by the district to project and spatially distribute population for water supply planning purposes.

The report documents establishment of minimum flows and levels for Blue Spring in Volusia County, the impact of groundwater withdrawals on average annual discharge to the spring and the development of alternative water supplies in Volusia County.

The report documents four studies regarding the improvements to water quality in the Upper Ocklawaha River Basin through the removal of gizzard shad.

Key hydrologic, water quality, and biological data are compiled and reviewed from a 2-year period to present a base evaluation of potential fatal flaws for a set of candidate alternative water supply project study zones along portions of the St. Johns River. Includes a discussion of mass balance analysis for each potential demineralization water treatment plant location, an evaluation of mixing zone feasibility for the potential outfalls, and the preparation and documentation of a mass balance spreadsheet model to estimate the effects of concentrate loading on the river.

Estimates are provided for comparison purposes considering 60% reuse, 75% reuse, and 100% reuse targets, for utilities looking for opportunities to maximize reclaimed water use to offset potable water supply and to reduce total maximum daily load discharges to the lower St. Johns River for compliance by year 2030. Results are presented against a base case scenario and a $300 million capital cost constraint to assist utilities in master planning. With utilities’ input, alternatives are represented in an optimized systems model — a water balance model that uses optimization techniques to estimate resulting infrastructure.

The feasibility of diverting storm water from the Nova Canal drainage basin system to supplemental regional reclaimed water systems, or other nonpotable uses, is documented. The study assesses the timing and quality of storm water that potentially could become available from canal system construction, taking into consideration the capital and unit production costs for facilities needed to recover storm water and for pumping to a storage or recharge facility.

Two management strategies are evaluated: active hydration and passive hydration, as feasible alternatives for avoiding or reducing impacts from groundwater drawdown effects in wetlands. A tabular summary of the results is presented, including a decision flowchart, to demonstrate the implementation of these strategies at four sites within SJRWMD.