Technical reports

This paper provides an overview of the steps taken to investigate and remediate pesticide residue at the North Shore Restoration Area after the St. Johns River Water Management District took possession of the former farmlands.

The data presented in this paper are from a variety of sources and were used to develop historical estimates and reported quantities of public supply utility groundwater withdrawals during the period 1945 to 2010 in the central Florida region.

An investigation by the St. Johns River Water Management District was undertaken to determine the source of the water that discharges from Green Cove Spring in Clay County, Florida.

St. Johns River Water Management District established minimum flows and levels (MFLs) for Blue Spring, Volusia County, in 2006 as a minimum flow regime (MFR). An evaluation of available spring discharge data, for the period March 1932 to June 2006, was conducted, the summary of which is presented here. This paper finalizes the draft information presented in an earlier report, SJ2007-SP17: Analysis of Blue Spring discharge data to determine a minimum flow regime.

Existing data from published studies of benthic algae and macroinvertebrates were analyzed to evaluate the existence of relationships of how changes in algal communities may affect the fauna of springs and spring-run streams.

This atlas contains Lower St. Johns River Basin submerged aquatic vegetation (SAV) data for 2006. Ground-truthing transects and ground-truthing polygons from field-collected data were mapped and assessed, and hyperspectral imagery was collected and analyzed.

Human activity has increased the amounts of nitrogen going into surface waters and groundwater in the last century. This report documents the emerging body of research data that suggests that there are toxic effects of nitrogen enrichment on aquatic fauna.

A geographic information systems-based model was developed to predict the likelihood of harm to lakes in the St. Johns River Water Management District from future groundwater withdrawals. Six spatial data layers were combined to produce a map of lake susceptibility to groundwater withdrawals.

Sediment samples were taken to characterize littoral sediments, compare littoral sediments to pelagic sediments and explore associations among submersed aquatic vegetation and sediment quality.

Mapping of submerged aquatic vegetation began in 1995 to evaluate the quality and distribution of estuarine and freshwater submerged habitats. The ongoing effort is designed to quantify ecosystem change in response to restoration efforts and to provide information necessary for the development of pollutant load reduction goals and total maximum daily loads.

This atlas shows results of submerged aquatic vegetation (SAV) monitoring for 2001. Two methods were used to monitor SAV: (1) aerial photography followed by interpretation and (2) groundtruthing transects.

The effectiveness of glass prisms in boat docks was assessed to determine if shading impacts to submersed aquatic vegetation (SAV) were reduced. Six experimental docks with and without prisms were constructed in the lower St. Johns River. SAV percent coverage, canopy height, and photosynthetically active radiation were monitored under each dock and in an adjacent control area with no docks.

Since 1995, a geographic information system model has been used to define areas of the St. Johns River Water Management District where wetlands vegetation is likely to be harmed from future groundwater withdrawals for agriculture, industry, and public water supply. For the 2025 likelihood of harm assessment, a set of detailed constraints was generalized to create a new drawdown scale. This revised scale, in conjunction with drawdown estimations for 2025, was tested in the likelihood of harm model for the east-central Florida area.

Submerged aquatic vegetation (SAV) is an important food source and habitat for many organisms. This report compares three methods that were used to survey SAV distribution in the lower St. Johns River, Crescent Lake, Lake George, and Doctors Lake. Included are 37 aerial photographs.

Two analytical models were used to simulate changes in the water table and the potentiometric surfaces of the surficial aquifer system and the Upper Floridan aquifer, based on 2010, 2015, and 2020 projected pumpages at the city of St. Augustine wellfield as a part of the water supply assessment performed by the St. Johns River Water Management District.

Two analytical models were used to simulate changes in the water table and the potentiometric surfaces of the surficial aquifer system and the Upper Floridan aquifer, based on 2020 projected pumpages at the Tillman wellfield as a part of the water supply assessment performed by the St. Johns River Water Management District.

As part of requirements under Florida law, this report is part of a water supply assessment used to simulate changes in the water table and the potentiometric surfaces of the surficial aquifer system and the Upper Floridan aquifer, based on 2010, 2015, and 2020 projected pumpages at the city of Vero Beach and Indian River County wellfields.

This report shows how an analytical groundwater flow model was used to estimate the relative contributions of various water users to drawdowns in the potentimetric surface of the Upper Floridan aquifer of east Putnam and southwest St. Johns counties during the potato irrigation season (March 1-May 1).

Once a conventional and highly structured flood control project, the Upper St. Johns River Basin Project was transformed in the 1980s into a national model of modern floodplain management. This report shows how the current project is designed to balance the multiple uses of the St. Johns River and to provide for major environmental habitat restoration and water quality protection benefits while maintaining its primary mission of flood control.

Expansion of coastal plain willow was investigated in a relatively unimpacted, 8,400-acre area. Two remote-sensing approaches using color infrared aerial photographs were used to quantify the pattern and the rate of spread of willow.

Three linear analytical groundwater models, DRAWDOWN, MLTLAY, and SURFDOWN, were used in this study. The DRAWDOWN model calculated changes in the potentiometric surfaces of the water table in the surficial aquifer system and of the intermediate aquifer system, based on 1988 pumpage values and 2010 projected pumpages at the southwest wellfield of Palm Coast Utility Corp. The MLTLAY model calculated changes in the potentiometric surfaces of the intermediate aquifer system and the Floridan aquifer system, based on 1993 pumpage values and 2010 projected pumpages at the “LW” wellfield. The SURFDOWN model calculated the drawdown of the water table in the surficial aquifer system for the “LW” wellfield.

Two linear analytical groundwater models, MLTLAY and DRAWDOWN, were used to simulate changes in the potentiometric surface of the surficial aquifer and Floridan aquifer systems, based on 1988 pumpage values and 2010 projected pumpages for the city of Leesburg.

Groundwater samples taken from 187 wells were used to determine concentrations of chloride, sulfate, and total dissolved solids in the Floridan aquifer system in the Crescent City Ridge area.

A geographic information system methodology was developed to ensure the adequate placement of the locations of current groundwater flow models used by the St. Johns River Water Management District and to delineate areas where new analyses should be performed.

A linear analytical groundwater model, DRAWDOWN, was used to simulate changes in the potentiometric surface of the Upper Floridan aquifer, based on 2010 projected pumpages at the city of Ocala wellfield. The model calculates the drawdown in a two-layered, coupled, leaky-artesian aquifer.

A linear analytical groundwater model, DRAWDOWN, was used to simulate changes in the potentiometric surface of the Upper Floridan aquifer, based on 2010 projected pumpages at the Murphree wellfield.

A numerical groundwater flow model for the Wekiva River Basin is used to predict groundwater levels and associated spring discharges within the basin. Spring discharge rates are totally dependent on spring conductance coefficients and head differences between the elevations of the potentiometric surface of the Floridan aquifer system and the pool elevations at the spring sites.

Two analytical models, MLTLAY and SURFDOWN, were used to simulate changes in the water table and the potentiometric surfaces of the surficial aquifer system and the Upper Floridan aquifer between 1988 and 2010 at the Tillman Ridge wellfield.

Two analytical models, MLTLAY and SURFDOWN, were used to simulate changes in the water table and the potentiometric surfaces of the surficial aquifer system and the Upper Floridan aquifer, based on 2010 projected pumpages at the city of St. Augustine wellfield.

An analytical model, MLTLAY, was used to simulate changes in the potentiometric surfaces of the surficial aquifer system and the Floridan aquifer system, based on 2010 projected pumpages at the city of Vero Beach and Indian River County wellfields.

Two analytical models, MLTLAY and SURFDOWN, were used to simulate changes in the water table and the potentiometric surfaces of the surficial aquifer system and the Upper Floridan aquifer, based on 2010 projected pumpages at the Palm Bay Utility Corp. wellfield.