Overview
The Cone Ranch Wellfield is one of a number of potential new water resource projects in the second phase of our Master Water Plan. The diversity of the projects included in the Master Water Plan will ensure that the regional water supply needs of an ever-growing population can be met while fully protecting our environment.
In many important ways, this project is significantly different than previous groundwater projects in the Tampa Bay area. Since historical groundwater pumping has been associated with environmental impacts to wetland and lake systems in northwest Hillsborough County and Pasco County, regional water supply managers, the public and water supply regulators have agreed that a new approach must be taken to plant and implement new groundwater supply systems.
These differences center on the following key issues:
The Southwest Florida Water Management District (SWFWMD), the state agency that regulates groundwater pumping, is applying much stricter permitting standards to new groundwater supply projects. These permitting standards are intended to protect the environment and the interests of the public and existing water supply users.
Advances in technology have created better tools to predict the effects of groundwater withdrawal.
More than 14 years of historical ecological data has been compiled on the Cone Ranch property. This wealth of historical data will allow regulators and project planners to more specifically understand and evaluate the environmental and hydrological conditions on the site an the potential effects that groundwater pumping may have on surface water features. This will allow Tampa Bay Water to manage wellfield operations in a manner that protects site and regional ecology and water supplies.
In the past, Tampa Bay Water has developed large amounts of water from small sites. Now, at Cone Ranch, we would develop a small quantity of water from a large site. Compared to past wellfields, it’s about half the amount of water from twice the amount of land.
Background
Originally purchased in 1988 by Tampa Bay Water (formerly West Coast Regional Water Supply Authority), ownership of the 20-square mile property was later transferred to Hillsborough County. Tampa Bay Water retained the right and responsibility for evaluating and developing a drinking water supply on this property.
Groundwater, surface water and ecological monitoring of the site began in 1989. Tampa Bay Water's project team conducted detailed analyses of test well data and monitoring data collected over the last 10 years. The purpose of the analyses is to evaluate the potential water yield and environmental effects of the proposed project. Surficial aquifer and Floridan aquifer monitoring wells were constructed to establish site-specific hydrologic characteristics. Groundwater contamination sites in the Cone Ranch area that might affect groundwater development were located and evaluated. The identified sites were detemined to be of no threat to the development of a water supply facility.
A feasibility study that incorporated over 10 years of historical hydrological data was conducted during 1999-2001 to assess the quantity of water that could be withdrawn from the Cone Ranch property without impacting the area’s ecological system or existing legal water users. The project team used an integrated surface and groundwater model which incorporated all aspects of the hydrologic cycle to assess pre- and post-pumping conditions that would exist at the site and in the area. A series of water use permit (WUP) pre-application meetings were held which allowed SWFWMD regulators and member government representatives to participate in the feasibility study analyses.
During the study, it became apparent that while the integrated surface and groundwater model being used to assess hydrologic impacts was appropriate for multi-year evaluations, enhancements to the model were deemed necessary to assess potential short-term impacts. Two independent peer review evaluations of the model were conducted and specific model enhancements were identified.
Enhancements to the model will improve high and low water level predictions and river flow on a seasonal basis, resulting in improved predictions of wellfield effects under different hydrologic conditions, including drought. The Integrated Hydrologic Model (IHM) will also provide hydrologists with more reliable predictions regarding the potential effects of the Cone Ranch Wellfield on Crystal Springs, domestic wells and nearby wetlands and ponds.
Once the IHM is available, the project team will re-assess the quantity of water that can be safely withdrawn from the Cone Ranch property without causing adverse impacts to existing legal users or the environment. If the project is selected for implementation by the Tampa Bay Water board, a timeframe for the development and submittal of the water use permit application will be prepared.
An important project element is to assess opportunities to modify historic drainage alterations on the property as a way of mitigating potential impacts to wetlands resulting from proposed groundwater withdrawals. The project team will be evaluating "hydration" of water features such as wetlands.
