The District has adopted a comprehensive management plan to address future freeze events in the Dover/Plant City area.

Over the past 40 years or more, farmers in the Dover/Plant City area have pumped groundwater to protect their crops by irrigating when temperatures drop below freezing. This has been a best management practice for many agricultural commodities such as strawberries, blueberries, citrus, nurseries and aquaculture. Because most farmers in the area turn on their irrigation systems to their full capacity all at the same time, a tremendous strain is placed on the aquifer resulting in lowered groundwater levels. These reduced groundwater levels in turn have resulted in impacts to residential wells and have caused sinkholes to form.

During the 11-day January 2010 freeze event, approximately 750 residential wells were impacted and more than 140 sinkholes were reported. Moreover, significant freeze events resulting in well failures and sinkholes have occurred three times over the past 10 years. As a result, the District has developed and adopted a multifaceted, comprehensive management plan to significantly reduce the impacts from groundwater pumping during future freeze events.

The management plan includes:

  • Declaring a 256-square-mile water use caution area in the Dover/Plant City area
    • The purpose of the water use caution area (WUCA) is to identify the area where the District will impose special requirements for existing and future permit holders to prevent or remedy regional problems caused by water withdrawals. The District developed special regulatory rules affecting the 256-square-mile Dover/Plant City WUCA that apply to existing and future water use permit holders with crops that require frost/freeze protection. These rules are intended to ensure impacts from groundwater withdrawals during future freeze events do not worsen.
  • Establishing a Minimum Aquifer Level and Minimum Aquifer Level Protection Zone
    • A minimum aquifer level is the level at which further withdrawals will cause significant harm. The Minimum Aquifer Level Protection Zone is the most impacted area where the greatest concentration of withdrawal impacts, such as well complaints and sinkholes, have occurred. In the Dover/Plant City area, the proposed minimum aquifer level has been set at 10 feet above sea level at the District’s DV-1 monitor well. The District determined that the majority of the well failures and sinkholes happened after water levels fell below this level. The Minimum Aquifer Level Protection Zone has been established in the surrounding area where freeze protection groundwater withdrawals have lowered the aquifer by more than 30 feet.
  • Developing a recovery strategy to help meet the Minimum Aquifer Level
    • The District is required by Florida statute to develop a recovery strategy whenever a water body is not meeting its established minimum flow or level. The aquifer levels in the Dover/Plant City area fell well below the minimum aquifer level in January 2010 as well as several times in previous years. Since aquifer levels in the Dover/Plant City area fall below the minimum aquifer level during significant freeze events, a recovery strategy is required. The goal of the recovery strategy is to reduce groundwater pumping for freeze protection by 20 percent within 10 years. This is to be accomplished through voluntary, incentive-based cooperative projects with area farmers to implement alternative freeze protection methods. It’s expected that such reductions would keep groundwater levels above the minimum aquifer level and avoid or minimize significant impacts.
  • Expanding the FARMS Program and increasing incentives for alternative frost/freeze protection methods
    • The District’s Recovery Strategy includes financial incentives for alternative freeze protection methods such as tailwater recovery ponds and crop covers. These incentives are available through the District’s Facilitating Agricultural Resource Management Systems, or FARMS, Program. FARMS is a cost-share program to reduce groundwater use through water conservation best management practices in agricultural operations. The District has increased its share of costs for projects that reduce groundwater pumping for frost/freeze protection in the Dover/Plant City area from 50 percent to up to 75 percent.
  • Requiring automatic meter reading devices
    • Flow meters and automatic meter reading devices will be required on withdrawal points, such as wells and reservoirs, for all permits with crops that utilize frost/freeze protection quantities. The District will provide funding for flow meters and installation for existing permit holders. Permit holders will be responsible for any maintenance or replacement of these meters. The District will also fund automatic meter reading equipment and installation. The District will be responsible for all ongoing costs associated with the automatic meter reading equipment. The District plans to implement the flow meter and automatic meter reading equipment within the next five years.
  • Creating a new process for allocating dry well complaints
    • The District designed a new process for determining which permit holder is responsible for responding to dry well complaints during freeze events. This process results in a very equitable approach to assign permit holders a relative responsibility based on the volume of groundwater they are permitted to use for crop protection and their proximity to the complainant’s well.
  • Expanding the area where special well construction standards apply
    • The Dover Special Well Construction Area was expanded to reduce the likelihood that homeowners will experience well failures during prolonged freeze events. Well construction standards in this area require residential wells to be drilled and cased deeper than typical residential wells. All new residential wells constructed within the area are now required to meet additional casing depth standards. Hillsborough County is also enforcing local pump depth requirements within the area.
  • Expanding the data collection network for freeze events
    • The District is expanding its data collection network by drilling additional monitoring wells to more accurately track the cone of depression associated with withdrawals during crop establishment and frost/freeze events. In addition, expanding the network will improve the quality, timeliness and accuracy of frost/freeze protection water use data and help staff better correlate the relationships between groundwater pumping and lowered groundwater levels.
  • Enhancing communication for freeze events
    • District communication before, during and after freeze events will include reminder letters to permit holders at the beginning of the cold season. In addition, the District’s website will continue to contain the most up-to-date information during freeze events, and permit holders will receive timely communication from the District when mitigation is required.
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