As of March 2021, plans, specifications, and permit documents are under development.
In recent years, large amounts of sand have accumulated at the entrance of Grand Canal (Dents Channel). A recent feasibility study by coastal engineers at APTIM found that, without human intervention, the entrance to Grand Canal could close within the next five years. In addition to impeding vessel access, a closure would adversely impact property values. To reduce the probability of closure, the County proposes that a navigational dredging (NAVDRG) project be undertaken.
As depicted in Figure 1, the NAVDRG Project entails dredging both Grand Canal entrance channel and potentially Basin A. As proposed, the Grand Canal entrance channel would be dredged to approximately 12-feet deep, 150-feet wide, and 3,000-feet long. This dredging would permit large vessels to continue to access navigable waters via the Grand Canal. Basin A, which is approximately 5.5 acres, could also be considered as part of this project and would be dredged to a depth of 8 feet. Basin A would act as a sand trap and would capture a significant amount of sand before it accumulates in the Grand Canal Entrance Channel.
History and Background Information
The Shell Key Preserve, including the island and surrounding waters, covers 1,828 acres and has been managed by Pinellas County since 2000. The management plan focuses on balancing public use with habitat preservation, particularly for nesting and migratory shore birds. The original plan was approved in 2000 by the Florida Department of Environmental Protection, Acquisition Restoration Council. The first plan update was approved by Pinellas County in October 2007. The latest plan update was drafted in 2018.
June 2011: Waterfront residents adjacent to the Preserve became concerned about the closing of the pass located between Shell Key and Collany Island, referred to as the Shell Key North Pass (SKNP).
2013: The residents hired a dredge to dredge the channel; however, by early 2015, the SKNP had filled in and closed.
October 2015: Tampa Bay Watch held a public meeting where concerns were heard ranging from water quality to predation of shorebirds and sea turtles. Data showing changes in predation due to pass closure is lacking and County analysis suggested that the overall water quality conditions in the Preserve have remained healthy and seagrass coverage has been improving.
May 2016: Pinellas County contracted with the University of South Florida to complete a dual-inlet study of Bunces Pass and Pass-A-Grille Inlet, which included the Shell Key Preserve and adjacent coastal waters. The 2018 study found the estimated maintenance dredging cycle among the three scenarios ranged from 1 year for a 20-meter-wide cut, to 5 years for an 80-meter-wide cut.
December 2018: A coastal engineering feasibility study by the County developed an alternatives analysis to identify the options to re-open the SKNP and/or mitigate the potential closure of the southern opening of the Grand Canal. Public input was sought at key stages in the study and several public meetings were held. The dredging of the entrance channel and Basin A as described above are progressing according to schedule.