Lido Key Summary & Conclusions

• The shoreline was extended an average of approximately 190 feet within the non-tapered project area (R-36 to R-39) with construction of the project.
• The results of the one-year post-construction survey performed in May 1999 demonstrate the adjustment to natural equilibrium slope that has occurred since project construction. The shoreline has receded approximately 85 feet between profile lines R-36 and R-39, and an average recession of approximately 15 feet has occurred over the entire study area (R-32 to R-43).
• During the two year post-construction period, sand will most likely continue to move offshore and narrow the beach until the system reaches a natural equilibrium slope.

• While much of the placed material remains within the project area, a significant amount of sand has moved from the project area limits to adjacent eroded beaches. Considering only the center (full fill section) project area (R-36 to R-39), 99,600 cubic yards or less than 40% of the originally placed volume has been retained to the -12 foot (NGVD) contour within this immediate region. The remaining beach width within this region is 37% of the original construction width of 190 feet or about 70 feet in width. Considering the relatively short project length of 4,950 feet, movement of sand from the central project area is consistent with theoretical diffusive losses from a project of this size and dimension.
• The interim (south) Lido Key beach nourishment project has been constructed in 2001, with the placement of almost 400,000 cubic yards of sand from R-36.5 southward to near the southern end of the key, R-44.2. Combining the central Lido Key project (the subject of this monitoring report) with the recently completed southern fill will provide a larger project with greater longevity.
• Study results clearly indicate that Lido Key should be addressed as one large project, with the possible inclusion of sand retaining structures at the southern end of Lido Key. With limited sand resources available for further beach renourishment, the City should implement a program which extends the life of beach nourishment efforts for Lido Key, including nourishment of the entire Key and potentially, placement of structures at the southern end of the Key to retain the sand.

• From 1998 through 2003, the City of Sarasota has nourished Lido Key on three occasions. Approximately 770,000 cubic yards of sand has been placed on the beach during the six-year period.
• Comparison of surveys conducted in 1998 and 2003 indicate that the projects were highly successful in restoring the beach.  The mean high water shoreline, on average, has advanced 182 feet in the project areas.  Additionally, the measured volumetric gain within the project area is 762,511 cubic yards, or 99% of the total volume of sand placed through beach nourishment since 1998.

• After completion of the monitoring survey in July 2004, Lido Key was impacted by the effects of four hurricanes (Charley, Frances, Ivan and Jeanne).  Although none of the storms hit Lido Key directly, waves from the storms impacted the beach.
• The total volume lost was almost 88,390 cubic yards as measured from the pre-storm -6 feet contour (NAVD) and nearly 10,930 cubic yards landward of the -18 feet contour.  Approximately 77,460 cubic yards of sand lost from the nearshore zone was found between the -6 feet and -18 feet depth contours.  The most significant volumetric loss occurred landward of the -6 NAVD contour between profile monuments R-39 through R-40 and R-40 through R-41, approximately 23,820 and 25,230 cubic yards respectively.