Temporary water drawdown in upper St. Johns River to aid in updating hydro models

PALM BAY, Fla., Jan. 4, 2017 — St. Johns River Water Management District plans to temporarily lower water levels slightly in two areas of the headwaters of the St. Johns River to facilitate land elevation data collection. These new data will update hydrologic models and ensure environmental goals for both project areas are met.

“Ground elevations in both the Blue Cypress Water Management Area and Ft. Drum Marsh Conservation Area are based on only a few old survey transects,” said District Executive Director Dr. Ann Shortelle. “A temporary drawdown – less than a foot in Blue Cypress – will allow us to gather critical data we need to manage these important natural resources.”

A contractor will use Light Detection and Ranging, or LIDAR, to survey Blue Cypress and Ft. Drum. LIDAR is a surveying method that creates a 3-D surface model of the ground using laser light pulses emitted and collected from a plane. The laser pulses reflect off land, but standing water obscures the pulses. LIDAR has been used over many parts of Florida and the district is working to fill gaps in coverage throughout the district. The technique allows for detailed elevation data to be collected over large areas much less expensively than traditional survey methods. Expect slightly lower water levels in Blue Cypress through March and in Ft. Drum through May.