District provides an update on rainfall, aquifer and surface water conditions as Hurricane Michael approaches the panhandle

A map illustrates groundwater conditions across the St. Johns River Water Management District.

A map illustrates groundwater conditions across the St. Johns River Water Management District.

PALATKA, Fla., Oct. 9, 2018 — The St. Johns River Water Management District recently presented data that provided a snapshot of rainfall, aquifer and surface water conditions across the district’s 18-county service area.

  • As Hurricane Michael approaches Florida, the National Weather Service has issued a Coastal Flood Advisory along the coast and along portions of the St. Johns River Basin around the times of high tide, due to high astronomical tides. This advisory affects the lower St. Johns River basin in the northeast Florida region.
  • Below-average rainfall has decreased surface water flow across the district. By the end of September, surface water flow decreased and dropped into the low range in the headwaters of the St. Johns River and in Orlando-area tributaries. Surface water flow also dropped into the average range further downstream in the St. Johns River Basin. The tidally influenced river near Jacksonville was in the very low range, dominated by the incoming Oct. 1 tide.
  • September rainfall was well below average across the district. As a result, the 12-month rainfall totals are now near the long-term average, after being well above average for many months. Coastal counties had the largest rainfall deficits during September. St. Johns, Flagler, Brevard and Indian River all had deficits of greater than 4.5 inches compared to the monthly rainfall average.
  • Aquifer conditions remain high. At the end of September, Upper Floridan aquifer conditions remained mostly in the high range, with normal conditions measured in Nassau, Duval and northern St. Johns counties. In fact, groundwater levels in more than half of the wells used to generate data and maps are still in the 90th percentile or higher, meaning that for all the measurements ever taken, only about 10 percent of the time have levels been higher.