Monthly rainfall update shows typically dry November

A map illustrates rainfall conditions in November across the St. Johns River Water Management District.

PALATKA, Fla., Dec. 10, 2019 — Although November rainfall was average or below-average across much of the St. Johns River Water Management District, groundwater in the Floridan aquifer system remained in the normal to high range for much of the 18-county region. A full report outlining hydrological conditions was presented at the district’s December Governing Board meeting. Highlights included:

November rainfall

• In November, most of the district was near or below the long-term average of 2.06 inches of rainfall.
• Marion County had the lowest rainfall amount, with 1.3 inches.
• The north region and several coastal counties were higher than average. Baker County had the most rainfall, with 4.4 inches, followed by Nassau County, with 3.6 inches.
• Districtwide, the cumulative rainfall total over the last 12 months is 50.1 inches, just under the long-term average of 51 inches.
• The central region has had above average rainfall, with the highest total in Marion County, which received a 12-month total of 59.4 inches
• The district’s southern and northernmost counties have 12-month deficits, despite more abundant rain in November. The lowest 12-month rainfall totals are Indian River County, with 43.2 inches, and Nassau County, with 44 inches.
• The U.S. Drought Monitor shows abnormally dry conditions persisting in Baker County and are beginning to expand in Indian River, Osceola and southern Brevard counties.

Groundwater

• Upper Floridan aquifer conditions at the end of November were in the normal or high range across the district.
• Groundwater levels are in the 82^nd percentile districtwide. This means that only 18 percent of the time since 1980 have aquifer levels been higher than they are now.

Surface water flows

• Surface water flow conditions in the Upper St. Johns River Basin were average or low, while flow in the middle St. Johns River and its tributaries was average.
• The St. Marys and Ocklawaha rivers also had average flow conditions for this time of year.

Lake levels

• Lake Apopka’s water level remained steady and level with its regulation schedule.
• Lake Brooklyn water levels decreased 0.7 feet but remains above the long-term average at 105 feet.
• Lake Weir and Lake Winnemissett levels each decreased 0.2 feet in November. Blue Cypress Lake levels also decreased 0.2 feet, remaining below both the average and its regulation level for this time of year.

Spring flows

• The mean monthly flow at Silver Springs for November was 708 cubic feet per second (cfs), or 458 mgd, with daily flow conditions in the normal range throughout the month.
• Flow in Blue Springs increased during with a monthly mean of 114 cfs (74 mgd).
• Flow at Rock Springs was in the high range throughout the month, with a mean monthly flow of 62 cfs (40 mgd). Wekiwa Springs flow was also in the high range, with mean flow of 71 cfs (46 mgd).

To learn more about rainfall totals and other hydrologic data collected, visit www.jrwmd.com.