December rainfall was above average

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

PALATKA, Fla., Jan. 13, 2020 — December brought above-average rain across most of the 18 counties of the St. Johns River Water Management District, increasing lake levels in the Upper Ocklawaha River Basin and groundwater levels in the Floridan aquifer.

A full report outlining hydrological conditions was presented at the district’s January Governing Board meeting. Highlights included:

Rainfall

• December rainfall was well above average across the district, with a districtwide total of 4.65 inches, which is more than 2 inches above the long-term average.
• The highest rainfall occurred in Nassau County, which had 6.5 inches, followed by Brevard with 5.3 inches. Most of the other counties had between 4 and 5 inches of rain during December.
• Districtwide, the cumulative rainfall total over the last 12 months is 48.75 inches, which is 2.25 inches below the long-term average.
• Counties with 12-month rainfall totals that are above the long-term average are Brevard, Seminole, Marion, Orange, Volusia and Lake.

Groundwater

• Upper Floridan aquifer conditions (groundwater levels) at the end of December were in the normal or high range across the district.
• Groundwater levels are at the 77th percentile districtwide. This means that only 23 percent of the time since 1980 have aquifer levels been higher than they are now.

Surface water flows

• Surface water flow conditions in both the upper and lower St. Johns River basins were in the high range for this time of year, while flow in the middle basin was average.
• The Wekiva River and St. Marys River flows were in the high range
• Flow in the Ocklawaha River and Econlockhatchee River was in the very high range.

Lake levels

• Lake Brooklyn water level decreased 0.3 feet but remains above the long-term average.
• Lake Weir increased 0.3 feet.
• Lake Winnemissett levels have increased 0.2 feet since Dec. 1.
• Lake Apopka’s water level rose 0.3 feet, rising above its regulation schedule. In response to this and similar conditions in other Upper Ocklawaha River Basin lakes, the district is operating flood control structures to manage water levels throughout the basin.
• Blue Cypress Lake levels increased 0.3 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 December was 670 cfs (433 mgd) with daily flow conditions in the normal range throughout the month.
• Flow in Volusia Blue Spring increased during December, with a monthly mean of 139 cfs.
• Flow at Rock Springs was in the high range throughout the month, with a mean monthly flow of 62 cfs.
• Wekiwa Springs flow was also in the high range, with mean flow of 69 cfs.

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