Decreasing Rains, Dropping Aquifer: Hydrologic Summary for January-June
FlaglerLive | August 1, 2010
Every six months, by Florida law, the state’s water management districts must produce a report on water conditions in the region. Flagler County is part of the 18-county St. Johns River Water Management District, whose latest hydrological report was just released, covering the months of January through June 2010.
The district’s Division of Hydrologic Data Services (HDS) collects hydrologic and meteorologic data to measure changes in surface water levels, aquifer levels and monthly rainfall totals. HDS operates and maintains more than 1,000 monitoring stations throughout the District and processes data from approximately 200 additional sites collected by other agencies. More than 16 million measurements are collected, verified, processed and stored by program staff each year.
Hydrologic and meteorologic data are used for water use planning and management, environmental protection and restoration, and flood control purposes. HDS also compiles a monthly Hydrologic Conditions Report and provides it to the District’s Governing Board each month. A summary of the major hydrologic constituents that are monitored follows.
The District’s average rainfall for the month of January was 3.58 inches. The year–to–date (YTD) surplus was 0.96 inches. The Keetch–Byram Drought Index (KBDI) showed low levels of drought for most of the District, indicating a low risk for wild fires.
During February 2010, average rainfall for the month was 3.61 inches, with a YTD total of 7.19 inches. The YTD surplus was 1.9 inches. During March 2010, the District’s average rainfall was 5.84 inches, with a YTD total of 13.03 inches. The YTD surplus was 4.27 inches.
During April 2010, average rainfall for the month was 1.8 inches, with a YTD total of 14.83 inches. The YTD surplus was 3.48 inches. The KBDI showed wet conditions throughout the District.
The District’s average rainfall for May 2010 was 3.39 inches, with a YTD total of 18.22 inches. The YTD surplus was 3.41 inches. The District’s average rainfall for June 2010 was 5.26 inches; with a YTD total of 26.43 inches, and a YTD surplus of 1.93 inches. Rainfall amounts YTD were not evenly distributed across the District. Coastal areas of Nassau, Duval and St. Johns counties, as well as isolated coastal portions of Brevard and Indian River counties, carried rainfall deficits for the six-month period of more than 10 inches. Small areas of Marion, Lake and Osceola counties showed greater than 10 inches of surplus over the same period.
Through March, monthly and YTD rainfall surpluses were recorded as a result of El Nino rains. The subsequent development of drier La Nina conditions since April resulted in monthly rainfall deficits. Even with those recent deficits, YTD rainfall remains at a surplus districtwide through the end of June.
The KBDI report from the Division of Forestry has been inactive since mid-April due to a change in National Weather Service reporting procedures. Consequently, current values are not available for this data source.
Stream flow and water levels at major, long–term gauging stations and lakes began the period with slightly below average flows in the main stem of the St. Johns River and the Ocklawaha River, although the Upper St. Johns River Basin gauges were at levels just over their respective averages. Stream flow conditions in all systems increased incrementally until March due to El Nino rains. The increase was seen first in early to mid-March in the Ocklawaha and St. Marys rivers, which both rose to the 95th percentile at Conner and near Macclenny, respectively. The St. Johns River reached its seasonal maximums, near the 90th percentile range, in late March. Beginning in April, river levels districtwide declined steadily as the rainfall surpluses of the early portion of the year turned to slight deficits due to the dryer conditions associated with La Nina. As June ended, all river systems were at or just above average levels, with the exception of the Ocklawaha River, which was higher than normal for the season because of late June rains in its upper reaches.
In addition to the generalized information referenced above, the District produces detailed, controlled water level information for selected areas of the Upper St. Johns River and Ocklawaha River basins.
The reports are:
- Weekly Upper Ocklawaha River Basin Water Conditions Report
- Weekly Upper St. Johns River Basin Project Water Conditions Report
- Daily Upper Ocklawaha River Basin Water Control Report
- Daily Upper St. Johns River Basin Project Water Control Report
The District also produces a Keystone Heights–area hydrologic conditions report.
The District maintains a groundwater resource assessment program through the Division of Groundwater Programs. The resource assessment group performs detailed hydrologic investigations, designs and evaluates monitoring networks, and conducts interpretive investigations. The field services group constructs and maintains monitoring wells, oversees contractual drilling services, conducts aquifer performance tests and related hydrologic testing, and provides geophysical logging services. This program directly supports the water supply planning, the consumptive use permitting and the minimum flows and levels programs, as well as other District programs. The assessment program also provides the means to evaluate the groundwater resources, identify long–term trends, detect potential problem areas, and develop appropriate resource management strategies.
The major focus of the groundwater program is the Floridan aquifer, which is the major source of potable (drinking) water throughout the District. Groundwater levels in wells open to the Floridan aquifer rose through March to about a districtwide 75th percentile because of the relatively strong El Nino rains of winter. However, a rapid shift to dryer La Nina conditions in ensuing months resulted in a drop of Floridan aquifer levels to near the 50th percentile by the end of June.
The District Governing Board held a third workshop on March 8 to discuss concepts to improve water conservation by considering changes to District consumptive use permitting and environmental resource permitting rules.
In response to the workshops, District staff will request approval from the Governing Board to initiate rulemaking in July.
On March 14, watering restrictions returned to no more than two days a week for daylight saving time. The restrictions specify the days and hours for residential and nonresidential irrigation. The District and its utility partners implemented a mass media campaign to inform the public about the restrictions. Upon the return of Eastern Standard Time (first Sunday in November), restrictions will return to one day per week.
April 2010 was recognized by the Governing Board as water conservation month. April has been formally recognized as water conservation month in Florida for the past 12 years. Declaring April as water conservation month helps heighten awareness about the importance of conservation. Florida is the only state in the country to designate a month promoting water conservation.
Also, in April, the Governing Board approved more than $2 million in cost-share funding for water conservation projects that implement innovative water conservation initiatives.
Projects considered for funding were required to be in one of the following categories:
- Reliability and performance testing of new landscape irrigation technology
- Automated tracking of historical customer water use information
- Reliability and performance testing of new high-efficiency indoor fixtures
- Other (new and innovative technology and practices)
July 2 marked the closing of the second application cycle, in which an additional $2 million in cost-share funding was made available. Projects in the second cycle will be awarded by the end of September. This cycle included an additional project-type category for enforcement of landscape irrigation ordinances that implement the District’s irrigation rule, and for related education efforts.