The Southwest Florida Water Management District urges year-round water conservation. Water levels may rise and fall, but our water resources remain limited. The District encourages efficient, non-wasteful uses of water to sustain our high quality of life. For more information about ways to conserve water, contact the District at 1-800-423-1476 or visit the District’s website atWaterMatters.org
September Water Resource Monthly Update
Aquifer* Levels (percentile)
|Regions **||Sept. 30 percentile***||Previous week percentile||Same date
last year percentile
|Normal range percentile****|
* Aquifers are underground layers of rock and sand that hold water. In southwest Florida, more than 80 percent of the water supply comes from aquifers.
** North (Citrus, Hernando, Lake, Levy, Marion and Sumter counties)
Central (Hillsborough, Pasco, Pinellas and Polk counties)
South (Charlotte, DeSoto, Hardee, Highlands, Manatee and Sarasota counties)
*** The percentile compares current aquifer levels to historical levels during the same time of year on a scale of 0-100. For example, the if groundwater level is at the 50th percentile, it means that half of the historical levels for this time of year were higher and half were lower than the current level.
**** Any level that falls between the 25th and the 75th percentile is considered normal. Less than the 25thwould be considered below normal and above the 75th percentile is above normal.
2018 Rainfall (in inches) *
|Actual **||Historic Avg.***||Normal Range***||Actual**||Historic
|North||3.80||6.26||4.18 – 8.01||52.01||46.09||41.41 – 50.48|
|Central||5.50||6.94||4.89 – 7.98||49.08||45.61||39.99 – 49.48|
|South||6.47||7.55||5.38 – 9.18||49.30||45.60||40.62 – 50.30|
Historic Rainfall (January – December in inches)
|2017||2016||2015||2014||2013||2012||2011||2010||Jan. through Dec.|
|Actual||Actual||Actual||Actual||Actual||Actual||Actual||Actual||Historic Avg.***||Normal Range***|
|North||52.41||48.49||52.04||61.12||50.54||55.81||48.35||49.61||53.45||48.62 – 58.07|
|Central||51.37||55.38||57.27||56.16||47.92||50.30||53.44||49.29||52.36||46.77 – 56.55|
|South||57.43||56.79||54.24||52.57||52.64||47.36||46.40||48.61||52.44||47.04 – 57.17|
* The rainfall values for the current month and year are considered provisional and subject to revision. The other annual figures are final.
** Actual rainfall for the time frame referenced at the top of the column.
*** Historical average rainfall for the time frame referenced at the top of the column. The District’s historical rainfall records date back to 1914. The “normal range” is defined as rainfall totals that fall on or between the 25th to 75th percentile values derived from the historical data for each month.
Lake Levels (in feet, relative to MLM) *
|Regions **||September levels||Previous month||Same date last year|
|Lake Wales Ridge||0.84||0.85||1.26|
* Each month the District measures water levels in 76 lakes. The lake levels are compared to the lakes’ adopted minimum low management (MLM) levels. The MLM level is how low each lake has historically dropped at the end of the dry season each year.
** Northern (Citrus, Hernando and Sumter counties)
Tampa Bay (Hillsborough and Pasco counties)
Polk Uplands (Northern Polk County)
Lake Wales Ridge (Portions of Polk and Highlands counties)
|Previous month percentile||Same date last year percentile||Normal range percentile ***|
|Withlacoochee River near Holder||77||83||67||25-75|
|Withlacoochee River near Trilby||70||86||96||25-75|
|Hillsborough River near Zephyrhills||74||95||95||25-75|
|Peace River at Arcadia||78||84||82||25-75|
|Peace River at Bartow||92||97||92||25-75|
* Streamflow, also known as discharge, is the volume of water passing a location in a certain amount of time, usually measured as cubic feet per second.
** The percentile compares current flows to historical flows during the same time of year on a scale of 0-100. For example, if the river is shown at the 50th percentile, it means that half of the historical flows for this time of year were higher and half were lower than the current flow.
*** Any flow that falls between the 25th and the 75th percentile is considered normal. Less than the 25thwould be considered below normal and above the 75th above normal.