Florida Regulations 40B-8.121: Minimum Surface Water Levels for Lakes
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(1) The following terms, as used in this rule, shall have the following meanings:
(a) “”High Minimum Lake Level”” means the surface water level the lake must meet or exceed ten percent of the time on a long-term basis to ensure it reaches higher levels on a periodic basis.
(b) “”Minimum Average”” means the surface water level or flow necessary over a long period to maintain the integrity of hydric soils and wetland plant communities.
(c) “”Minimum Frequent High”” means a chronically high surface water level or flow with an associated frequency and duration that allows for inundation of the floodplain at a depth and duration sufficient to maintain wetland functions.
(d) “”Minimum Frequent Low”” means a chronically low surface water level or flow that generally occurs only during periods of reduced rainfall. This level is intended to prevent deleterious effects to the composition and structure of floodplain soils, the species composition and structure of floodplain and instream biotic communities, and the linkage of aquatic and floodplain food webs.
(e) “”Minimum Lake Level”” means the surface water level the lake must meet or exceed fifty percent of the time on a long-term basis to maintain average conditions.
(f) “”Seasonally Flooded”” means a hydroperiod category where surface water is typically present for extended periods (30 days or more) during the growing season, resulting in a predominance of submerged or submerged and transitional wetland species. During extended periods of normal or above normal rainfall, lake levels causing inundation are expected to occur several weeks to several months every one to two years.
(g) “”Semi-Permanently Flooded”” means a hydroperiod category where surface water inundation persists in most years. When surface water is absent the water table is usually near the land surface. In many lakes with emergent marshes this water level is near the lower elevation that supports emergent marsh or floating vegetation and peat substrates, or other highly organic hydric substrates. This characterization may not be true for herbaceous wetlands around sandhill type lakes, which often have emergent vegetation that follows declining water levels to below the lower elevation of peat substrate. Water levels causing inundation are expected to occur approximately eighty percent of the time over a long-term period of record. Exposure of these ground elevations is expected to re-occur, on average, about every five to ten years for extended periods (several or more months) during moderate droughts.
(h) “”Typically Saturated”” means a hydroperiod category where, for extended periods of the year, the water level should saturate or inundate. This condition results in saturated substrates for periods of one-half year or more during non-flooding periods of typical years. Water levels causing inundation are expected to occur fifty to sixty per cent of the time over a long-term period of record. This water level is expected to have a recurrence interval, on the average, of one or two years over a long-term period of record. Obligate wetland plant species are expected to be predominate near this water level.
(2) The following minimum surface water levels are established:
Water Body Name
County
(Latitude/ Longitude)
Minimum Level
Level
(Feet NAVD)
Event
Hydroperiod Category
Duration (Days)
Return Interval (Interval Measurement Period)
Lake Butler
Union
(30°02’00”N/ 082°20’12”W)
Minimum Frequent High
129.55
Flooding
Seasonally flooded
30
2 years (June 1 to May 31)
(b) “”Minimum Average”” means the surface water level or flow necessary over a long period to maintain the integrity of hydric soils and wetland plant communities.
(c) “”Minimum Frequent High”” means a chronically high surface water level or flow with an associated frequency and duration that allows for inundation of the floodplain at a depth and duration sufficient to maintain wetland functions.
(d) “”Minimum Frequent Low”” means a chronically low surface water level or flow that generally occurs only during periods of reduced rainfall. This level is intended to prevent deleterious effects to the composition and structure of floodplain soils, the species composition and structure of floodplain and instream biotic communities, and the linkage of aquatic and floodplain food webs.
(e) “”Minimum Lake Level”” means the surface water level the lake must meet or exceed fifty percent of the time on a long-term basis to maintain average conditions.
(f) “”Seasonally Flooded”” means a hydroperiod category where surface water is typically present for extended periods (30 days or more) during the growing season, resulting in a predominance of submerged or submerged and transitional wetland species. During extended periods of normal or above normal rainfall, lake levels causing inundation are expected to occur several weeks to several months every one to two years.
(g) “”Semi-Permanently Flooded”” means a hydroperiod category where surface water inundation persists in most years. When surface water is absent the water table is usually near the land surface. In many lakes with emergent marshes this water level is near the lower elevation that supports emergent marsh or floating vegetation and peat substrates, or other highly organic hydric substrates. This characterization may not be true for herbaceous wetlands around sandhill type lakes, which often have emergent vegetation that follows declining water levels to below the lower elevation of peat substrate. Water levels causing inundation are expected to occur approximately eighty percent of the time over a long-term period of record. Exposure of these ground elevations is expected to re-occur, on average, about every five to ten years for extended periods (several or more months) during moderate droughts.
(h) “”Typically Saturated”” means a hydroperiod category where, for extended periods of the year, the water level should saturate or inundate. This condition results in saturated substrates for periods of one-half year or more during non-flooding periods of typical years. Water levels causing inundation are expected to occur fifty to sixty per cent of the time over a long-term period of record. This water level is expected to have a recurrence interval, on the average, of one or two years over a long-term period of record. Obligate wetland plant species are expected to be predominate near this water level.
(2) The following minimum surface water levels are established:
Water Body Name
County
(Latitude/ Longitude)
Minimum Level
Level
(Feet NAVD)
Event
Hydroperiod Category
Duration (Days)
Return Interval (Interval Measurement Period)
Lake Butler
Union
(30°02’00”N/ 082°20’12”W)
Minimum Frequent High
129.55
Flooding
Seasonally flooded
30
2 years (June 1 to May 31)
Minimum Frequent Low
127.30
Exposure
Semi-permanently flooded
120
5 years (October 1 to September 30)
Lake Hampton
Bradford (29°51’42”N/ 082°10’10”W)
High Minimum Lake Level
128.86
Minimum Lake Level
128.15
Lake Santa Fe
Alachua (29o44’45”N/082o04’45”W)
Minimum Frequent High
139.10
Flooding
Seasonally flooded
30
2 years (June 1 to May 31)
Minimum Average
137.89
Exposure
Typically saturated
180
1.7 years (October 1 to September 30)
Minimum Frequent Low
136.52
Exposure
Semi-permanently flooded
120
5 years (October 1 to September 30)
Rulemaking Authority 373.044, 373.113 FS. Law Implemented 373.042, 373.0421, 373.103 FS. History-New 8-9-21, Amended 3-12-23.