Public Notice: Lake Bonney Flood Conditions

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Intro

There are some areas around Lakeland that were hit very hard with flooding (photo attached) due to the impacts from Hurricane Milton.  The Lakeland area experienced over 12 inches of rain in 24 hours taxing the City’s stormwater system.  All area lakes are flooded, and it is very difficult to alleviate flood conditions and lower lake levels. Most of the drainage lakes, tributaries and rivers have high levels and that is not helping flood situations because of the higher-than-normal rainfall over the summer.  

Rainfall Total in Inches
Source	Jun-24	Jul-24	Aug-24	Sep-24	Oct-24
Hollingsworth Rain Gauge	11.7	10.6	16.85	12.2	11.3
COL Northside WW Plat	14.06	9.36	10.4	6.47	13.14
NWS	10.63	5.74	10.73	12.54	18.56
Monthly Normal Average (U.S. Climate Data)	7.01	7.52	7.32	6.34	2.28

Local Hydrology

There are three major watershed basins in the City of Lakeland, and outflows from area lakes flow into either the Hillsborough River or the Peace River.  The Peace and Hillsborough Rivers eventually flow into the Gulf of Mexico.  Water flows from higher elevation to lower elevation.  The downstream rivers (Peace and Hillsborough) flow through relatively flat terrain with little elevation changes, which leads to significant regional flooding after major storm events.  The Peace and Hillsborough Rivers have been in flood stage since the passing of Tropical Storm Debby, and Hurricanes Helene and Milton have fully exacerbated the flooding situation.  This makes it very difficult to drain flooded upstream waters. 

The largest surface water drainage system is Lake Parker. Lakes at higher elevation that flow into Lake Parker include Lake Gibson (via Lake Crago) and Lake Mirror.  Lake Bonny is at a relatively equal elevation to Lake Parker, and the City has been pushing water from Lake Bonny to Lake Parker with a very high-volume pump (picture attached) at 5,000 gallons per minute since August 5, 2024.   The water from Lake Parker eventually flows to the Peace River via Lake Hancock but both those water bodies are also at flood level. Flooding occurred throughout the City and Polk County and the drainage continues to impact the Lake Parker/Bonny watersheds, with water slowly draining into the lakes. Even though a high-volume pump is removing water from Lake Bonny, the urbanized drainage basin continues to input water to the lake.

The Lake Bonny – Lake Parker Connection

Lake Bonny and Lake Parker are connected through a drainage conveyance that includes open ditches, canals, and underground piping (map attached).  The water levels between the two lakes are generally at the same elevation, and water may flow from Lake Parker to Lake Bonny or vice versa.  Lake Parker is 2,185 acres and averages 5 feet in depth as compared to Lake Bonny at 249 acres with an average depth of 3 feet.  A flood control structure was installed in the conveyance system in the early 2000s by the County to control the flow of water from Lake Parker into Lake Bonny during severe storm events. Lake Bonny receives stormwater inputs from a highly urbanized watershed surrounding the lake, especially along the 98S corridor from Main Street to South Crystal Lake Avenue.  The only outfall is the connected drainage conveyance to Lake Parker as described above.

Lake Bonny Flooding History

In 2015, after several years of high rainfall totals resulting in Lake Bonny experiencing high water levels, the City obtained a permit from the Southwest Florida Water Management District (SWFWMD) to construct and operate an emergency pump to increase water flow from Lake Bonny to Lake Parker.  SWFWMD allows the pump to be operated when Lake Bonny reaches the 10-year flood stage at elevation 130.10.  This number is feet in elevation per the North American Vertical Datum (NAVD) of 1988.  This is the standardized reference system used to measure and compare elevations in the United States. The pump was installed next to the flood control structure.  For the pump to operate effectively, the flood control structure must be closed to prevent backflow into Lake Bonny while the pump is operational.  The pump pushes significantly more water than the natural flow through the canal.

Summer Storms

When Tropical Storm Debby came through on August 5, 2024, water levels reached the 10-year flood stage, and the emergency pump was turned on.  Since August 5, 2024, the pump has been running 24/7 with an average output of about 5,000 gallons per minute.   With the pump running at full capacity, water levels can be reduced an average of 2/10 foot per day.  However, several significant afternoon storms and then Hurricane Helene on September 26, 2024, contributed more water to the lakes systems than what could be pumped even at full capacity.  The day before Hurricane Milton (October 9), water levels in Lake Bonny were recorded at elevation 131.78 and water levels in Lake Parker were 130.00.  The day after Milton, Lake Bonny water levels rose 1.82 feet in just 12 hours to elevation 133.60 and Lake Parker water levels rose 2.46 feet to 132.46.  

Stormwater Outfall

The City has continued to operate the pump at full capacity to push water out of Lake Bonny to Lake Parker.  Lake Parker has also flooded and crested over Memorial Boulevard, East Lake Parker Drive and Lakeshore Drive.  SWFWMD operates a flood control structure at the outfall from Lake Parker (movie clip attached) and has been releasing water from Lake Parker since late June 2024.  Water leaving the Bonny/Parker system flows through Saddle Creek to Lake Hancock.  SWFWMD operates another flood control structure at Lake Hancock and has been releasing water from Lake Hancock to the Peace River but must do so judiciously at a level that the downstream drainage system can manage since the Peace River is also at flood stage.  

It must be noted that flooding occurred throughout Polk County.  The stormwater system and urbanized watersheds continue to naturally drain very slowly into the lakes. Although the high-volume pump is removing water from Lake Bonny, the drainage system continues to input water into the lake. The lake reduced in level by a quarter of an inch in the last 24 hours, this equates to over 7,000 million gallons of water.  Lake Bonny under normal conditions is approximately 400 million gallons.

Misinformation

There is misinformation being circulated regarding Lake Bonny.  Lake Mirror does not connect to Lake Bonny, there are no pumps connecting the two lakes. Lake Mirror is connected to Lake Parker.  Lake Mirror is 30’ higher in elevation than Lake Parker.  Stormwater is gravity fed to Lake Parker in high water situations.

The 5,000 gallons per minute pump does at times receive sediment and litter that is part of storm debris.  This debris may temporarily slow the water, but the pump is checked regularly to ensure it is operating at full capacity.

There are FDOT drainage ditches that are part of the Highway 98 South drainage system that do flow into Lake Bonny.  Lake Horny is adjacent to one of these FDOT drainage ditches, but Lake Horny does not drain into Lake Bonny.  Lake Horny drains via piping system to Lake Hollingsworth, that goes through a similar system to Banana Lake, then Lake Hancock and eventually to the Peace River.

Misinformation has been circulating about a collapsed pipe at the CSX railroad crossing that is blocking flows from Lake Bonny to Lake Parker. Dye test (pictures attached) have indicated that this isn’t true.

    

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