Lake Hancock Is Held a Foot and a Half Higher for the Peace River

The structure that controlled Lake Hancock from August 1963 until May 2013 was a concrete and steel sheet pile weir with two metal radial gates, 7 feet high and 20 feet wide. Water flowed over the top of it at 98.7 feet above sea level. In the District's stage record for the lake, kept at two gauges and carried through December 31, 2014, 98.7 feet is also the elevation Lake Hancock's water surface equaled or exceeded ten percent of the time. The lake's high water was the top of the weir.

In 2003 the Southwest Florida Water Management District began evaluating whether to replace that weir and raise the lake, and the reason was downstream. The upper Peace River, from Bartow to Zolfo Springs, was often not achieving the minimum flows the District had set for it. A District news release dated August 2, 2006 reported that its Governing Board had approved a memorandum of agreement with Polk County for the Lake Hancock Lake Level Modification Project. The release put the lake at 98.5 feet above sea level, said it had historically been two feet higher, and reported that the District had evaluated raising it as high as 100.5 feet. The proposal called for 100.

A contractor began the new P-11 structure on November 14, 2011, about 220 feet downstream of the old one, and finished in April 2013; the 1963 weir was demolished that May. It is an earthen embankment, a concrete spillway and three concrete bays on steel sheet pile driven to hard lime rock. Two of the bays carry roller gates measuring 20 feet by 10 feet, with inverts at 92.0 feet above NGVD29. The third bay holds two weir gates, each 10 feet by 4 feet, with inverts at 96.0 feet, designed for releasing relatively small volumes of water at precise flow rates during the dry season to meet the upper Peace River minimum flows. The structure was first used for conveyance on August 5, 2013, and became remotely operable from the District's Brooksville office on January 15, 2014.

The rise is a foot and a half. The control elevation of the lake's outflow went from 98.5 to 100 feet NGVD, a figure the District's project page gives instead as a rise from 98.7 feet, the crest of the old weir. Between 97.6 and 100 feet, the raised lake holds about 13,377 acre-feet, roughly 4.359 billion gallons. Inflows were stored for about a year, and in late 2015 the District began operating P-11 to help meet the minimum flows in the river. The 100-foot operating level was determined to be the approximate historical level of the lake, before the area was mined for phosphate and the natural lake outlet deepened.

The minimum levels report the Governing Board approved on October 27, 2015, adopted into District rules on November 10 and effective November 30, set a Minimum Lake Level for Lake Hancock of 97.6 feet above NGVD and a High Minimum Lake Level of 98.8 feet. The guidance levels proposed in the same report were never adopted into rule, because they were built on water level conditions from before P-11 was modified, and the District expected the lake's current and future levels to differ. The USGS gauge 65 feet below the old weir, Saddle Creek at Structure P-11 near Bartow, number 02294491, had recorded continuous flow from December 1, 1963 through October 7, 2014; it was discontinued after the new structure went in and has not been replaced. One of those two gauges, station 24532, is still reporting, and the Polk County Water Atlas carries its Lake Hancock readings from December 9, 1981 forward within a historic range of 90.39 to 103.44 feet NAVD88.

Operating protocols for the structure set a low operating level of 97.5 feet and a maximum desirable level of 100 feet. On April 23, 2026 the District announced it was closing P-11 to maintain minimum lake levels in Lake Hancock, with portions of the upper Peace River from the lake down to Fort Meade expected to go dry and become non-navigable within days. A below-average 2025 rainy season had left a 12.8-inch regional rainfall deficit against the average 12-month total, and fish kills were expected in the lake as well as the river, from low dissolved oxygen. Dry conditions in the upper Peace were common before 2015; since the project was finished, the District has been able to store water in the lake and release it to the river during the dry season, except for a short period at the end of the dry season in May 2017. When the lake falls below 97.6 feet above NGVD, no releases are made through P-11, regardless of downstream flow needs.