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DeSoto, Hardee, Highlands, Polk and Sumter counties of Florida


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Lake Hancock
Mining as a Restoration Technique

Lake Hancock is the largest lake in the Bone Valley Region and is the largest lake in the headwaters of the Peace River (the major river of the Bone Valley region). The Peace River is also a major source of water for all areas down stream to Charlotte Harbor. Water quality and quantity are, therefore, of paramount importance to several hundred thousand people. Proposals to restore Lake Hancock, which is hypereutrophic largely because of human impact, have been around for years. The following paper is an assessment of the issue in 2000; because of environmental liability concerns, IMC has decided at this time not to pursue mining the lake but other mining entities have expressed an interest in pursuing this project.

Lake Hancock Restoration Issues

The "Restoration" of Lake Hancock is a very complicated issue. The basis for any "Restoration" claim, to date, is the removal of organic detritus, "muck", from the lake. This muck covers the bottom of Lake Hancock's 4553 acres to a average depth of approximately 2.5 feet below the surface.

The Governor and Cabinet have granted IMC/Agrico a five year royalty free lease to mine/restore Lake Hancock. IMCA, however, is not sure there is enough phosphate to warrant mining even royalty free. (Royalties represent a $6 9 million dollar investment by the State of Florida.) Even if there is enough phosphate to warrant mining, it is questionable that there will be enough to also pay the cost of removing the muck from the unmined portion (53%) of the lake bottom. The simplest way to remove the muck would be to dry it and scrape the dried material off the lake bottom and deposit it in the mine hole itself. Drying the lake bottom is problematic due to high ground water levels and the connectivity between the lake and groundwater. There are more complications - but enough for now.

blue-green algae on Lake Hancock
Blue-green algae on Lk. Hancock Copyright © 2003, Richard Coleman, All Rights Reserved

If we assume that the lake is scraped to the sand bottom and the soils disturbed by mining contribute nothing to the nutrient budget, we are still faced with the nutrient composition of the inflowing waters from Banana Lake, Saddle Creek, Lake Lena Run and other assorted storm water sources. The question becomes will these nutrient sources create the same blue green algae dominated hyper eutrophic mess that currently exists?

Banana Lake, which flows to Lake Hancock was "Restored" in 1992 at an expense of $2 million through deepening and it is still hyper eutrophic showing higher Trophic State Index numbers than Lake Hancock. It is blue green algae dominated. The problem with Banana Lake is that deepening in 1992 did not impact the nutrient inflow to the lake. Even though city waste effluent was diverted and the nutrient inflow reduced by 90%, the remaining 10% of the original nutrient load has been enough to maintain a blue green hyper eutrophic condition. All of this begs the question, "what are the nutrient loads coming to Lake Hancock?" No one knows! Are they being monitored? Not currently!

Nitorgen to Phosphorus ratios are low. This means that nitrogen is likely to be the limiting nutrient for growth in Lake Hancock. Blue green algae fixes its own nitrogen when it has to. The exposure of phosphate ore is expected to increase phosphorus concentrations in the water column in Lake Hancock both during and after mining. Increased Phosphorus concentrations will drive nitrogen to phosphorus ratios even lower favoring blue green algae. The blue green algae are truly bad actors! There may be solutions even to this problem, but no one is talking.

If Ecosystem Team Permitting is implemented, we can expect the Bureau of Mine Reclamation (BMR) to dominate the process as the permitting agency. The BMR does not have to heed input from the wetlands specialists within DEP nor does it have a history of implementing the recommendations of the Florida Game and Freshwater Fish Commission or the concerns of the Water Management District. It has never heeded the concerns of the public or other outsiders. Participation for "restoration" under these conditions can be expected to be minimal. The BMR will tout the wonderful work it has done, but keep in mind they measure results against their own regulations and one needs only to fly over mined counties to judge those standards!

We, the Sierra Club, have no problem with the issuance of a lease for the purposes advertised in public meetings in the Polk County area to evaluate the feasibility of restoration of Lake Hancock as an adjunct to the mining of the lake and/or other alternatives such as drawdowns which have been proposed by the Florida Fish & Wildlife Conservation Commission (FF&WCC) in the past. Our concern is that the lease does not contain conditions which would assure the state of benefits claimed by the Bureau of Mine Reclamation. Restoration and reclamation are significantly different. We can reclaim lands to some form after mining but the soil and hydroperiods are forever changed and the chemical composition of water both contained and released is changed for the foreseeable future. Despite the seductive publicity regarding phosphate reclamation and the few demonstrations the industry and the Bureau of Mine Reclamation hail, reclaimed lands fail to look or function like the natural systems they replace. (Keep in mind that the Florida Institute of Phosphate Research, a state agency specializing in phosphate mining and reclamation with emphasis on wetlands, has been unable to establish criteria for successful reclamation despite its best extensive and expensive efforts.)

Our primary concern is the ability of appropriate government agencies to participate as equals in restoration proposal development and decision making processes and strategy. The Ecosystem Management Team Permitting process will fail the public unless active and equal participation of the best talent available is brought to the decision making and development of restoration options for this public waterway. We can't afford failure for the lake and river that supplies potable water to downstream users and provides critical habitat in the Bone Valley Ecosystem.

Since April of this year, we have discussed mining options and ongoing water quality and habitat enhancement plans with several state agencies. Because of these discussions we have increasing concerns that the coordination between the agencies is not occurring as it should be to maximize the restoration achieved for the tax dollars spent.

Major concerns are briefly described here:

  1. Who will define restoration and for what purpose? Restored to what--to the marsh it might have become?--to a deep pit lake that it never was? If the Bureau of Mine Reclamation is allowed to define restoration, it is not likely to include the best information available or produce a sustainable, holistic ecosystem. At risk is the loss of notable fisheries, a unique occurrence of wading and migratory bird species, one of the densest Osprey nesting areas in the state and a very large alligator population. Lake Hancock and an upland buffer of the remaining undeveloped shoreline are key to the ecosystem restoration efforts of the Bone Valley Region.
  2. It is alleged that deepening the lake, to the six to eight foot depth that Hancock will be after mining, will help improve water quality. Sierra has access to nearly 300 studies concluding that deepening lakes does not improve water quality. The last lake in this system "restored" by deepening was Banana Lake. For $2 million we have achieved a Trophic State Index (TSI) of 90.68 which is highly eutrophic virtually indistinguishable from Lake Hancock's TSI value of 91.84. Banana Lake and several other highly eutrophic lakes will continue to flow into Lake Hancock.
  3. It is alleged that the quality of water entering the Peace River from Lake Hancock will be improved from current conditions and biological diversity should increase once mining and restoration have been completed. Water quality improvements will not be as significant as implied. Lake Hancock's mean TSI value for 1997 was 91.84. The chlorophyll "a" (MG/M3) mean value was 111.74. Those corresponding values for Banana Lake, which was "restored" in 1991 are: TSI 90.68, chlorophyll "a" : 114.57. Restoration, obviously, includes a long term ecosystem management approach of the lake and its environs. There are three stream inflows to the lake Saddle Creek, Lake Lena Run and Banana Lake Run. Without adequate consideration and mitigation of these nutrient loading inflows, the proposed "restoration" of Lake Hancock will be a very temporary condition. Additionally, the proposed DRI Old Florida Plantation, if approved, could result in new loading from 15,000 residents and accompanying roads and golf courses along the southeastern shore of the lake.
  4. Islands are proposed to be built which will improve the habitat value of the area. This proposal, if implemented could eventually add habitat; however, it is vitally important to acquire and conserve existing habitat around the lake's shoreline. Additionally, the "Foraging Ecology of Wading Birds Using An Altered Landscape in Central Florida," by Edelson & Collopy, September 1990, a Florida Institute of Phosphate Research Publication, makes recommendations on Lake Hancock restoration. Some general recommendations include:
    • Any draw down of the lake should be conducted during the wading birds' non breeding season (August - November);
    • Create a wider (e.g. shallower) littoral zone;
    • Monitor the fish population and the number of nesting and foraging wading birds at the lake after restoration; and
    • Protect off lake foraging areas to offset any losses associated with the lake's restoration.
  5. Edelson and Collopy also state, "The reclamation of phosphate mine lands should consider:
    • Creating islands within deep water mined out areas to provide nesting habitat for wading birds; and
    • Reclaiming some of the mined out areas and clay settling ponds as temporary wetlands, and some as permanent wetlands with a wide, shallow littoral zone."

Based on all the information accumulated thus far, we believe that birds, fishes and many other wetland creatures, including mammals, that inhabit our subtropical natural systems will benefit from the "restoration" of Lake Hancock. Further, with reasonable review of available data and a thoughtful ecosystem management and planning approach to restoration, these benefits can occur without a major disruption of existing wildlife and fisheries. We expect water quality and wildlife habitat will improve and water quantity will remain rain dependent.

definitions, standards

littoral zone - between the high water mark and the open water - the "grassy" area between shore and open water.

eutrophic - Over enriched - usually with colored water from green or brown algae blooms and extensive areas of macrophytes (plants) exhibiting low dissolved oxygen and large but mostly undesirable fish populations.back to the article

trophic state index (TSI) values range from 1 to 110 or more. Generally, the lower the value the clearer the water. Lakes with high values (60 or more) usually have green water due to chlorophyl a plant pigment contained in the microscopic algae that floats near the surface of lakes. Lakes with higher TSI values support greater numbers of fish than lakes with low values. Water quality improvement projects of the inflows and acquisition of lands surrounding the lake could prove more cost effective than the proposed mining of the lake. Additionally, some professionals have suggested removing the control structure from the Saddle Creek outfall and "restore the lake to a wide spot in the river" a condition more natural in Lake Hancock case than deepening. The experience in the Kissimmee River restoration, using restored water flow to "blow: detritus out of silted in oxbows, shows that detritus washed down the river was insignificant to water quality in fact the detritus was never found! back to the article

For more information, contact:
Marian Ryan, 863-293-6961, marian.ryan@verizon.net


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Tussock Islands floating on Lake Hancock


masthead picture: Tussock Islands floating on Lake Hancock , published with permission
Copyright © 2003, Richard Coleman, All Rights Reserved

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