Ecological Engineering 138 (2019) 155–159

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Ecological Engineering
journal homepage: www.elsevier.com/locate/ecoleng

Short communication

Restoring the Florida Everglades
Comments on the current reservoir plan for solving harmful algal blooms
and restoring the Florida Everglades

T

William J. Mitsch
Juliet C Sproul Chair for Southwest Florida Habitat Restoration, Everglades Wetland Research Park, Florida Gulf Coast University, 4940 Bayshore Drive, Naples, FL 34112,
USA

ARTICLE INFO

PREFACE

Keywords:
Wetland restoration
Florida Everglades
Water quality
Harmful algal blooms
Red tide
Phosphorus
Treatment wetlands
Wetlands
Rivers

This is an updated version of a review written by the author in April 2018 at the request of The Friends of the
Everglades, an NGO based in Miami, Florida, on a plan developed primarily by the South Florida Water
Management District (SFWMD) to mitigate coastal pollution that has resulted from discharges from Lake
Okeechobee to the Gulf of Mexico and Atlantic coastline and eventually to “send the water south” to the Florida
Everglades instead. This EAA Reservoir project was included by the U.S. Army Corps of Engineers in a 2018 U.S.
Congressional bill that was approved. In May 2019, U.S. President Donald Trump pledged to spend $200 million
to begin construction of this restoration, three times the amount requested by the state of Florida. While supported with enthusiasm by the Florida state legislature, the SFWMD, and some NGOs such as The Everglades
Foundation, a change in leadership in the state of Florida after November 2018 elections and especially in the
leadership of the South Florida Water Management District (SFWMD) has led to a renewed public optimism for
major improvements in water quality management in south Florida. It is therefore timely for this review of the
advantages and shortcomings of this “EAA (Everglades Agricultural Area) Reservoir Plan” to be widely disseminated in an international forum such as Ecological Engineering to encourage discussions among scientists
and engineers.

1. Introduction
The Florida Everglades restoration is now at a crucial crossroad that
will determine its long-term success or failure, so I consider it prudent
to make some comments on the EAA Reservoir Plan as it is currently
described. We were unable to delve into the details of hydrologic
modeling performed by the South Florida Water Management District
(SFWMD) related to this project given the short time allowed for
comments and lack of support for a rigorous modeling effort, but I am
providing this hopefully constructive critique so that the U.S. Army
Corps of Engineers and the SFWMD can fine-tune the EAA Reservoir
Plan so that it becomes a significant step forward toward completion of
a sustainable Florida Everglades restoration.
I first express my support for an ambitious effort to eliminate decades of stalling with a serious “sending the water south” strategy, the
mantra for a generation of those who understand the big picture of
what the Florida Everglades restoration is all about. The South Florida
Water Management District claimed that the EAA Reservoir project will
— when used in conjunction with other existing and planned projects
— reduce the number of damaging discharge events from Lake
Okeechobee to the St. Lucie and Caloosahatchee rivers by 63% and
increase the flow going south to the Everglades and Florida Bay by 76%

from 0.26 to 0.46 billion m3/year (160,000 to 370,000 acre-ft/year).
But if this plan results in pollutants, particularly phosphorus and
nitrogen, getting into greater Everglades water conservation areas
(WCAs) and south to the Everglades National Park, or develops an
unsustainable, un-ecological and/or simply polluted reservoir to
manage in perpetuity, we will regret the day we said OK “just to spend
the money.” I am not assured from what I see written so far that this
project is properly focused on what is important—sending clean water
to the greater Florida Everglades. If ever there was a time for an ecological engineering and not just civil engineering approaches to lead the
Everglades restoration, it is now.
2. Background
One-third of the original Florida Everglades was drained during the
20th century and converted into productive agricultural land (EAA),
mostly for sugar farms. Eventually $1 to 2 billion dollars of Florida
taxpayers’ money was spent to create and maintain treatment wetlands
(called stormwater treatment areas (STA)) to treat runoff rich in nutrients from this EAA to protect the downstream Everglades National
Park. The Florida Everglades is currently in the middle of a manydecades, multi-billion US $ restoration plan. As I stated in an editorial

https://doi.org/10.1016/j.ecoleng.2019.07.009
Received 9 May 2019; Received in revised form 1 July 2019; Accepted 7 July 2019
0925-8574/ © 2019 Published by Elsevier B.V.

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W.J. Mitsch

in Ecological Engineering three years ago:

to clean other EAA polluted stormwater prior to discharge to the
Everglades (Fig. 3).

“There is currently major concern being expressed throughout
Florida USA about the recent pulses of an excessive amount of
polluted farm water from the 1890-km2 shallow and eutrophic Lake
Okeechobee (also known as “Lake O”) into the Caloosahatchee River
to the west and into the St. Lucie River to the east by the U.S. Army
Corps of Engineers (Fig. 1). This is part of the scheme for managing
hydrology in the 46,000-km2 Greater Florida Everglades, one of the
largest wetland restorations in the world” Mitsch (2016).

4. Concerns
1. My first comment concerns the false expectations by the public now
that they see government approvals of up to $2 billion for this EAA
project. I have frequently heard “Well the project is not perfect, but
let’s do it while the money is there.” The volume of water being
discharged south needs to be put in perspective; the 0.46 billion m3/
year (121 billion gallons/year) of water eventually being sent south
to the Everglades and Florida Bay in the EAA reservoir plan will not
solve the estuarine pollution of the Gulf of Mexico and Atlantic
Ocean coastlines. Fig. 1 illustrates the Everglades Restoration plan
that I have included in several editions of my books since we first
published it in the Mitsch and Jørgensen (2004) ecological engineering book 15 years ago and it continued to be published in the
4th and 5th editions of “Wetlands” (Mitsch and Gosselink, 2007,
2015). I am aware that the restoration plan shown in the 3rd panel
has been changed in several more recent publications and in prominent locations including the well-known wall maps at Corkscrew
Swamp Sanctuary lobby in Naples, Florida, that now suggests there
will always be significant water flowing east and west to the coastal
estuaries even when the restoration is complete. It is not clear that
the public is aware that this subtle change in graphics represents a
major change in the overall restoration goals of the Florida Everglades in the past decade.
2. To put 0.46 billion m3 of water per year (121 billion gallons per
year) in perspective, 3.1 billion m3 (819 billion gallons) were discharged to the St. Lucie and Caloosahatchee rivers in the El Nino
flooding year of 2016 (Table 1), 6.2 times the flow expected to go
south with the EAA Reservoir plan. Even in the 10- year period of
2008–2017, an average of 1.5 billion m3 per year (Table 1) is 3 times
the 0.5 billion m3 per year that will be sent south according to the
plan.
3. There is insufficient detail on water quality in the plan relative to

Major coastal pollution, unanticipated in the original Everglades
restoration plan, has accelerated recently, particularly in 2013, 2016,
and 2018. The coastal pollution of estuaries, freshwater rivers, wetlands
and even beaches has sidetracked and even threated to derail the restoration of the Florida Everglades that was once viewed primarily as a
hydrologic project but now has become much more focused on water
quality. If this same Lake Okeechobee water is discharged south to the
Everglades and is not dramatically improved in water quality to low
concentrations of phosphorus and nitrogen, then the project needs
dramatic redesign to focus much more on water quality rather than only
moving massive quantities of water around annually.
3. The plan
A current plan, referred to as C240A (Smith, 2018), calls for sending
Lake Okeechobee water to an “EAA Reservoir” to be constructed about
50 km (30 miles) south of Lake Okeechobee with the following design:
A 7-m (23-foot)-deep, 4087-ha (10,100-acre) reservoir with the capacity to store up to 300 million m3 (240,000 acre-ft or 78.2 billion gallons) of excess Lake Okeechobee water (Fig. 2). The plan also involves
completion of a previously approved 6070-ha (15,000–acre) A-1 Flow
Equalization Basin with a maximum water storage of 74 million m3
(60,000 acre-feet or 20 billion gallons) and the design and construction
of 2630 ha (6500 acres) of shallow treatment wetlands, sometimes referred to by the SFWMD as Stormwater Treatment Areas (STAs), similar
to the 25,600 ha (63,200 acres) of STAs already created or in progress

Fig. 1. Three-picture summary of historic, current, and restoration water flow in the Florida Everglades as provided by the U.S. Army Corps of Engineers in the early
2000s (from Mitsch and Jørgensen, 2004).

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W.J. Mitsch

Fig. 2. Major features and map illustrating the location of the proposed Everglades Agricultural Area (EAA) Reservoir Plan in south Florida. Flow of polluted water
from Lake Okeechobee will be directed to public lands south of the EAA region to a reservoir and flow-equalization basin system with 2600 ha of treatment wetlands
toward the Florida Everglades to the south of the EAA. (Map based on one supplied by SFWMD).
Fig. 3. Illustration of location of current treatment
wetlands (called locally STAs or stormwater treatment areas) south of the EAA. There is no clear indication if these wetlands will receive double duty
with additional inflows from the EAA Reservoir
Plan. Currently 25,600 ha (63,200 acres) of these
wetlands have been created or are on the drawing
boards to be created. Our conservative estimate is
that 40,000 ha (100,000 acres) more of these treatment wetlands will be needed to ensure that the EAA
Reservoir Plan will be successful.

water volume and flow. The flow south to the Everglades will increase by 76% from 0.26 million m3/year (210,000 acre-ft/year or
68 billion gallon/yr) to 0.46 billion m3/year (370,000 acre-ft/yr or
121 billion gallon/yr) according to the EAA Reservoir plan (Smith,
2018). Despite the 76% increase in flow, the project shows only an
11% increase in treatment wetlands of 2630 ha (6500 acres) to
improve water quality directly. I estimate an additional minimum of

at least 17,500 ha (43,000 acres) of treatment wetlands (STAs or
passive wetlands) will be needed to treat the water flowing south
and have recommended previously that 40,000 ha (100,000 acres)
should be set aside for treatment wetlands (Mitsch, 2016) to allow
for a safety factor of 2, a reasonable design allowance for this type of
ecological engineering project.
4. Further, we note that the estimated average concentration of total
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W.J. Mitsch

Table 1
Freshwater discharges from Lake Okeechobee to the sea over the 10-year period 2008–2017, and annually in 2013, 2016, 2017, and 2018.
Discharge from Lake Okeechobee
9

3

Discharge to Caloosahatchee and Gulf of Mexico (×10 m )
Discharge to St. Lucie and Atlantic Ocean (×109 m3)
TOTAL Discharge to the sea (×109 m3)
Equivalent depth of Lake O discharged to sea (m)*

2008–2017

2013

2016

2017

2018

1.3
0.2
1.5
0.8

1.6
0.6
2.2
1.1

2.2
0.9
3.1
1.6

1.7
0.6
2.3
1.2

1.1
0.4
1.5
0.8

Discharge data from:
USGS 02292010 CALOOSAHATCHEE CANAL DWS OF S-77 AT MOORE HAVEN FL.
USGS 02276877 ST. LUCIE CANAL BLW S-308.
*Based on Lake Okeechobee surface area of 1891 km2 (730 mile2).
Source: https://en.wikipedia.org/wiki/Lake_Okeechobee.

phosphorus flowing out of Lake Okeechobee will be higher than the
current concentrations of total phosphorus flowing into the current
STAs (SFWMD, 2018). Due to the higher flow, it is probable that the
phosphorus concentrations reaching future treatment wetlands
(STAs) will be higher than the concentrations reaching the current
STAs and, in that case, will threaten existing state and federal
standards on Everglades water quality.
5. The new EAA Reservoir will not resemble any natural feature of
aquatic ecosystems in the greater Florida Everglades in ecology,
morphology or hydroperiod. It will in no way represent “restoration” of the Florida Everglades as it sometimes being portrayed. The
hydroperiods will be wrong and exaggerated for south Florida
ecology, similar to the way in which wetland hydroperiods were
shifted in the Great Lakes coastal marshes with the diking of marsh
hunt clubs and conservation areas (Mitsch et al., 2001; Mitsch and
Gosselink, 2015). The potential amplitude of the annual hydroperiods of up to 7 m (23 feet) in the EAA reservoir is exceeded only
rarely in natural or human-created ecosystems, e.g., the Amazon
River (Junk et al., 1989) or Three Gorges Dam reservoir (Mitsch
et al., 2008). The reservoir may become a “freak ecosystem” over
time, i.e., an aquatic ecosystem dissimilar in hydrology and probably ecology to any other aquatic ecosystem in Florida.
6. Most eutrophic lakes in our experience become occasional or even
permanent sources rather than sinks of nutrients—Buckeye Lake,
Ohio (W.J. Mitsch, personal experience), Taihu Lake in China
(Kelderman et al., 2005), and even Lake Okeechobee (Havens and
James, 2005). It is highly probable that the EAA Reservoir will not
be a nutrient sink in most years, although that is an assumption
included in this plan. Using a Vollenweider-type model (Hejzlar
et al., 2006) in SFWMD’s Dynamic Model for Everglades Stormwater
Treatment Area (DMSTA) model as proof that the EAA Reservoir
will always be a nutrient sink is ecologically and hydrologically
inaccurate and misleading. The DMSTA model was developed to
evaluate multiple STA design alternatives. Model simplicity resulted
from aggregation of key variables and processes controlling phosphorus storage and cycling (Walker and Kadlec, 2011). But the
DMSTA has not been calibrated for reservoirs.

•

Acknowledgements
I appreciate the support and encouragement provided by Alan
Farago and the Friends of the Everglades (FOE) that made the original
assessment possible. The FOE also provided useful editorial and content
suggestions. I also acknowldge the useful discussion on this subject that
we had with Tom Van Lent and Melodie Naja of the Everglades
Foundation. Finally, Dr. Li Zhang gave great help on many of the flow
calculations I used in this paper. The views and conclusions in this
paper are mine and do not necessarily represent the views of my university, sponsor, or anyone I consulted.
References
Havens, K.E., James, R.T., 2005. The phosphorus mass balance of Lake Okeechobee,
Florida: implications for eutrophication management. Lake Reservoir Manage. 21,
139–148.
Hejzlar, J., Šamlova, K., Boers, P., Kronvang, B., 2006. Modelling phosphorus retention in
lakes and reservoirs. Water Air Soil Pollut. Focus 6, 487–494.
Junk, W.J., Bayley, P.B., Sparks, R.E., 1989. The flood pulse concept in river-floodplain
systems. In: Dodge, D.P., (ed.) Proceedings of the International Large River
Symposium. Special issue of the Journal of Canadian Fisheries and Aquatic Sciences
106: 11–127.
Kelderman, P., Wei, Z., Maessen, M., 2005. Water and mass budgets for estimating
phosphorus sediment–water exchange in Lake Taihu (China P. R.). Hydrobiologia
544, 167–175.
Mitsch, W.J., 2016. Restoring the Greater Florida Everglades, once and for all. Ecol. Eng.
93, A1–A3.
Mitsch, W.J., Gosselink, J.G., 2007. Wetlands, fourth ed. John Wiley & Sons Inc.,
Hoboken, NJ.
Mitsch, W.J., Gosselink, J.G., 2015. Wetlands, fifth ed. John Wiley & Sons Inc.,
Hoboken, NJ.
Mitsch, W.J., Jørgensen, S.E., 2004. Ecological Engineering and Ecosystem Restoration.
John Wiley & Sons Inc., Hoboken, NJ.
Mitsch, W.J., Wang, N., Bouchard, V., 2001. Fringe wetlands of the Laurentian Great
lakes: effects of dikes, water level fluctuations, and climate change. Verh. Internat.

5. Conclusions

• The EAA Reservoir Plan is considered the future heart of this recent

•

acres) and hopefully more than 40,000 ha (100,000 acres) of treatment wetlands (STAs) need to be created or restored in proximity to
the new EAA Reservoir; 2630 ha (6500 acres) of new treatment
wetlands as described in the EAA Reservoir Plan will be grossly
insufficient to protect the Everglades.
The plan for an EAA Reservoir immediately south of Lake
Okeechobee should be re-examined. For example, purchase of
farmland at a fair price coupled with conversion of that land to
treatment wetlands (perhaps as much as 60,000 ha (150,000 acres)
from the 280,000 ha (700,000 acre) EAA in lieu of construction of a
~$2-billion EAA reservoir is a reasonable alternative to the reservoir for water storage and water quality and should be examined.
Additionally, state-owned lands currently leased to agricultural tenants could be incorporated in any comprehensive review of alternatives. Providing treatment wetlands to achieve water quality goals
in the Florida Everglades is closer to true “restoration”; creation of
large difficult-to-manage deep reservoirs is not. Federal acceptance
of this plan needs to be conditioned with the requirement of adequate stormwater wetlands (STAs) and flow equalization basins
(FEBs), to mitigate the chances of falling short.

attempt to send water south in the Florida Everglades and is a good
start of the discussion of solving water excess and scarcity problems.
The Florida State Legislature and the South Florida Water
Management District plan to increase the southerly flow by 76% and
send an annual average of 0.45 billion m3 (121 billion gallons) of
water south to the Everglades and Florida Bay is noteworthy.
Nevertheless, there is considerable ambiguity in the plan and its
model predictions about the quality of the water as it enters the
greater Everglades south of the EAA Reservoir and through
Miccosukee Tribal lands on its way to the Everglades National Park
and Florida Bay. At a minimum, approximately 20,000 ha (50,000
158

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W.J. Mitsch
Verein. Limnol. 27, 3430–3437.
Mitsch, W.J., Lu, J., Yuan, X., He, W., Zhang, L., 2008. Optimizing ecosystem services in
China. Science 322, 528.
South Florida Water Management District. 2018. The 2018 South Florida Environmental
Report, West Palm Beach, Florida, p. 13.
Smith, E.C., 2018. Letter dated March 5, with attached 10-page document OGC 18-0138,

describing the “Final Order Approving the Central Everglades Planning Project Post
Authorization Change Report, Everglades Agricultural Area Reservoir,” Florida
Department of Environmental Protection, Tallahassee, FL.
Walker JR, W.W., Kadlec, R.H., 2011. Modeling phosphorus dynamics in Everglades
wetlands and Stormwater Treatment Areas. Crit. Rev. Environ. Sci. Technol. 41 (S1),
430–446.

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