E & E Publishing

Comprehensive Everglades Restoration Plan (Yellow Book) Excerpt

Hydrology and Hydraulics Modeling

B.2.5.9 Flowways

A flowway is generally described as a broad, shallow march area that is used to flow water freely from Lake Okeechobee to one or more of the WCA’s. The concept includes creation of an Everglades-type environment having both storage and water quality benefits. Evaluation of the concept shows several erroneous assumptions about the feasibility. Problems with soil subsidence, ET, seepage management, vegetation, timing of flows, and lack of flow events is evident. Addressing other EAA issues would be required if a flowway cuts through and dividing the area, including numerous roads, bridges, and railroad relocations.  

Soil subsidence in the EAA has substantially reduced the hydraulic head that drives the southward flow of water; hence, velocities and flow rates are greatly reduced. By spreading the water over shallower areas (as opposed to reservoirs) and maintaining proper hydration of a functioning marsh habitat, the ET loss could easily be doubled. A long, rectangular configuration can have a 75 percent longer levee than a squared one, thus increasing seepage management features. Because nutrient-laden soil would be flooded for the flowway, cattails would most likely dominate the vegetation and not the desirable Everglades habitat.  Flowways would not be able to hold back water going to the WCA’s. The continuous delivery of that water would exacerbate the already high stages in the northern parts of the WCA’s. Thus, the timing of flows from flowways would not be manageable or beneficial for the remaining Everglades. Perhaps the most crucial element- water flowing from the Lake to the WCA’s – is not present in dry or even normal years! For example, during the long periods from 1970 – 1982 or 1985 – 1994, no significant excess Lake water was available for the flowway. Only demand releases to the Everglades were made from the Lake during those periods. Water delivered to the Everglades on a demand basis through a flowway would not be effective because of increased travel times and increased ET losses. The only years where water could flow for a long duration are wet periods similar to the 1969-1970, 1982-1983, and 1994-1995. In those years, the stages in the WCA’s are already too high and additional flow from flowways would be damaging, not beneficial.  

Summarizing, the flowway is a concept that creates a water supply burden on the system without clear hydrologic benefits. The need for flowways would have to be justified for other reasons rather than hydrology alone.

Arthur R. Marshall Foundation and Florida Environmental Institute, Inc 

Comments on Yellow Book Section B.2.5.9 Flowways: 

Page B-19 of the CERP Yellow Book is the reference for the SFWMD contractor comments at the 10 County Coalition meeting, June 7, 2007, subsequently relayed to the SFWMD Governing Board, June 11, 2007, that provided the basis for the SFWMD representative to recommend no further evaluation. 

TheseB.2.5.9 findings contradict what is said about the hydrologic and ecologic benefit of flow-ways in the April 1999 ReStudy/CERP 4033 pages, the National Research Council peer review reports and the Science Coordination Team on flow investigations 2000 – 2003.   

The B-19 statements are also totally contradictory to what is said in the 1994 Recon Study, to wit:  Plan 6 flow-way maximizes planning objectives (restore hydrologic function, reduce fragmentation of habitat, and reduce flood damages); these objectives are reiterated in CERP Table 5-1 Goals and Objectives.   

There was no hydrologic modeling of a Plan 6 flow-way during the Re-Study (1998-99), only modeling of reservoir storage.  There is no visible cost-effective analysis or cost-benefit study along the lines of CERP Section 7.5.3 to ascertain the validity of the B.2.5.9 statements made above.   The latter is what is being called for, to validate the statements of this section.  

The statements of Page B-19 also contradict findings of Peer Review literature on the value of flow-ways published by the Task Force Science Coordination Team and the National Academy of Sciences’ (NAS) Peer review.  

The NRC has recommended a relook at flow-ways in the EAA. Our findings also follow the NAS/NRC 2006 CERP progress review, P.64:  A systematic approach to analyze costs and benefits across multiple projects is notably lacking.   See Summary of NRC findings on an EAA flow-way, and the restoration of sheet flow in general. 

The extent of any feasibility study regarding a Plan 6 flow-way appears to be limited to the unsubstantiated statements of CERP Yellow Book Section B.2.5.9 Flow-ways, page B-19. 

What the conservation community and many others are asking for, is a re-evaluation of the Plan 6 flow-way that includes a science and economic-based full-cost analysis, including cost-benefit and cost-effectiveness analysis along the lines of CERP Section 7.5.3 calling for analysis of alternatives. 

A major alternative would be ASR, and the ASR contingency plan, announced in 2001, and yet to appear, ought to consider the restoration of Dynamic Storage and Sheet Flow as described in CERP Section 2.3.1. 

It is fairly easy to conclude that a re-evaluation of a Plan 6 flow-way, or something like it, would be a fair substitute for an ASR Contingency Plan.  

CERP-required analysis of alternatives would appear to consider the cost-benefit and cost-effectiveness of a dynamic storage flow-way in the EAA v. ASR. 

To Whom it may concern:   Thanks for your consideration to make science and full-cost economics in the decision-making process.