on March 25, 2015 at 6:04 PM, updated March 26, 2015 at 6:28 AM
A scientific advisory panel gave the green light Wednesday (March 25) to the state’s continued planning for construction of four major sediment diversions on the lower Mississippi River, although it raised questions about state’s ongoing socioeconomic analysis of the diversions’ potential effects.
In a report to the Coastal Protection and Restoration Authority board Wednesday, “Expert Panel on Diversion Planning and Implementation” Chairman John Wells said the panel was presented enough information over the past year to indicate the state’s planning process is on the right track. Wells is dean of the Virginia Institute for Marine Science.
The panel of a dozen scientists and engineers from across the country was created by the Baton Rouge-based Water Institute of the Gulf to advise the state Coastal Protection and Restoration Authority on science issues involving the design and construction of sediment diversions.
In December, the CPRA staff agreed it had enough information to move forward with planning and design for Mid-Barataria and Lower Barataria diversions on the west bank of the Mississippi River and for Mid-Breton and Lower Breton diversions on the east bank. The CPRA expects to consider a go or no-go decision on building the diversions by the end of the year.
“We conclude that the four sediment diversions below New Orleans are viable projects that meet basic criteria for advancement to the next phase,” said the report, even though detailed design and other issues remain unresolved.
“Understanding of the ecosystem continues to advance quickly, and there is enough overall knowledge to know that the diversions will almost certainly take us in the direction of achieving the goal of building new deltaic land,” the report concluded.
The report warned, however, that information provided by state planners is confusing on the subject of both the cost of various project alternatives and on the elements of the initial design of the diversions.
“This information is of general interest to the panel, but of vital interest to decision-makers and the public,” the report said.
Two sets of contractors are developing initial designs for the projects on the east and west bank. Each will include a major structure at the river that will withdraw water and sediment from well below the river’s surface and then pump it along a concrete or earthen channel inland to open water areas, where the sediment will both form new land and filter into existing wetlands, helping them survive sea level rise and subsidence.
The report also said the panel didn’t get enough information to back the state’s decision to build the channels directing water from the river into wetlands to a depth of 40 feet below ground level, and it urged the state to also do a better job explaining the potential long-term effects of both subsidence and sea level rise related to global warming.
State officials also haven’t provided the panel with enough information yet to determine whether planned studies of the social and economic effects of the diversions on communities will be adequate, the report said.
It said three studies already under way — Coastal Valuation, Commercial Fisheries, and a Coastal Atlas — are static exercises meant to document conditions now existing across the state, but the information on its own doesn’t allow for “comparison of outcomes across diversion projects or between diversions and the no-action option,” the report said. “It is therefore unclear how this work can be used to support policy choices associated with the diversions.”
As the state moves towards a planned fall 2005 go or no-go decision on the diversions, the panel recommended that the state expand its planning process to provide greater detail on the habitat and ecological modeling and socioeconomic studies and the linkages between the two.
It should use the results from the refined modeling and socioeconomic analysis process to explain the viability of the diversions to stakeholder groups over the next six months and to get their feedback.
The monitoring and modeling efforts should be reviewed by independent subject matter experts, and make the results of those views public.
“Transparent technical review ensures that conclusions drawn from the technical analyses are in fact well supported and will add credibility to difficult or controversial aspects of diversion implementation,” the report said.
Wells told the board that such a review could consist of sending reports on the results of the monitoring and modeling efforts to experts, rather than convening a meeting of a panel of experts and holding public sessions.
It also recommended that the basin-wide socioeconomic study be designed so that differences in operating the diversions on the socioeconomic outcomes can be compared, and that available resources be focused on this study, rather than “other more descriptive studies that do not have clear relevance to diversion decisions.”