Restoration in the Loire estuary

At the beginning of September, early in the morning, a group of government officials with responsibilities for the Loire invited the press out to La Varenne, a small town on the left bank about a half hour drive upstream from Nantes.  The journalists had been invited to a presentation of a complex contract among multiple parties to begin to try to fix serious problems in the river.

Since the early 20th century public authorities, employing multiple methods, concentrated the flow of water, to deepen the channel and maintain the port at Nantes.  The methods included closing off secondary arms as they passed around islands, constructing hundreds of wing dams, mining sand and gravel from the main channel, and eliminating a rocky underwater sill at Bellevue, just above Nantes.

A secondary arm blocked off.

From GIP Loire-Estuaire press kit,

2 September 2015

All this turned out to be too successful.  The force of the channelized water has been scouring out the river bottom to the extent that the measured low water mark at Nantes is 3.5 meters (11.48 feet) below the mark at the beginning of the 20th century.  This has undermined docks, bridges and riverbanks.  It has threatened, and in some cases eliminated, habitats around secondary arms and oxbow lakes.  Concentrating the river also opened it up to tidal effects.  Initially, tidal salt water would advance to a point just below Nantes.  These days, it has pushed a further 35 km (22 miles) up to Ancenis.  Drinking water utilities for Nantes and other towns have had to likewise move upstream for their supplies.

Since at least 2002, a special purpose public agency, the GIP (Groupement d'intérêt public) Loire-Estuaire has been looking for ways to halt the scouring and perhaps reverse the process.  They want to slow down the flow so more suspended material can be deposited; they also want to reconnect the river with old secondary branches.  The GIP has experimented with reducing or taking down the wing dams, creating artiificial sills, and using heavy equipment to reconnect the river to previoiusly blocked off parts.

Over the next two years, the first phase of restoration work is expected to cost 6.92 million euros ($7.4 million). This figure is expected to increase to 18 million euros ($19.2 million) during the 2018-2020 phase, primarily for work filling in the main channel.  Eventually over the full 15 years envisioned for the project the restoration should cost in the neighborhood of 62 million euros ($66 million).

As encouraging and really exciting as all of this is, I have to say something about the arrangements for management and oversight.  For a country known for its centralized administration, the arrangements are complicated, to say the least.  The press document prepared at the beginning of September includes a long list of “actors in the contract.”  These include major actors like the Agence d’eau Loire-Bretagne, the Region, the State, the GIP Loire Estuaire, and the Conservatoire d’espaces naturels des Pays de la Loire.  But they also include individual towns and groups of towns along the river.  A diagram shows these all grouped within a Commission des acteurs de la Loire, tied to a (presumably) executive Comité de pilotage, itself connected to a Comité des procédures (directed by the prefet of the department of the Loire-Atlantique) and a Comité technique (including technical experts).  But where are the authorizing and funding agencies?  How can they be held accountable for use of public funds in an arrangement that appears to make it difficult to do so ?