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 ?

A paddle wheeler on the Loire

Consider a new way to see the heart of France.  In April, the European river tour company, CroisiEurope, began offering voyages along the Loire.  Its brand new Loire Princesse, with very comfortable looking accommodations for about 100, promises travelers views along the river from Saint Nazaire on the Atlantic up to Angers and its famous chateau, a distance of about 150 km or just over 90 miles.

Map: Ouest France

The ship, built in the Saint-Nazaire shipyards, was specially designed to accommodate the often shallow and unpredictable river.  It’s 90 meters long by 15 meters wide (about 300 feet by 50 feet), but draws only 80 centimeters (2.6 feet) of water and, rather than propellers, is driven by side paddle wheels.  The Loire Princesse may be the first passenger ship on the river since the early steam-powers ships of the mid-19th century, the curiously-named inexplosibles.

Photo: Bernard Biger

But this year, according to an mid-summer article in the Nantes newspaper, Ouest France, the river turned out to be even more unpredictable than CroisiEurope anticipated.  An especially dry summer meant a shallower river than anticipated, so much so that several times even the 80 centimeter draft was too much and the ship ran aground.  And it was discovered that dealing with the current, when squeezed between bridge footing, required more push than the paddle wheels could manage.  The company had to call in tugs for an occasional extra push.

Contacted by Ouest France, environmentalists in the area seemed mildly bemused.  Tourism in the river isn’t necessarily a bad thing they said.  It could build appreciation for the area's natural beauty.  They’re concerned, though, that as the ship's difficulties get resolved that it be the one to adapt to the river and not the reverse.  That makes good sense.  Meanwhile, it will be interesting to follow how this all works out.

Dredging and the Nantes-Saint-Nazaire Port

The Grand Port Maritime de Nantes et Saint-Nazaire (GPM) is likely the most important economic actor in the Loire estuary.  Along the stretch of the river from the Atlantic Ocean to Nantes, the GPM is responsible for nearly 25,000 jobs.  The Saint-Nazaire-Nantes complex is France’s fourth largest port with nearly 27 million tons of goods passing in and out, 90 percent of which involves facilities at Saint-Nazaire along the north side of the river.  

Portion of Saint-Nazaire Port with Airbus transport ship in the foreground

Last week, as required by French law, the GPM published its strategic plan for the next five years, including plans for 170 million euros in new investments.  Clearly almost anything the Port does will have implications for the estuary environment.  And the planning document doesn’t ignore this.  Virtually a third of its 60 pages are given to “spacial planning and sustainable development” (aménagement et développement durable).

I’ll probably come back to the Port and to more of this document, but right now I just want to highlight one element.  That has to do with dredging.  To provide access to larger ships, the Port dredges along the docks and out into the Atlantic.  It also clears out the channel at several critical points upstream for ships going to the few port facilities at Nantes.

Multiple studies have identified a severe drop in the river’s low-water level as the most serious environmental issue in the estuary.  The combination of sand and gravel extraction, wing dams to concentrate water flow, and dredging to provide ship access has caused the river to dig deeper and deeper into its bed.  Near Angers the bed is about six and a half feet below what it was in 1900; at Nantes it’s about 12 feet lower.

This has had serious consequences, especially between Les Ponts-de-Cé (on the river just below Angers) and Nantes.  Wetland environments in arms of the river have dried up; bridge pilings have been exposed to erosion; the tidal effect carrying salt water upstream has advanced beyond Nantes requiring that city and others to relocate pipes for drinking water supplies.  A massive silt plug between Saint-Nazaire and Nantes seriously impedes migratory fish like salmon and eels.

The GPM plan does mention dredging and promises “to reduce the environmental impact” but is non-specific beyond that.  Also, it’s quite possible that by “environmental impact” the Port is not even referring the effect on the river bed, but to a separate issue relating to disposal of dredged material.

Meanwhile, it appears that a restoration project aimed at the stretch upstream between Nantes and Les Ponts-de-Cé is finally getting underway.  I’ll say more about this in another post.  For now, it strikes me as unfortunate, to say the least, that the Port’s planning document doesn’t connect to the this project.

Ibis in the Estuary

I was out on my first day of walking.  I’d just left a path cutting through summer pasture lands along the west side of the Lac de Grand-Lieu.  The lake is barely 15 miles from Nantes to the southwest.  Winter rains turn it into the largest lake in France.  In the summer, though, with less rainfall and the local water authority releasing water into the Loire, the lake surface is cut in half, opening up pastures where local farmers graze dairy and beef cattle.  I was getting bearings before going off in a new direction and I noticed three birders coming up the path, binoculars around their necks.  We exchanged “bonjours” and one asked if I’d happened to see any ibis on my walk.  I said no, that with all the cows I’d mostly had my head down concentrating on where I put my feet.  I think they smiled.

I knew just barely that Lac de Grand-Lieu was an important stopover for birds on a major north-south flyway.  I though I might see herons or storks, but not this bird from Egyptian mythology.

Then, a week later, I saw two of them.  By now I was quite a ways from the Lake, maybe 25 miles to the northwest.  I was out on a day hike looking, not for birds, but for the Menhir de Pierre Bonde.  According to the map, it was supposed to be in a marshy field a mile or so south of the Loire.  Menhirs are sprinkled all over France.  Many, if not most, are like this one, large stones usually standing upright, frequently alone.

  The fact that they have no geologic reason for being where they are means, most likely, that an ancient people put them there.  The mystery is how and why.  Maybe, like England’s Stonehenge, they had some ceremonial function.  Here, the menhir stood out, orange lichens coloring the top, rising up in the middle of someone’s private, fenced-off field.  

And there, just off to the right of the stone, were the two ibis.  These were sacred ibis with large white bodies, black tail feather, black feet, and a black head which seemed to have been compressed by powerful forces to squeeze out a long, downwardly-curved, black beak.

 

Later, at the bed & breakfast where I was staying, thinking I had a rare sighting, I mentioned it to the host.  Oh, she said, they aren’t at all rare, in fact, she added, they’re considered an invasive species.  I read later that a zoo in the area had imported the birds sometime in the 70s.  At some point, a few birds escaped and began to reproduce.  A 2006 census counted 1,700 pairs and a total of about 5,000. 

Concerns had been growing about the possible consequences of this new bird.  It was said that ibis were eating the eggs and chicks of other birds like herons and terns.  More, they might be carrying diseases picked up from feeding on waste dumps.  As a result the government began an eradication program, shooting birds and piercing eggs in the nests.  It was successful.  Another census in 2013 found the ibis population had been cut by nearly 80 percent.

Is it possible that this was all a mistake?  That this invasive species isn’t necessarily harmful and might even be beneficial?  This was the conclusion of an article published two years ago based on more than 10 years of analysis of the ibis diet.  All of the data came from birds in the local department of Loire-Atlantique.  Loïc Marion, a researcher at the University of Rennes, found no evidence that ibis eat eggs or chicks of other birds, nor than they eat more than incidentally from waste dumps.  On the other hand, he found than more than 40 percent of the birds’ diet consists of Louisiana crayfish, itself an invasive species that has infested the Lac de Grand-Lieu.

There’s probably an important lesson in this.  Certainly some invasive species create serious problems.  Besides the Louisiana crayfish, nutria and catfish are also causing headaches along the Loire.  But, as the case of the ibis suggests, simply saying a species is invasive isn’t enough to establish that it’s really a problem.  In a world where so many plants and animals are already dispersed and intermixed, some amount of careful analysis is needed before deciding on the kind of eradication program used against the ibis.  Happily, for the moment at least, it’s still possible to happen on a pair in a field somewhere along the estuary.