Information about the Garonne crossing (Baïse-Lot connection)

The Garonne crossing is the gateway to the navigable river Lot, unfortunately now officially unusable because the pilotage service accompanying boats through this link between the Baïse and the Lot has been withdrawn (with a final cutoff date of January 26, 2018). The free-flowing river Garonne runs for 4.7km from Saint-Léger lock at the outlet from the river Base to the entrance to the Lot navigation at Nicole lock. Passage is only possible when there is neither too little nor too much water in the river. The problem with low river levels is that the flow concentrated in the narrow passage becomes rapid and dangerous for all craft, while shoals are also then virtually impassable just downstream of Saint-Léger lock and at the actual Lot-Garonne confluence. Works are needed before the crossing can become sufficiently navigable for regular use, but there are currently no plans for even studies of these works, let alone their implementation. For boats ‘trapped’ on the river Lot, road transport will be the only practical option from 2018. This page and all the details remain as a ‘holder’, in the hopes that the connection will be restored in the not-too-distant future. See our blog post announcing this closure.

 

 

 

 

History – The free-flowing Garonne between the rivers Baïse and Lot is a recent oddity of French waterways, because historically the commercial traffic on the river Lot only went downstream on the Garonne (or upstream from the port of Bordeaux), never up the Garonne and Baïse to join the Canal de Garonne. The connection was needed to develop recreational navigation on the river Lot. Studies in 1993 (in which the author participated) led to a partial solution, clearing a narrow channel through the sill of marl above the confluence of the Lot. This was after a hydraulic scale model study had found the originally planned solution, a series of groynes to provide a ‘self-scouring’ channel, to be ineffective. The result, from 1995, was only a semi-navigable river, with long seasons of unavailability during low or high flows. It has been suggested that the problem should be overcome by dredging a deeper channel. Damming the river downstream from the Lot canal outlet at Nicole to maintain depth is excluded by regulations, which dictate that the Garonne must remain a free-flowing river to allow the rare Gironde sturgeon to return. The sill depth of the extra lock chamber built at Saint-Léger is another restriction. The most viable solution would be to create a completely new short branch canal between the Canal de Garonne and the river downstream from Nicole at a point where both waterways are just 1700 m apart. This section of the Garonne is deep and steady, and navigable practically at all stages of the river. The crossing is officially closed to navigation from 2018, and only a substantial dredging effort would make it regularly available again. 


Key Waterway Dimensions

  • Max beam: 5.00m
  • Max height: 4.40m
  • Max draught: 1.20m

Navigation

After locking down from the Canal de Garonne to the river Baïse at Buzet and following the river for 5km to its confluence with the Garonne, Saint-Léger lock gives access to the Garonne. The river is followed for 4.7km, downstream past the confluence of the river Lot to the ‘canalet’ that bypasses the last, shallow, 3km of river itself.

This passage is no longer available from 2018, after years of unsatisfactory operations. During low water periods, the difficulty was not only the passage through the marl sill mentioned above but also the banks of gravel transported into the Garonne by the Lot itself, and a pronounced shoal just below Saint-Léger lock. Garonne levels are further reduced during periods of drought because water abstraction from the river by agriculture increases, compounding the problem.

Until January 26, 2018, pilotage (hence operation of the Buzet lock at Saint-Léger and the Lot canalet lock at Nicole) is only available when conditions allow, and advance notice should be given (contact details below).

Draught – Depths are highly variable according to the stage of the river. The pilot’s advice should always be obtained, but vessels drawing up to 1.50m are generally able to make the passage when the pilotage service is operated.

Headroom – The bridge at Saint-Léger leaves a minimum headroom of at least 6.00m above the highest navigable water level.

Authority – Conseil Départemental de Lot et Garonne, Direction des Infrastructures, Transports et Logement, Service Routes et Navigation, Côteau de Romas, 47130 Port Sainte-Marie (for the pilotage service and the connected waterways)

VNF – Subdivision d’Aquitaine
107 avenue Général de Gaulle, 47000 Agen
To book the pilot for the crossing when conditions allow, up to January 26, 2018, call
06 08 02 31 51 or 06 07 99 62 41.

When is the passage viable? 

a) The Vigicrues website

The Vigicrues website provides mapped data about river levels, present and past, for the Garonne and all of its ‘feeder’ rivers joining from north and south. The Garonne itself rises in the Pyrenees. From the site one can see if levels are currently below, at or above ‘normal’ conditions. If they are significantly below then the prognosis is unfavourable.

The most significant monitoring stations for the Garonne Crossing are at Agen and Lamagistère. See here for the combined 3-day graph. There are two useful pieces of information that can be obtained:

  • When the graph level at Agen (upstream from St-Leger) is higher than -0.5 the crossing is probably feasible.
  • If the line showing the Lamagistère level is higher than Agen’s this indicates that additional water is travelling downstream. The levels at Agen and then Saint-Léger levels could then be counted on to rise in due course.

b) Visual Checks at Saint-Léger lock

Sufficient Depth
Sufficient Depth (click)
  • Inspect the water level against the vertical level scale fixed to the lock wall by the Garonne gates.
  • Navigation should be possible between +116 above 0 (i.e datum) and -119 below it.
  • Below -119 there is insufficient depth, above +116 there is too much water flowing.
  • Look at the concrete channel guide immediately outside the lock gates. It has a chamfered top edge and a steel marker post at its end.
    If the river level is noticeably below the bottom line of the chamfer then there is insufficient depth.
Click to enlarge

 

Route description
(zoom disactivated for this map, which is clear enough)

Note This information is no longer relevant from January 26, 2018, when the pilotage service will be permanently withdrawn. Passage must have been booked at the double lock down to the Baïse from the Canal de Garonne at Buzet.

Garonne Saint-Léger - NicoleThere is no permanent lock-keeper at Saint-Léger. If making the crossing in a hired boat, note that you will not be allowed to remain on board, but will be taken by car to pick up the boat at the pontoon after the crossing.

Going downstream, the pilot boat will precede and indicate the safe channel, particularly at the point of confluence with the River Lot where it is restricted by gravel banks and runs faster.
Towards Nicole the pilot will go ahead, moor up on the outside pontoon and prepare the lock. 

Going upstream, one will often need the assistance of the pilots to tow or (more usually) push. One pilot will usually accompany the skipper on board the boat. The pusher boat has sufficient power to overcome the current. Once beyond the road bridge at Saint-Léger conditions become much easier, but the turn into the lock there still needs care.

The obligatory pilotage service means that there can be no stopping on the Garonne between Saint-Léger and Nicole.

PK 0.0     Junction with river Baïse l/b, d/s of Saint-Léger lock
PK 0.5     Bridge (Saint-Léger)
PK 3.3     Narrow channel through marl sill
PK 4.0     Confluence of river Lot, r/b (no access)
PK 4.7     Junction with river Lot navigation, r/b, Nicole lock
Waiting pontoon downstream of the lock. 

Baise-Garonne-Lot crossing
Garonne crossing, looking upriver in high summer. Shallows are very evident.

From the skipper’s point of view the turn into the Nicole écluse entrance can be tricky. The river current tends to carry the boat sideways downstream, towards the boulders retaining the bank outside the lock and there are also significant back-eddies to spoil the approach. If in doubt, do what the pilots do, which is to turn back well downstream from the lock, heading directly into the current, thus getting improved steerage and control.