Information about the 65km long river Lys

River Lys France map

The navigable river Lys extends from the junction with the Dunkerque-Escaut waterway (PK 93) near Aire-sur-la-Lys to the confluence with the Scheldt/Escaut at Ghent in Belgium. The length of waterway given in the route description below is 65km, ending at the point where the river enters Belgium at Halluin/Menin. The river itself forms the border over a distance of almost 24km downstream from Armentières, the right bank being in France and the left bank in Belgium (hence the official name of this section : Lys mitoyenne). The two countries have upgraded this shared section to provide a direct high-capacity link with the Canal de la Deûle, a branch of the Dunkerque-Escaut waterway. The Deûle joins the Lys at Deûlémont (PK 48). The Lys also used to connect with the Hazebrouck canals on the left bank at PK 5 and at PK 19, but these have long been closed to navigation. The secondary arms of the Lys may be navigated at a number of places, as indicated.
Between Aire-sur-la-Lys and Armentières the river flows quietly through rural Flanders and makes a very attractive cruising waterway, while the towpath has also been carefully landscaped and planted for the enjoyment of cyclists and walkers. Ports de plaisance have been developed on the bypassed loop of the river at Prés Duhem, near Armentières, and at the border town of Halluin, and attractive moorings at many other locations.
Lys region map

History – The Lys was a commercial navigation from the Middle Ages, but it was the river’s devastating floods rather than navigation improvements which justified major works and meander cut-offs started around 1670. The 9 m difference in elevation between Aire-sur-la-Lys and the border was gradually overcome by six locks and weirs, completed in 1780. The river carried a heavy traffic in grain and linen through to Ghent and Antwerp. The navigation was leased out to a company around 1825, and the locks upgraded to 5.20 m wide, for a draught of 1.60 m. The river was given its present depth by the Freycinet programme. The section below Armentières was enlarged to class III from 1930, and the border section was improved to class Va starting from 1960. This section is part of the EU’s priority project 30 for the Seine-Escaut waterway. The upstream section, by contrast, is used almost exclusively by recreational craft, and is at present heavily silted. The Lawe, a tributary of the Lys shown on the map below, had locks 95 by 5.20 and 1.30 m, built starting in the 18th century, but fell into disuse, and has long been abandoned.

Key Waterway Dimensions

  • Max Beam: 5.18m
  • Max Height: 3.90m
  • Max Draught: 1.80m

Local Waterway Links

Commercial traffic will be encountered downstream of Armentières, and especially on the high-capacity waterway downstream of Deûlémont. AboveAire-sur-la-LysPlan

Armentières the plaisancier will be practically alone to enjoy the river and its charming villages.

Locks – There are eight locks between Aire-sur-la-Lys and Halluin/Menin, overcoming a difference in level of 11.00m. The first five are of standard 300-tonne barge dimensions, 38.50 by 5.18m. Armentières lock is of Campenois barge dimensions, 85 by 8m. The last two locks at Comines (PK 54) and Menin (PK 63), come under Belgian adminis­tration and have been rebuilt to grand gabarit dimensions.

Draught – The maximum authorised draught is 1.80m from Aire-sur-la-Lys to Armentières, increased to 2.00m from this point downstream.

Headroom – The fixed bridges offer a minimum headroom of 3.90m above normal water level, reduced to 3.60m above the highest navigable water level. Bridges on the Lys mitoyenne leave a clear headoom of 5.25m (to be raised to 7.10m).

Towpath – The towpath is practicable throughout for walking and off-road biking, following substantial works under the Lys sans Frontières development programme. This natural approach to treatment of the banks (as shown by the photo on page 01) was preferred to the cycle path solution that is prevalent on many French canals.

Authority – VNF – Direction territoriale Nord – Pas de Calais
–    113 avenue Max Dormoy, BP56, 59004 Lille

Click to enlarge

Lys waterway strip

Route description

PK 0.0     Aire-sur-la-Lys, junction with Canal d’Aire and Canal de Neuffossé, footbridge, river navigable with difficulty for a further 300m upstream to basin (500m from town centre, see plan), moorings
PK 0.6     Lock 1 (Fort-Gassion)
PK 3.7     Thiennes lift bridge, quays upstream, village 1000m l/b
PK 4.1     Footbridge (Oxyduc)
PK 4.5     Railway bridge
PK 4.6     Junction with Canal de la Nieppe (disused), l/b
PK 5.4     Houleron quay r/b, small village
PK 6.7     Lock 2 (Cense à Witz) and weir
PK 10.6     Footbridge (Haverskerque)

Picnicking beside the Lys at La Gorgue, PK 24. © LSF
Picnicking beside the Lys at La Gorgue, PK 24. © LSF

PK 12.4     Haverskerque (Port de Flandre-Lys) l/b, 6 visitors’ berths, night €8, water €5, electricity €9, showers €2, slipway, wifi, Saint-Venant village 300m r/b

A charming, compact port de plaisance in a small basin on the left bank, with shops, restaurants and services on site and across the bridge in Saint-Venant. Boats longer than 15m are to moor on the right bank (grass bank with bollards).

PK 12.6     Lock 3 (Saint-Venant)
PK 12.7     Road bridge (D916, Saint-Venant bypass)
PK 14.5     Saint-Floris village 500m r/b
PK 17.4     Le Sart quay, village 500m l/b
PK 19.0     Footbridge (Basse-Boulogne)
PK 19.2     Confluence with Bourre and entrance to lock-cut r/b
PK 19.4     Lock 4 (Merville), lift bridges u/s and d/s, small town
PK 19.9     Confluence of Merville arm of Lys, navigable u/s 800m to town
PK 20.1     Site of a former railway swing bridge, pipeline bridge, quay d/s r/b
PK 22.3     Private quay r/b and private footbridges
PK 24.4     Confluence of Lawe (formerly navigable) r/b

PK 24.6     La Gorgue bridge (Pont de la Lys), village 500m r/b

Picnicking beside the Lys at La Gorgue, PK 24. © LSF
Picnicking beside the Lys at La Gorgue, PK 24. © LSF

PK 25.7     Estaires bridge (Pont de la Meuse), quay u/s l/b, small town 300m l/b
PK 26.6     Private footbridge
PK 26.7     Bridge (Pont d’Estaires)

PK 30.2     Sailly-sur-la-Lys bridge, pontoon moorings d/s r/b, capacity 4 boats, village 400m r/b
PK 32.5     Lock 5 (Bac-Saint-Maur) and weir
PK 32.9     Bac-Saint-Maur bridge, small village r/b
PK 33.9     Entrance to Erquinghem cutoff, r/b
PK 34.9     Railway bridge (high-speed line to Channel Tunnel)
PK 35.7     End of Erquinghem cutoff
PK 36.1     Bridge (D945)
PK 36.2     Entrance to cutoff, l/b
PK 37.1     Motorway bridge (A25), end of cutoff
PK 37.9     Railway bridge
PK 38.5     Entrance to cutoff, r/b
PK 39.1     Armentières bridge (D933), centre 800m r/b
PK 40.2     End of cutoff, Armentières marina (Prés-du-Hem) and water sports centre on old course of river, l/b (see plan), 60 berths, night €11, water €12, electricity, showers, slipwayArmentieresPlan

Long-esablished and popular port de plaisance run by former marinier Thierry Decoster with capacity for 60 boats, 10 visitor moorings (maximum length 12m).

PK 40.2     Bridge (Bizet)
PK 40.4     Armentières industrial quays
PK 40.6     Bridge (Pont Aristide Briand)
PK 41.1     Footbridge (Bayard)
PK 41.4     Lock 6 (Armentières) and weir, VHF 18, beginning of Lys mitoyenne (border with Belgium)
PK 41.8     Railway bridge (Houplines), disused, entrance to Ploegsteert cutoff, l/b

Boat harbour Lys Armentieres-LSF
The extensive boat harbour at Armentières. © LSF

PK 42.3     Bridge (Ploegsteert)
PK 43.6     End of cutoff
PK 43.8     Bridge (belgian N58)
PK 44.9     Frélinghien bridge, village 200m r/b
PK 47.1     Bridge (Pont Rouge)
PK 47.7     Junction with embranchement Bauvin-Lys (Canal de la Deûle) r/b
PK 50.5     Warneton bridge, village l/b (in Belgium)
PK 54.0     Lock 7 (Comines) and weir, quay u/s r/b
PK 54.6     Former junction with disused Canal de Comines à Ypres, l/b
PK 55.1     Comines bridge, town centre 200m l/b
PK 55.6     Industrial quay d/s r/b
PK 56.8     Bridge

Boat harbour Lys Armentieres-LSF
The extensive boat harbour at Armentières. © LSF

PK 57.5     Footbridge, pontoon l/b
PK 58.6     Wervicq bridge, quay d/s r/b, town 400m r/b
PK 61.6     Bousbecque r/b
PK 63.1     Lock 8 (Menen)
PK 64.7     Bridge

PK 65.3     Halluin boat harbour, 35 berths, night €13.80, water, electricity, shower €1.70, slipway, restaurant, end of Lys mitoyenne, Belgian border, Menin bridge 200m d/s

The historic town of Courtrai (Kortrijk) is just 11km from the border, with no intermediate locks. It is part of the European metropolis of Lille-Kortrijk-Tournai, and an ideal short-stay round cruise via the Canal de Roubaix.