The Amstel Locks

A complex of locks in the Amstel river, between Prinsen­gracht and Singel­gracht, in front of Theater Carré (the theater is from 1887), is called Amstel­sluizen. They are a national monument, constructed in 1673, inititiated and designed by Amsterdam mayor and mathema­tician Johannes Hudde (1628-1704). The locks were created to control the water level in the Amstel river (which was still subject to tides from the IJ, so salt water from the IJ needed to be kept out) and they were also needed to drain the water from the polders outside Amsterdam. Until a few years ago they were still manually operated with capstans, now with the use of hydraulics.

View of the Amstel locks in front of Theater Carré (June 2020).

The Layout of the Amstel Locks

The locks consist of three lift-locks, a big one in the middle and two narrower ones to the sides. The length of the locks is 47 m (51.4 yd). Special drainage sluices were once between both outer locks and the quays. In 1872, after the Oranje­sluizen (Orange Locks) on the eastern part of the IJ were deployed and the IJ had been closed off from the North Sea by the Afsluitdijk, the function of the Amstel­sluizen changed and they were redesigned and renovated.

Amstel river, seen from Hoge­sluis bridge in northern direction towards the Amstel locks, the Magere Brug (Skinny Bridge) and the Blauwbrug (Blue Bridge). Etching from around 1702-1713 by Daniël Stoopen­daal (Stads­archief Amsterdam).

Water Issues in the 17th Century

In 1649 the Nieuwe Vaart ditch was dug (from the Oosterdok to the East), meant to increase the water flow in the city and to prevent the silting of the IJ, which had become a major problem after the construction of Kattenburg, one of the Eastern Islands. In 1675 there was an ongoing battle in Amsterdam to deal with water management issues: the tides in Zuiderzee and IJ, the inadequate refreshing of water in the city canals and draining the water flowing in from the Amstel river. A team consisting of Daniël Stalpaert, Nicolaas van der Heijden and Douwe Claesz, led by Amsterdam mayor Johannes Hudde (1628-1704), tried to deal with these problems.

Under the lens the Amstel Locks on a map from 1882, below it the Paleis van Volks­vlijt (burned down in 1929).

Locks & Water Mills

The Amstel locks were primarily constructed to control the inflow of water from the Amstel river and the Amsterdam polder hinterland. To improve the water quality in the city the team proposed in 1675 to keep the water level inside the town at the highest possible level, just below the point where cellars and lower house parts would be flooded. The Amstel locks would be closed every time that point was reached — but that also meant that water could not flow out to the IJ anymore at that point. The increased waste water in town, the leakages every time the locks were used and the rapidly rising water levels whenever it rained complicated matters.

Amstel Locks between 1890 and 1900 (Stads­archief Amsterdam).

Hudde proposed to employ three horse powered water mills, just outside the Amstel locks, to get rid of the excess water, pumping it out of the city and back into the Amstel river. On both sides of the river water barriers were constructed in the Singel­gracht, which basically sent the water back to the Amstel­land area. The Amstel­land Water Authority was not happy about this and only allowed it when the town was in direct danger of being flooded — the city water pumped out was very dirty and smelly most of the time.

Amstel Locks seen from the water (June 2020).

The End of the Dirty Water Mills

The idea was to combat the increased pollution of the river and smelly city canals by the intake of fresher water, flushing the canals and using the sluices on the western side of the city to let the stagnant water out into the IJ. But there was a diminished ebb and flow effect, as well as a lack of under­standing how salt water and fresh water behaved during flushing (the fresh water flowing over it, the salt water remaining below, which caused the silting of the canals with smelly mud). All this meant that the 17th century water management theories soon proved inadequate — the horse-powered water mills near the Amstel locks were demolished in 1687.

They were replaced with four windmills (two on each outer side of Amsterdam near the IJ in the East and in the West). But city council stinginess meant that these were not nearly enough windmills (at least 12 would have been needed) to provide an effective solution to the dirty water problem. In 1812 the city demolished the last one. Adequate canal flushing was only achieved in 1874 when a steam powered mill was placed near Zeeburg.

Amstel Locks with Theater Carré in the background (June 2020).

Changes to the Locks

In the 19th century the locks were extensively renovated and redesigned. The western drainage lock was removed (on the west side, across from Carré). The lock doors of the eastern double door drainage lock (on the Carré side) have been replaced after the Second World War. They are now made of cast steel, where the original ones were either wrought iron or bronze. Three lock keepers operate these locks. The small buildings on top of the locks were once used for collecting city excise. The small brick house in the center was meant for the lock keeper, since 2021 it’s in use sometimes as an alter­native hotel.

Amstel Locks, viewed towards the northwest. In the distance the Skinny Bridge and the Stopera (City Hall) (June 2020).