How is flow estimated?

EA COOKHAM Downstream graph
EA COOKHAM Upstream graph

from Environment Agency Guide 2012-2013

Left bank lock, tel: 01628 520752, length: 183', width: 25'
CAMPING on Right bank of lock. Very helpful lock keeper

1369:  Cookham Mill under repair
1585: Bishop: Hedgeworth weir belonging to Hugh Cottrell
& 1632:  John Taylor: Cottrell's Weir

1794: Report of a survey of the river Thames between Reading and Isleworth ... John Rennie (the Elder)

From the Wycomb stream to Cookham Ferry, there is a sufficient depth of Water.
But [downstream from Cookham Ferry - round Hedsor Water] commences one of the most difficult and dangerous places on the Thames. The fall is not only considerable, but the stream is so divided between the barge channel, the paper mill, and the fishing bucks and pleasure grounds of Sir George Yonge, Mr. Martindal, and others, that I see no way of improving the channel itself, without manifest injury to their property.
The inconvenient turn at Hedsor Wharf; the danger arising from large chalk stones that tumble from the cliffs above, and lodge in the bottom of the river; the inconvenience of a double ferry, and the difficulties hitherto experienced in this district, have induced me to recommend, that A NEW CUT, WITH A POUND LOCK, may be made from a little above Cookham Ferry, by Messrs. Darby and Allnut's Brewhouse, to join the river again at the tail of the paper mill stream, adjoining Sir George Yonge's.
By this cut all the difficulties of Hedsor Bucks will be avoided, and the towing path may be continued on the same side of the river from Boulter's Lock, to near Spade Oak Wharf. The rise of this lock will be two feet three inches, as the river now stands; but as the shoal at Clifden Ayt should be removed, the rise will be considerably increased.
It does not appear to me that there will be any great necessity for making a dam at Cookham Ferry, as the shoal will be sufficient to answer the purpose, and therefore the land owners will have no occasion to complain of any injury to their lands, as the river will remain exactly in the same state as it now is.
But it would be well for the Commissioners to encourage any contractions, such as may be done by the planting of willows, or the like, under the departure of the side cut from the river, as thereby the depth of water would be generally improved upwards to Marlow Lock.

1807:  Plan for a lock and cut on the south side of Hedsor.
1830:  Cookham pound lock opened for traffic.  It did not at first have a weir, but relied on the natural holding up effect of the Hedsor bend.  A weir was soon installed and this started the ongoing wrangle about rights in Hedsor Water which has only finally been resolved in the 21st century.  (See Hedsor section).

1880: Cookham Lock, Henry Taunt -

Cookham Lock, Henry Taunt, 1880
Cookham Lock, Henry Taunt, 1880
© Oxfordshire County Council Photographic Archive; HT03596

1885: The Royal River -

Cookham Lock, 1885
Cookham Lock, 1885

1886:  Julia Isham Taylor, Down the Thames -

Of all the locks, Cookham is considered to have the loveliest situation.  It lies under the woods of Hadsor and Cliveden, and passing through it one enters upon an ideal vista between Formosa Island and the remarkably beautiful banks of Cliveden Park.

1892:  The lock was lengthened
1893:  A boatslide provided

Cookham Lock lantern slide, 1883-1908, W C Hughes, research by Dr Wilson, courtesy of Pat Furley.

1899:  Cookham Lock and Odney Approach, Francis Frith

1899:  Cookham Lock and Odney Approach, Francis Frith
from Down Stream - 1899:  Cookham Lock and Odney Approach, Francis Frith

1901: And here is the boatslide (which presumably disappeared in 1956, if not before) -

Cookham Lock, 1901
Cookham Lock with a boatslide, 1901

1956-7:  Lock totally rebuilt and electric controls installed.  A third set of gates was also added.
1974:  Hydraulic controls installed.

Cookham Lock, 1999
Cookham Lock, 1999

Cookham Lock Cut Footbridge

Height: 12' 6" (3.81m)

Cookham Lock Cut Footbridge
Cookham Lock Cut Footbridge

1901: The Thames Illustrated by John Leland -

The Cookham backwater is particularly famous, and the canal to the Lock is the most beautiful lock-cutting on the river.

Cookham Lock Cut Footbridge, Doug Myers © 2005
Cookham Lock Cut Footbridge, Doug Myers © 2005