There are no known records detailing use of the river by boats prior to the 17th century, but in 1634, Daniel Biatt, the mayor of Sudbury, met with Mr Doctor Warren and Mr Spencer to plan how to make the river navigable. On 11 December 1638 Spencer obtained
letters patent authorising him to make the river navigable from Manningtree to Sudbury. No progress was made, due to unrest around the time of the civil war, Spencer's pre-occupation with a similar project on the River Ouse, and his own financial difficulties. A similar scheme was proposed by Mr Maynard in 1658, but again no progress was made. By the late 1600s, John Little and Benjamin Dodd had obtained the rights of the Letters Patent, and later claimed they had spent a lot of money improving the river. What they did is unknown, for in 1703 the mayor and corporation of Sudbury presented a bill to Parliament to make the river navigable. Little and Dodd objected, as they already had rights under the letters patent, but their case was dismissed, and an act of Parliament, the ''''
(4 & 5 Ann. c. 2), was granted to Sudbury on 16 February 1706. It was entitled An Act for making the River Stower navigable from the town of
Manningtree, in the county of Essex, to the town of
Sudbury, in the county of Suffolk''. A long list of commissioners was established, and the work was to be carried out by the mayor and aldermen of Sudbury and ten others. It had to be started before 24 June 1708 and completed by 24 June 1713. In order to placate the millers, they were given rights to carry millstones and building materials for their mills without payment of tolls. A towpath would be provided on parts of the river, but the path was intermittent. The act also allowed winches and other engines to be set up on the banks, so that boats could be hauled through the
flash locks which were built. A total of 13 flash locks and 13
pound locks were constructed. The posts on which the lock gates hung were continued above the top of the lock, and a lintel spanned the lock to prevent the posts collapsing inwards. Timber sides to the locks later replaced the earth walls, and in the 19th century the flash locks were removed, while the pound locks were rebuilt, so that there were 15 between Sudbury and the estuary. Unusually for a navigation, the act did not specify how money to fund the project should be raised. In practice, 48 shares with a value of £100 were issued. Cornelius Denn bought 24, while the other 24 were split between Dean Cock and some clothiers from Sudbury. Denn and Cock were both merchants from London. This provided insufficient capital to complete the work, and the subscribers were asked for more money. £9,000 was raised, of which £6,500 was spent on the navigation works, £800 on 16 barges, and £1,700 on warehousing and other amenities. It is not known if there was an official opening, but in May 1709 barges carried 2,211 tons of coal from Manningtree up the navigation to Sudbury. The company was continually short of money, and in 1722
Daniel Defoe noted that the navigation was not really adequate. The company ceased in 1736 to be solely responsible for barge traffic on the river, and allowed anyone to use it on payment of a toll. The commissioners failed to elect new members as older ones died, and by the 1770s there were only two left. Since a quorum of 15 was required to appoint new commissioners, a second act of Parliament, the '''''' (
21 Geo. 3. c. 75) was obtained. New commissioners included Golding Constable, the father of the painter John Constable, and two brothers of the painter Thomas Gainsborough, Samuel and John. The act also empowered the new commissioners to build a towpath along the entire navigable section, and to maintain bridges, stiles and gates. Golding Constable and William Strutt had surveyed the river by September 1782, and a programme of dredging was carried out. Income from tolls was £700 in 1782, but this had doubled by 1817, with a large proportion of the revenue derived from the carriage of coal.
Operation As trade improved, so did the river's profitability, with a dividend of 11 percent paid in 1817. There were proposals to build links to
Hadleigh,
Boxford and
Lavenham, but the only work carried out was a short cut near Sudbury to serve brickworks and limekilns, which was known as the Ballingdon Cut. Despite advice from
William Cubitt that railways would never offer serious competition in the carriage of heavy goods, the proprietors spent £12,000 on a modernisation programme, involving the construction of towing paths and a cut to bypass a long loop at Wormingford, which included two new locks. Tolls for using the river were restructured, and there was a proposal in 1842 to upgrade the river for a further to Clare, but the scheme was not pursued due to the cost and the number of locks required. The
Eastern Counties Railway missed Sudbury by when it opened in 1843, but the
Colchester, Stour Valley, Sudbury & Halstead Railway was them promoted. The promoters tried to buy out the navigation, but rejected the asking price of £1,000 per share. Income on the navigation peaked at £3,400 in 1848, but had dropped to £1,400 by 1852, when the railway was operating. The towing path was far from satisfactory, with horses having to jump over fences, of which there were 123 in 1850, and 20 locations where the horse was transferred to the opposite bank by jumping onto the moving barge and jumping off again at the other side. In 1862 the proprietors investigated steam barges, and ordered one which arrived in 1863. It was not a success, and despite various modifications, was out of use by 1867. There was a steady decline in traffic between 1864 and 1873, with many commodities dropping by 50 percent. Dividends were reduced from ten percent to two percent over the same period, and maintenance was less frequent, although a self-acting dredging crane was obtained in 1879, and worked successfully. Trade in bricks from the brickworks at Ballingdon Cut and in flour held up for some time, despite railway competition, but in 1892 the proprietors applied for an abandonment order. This was refused, as the river had not been disused for the required three years. Instead they formed a limited company, the River Stour Navigation Company Ltd. By 1906, tolls were no longer adequate to pay for maintenance, and on 8 October 1914, the company declared itself bankrupt. The shareholders then formed a Trust, and although the last barge to reach Sudbury did so in 1916, there was limited traffic on the lower reaches of the river. The
South Essex Waterworks Company rebuilt the locks at Brantham, Flatford, Stratford and Dedham in 1928 at a cost of £20,000, replacing the wooden sides with concrete walls. At the end of 1995, the Trust received a grant of £167,890 from the
Millennium Commission to help with the construction of Great Cornard lock. Additional funds came from the Trust's own fund and from local councils. The Environment Agency is the navigation authority for the river. They took over the role from the
National Rivers Authority in 1995. Powered boats are only allowed to use the section of the river near Sudbury from Ballingdon Bridge to Henny Mill, and a speed limit of is enforced. The rest of the once-navigable river from Brundon Mill to Cattawade can be used by canoes, kayaks and other non-powered craft, but have to be portaged around various fixed structures, often located where the locks once were. However, the Environment Agency are considering allowing the use of electric-powered boats on the lower river, and the River Stour Trust has permission to use electric trip boats on this section. The locks at Great Cornard, Stratford St Mary, Dedham and Flatford must be operated by Environment Agency staff, and advance notice of intent to navigate through them must be given. The locks rebuilt in 1928 were long, and wide, with a draught of . Dedham and Flatford locks have tilting weir structures fitted within them, and navigating them is not possible when the weirs are being used as part of the flood defences of the river. The
River Stour Trust, a
waterway restoration group, was set up in 1968 to protect and enhance the right of the public to navigate the River Stour. The trust seeks to restore through navigation from Sudbury to the sea, following on the successful restoration of the locks at Stratford St Mary, Dedham, Flatford and Great Cornard, by reinstating the remaining locks. Meanwhile, the Trust encourages use of the river by small craft and organises annual events for all age groups and abilities on different parts of it. Boat trips and private charters, skippered by volunteer crews from the Trust, are available in Flatford and Sudbury between Easter and October. The Stour Valley Adventure Centre hires out canoes, kayaks and paddle boards from a centre in Sudbury. The craft can be borrowed by the hour, and they also offer a two-day paddle from Sudbury to Cattawade, with transport to and from the start and end points to a campsite in Nayland, which forms the mid-point of the journey. ==Flood defences==