Initial plans faced spirited opposition from Maldon, which were overcome by avoiding the town and terminating at Heybridge, and the navigation opened in 1797.

They undertook major refurbishment work at the lock during the winters of 2016/17 and 2017/18, including replacement of the outer sea gate with a new design.

A proposed link from Springfield Basin has been thwarted by road building in the area, but a plan to replace the automatic weir below Chelmsford Town Centre with a new structure incorporating a navigation lock was recommended in 2020.

The navigation meanders in a broadly west to east direction between Chelmsford and Maldon, through countryside which is largely arable, and although it passes near to a number of villages, all of them are set back some distance from the waterway.

[1] Prior to the actual construction of the navigation, there had been almost 120 years of proposals for such a scheme, and opposition from the port of Maldon, which anticipated that its revenues would fall if vessels could travel to Chelmsford.

The first such scheme was proposed in 1677 by Andrew Yarranton, who published his idea in a work entitled England's Improvements by Sea and Land.

The new route would increase the length of the navigation by about 2 miles (3.2 km), but this plan formed the basis of a parliamentary bill.

3. c. 93), on 17 June 1793, creating The Company of the Proprietors of the Chelmer and Blackwater Navigation, with powers to raise £40,000 by the issuing of shares, and a further £20,000 if required.

[6] The grave of Richard Coates stands in Springfield churchyard, while Rennie's original survey book for the canal has been preserved.

Realising that this would make the final cut to Heybridge redundant, the Navigation Company opposed the bill, and it was defeated.

The Navigation Company built a granary, which was used to store perishable goods, while rope-makers and boat builders also established themselves nearby.

Further improvements were made,[15] including the rebuilding of Heybridge sea lock by James Green,[16] and trade developed steadily.

Traffic slowly declined until the last load of timber was delivered to Browns Yard (now Travis Perkins) on Springfield Basin in 1972.

Although commercial traffic ceased, the navigation continued to derive income from water abstraction and from the sale of wood from the willows which grow along the banks.

Leisure boats used the navigation for the first time in 1973, when the Inland Waterways Association (IWA) organised a rally at Kings Head Meadow, Chelmsford.

[12] Almost the entire canal is now a conservation area, after Chelmsford so designated the part within their jurisdiction in 1991, and Maldon and Braintree district councils took similar action subsequently.

[21] On 18 February 2016, the Chelmsford Civic Society held a meeting at the Essex Record Office to consider the option of extending the canal from Springfield Basin to a new destination nearer to the town centre.

[26] Chelmsford City Council commissioned a feasibility study, which proposed that the automatic gates could be replaced, and a navigation lock built alongside the new structure, on the north side of the river.

[25] Some 970 new homes are expected to be provided in the Chelmsford Waterside neighbourhood, and the council has obtained a grant of £10.7 million from the government's Housing Infrastructure Fund, enabling it to address issues of access, contamination of the land, and the presence of gas mains which currently hinder the development.

[28] Regular working parties help to keep the waterway, including the towpath, locks and other structures well maintained, and many of the recent improvements have been undertaken by the volunteers.

[31] The lock was originally constructed of masonry, but in the mid-1960s, it was extended at the seaward end, when a steel caisson gate was installed in a reinforced concrete structure.

It was moved into place by electric motors driving chains, and had a hollow centre, making it partially buoyant, with the buoyancy being adjusted by the addition of ballast.

Over time, the steelwork degraded, and the mechanism for controlling the flow of water into and out of the gate to alter its buoyancy ceased to operate, resulting in the rollers on which it moved seizing up.

In 2014 Northumbrian Water agreed that the structure was beyond economic repair, and due to the complexity of the work, decided to manage the replacement project themselves.

Having checked its dimensions, Northumberland Water commissioned MWH Global and Kenneth Grub to design a new gate which would fit into the existing pocket, so that no modification of the lock structure would be required.

[31] A re-usable stop-log dam was constructed, to enable the lock to be isolated while the installation of the new gate was carried out and for future maintenance.