In the later half of the 18thC came the Excavation of the Grand Junction Canal, which Opened in 1799.
The Grand Union Canal itself Links London to Birmingham, passing through rolling Countryside, Industrial Towns & peaceful Villages. It is our longest Canal, the ‘Trunk Route’ of the System. The word ‘Union’ offers a clue to the Heritage of this Canal. The Grand Union Canal was never Constructed as an Entity, but is the result of Amalgamations between 1894 & 1929 of several Independent Waterways – the Oldest being the Navigations around the River Soar in Leicestershire, the Longest the Grand Junction Canal from Braunston to the River Thames. Isambard Kingdom Brunel‘s last major undertaking was the compact Three Bridges, London, on the Canal. Work began in 1856, and was completed in 1859. The 3-Bridges are an overlapping arrangement allowing the Routes of the Grand Junction Canal, Great Western & Brentford Railway, and Windmill Lane to cross. It is a 3-Level crossing of Bridges near Hanwell in West London
From Marsworth Junction, the Ascent up the Northern Face of the Chilterns becomes Steeper, Locks 39 to 45 (Marsworth Top Lock) being encountered in under a mile.
Wendover Arm Branches off, passing close to the former Marsworth Toll House (Grade II-Listed) before skirting the edges of Tring, Aston Clinton & Halton to Terminate at the long disused Wendover Wharf, which lies a short distance from the Town Centre. It is at this Point that the Wendover Stream (the Outflow from a natural Spring at Wellhead, near St Mary’s Church) enters the Arm to provide much of the Water for the Tring Summit.
Weston Turville Reservoir lies about a mile to the North of Wendover Town Centre and adjacent to the Arm. It accumulates Water mainly from 2-Streams below the Level of the Canal and from any Overflow from the Canal itself. Built in 1797/8, it is the earliest and most Westerly of the 5-Reservoirs that lie along the Foot of the Chiltern Escarpment. Although not intended to Supply the Canal, in 1814, following several years of poor Water Flow, a temporary Newcomen-type Pumping Engine was installed to raise Water from the Reservoir as & when required. No clear information remains as to the capacity of this Pumping Station, but it is known that its Outflow Pipe into the Canal was 4-ins in dia. Weston Turville Pumping Station remained in use until about 1838, and was eventually Scrapped in April 1841. Since then Water has occasionally been taken for the Canal during Periods of Drought, but today the Reservoir is used for Recreation.
Further to the East lie the 4-Tring Reservoirs. They comprise Wilstone (1802, heightened in 1811 & 1827, and Extended in 1836 & 1839), Marsworth (1806), Tringford (1816) & Startops End (1817). Of these, Wilstone is by far the largest. The Opening of the Grand Junction Canal in 1800 resulted in more Traffic than had been anticipated, added to which the Aylesbury Arm imposed a significant Drain on the Main Line. Consequently, the demand for Water at the Summit increased. To Address this, the Tring Reservoirs were Built in Stages to provide further Supplies, which they accumulated from Local Streams and any Surplus from the Canal itself.
Canal Systems require a Lot of Water to Function. Cowroast Lock (46) is the beginning of what is known as the Tring Summit, which stretches on for 3-miles, all being the Highest Level of the Canal here. From either end, in use, the Locks empty Downhill, and every time a Lock is opened about 50,000-gals of Water is Lost. The 4-Tring Reservoirs were constructed in the early half of the 19thC to supply this need, & the Bulbourne Head Springs, then Via a Pond, already Flowed into the Summit. Still more Water was needed, resulting in Boreholes at Cowroast, 1st in 1848, and Later at Northchurch (Lock-49), 1st used in 1942, all for Pumping Water directly from the Aquifer. There is a mountain of evidence to show that these Pumps have had, and still have, great implications for the Health of the Bulbourne Chalk Stream.
Aston Rowant & Chilterns Spring Line Villages 