CONSERVATORS OF THE RIVER THAMES.

REPORT AND ACCOUNTS FOR THE YEAR ENDED
31ST DECEMBER 1921.

2. Revenue Account

3. Unappropriated Revenue Account

4. Capital Account-Receipts and Expenditure

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11.

Investments Account

Statement as to Borrowing Powers, Stock and Mortgage Loans

GENERAL REPORT of the PROCEEDINGS of the CONSERVATORS

of the RIVER THAMES during the Year ended 31st December 1921, with a STATEMENT of the ACCOUNTS of the CONSERVATORS for that Year.

Pursuant to the provisions of the Thames Conservancy Act, 1894, the Conservators of the River Thames have the honour to present the following General Report of their proceedings for the year ended 31st December 1921.

Rainfall, Regulation of Water, &c.-The average rainfall, as recorded in the 12 stations in the Thames Valley, was 16.52 inches for the year, which is 11.91 inches below the average for the preceding 38 years.

This is the lowest recorded rainfall, and it is 4.8 inches less than the previous lowest rainfall of 21.32 inches recorded in the year 1887. As regards the flow of the Thames, whilst the rainfall was far lower than has ever been experienced before, the flow of the River in itself was not quite the lowest on record. The total flow for the whole year at Teddington was 260,115 million gallons, while for 1905 it was 257,603 million gallons, and for 1902 it was only 240,585 million gallons, although the rainfalls of those two years were very considerably above the rainfall of the year 1921, being 24.80 inches and 23.19 inches respectively.

The following table shows in Column 2 the daily average natural flow of the River Thames; in Column 3 the daily average quantity abstracted from the River by the Metropolitan Water Board and Water Companies; in Column 4 the quantity left to flow over Teddington Weir. Similar data for the preceding 38 years are shown in Columns 5, 6 and 7 for purposes of comparison. The maximum and minimum day's flow in each month are shown in Columns 8 and 9. The monthly totals of rainfall for 1921 and the corresponding averages for the preceding 38 years are shown in Columns 10 and 11 respectively.

The apparent discrepancy of the rainfall, as compared with the flow, is probably to be accounted for partly by variations in density and distribution of rainfall during the years in question, but more perhaps from the fact that there has been a record period of high rainfall for the previous seven years. Consequently, at the commencement of the drought, the pervious rock formations in the Valley were fully charged with water, and the River has drawn its supplies from these underground sources, and there still is at the present time held up, in porous rocks and the chalk, a certain amount of water available for the supply of the River, though greatly depleted in quantity owing to the rain shortage.

It being apparent at the end of March 1921, from the rapid decrease in the flow of the River, that there was every likelihood of a shortage of water during the coming Summer, steps were taken to make the weirs as tight as possible, with a view to maintain a full head of water in all reaches of the River. At the same time the Metropolitan Water (15)75 625 6/22 Wt 2615 (No 20)

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Board and Water Companies were warned that a shortage of water might be expected.

Owing to the fact that Littleton Reservoir, the construction of which was stopped during the war, had not yet been completed, it seemed doubtful if there was sufficient storage for the Metropolitan Water Board to carry out their obligations without exceeding their statutory limits of abstraction from the River. This anticipation was fulfilled as early as 26th May, and the Conservators notified them accordingly.

In conjunction with the Water Board the whole position was placed before the Ministry of Health and the Ministry of Transport on the 10th June, and on subsequent occasions, and as a result of conferences with the Government Departments concerned, the Conservators decided, in view of the vital importance of London's water supply, to co-operate with the Water Board to the fullest extent and refrain from enforcing the statutory restrictions with regard to the abstraction of water from the River.

Notwithstanding that the Water Board drew from their storage reservoirs water to the quantity of approximately 1,120 million gallons, they abstracted from the River during the year in excess of the quantities authorised by Statute under the prevailing conditions 3,943.6 million gallons, and the number of days on which the Water Board so exceeded their powers was 141, as under :

Total excess abstraction over Statutory limits, in millions of gallons.

The level of water in the reaches of the River naturally suffered, both by reason of the drought and as a result of the abstraction by the Water Board, and it became necessary to restrict the draught of vessels navigating the River. At a later date restrictions were also made as to the number of hours during which the locks should be worked in order to conserve water, and wherever traffic could possibly be sent by way of boatslides this was done.

Constant supervision in the regulation of the water during day and night was necessary, with a view to meeting the needs of the Water Board and of the navigation, and it was only by the most careful adjustment of levels and regulation of flow in the upper reaches of the River, that a sufficient flow of water to meet the requirements of London's supply and of navigation was maintained in the lower reaches.

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Progress has been made by the Conservators in obtaining surveys of all the various tributaries of the Thames, and in many instances it has been found that tributary streams have become dry in parts. For example, the River Kennet, which joins the Thames at Reading, and which contributes a much larger quantity of water to the main river than any other tributary, and the River Lambourn, a tributary of the Kennet, were, at the end of 1921, respectively 16 miles and 4 miles shorter than under normal conditions.

In order that everything possible should be done to conserve the water in the River, the Conservators have taken steps to that end by carrying out protective works to the various weirs upon the Thames, which have suffered to an alarming extent through the scour which has taken place during the past few years, when it was impossible for them to undertake the work necessary to check the damage. At one weir in particular-Caversham Weir immediate steps had to be taken in March last to make this weir secure by filling in a large hole in the bed of the River with concrete and chalk (at a cost of about £2,500), where, owing to erosion at the tail of the weir, a maximum depth of 36 feet of water had formed over a considerable area, thus endangering, by undermining, the safety of the weir and the protective works of Caversham Lock Island.

Similar serious conditions had developed at Shepperton, Shiplake and Marlow Weirs, and in only a slightly lesser degree at practically all the weirs on the Thames.

Works, &c.-The Thames Conservancy Act, 1921, which received the Royal Assent in August, provides, inter alia, for increased payments to be made to the Conservators by the Metropolitan Water Board and Water Companies for five years from the 1st January 1921. This additional revenue will enable the Conservators to carry out works which have been deferred throughout the war and -since, owing to lack of funds.

A programme of works, based upon the list placed before Parliament during the progress of the Bill, estimated to cost £291,000, has been considered and adopted in principle by the Conservators. The various items will be proceeded with in order of urgency, commencing with the construction of a new lock at Goring, 180 feet long, which, by the fixing of an intermediate pair of gates, is adaptable for use as a lock, 180 feet, 114 feet, or 66 feet in length, as occasion requires, the reconstruction of Iffley and Odney Weirs and the construction of a more efficient gauge weir at Teddington.

During the year certain works of maintenance were carried out as far as finances would permit, prior to the passing of the Act, since when many protective works have been undertaken.

The following works have been carried out or have been put in hand in 1921 :

New lock gates have been fixed at Boveney and Shepperton Locks.

Repairs and improvements have been carried out at Marsh, Temple, Marlow, Cookham, Bray, Molesey and Teddington Locks. Repairs have been carried out to Eaton Weir.

The renewal of pile foundations at Benson Weir is in hand.