2016 No. 80 (W. 37)

Flood risk management, WALES

The Reservoirs Act 1975 (Capacity, Registration, Prescribed Forms, etc.) (Wales) Regulations 2016

EXPLANATORY NOTE

(This note is not part of the Regulations)

For the purposes of the Reservoirs Act 1975 (c.23) (“the 1975 Act”), these Regulations provide for—

(a)     how to calculate capacity for the purposes of section A1 of the Reservoirs Act 1975 (regulation 3);

(b)     the information about a large raised reservoir that must be registered (regulation 4); notification of changes to, and the keeping and inspection of, the Welsh register (regulations 5 and 6);

(c)     the making and content of reports by the Natural Resources Body for Wales (“NRBW”) to the Welsh Ministers (regulation 7);

(d)     the form of record to be kept for a high-risk reservoir and the information to be given in that record (regulation 8);

(e)     the form of certificates of engineers (regulation 9); the form of reports of engineers (regulation 10); and the form of directions of engineers (regulation 11);

(f)      the information to be provided by undertakers when intending to construct or bring back into use a large raised reservoir (regulation 12); and

(g)     the making of reports by undertakers to the NRBW in relation to incidents relating to the uncontrolled release of water from a large raised reservoir where emergency measures are taken (regulation 13).

These Regulations also revoke the Reservoirs Act 1975 (Registers, Reports and Records) Regulations 1985 (S.I. 1985/177), the Reservoirs Act 1975 (Registers, Reports and Records) (Amendment) Regulations 1985 (S.I. 1985/548) and the Reservoirs Act 1975 (Certificates, Reports and Prescribed Information) Regulations 1986 (S.I. 1986/468) (regulation 15). Those Regulations are replaced by the provisions in regulations 4, 6, 8 to 10 and 12.

Section A1(4) of the 1975 Act requires regulations to be made about how to calculate capacity for the purpose of establishing whether a raised structure or area is large under section A1(3) of the 1975 Act. Regulation 3 makes this provision.

Under section 2(2) of the 1975 Act the NRBW is required to maintain a register containing prescribed information about large raised reservoirs. Regulation 4 prescribes the information about large raised reservoirs that the Welsh register is to contain.

Regulation 5 provides for notification by the undertaker to the NRBW of any changes or proposed changes to the information required to be held in the Welsh register. Regulation 6 requires that the Welsh register and copies of it be kept at the principal office of the NRBW and that the NRBW ensure that certain information required to be in the Welsh register is in it.

Regulation 7 specifies the timing of reports to be made by the NRBW to the Welsh Ministers under section 3(1) of the 1975 Act; the information to be given in those reports.

Regulation 8 prescribes the form in which a record under section 11(1) of the 1975 Act which an undertaker of a high-risk reservoir is required to keep and the matters, additional to those specified in section 11(1)(a) and (b) of the 1975 Act, about which undertakers of high-risk reservoirs have to keep a record of.

Regulations 9 to 11 prescribe, as provided by section 20(1) of the 1975 Act, the form of various certificates, directions and reports where the 1975 Act requires the giving of certificates or directions or the making of a report by a civil engineer engaged in work in connection with a large raised reservoir.

Regulation 12 prescribes the information which must be contained in a notice under section 21(1) of the 1975 Act which an undertaker, who intends to construct or bring back into use a large raised reservoir, is required to serve on the NRBW.

Regulation 13 prescribes the form of, and specifies the incidents in relation to which, a report under section 21B of the Act is to be made.

The Welsh Ministers’ Code of Practice on the carrying out of Regulatory Impact Assessments was considered in relation to these Regulations. As a result, a regulatory impact assessment has been prepared, as to the likely costs and benefits of complying with these Regulations. A copy can be obtained from the Energy, Water and Flood Division of the Welsh Government, Cathays Park, Cardiff, CF10 3NQ.

 

2016 No. 80 (W. 37)

flood risk management, WALES

The Reservoirs Act 1975 (Capacity, Registration, Prescribed Forms, etc.) (Wales) Regulations 2016

Made                                  27 January 2016

Laid before the National Assembly

 for Wales                            29 January 2016

Coming into force                       1 April 2016

The Welsh Ministers, in exercise of the powers conferred by sections A1(4), 2(2) and (2C) to (2E), 3(1), 5, 11, 20(1), 21(1) and 21B of the Reservoirs Act 1975([1]), make the following Regulations.

Title, commencement and application

1.—(1)(1) The title of these Regulations is the Reservoirs Act 1975 (Capacity, Registration, Prescribed Forms, etc.) (Wales) Regulations 2016.

(2) These Regulations come into force on 1 April 2016.

(3) These Regulations apply in relation to Wales.

Interpretation

2.—(1)(1) In these Regulations—

“the 1930 Act” (“Deddf 1930”) means the Reservoirs (Safety Provisions) Act 1930([2]);

“the 1975 Act” (“Deddf 1975”) means the Reservoirs Act 1975;

“the NRBW” (CANC”) means the Natural Resources Body for Wales;

“Welsh register” (cofrestr Cymru”) means the register required to be established and maintained by the NRBW under section 2(2) of the 1975 Act;

“lowest natural level of any part of the surrounding land” (“lefel naturiol isaf unrhyw ran o’r tir amgylchynol”) includes the lowest bed level of any watercourse;

“natural level” (lefel naturiol”) is the level of the natural land remaining after the construction or any alteration of a large raised reservoir;

“panel” (“panel”) means a panel of civil engineers constituted under section 4 of the 1975 Act([3]);

“structure” (“adeiledd”) means a dam, reservoir wall or embankment that retains water;

“surrounding land” (“tir amgylchynol”) means the land contiguous to a large raised reservoir;

“toe” (“troed”) means the point on the downstream side of a structure forming part of the reservoir where its base meets the lowest natural level of any part of the surrounding land;

“top water level” (“lefel uchaf y dŵr”) means—

(a)     in the case of a reservoir with a fixed overflow sill, the lowest crest level of that sill;

(b)     in the case of a reservoir, the overflow from which is controlled wholly or partly by moveable gates, syphons or otherwise, the maximum level to which water may be stored exclusive of any provision for flood storage; or

(c)     in the case of a reservoir designed for the purposes of holding back floodwater, the maximum level to which floodwater may be stored during any flood event exclusive of any provision for overflow.

(2) In these Regulations—

(a)     any information required or notification given must be in writing;

(b)     a reference to any document or information includes that document or information in electronic form;

(c)     any document or information communicated by electronic means is deemed—

                           (i)    to have been sent where the sender can produce a copy of the electronic communication which—

(aa)        contained the document or information;

(bb)       shows the time and date the message was sent; and

(cc)        shows that the document was sent to the recipient;

                         (ii)    to have been sent by the person from whom it purports to originate; and

                       (iii)    not to have been tampered with or otherwise modified;

(d)     any requirement for a signature in a report, certificate or directions to which these Regulations apply may be satisfied by an electronic signature incorporated into the document;

(e)     “electronic signature” (“llofnod electronig”) means data in electronic form which are attached to or logically associated with other electronic data and which serve as a method of authentication.

Calculation of capacity

3.—(1)(1) For the purposes of section A1(3) of the 1975 Act capacity of a large raised reservoir is to be calculated by measuring the maximum volume of water in cubic metres capable of being stored—

(a)     above the bed of the reservoir; and

(b)     between the toe of the reservoir and its top water level.

(2) Water below the natural level of any part of the surrounding land is not  to be included in the calculation.

(3) In this regulation “bed of the reservoir” (“gwely’r gronfa ddŵr”) includes any silt or other material that is judged by the engineer giving a final certificate, or giving a certificate under section 13(2) of the 1975 Act, to be incapable of flowing out of the reservoir over natural land in the event of an uncontrolled release of water from the reservoir.

Registration requirements

4.—(1)(1) For the purpose of section 2(2C) of the 1975 Act, the information that is to be registered with the NRBW by an undertaker of a large raised reservoir is that prescribed in Schedule 1, paragraphs 1 to 7.

(2) The information prescribed in Schedule 1 must be registered—

(a)     before the end of the period of 28 days beginning with the day of the issue of a final certificate given in accordance with section 7 of the 1975 Act([4]) in relation to—

                           (i)    the construction of a new reservoir;

                         (ii)    the alteration of an existing structure or area that prior to its alteration was not a large raised reservoir; or

                       (iii)    the alteration of an area of a reservoir that prior to its alteration was not a large raised reservoir;

(b)     within 6 months of registration under section 2(2C) of the 1975 Act,

whichever is the sooner.

Notification of changes to the Welsh register

5.—(1)(1) Where there has been a change or addition to any of the information registered in accordance with regulation 4, the undertaker must provide the NRBW with the relevant up to date information within 28 days of the date of the change or addition.

(2) The NRBW may request confirmation from the undertaker that any or all of the information given by that undertaker for the purposes of the Welsh register is up to date or complete.

(3) Where paragraph (2) applies, without prejudice to paragraphs (4), (6) and (8), the undertaker must within 28 days beginning with the day on which the NRBW requests such confirmation—

(a)     confirm that the relevant information is up to date or, where any of that information is not up to date, provide the up to date information; and

(b)     where any of the information is not complete or is missing, provide the complete or missing information.

(4) Where an alteration so as to increase or decrease the capacity of a large raised reservoir is proposed to be carried out, the undertaker must notify the NRBW not less than 28 days before the commencement of alteration works.

(5) A notification referred to in paragraph (4) must contain the following information—

(a)     the date of the proposed commencement of the alteration;

(b)     a description of the nature and extent of the proposed work to the large raised reservoir.

(6) Where it is proposed that the use of a large raised reservoir be abandoned under section 14 of the 1975 Act([5]), the undertaker must notify the NRBW not less than 28 days before any such proposed abandonment of use.

(7) A notification referred to in paragraph (6) must include the proposed commencement date of the abandonment of use.

(8) Where a construction, supervising or inspecting engineer is appointed for the purposes of the 1975 Act, the undertaker must notify NRBW of the date of the appointment within 28 days.

(9) The undertaker must notify the NRBW within 28 days of the date on which an engineer ceases to be—

(a)     the construction engineer before that engineer has issued a final certificate;

(b)     the inspecting or supervising engineer.

(10) An undertaker who intends to cease being an undertaker must notify the NRBW of—

(a)     the date on which the undertaker intends to cease being the undertaker;

(b)     the name and address of the person who is intended to be the new undertaker;

(c)     the date on which that person is intended to become the new undertaker.

Keeping and inspection of the Welsh register

6.—(1)(1) The Welsh register must be kept at the principal office of the NRBW([6]).

(2) The NRBW must record the information prescribed in paragraphs 8 to 10 of Schedule 1 in the Welsh register.

Reports by the NRBW to the Welsh Ministers

7.—(1)(1) For the purposes of section 3(1) of the 1975 Act, the NRBW is to report to the Welsh Ministers –

(a)     in relation to the period 1 April 2016 to 31 March 2017 no later than 30 September 2017; and

(b)     at two yearly intervals thereafter.

(2) The NRBW must submit the report to the Welsh Ministers no later than 6 months after the end of the  period to which the report relates.

(3) The report must confirm—

(a)     the number of large raised reservoirs that have been registered;

(b)     the steps (if any) that the NRBW has taken to ensure the undertakers of a large raised reservoir have complied with the requirements of the 1975 Act; and

(c)     if the NRBW is itself the undertaker for any large raised reservoir, a statement as to—

                           (i)    the number of large raised reservoirs for which it is the undertaker; and

                         (ii)    any steps it has taken to observe and comply with the requirements of the 1975 Act.

Records of water levels etc.

8. To comply with section 11(1) of the 1975 Act, the undertaker of a high risk reservoir must

(a)     keep a record in the form prescribed in Schedule 2; and

(b)      record the  matters prescribed in Schedule 3.

Form of certificates of engineers

9. For the purposes of section 20(1) of the 1975 Act, the following certificates must be in the form prescribed in Schedule 4—

(a)     a preliminary certificate given under section 7(1) of the 1975 Act;

(b)     an interim certificate given under section 7(2) of the 1975 Act;

(c)     a final certificate given under section 7(3) of the 1975 Act;

(d)     a certificate of efficient execution of works given under section 7(6) or 8(7) of the 1975 Act([7]);

(e)     a certificate given under section 10(5) of the 1975 Act([8]) as to the report of an inspecting engineer;

(f)      a certificate given under section 10(6) of the 1975 Act as to the carrying into effect of safety recommendations;

(g)     a certificate given under section 12AA(3) of the 1975 Act([9]) as to the satisfaction of the requirements of a direction to prepare a flood plan;

(h)     an interim certificate given under section 13(1A) of the 1975 Act;

(i)      a certificate given under section 13(2) of the 1975 Act as to the completion and efficient execution of an alteration so as to discontinue a large raised reservoir;

(j)      a certificate given under section 14(3) of the 1975 Act as to the report of an engineer;

(k)     a certificate given under section 15(2) of the 1975 Act([10]) as to the carrying into effect of safety recommendations; or

(l)      a referee’s certificate given under section 19(4) of the 1975 Act([11]).

Form of reports of engineers

10. For the purposes of section 20(1) of the 1975 Act, the following reports must be in the form prescribed in Schedule 5—

(a)     a report under section 8(2) of the 1975 Act of an engineer made on the construction or alteration of a large raised reservoir;

(b)     a report under section 9(1) of the 1975 Act of an engineer made before the re-use of an abandoned large raised reservoir;

(c)     a report under section 10(1) of the 1975 Act made following an engineer’s inspection of a high-risk reservoir;

(d)     a report under section 14(1) of the 1975 Act of an engineer as to measures that ought to be taken on abandonment of a large raised reservoir.

Forms of directions of engineers

11. For the purposes of section 20(1) of the 1975 Act, the following directions must be in the form prescribed in Schedule 6—

(a)     a direction made under section 11(2) of the 1975 Act (recording of water levels etc.);

(b)     a direction made under section 12(6) of the 1975 Act([12]) (supervision of reservoirs: visual inspection by undertaker);

(c)     a direction made under section 12AA(4) of the 1975 Act (flood plans: testing);

(d)     a direction made under section 12AA(7) of the 1975 Act (flood plans: revision); or

(e)     a direction made under section 19(4A) of the 1975 Act (reference of disputed recommendations to a referee: direction to engineer to issue a certificate).

Prescribed information under section 21(1) of the 1975 Act to be provided by undertakers when intending to construct or bring back into use a large raised reservoir

12. The information that is to be given in a notice served by an undertaker under section 21(1) of the 1975 Act on the NRBW is the information prescribed in Schedule 7.

Reports to the NRBW

13.—(1)(1) This regulation applies in relation to any incident—

(a)     which results, or could result, in the uncontrolled release of water from a large raised reservoir; and

(b)     in respect of which emergency measures have been taken to prevent any or any further uncontrolled release of water and to minimise the danger to human life.

(2) Where this regulation applies, the undertaker must send to the NRBW—

(a)     a preliminary report of the incident as soon as practicable after the commencement of the emergency measures; and

(b)     a final report of the incident within one year beginning with the day after the day on which the emergency measures were commenced.

(3) The preliminary report must contain sufficient particulars to enable the NRBW to ascertain the date and time of the incident, the location of the reservoir and confirm the immediately observable facts.

(4) The final report of the incident referred to in paragraph (2)(b) must contain—

(a)     the facts of the incident;

(b)     analysis of its circumstances;

(c)     conclusions that can be drawn from that analysis with reasons for the conclusions;

(d)     confirmation of what steps are recommended to avoid a repeat of the incident.

(5) The NRBW may direct an undertaker to revise the final report but must —

(a)     explain the reasons why each revision is necessary; and

(b)     specify a period, not less than three months, within which the undertaker must make the revisions.

(6) Revisions to the final report are not be effective unless—

(a)     the undertaker has sent a version of the report to the NRBW which incorporates the revisions notified by the NRBW, and

(b)     the NRBW has accepted the revisions.

Revocations

14. The following Regulations are revoked—

(a)     the Reservoirs Act 1975 (Registers, Reports and Records) Regulations 1985([13]);

(b)     the Reservoirs Act 1975 (Registers, Reports and Records) (Amendment) Regulations 1985([14]);

(c)     the Reservoirs Act 1975 (Certificates, Reports and Prescribed Information) Regulations 1986([15]).

 

Carl Sargeant,

Minister for Natural Resources, one of the Welsh Ministers

27 January 2016

        SCHEDULE 1 Regulations 4 and 6

Information to be given in Welsh registers of large raised reservoirs

1. Name and situation of reservoir.

2. National grid reference of reservoir.

3. Name and address of all undertakers with responsibility for the reservoir.

4. A summary of the contents of all certificates or reports made under the 1975 Act, or the 1930 Act, including—

(a)     the name and address of the engineer giving the certificate or making the report;

(b)     the section of whichever Act the certificate is given under or the report is made;

(c)     where no final certificate has been given under the 1975 Act, a statement of that fact;

(d)     where no final certificate was given under the 1930 Act because the construction or alteration of the reservoir was completed before the commencement of that Act, a statement of that fact.

5. The following information if it is revealed by any certificate, report or statement—

(a)     the category of the reservoir (whether impounding or non-impounding);

(b)     year(s) in which the dam(s), reservoir walls or embankments(s) were completed;

(c)     the construction of the dam(s), reservoir walls or embankments(s) (i.e. whether constructed of earth, rockfill, gravity, buttress or by other means);

(d)     the level of the top of the dam(s), reservoir walls or embankments(s) of the reservoir with reference to Ordnance Datum;

(e)     the top water level of the reservoir with reference to Ordnance Datum;

(f)      the maximum height of the dam(s), reservoir walls or embankments(s) measured in metres from the lowest natural level of the surrounding land, to the top of the dam(s), reservoir walls or embankments, excluding the height of the wave wall;

(g)     the capacity of the reservoir;

(h)     the water surface area of the reservoir at top water level (in square metres or square kilometres).

6. Name and business address of the supervising engineer or, if the reservoir is under the supervision of the construction engineer, of that engineer.

7. Date when the next inspection is due under the 1975 Act or any date recommended for the next inspection under the 1975 Act by the supervising or inspecting engineer.

8. Particulars of any appointment made by the NRBW under section 15 of the 1975 Act.

9. Particulars of any appointment made by the NRBW under section 16 of the 1975 Act, including the date on which they were taken.

10. Whether the large raised reservoir is designated as a high risk reservoir.

 

 

                                SCHEDULE 2                           Regulation 8

Prescribed form of record for a high-risk reservoir

 

In this Form

·         “the 1930 Act” means the Reservoirs (Safety Provisions) Act 1930;

·         “the 1975 Act” means the Reservoirs Act 1975;

·         “fetch” means the effective length of the reservoir over which wind can build up waves;

·         “top water level” means—

(a)   in the case of a reservoir with a fixed overflow sill, the lowest crest level of that sill;

(b)   in the case of a reservoir the overflow from which is controlled wholly or partly by moveable gates, syphons or otherwise, the maximum level to which water may be stored exclusive of any provision for flood storage;

(c)   in the case of a reservoir designed for the purposes of holding back floodwater, the highest level of floodwater that  may be stored during any flood event exclusive of any provision for overflow.

·         Information is to be given in such a manner and at such intervals as the construction or inspecting engineer directs.

·         If any item of information is not applicable to the reservoir this should be stated, giving the reason why.

·         Information given may be supplemented by the use of any relevant drawings.

 

 

Name and situation of reservoir owned       National Grid Reference of reservoir

Owners of reservoir

 

Name     Address

Part of reservoir owned

 

            Part 1 – Water levels and depth of water

·         A record of water levels and depth of water including the flow of water over the waste weir or overflow must be kept by making the appropriate entries in the spaces provided below:

 

Date	Water level in Reservoir measured relative to Top Water Level (TWL). (Positive above TWL, negative below TWL)	Signature and position of engineer or other person responsible for the entry

 

Date	Depth of water flowing over waste weir or overflow, in metres	Signature and position of engineer or other person responsible for the entry

·         Method of recording water levels

 

·         Datum to which levels are referred, e.g. Ordnance Datum or the level of the overflow sill

 

·         Details of directions given by the construction engineer or inspecting engineer as to the manner in which and specifying the dates and times at which information about matters to which this Part relates is to be recorded

 

 

            Part 2 – Leakages, settlements of walls or other works and repairs and instrumentation readings

 

·         A record of leakages, settlements of walls or other works and repairs must be kept by making the appropriate entries in the spaces provided below:

 

Position and extent of any leakage from the reservoir or settlement of walls or other works, giving dates of discovery	Description of action taken consequent on discovery of leakage or settlement	Signature and position of engineer or other person responsible for each entry

 

·         A record of instrumentation readings must be kept by making the appropriate entries in the spaces provided below for each instrument

 

 

Site reference number of instrument:
Date and time of reading	Instrument reading including units, where relevant	Water level in Reservoir at time of reading, measured relative to Top Water Level (TWL) (Positive above TWL, negative below TWL)	Signature and position of engineer or other person responsible for each entry

 

·         Details of directions given by construction engineer or inspecting engineer as to the manner in which and specifying the date and times  at which information about matters to which this Part relates is to be recorded

 

 

            Part 3 – Persons having a function in relation to the reservoir provided for by the 1975 Act

 

·         Undertakers

 

Name     Address E-mail address, if available

Nature of undertaking

 

·         Natural Resources Body for Wales

 

Name     Address E-mail address, if available

·         Construction engineer or engineer appointed for the purposes of section 8 of the 1975 Act

 

Name     Address E-mail address, if available

 

·         Any engineer appointed under section 15 of the 1975 Act by the Natural Resources Body for Wales

 

Name   Address E-mail address, if available   The purpose for which the appointment was made e.g. for the purposes of section 8 of the 1975 Act

·         Inspecting engineer

 

Name   Address E-mail address, if available   ·         Occasion for appointment of inspecting engineer (See section 10(2) of the 1975 Act (e.g. on recommendation of supervising engineer)

·         Dates of appointment of—

 

·         Construction engineer or engineer appointed under section 8 of the 1975 Act ·         Inspecting engineer ·         Engineer appointed under section 15 of the 1975 Act

From………………   From……………… From………………

To………………   To………………. To……………….

·         Supervising engineer

 

Name   Address E-mail address, if available   Office telephone number Home telephone number

Part 4 – flood plan details

·         A summary of flood plan information must be kept by making entries in the spaced provided below:

 

Date of flood plan	Location of flood plan	Date of last test of flood plan

Key actions from the flood plan to be taken by the undertaker to prevent an uncontrolled escape of water from the reservoir

 

Key actions from the flood plan to be taken by the undertaker to control or mitigate the effects of a flood

 

List of people and organisations sent a copy of the flood plan

 

Name and contact details of person and organisation	Version of plan sent	Date sent

Details of compliance with a direction by the Welsh Ministers

 

Matters to be included and requirements of the Natural Resources Body for Wales	Manner of compliance

Part 5 – Access, capacity etc.

 

1.     Description of access giving any restrictions on load, width or height of vehicles using access and details of the construction of the access route

 

2.     Category:           Impounding                                   Non-impounding

 

3.    The level up to which water may be stored, exclusive of flood storage, as it was last specified in a certificate given either under the 1930 Act or the 1975 Act

 

4.     Capacity of reservoir                                                           cubic metres   ·       At top water level ·       Between the lowest natural level of any part of the surrounding land and top water level ·       Between the lowest natural level of any part of the surrounding land and the level, as last specified in a certificate given under the 1930 Act or under the 1975 Act, exclusive of any provision for flood storage

 

5.     Surface water area:-                                                                                    m2 or km2   ·       At level specified in item 3   ·       At top water level

 

6.     Effective fetch to dam, reservoir wall or embankment         in metres           Direction

 

            Part 6 – Dam, reservoir wall or embankment

 

Type (please tick the appropriate box)   Earth                Rockfill (specially sealing membrane or core)     Gravity             Buttress   Other (please specify)

Date construction completed

 

Levels above Ordnance Datum in metres:     of the top of the dam and reservoir wall or embankment     of the top of the wave wall

Maximum height in metres of the dam and reservoir wall or embankment from the lowest natural ground level at the toe (including stream bed) to top of the dam, wall or embankment (excluding wave wall)

 

Details of:     ·         draw off works                                 Maximum rate of                                                              discharge, m3/s     ·         bottom outlets                                   Maximum rate of                                                              discharge, m3/s     ·         any other means of lowering              Maximum rate of                                                              discharge, m3/s

            Part 7 – Catchment and standard average annual rainfall on direct and indirect catchment      areas

Direct Catchment area (m2 or km2)

 

Indirect catchment area (m2 or km2)

 

Method of bringing water into the reservoir from the indirect catchment area, with details of any control or pumps provided and of maximum inflow capacity

 

Physical characteristics of direct and indirect catchment areas which affect the rate of storage of water

 

Details of standard average annual rainfall on the direct and indirect catchment areas of the reservoir according to meteorological office records

            Part 8 – Spillway works: their type, location and level and the safety provisions made in           connection with their operation

 

(a)   Type and location, if independent of main dam structure

 

 

(b)   Particulars, with crest levels and lengths in metres of:

·         fixed crest weirs

 

·       syphons (state whether air regulated saddle siphons or not)

 

·       other gates or valves not specified elsewhere in this Part

 

·       movable crest gate

 

·       tunnels or other features affecting discharge capacity

 

·       emergency spillway

 

 

 

(c)   Particulars of movable gates or valves (please tick the appropriate box)

·         Methods of operation:

Manual              automatic                      float control

 

·         Sequence of operations

 

 

·         Source of power

 

·         Standby arrangements

 

            Part 9 – Measures taken in the interests of safety or that might affect safety

 

Details of any safety measures recommended under the 1975 Act or the 1930 Act	Dates when such recommendations were carried out

 

 

Details of any action taken by either Environment Agency or Natural Resources Body for Wales under section 16 of the 1975 Act

 

 

 

Details of any measures taken that might affect safety	Dates when such Measures were carried out

 

            Part 10 – Supervising Engineer directions and recommendations

 

·         A record of the inspections of the reservoir paying particular attention to the matters that have a bearing on the safety of the reservoir as set out in a direction by the Supervising Engineer under section 12(6) of the 1975 Act must be kept by making entries in the spaces provided below

 

Date of inspection	Matter for particular attention	Findings of inspection	Signature and position of engineer or other person responsible for each entry

 

            Part 11 – Unusual events which could affect the safety of the reservoir

 

·         A record of unusual events that have a bearing on the safety of the reservoir must be kept by making entries in the spaces provided below:

 

Details of any unusual events, such as seismic activity, which have occurred at or near the reservoir	Date(s) of occurrence of any such event

            Part 12 – Certificates, reports, directions, and referees

·         A record of certificates given, reports made, directions given, or referees appointed under the 1930 Act or the 1975 Act must be kept by making entries in the spaces provided below:

            Certificates

 

Date	Type (e.g. preliminary certificate)	Section and subsection of whichever Act the certificate was given under (e.g. under section 7(1) of the Reservoirs Act 1975)

Reports

 

Date	Section and subsection of whichever Act the report was given under (e.g. under section 10(3) of the Reservoirs Act 1975)

Directions

 

Date	section and subsection of the 1975 Act the direction was given under (e.g. under section 12(6) of the Reservoirs Act 1975)

Appointment of Referees

 

Name of referee	Date of appointment

Part 13 – Re-use, abandonment and discontinuance of reservoirs

 

·         Re-use

 

Name and address of qualified civil engineer acting under section 9 of the 1975 Act	Date of engineer’s appointment	Details of any action taken by the Natural Resources Body for Wales under section 9 of the 1975 Act

·         Abandonment

 

Name and address of qualified civil engineer reporting under section 14 of the 1975 Act	Date of engineer’s appointment	Details of any action taken by the Natural Resources Body for Wales under section 14 of the 1975 Act

·         Discontinuance

 

Name and address of qualified civil engineer acting under section 13 of the 1975 Act	Date of engineer’s appointment

Part 14 – Drawing register

 

·         A register of drawings of the reservoir and its component parts must be kept by making entries in the spaces provided below:

 

Drawing number	Drawing title	Revision number	Approval date

Part 15 – Instrumentation at the reservoir

 

·         A record of the type, location, age and condition of instruments installed at the reservoir must be kept by making entries in the spaces provided below. The locations of instruments with their reference numbers shall be shown on the relevant drawings of the reservoir.

 

Site reference	Type and serial number of instrument and key details	Location at the reservoir	Date of installation	Condition and assessment date

            Part 16 – Extent of opening of valves, gates and penstocks

 

·         A record of the extent that valves, gates and penstocks are open must be kept by making the appropriate entries in the spaces provided below:

 

Date	Type and location of equipment (gate, valve or penstock)	Extent of opening	Signature and position of engineer or other person responsible for the entry

·         Method of recording extent of opening for each type of equipment

 

·         Procedures used for operating each type of equipment and for reading the extent of opening

 

·         Details of directions given by the construction engineer or inspecting engineer as to the manner in which and specifying the date and times at which information about matters to which this Part relates is to be recorded.

 

                   SCHEDULE 3     Regulation 8

Prescribed matters relating to high-risk reservoirs of which an undertaker is to keep a record

Interpretation

1. In this Schedule “fetch” (“cyrhaeddiad”) means the effective length of the reservoir over which wind can build

up waves.

Prescribed matters

2. An undertaker of a high risk reservoirs must keep a record of the following matters—

(a)     any person who has acted as an undertaker or engineer under the 1975 Act;

(b)     flood plan details;

(c)     means of access to the reservoir;

(d)     category of the reservoir (i.e. whether impounding or non-impounding), its use, the certified level up to which it may store water, its surface water area, capacity and fetch;

(e)     structural character of the dam(s), reservoir walls or embankments, their date of completion, height, level of the top of the dam(s), reservoir walls or embankments and of the wave wall above Ordnance Datum;

(f)      details of draw off works, bottom outlets, or any other means of lowering the water level, together with their maximum rates of discharge;

(g)     physical characteristics of direct and indirect catchment areas of the reservoir and method of filling from indirect catchment area;

(h)     standard average annual rainfall on direct and indirect catchment areas of the reservoir;

(i)      spillway works, their type, location and level and the safety provisions made in connection with their operation;

(j)      measures taken in the interests of safety on the recommendation of a qualified civil engineer;

(k)     supervising engineer directions and recommendations;

(l)      unusual events which could affect the safety of the reservoir;

(m)   certificates given under the 1975 Act or under the 1930 Act;

(n)     reports made under the 1975 Act or under the 1930 Act;

(o)     directions made under the 1975 Act;

(p)     appointment of referees under the 1975 Act;

(q)     re-use, abandonment and discontinuance;

(r)      drawing register;

(s)      instrumentation at the reservoir;

(t)      records of extent of opening of valves, gates and penstocks, related information and directions by an engineer.

                   SCHEDULE 4     Regulation 9

Certificates

The italicised letters in the forms of certificates in this Schedule indicate the information to be included as follows—

(a)     name of engineer;

(b)     address of engineer;

(c)     name of panel to which engineer is appointed;

(d)     name of undertakers;

(e)     name of reservoir;

(f)      situation of reservoir, with sufficient detail to identify it (including the National Grid Reference of the approximate centre of the reservoir);

(g)     level above Ordnance Datum to which water may be filled, excluding the allowance made for flood conditions;

(h)     level above Ordnance Datum to which water may be stored, excluding the allowance made for flood storage;

(i)      date of preliminary or interim certificate as appropriate;

(j)      conditions subject to which the reservoir may be filled with water or water may be stored up to the level specified;

(k)     date of report, certificate, direction, as appropriate;

(l)      date of completion of works;

(m)   period recommended in the report within which the next inspection should be made;

(n)     date of inspecting engineer’s report;

(o)     name of inspecting engineer;

(p)     name of referee;

(q)     address of referee;

(r)      date of referee’s decision;

(s)      name of person appointing referee;

(t)      volume of water that makes a reservoir a “large raised reservoir” under the Act;

(u)     the time by which the water level must be reduced.

In these forms of certificates, square brackets and the words within them are not to be included where they are inappropriate.

Reservoirs Act 1975 Preliminary Certificate ·         I(a) of (b), being a member of the (c), appointed by (d) to be responsible for the [construction of a new large raised] [construction of a new large raised reservoir by the alteration of an existing] [alteration to the capacity of a large raised] [reuse of an abandoned] reservoir known as (e) situated at (f), consider that the [alteration to the] reservoir can properly be filled [wholly] [partially] with water up to a level of (g) [subject to the following conditions (j).] [This preliminary certificate is given further to a previous preliminary certificate given by (a) of (b) on (i) and supersedes that certificate in so far as it varies the [water level] [conditions] specified in that certificate.]   Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Interim Certificate on Alteration of a Reservoir ·         I(a) of (b), being a member of the (c), appointed by (d) to be responsible for an alteration to a large raised reservoir, known as (e) situated at (f), consider that the alteration to the reservoir ought not to be filled with water up to a level or subject to the conditions that, if this certificate were not given, would otherwise be lawful, but that, until the issue of a preliminary certificate, it may be filled with water up to a level of (g) [and any reduction of water level to (g) must be carried out by (u),] [subject to the following conditions (j).]. [This interim certificate is given further to an interim certificate given by (a) of (b) on (i) and supersedes that certificate in so far as it varies the [water level] [conditions] specified in that certificate.]   Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Final Certificate ·         I(a) of (b), being a member of the (c), appointed by (d) to be responsible for the [construction of a new large raised] [construction of a new large raised reservoir by the alteration of an existing] [alteration to the capacity of a large raised] [reuse of an abandoned] reservoir known as (e) situated at (f), [for which a preliminary certificate was given on (i) (see Note 1)] am satisfied that the [alteration to the] reservoir [is sound and satisfactory and (see Note 2)] may safely be used for the storage of water up to a level of (h) (subject to the following conditions (j)]. [I am also satisfied that the recommendations as to measures to be taken in the interests of safety included in the report dated (k) made by (Name of Engineer making report) have been carried into effect.  (see Note 3).]   Signature of Engineer   Date of Certificate

Annex to Certificate (see Note 4) Notes 1.  Where a final certificate is given under section 8 of the Act it may be that no preliminary certificate has been issued. 2. A final certificate given under sections 8 or 9 (except one given in the circumstances described above in section 8(5)) need not state that the engineer is satisfied that the reservoir, or the addition to it, is sound and satisfactory. 3. If a final certificate does not, for the reasons given in Note 2 above, state that the engineer is satisfied that the reservoir is sound and satisfactory and a report made either under section 8(2) or 9(1) of the Act includes any recommendations as to measures to be taken in the interests of safety, the engineer must state that those recommendations have been carried into effect – sections 8(6) and 9(5) of the Act. 4. The engineer must include in an annex to the certificate a note of the matters, if any, he considers need to be watched by a supervising engineer during the period before an inspection of the reservoir is made under the Act – section 7(5) of the Act.

Reservoirs Act 1975 Certificate of Efficient Execution of Works under section [7(6)][8(7)]   ·         I(a) of (b), being a member of the (c), appointed by (d) to be responsible for the [construction of a new large raised] [construction of a large raised reservoir by the alteration of an existing] [alteration to the capacity of a large raised] reservoir known as (e) situated at (f), which was completed on (l) certify that [so far as I am able to ascertain (see Note 1)] those works have been efficiently executed in accordance with the drawings and descriptions annexed to this certificate (see Note 2).   Signature of Engineer   Date of Certificate   Annex to Certificate (see Note 2) Notes 1. A certificate of execution of works given under section 8(7) of the Act should, unlike a certificate given under section 7(6), contain these words. 2. Detailed drawings and descriptions giving full information of the works actually constructed including dimensions and levels and details of the geological strata or deposits encountered in trial holes or excavations made in connection with the works are required to be annexed by the sections mentioned in Note 1.

Reservoirs Act 1975 Inspecting Engineers Certificate under section 10(5) ·         I (a) of (b), being a member of the (c), appointed by (d) to carry out an inspection of the reservoir known as (e) situated at (f), made a report of that inspection on (k) which [does not include] [includes] recommendations as to measures to be taken in the interests of safety and which [does not include] [includes] recommendations as to the maintenance of the reservoir.  [That report includes also a recommendation as to the time of the next inspection of the reservoir, which should be made within (m).]   Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Certificate under section 10(6), as to the carrying out of safety recommendations ·         I(a) of (b), being a member of the (c), appointed by (d) to supervise the carrying into effect at the reservoir known as (e) situated at (f), of measures taken in the interests of safety recommended in a report made on (n) by (o), [which was modified by the decision of (p) of (q), acting as referee, given on (r),] am satisfied that those measures have been carried into effect.   Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Certificate under section 12AA(3), as to the requirements of a direction under section 12A(2)(a) and (b) being satisfied ·         I(a) of (b), being a member of the (c), appointed by (d) to consult on the preparation of a flood plan under section 12A for the reservoir known as (e) situated at (f), am satisfied that the requirements of a direction under section 12A(2)(a) and (b) are satisfied.   Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Interim Certificate under section 13(1A), on Discontinuance ·         I(a) and (b), being a member of the (c), appointed by (d) to [design] [approve] and to supervise the alteration of the reservoir known as (e) situated at (f), so as to render it incapable of holding more than (t) cubic metres of water above the natural level of any part of the land adjoining it, consider that the level of the water in the reservoir should be reduced up to a level of (g) by (u) [subject to the following conditions (j)].     Signature of Engineer   Date of Certificate

Certificate under section 13(2), on Discontinuance ·         I(a) of (b), being a member of the (c), appointed by (d) to [design] [approve] and to supervise the alteration of the reservoir known as (e) situated at (f), so as to render it incapable of holding more than (t)] cubic metres of water above the natural level of any part of the surrounding land, am satisfied that the alteration has been completed and has been efficiently executed.   Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Certificate under section 14(3), on Abandonment ·         I(a) of (b), being a member of the (c), appointed by (d) to give a report as to the measures (if any) that ought to be taken in the interests of safety to secure that the reservoir known as (e) situated at (f), is incapable of filling accidentally or naturally with water above the natural level of any part of the land adjoining the reservoir or is only capable of doing so to an extent that does not constitute a risk, have today given a report under section 14(1) of the Act which [does not include] [includes] recommendations for measures to be taken in the interests of safety.   Signature of Engineer   Date of Certificate

Reservoirs act 1975 Certificate under section 15(2), as to the carrying out of Safety Recommendations ·         I(a) of (b), being a member of the (c), appointed by the Environment Agency, following the failure of (Name of undertakers) to comply with a Notice from the Environment Agency requiring them to carry into effect recommendations contained in a report made under this Act by (a) on (k) [and modified by the decision of a referee] as to measures to be taken in the interests of safety at (e) situated at (f) to supervise the carrying out of those measures, am satisfied that those recommendations have been carried into effect. Signature of Engineer   Date of Certificate

Reservoirs Act 1975 Referee’s Certificate under section 19(4) ·         I(a) of (b), being a member of (c), having been appointed by (s) to investigate the complaint of [Name of undertakers), undertakers for the reservoir known as (e) situated at (f), regarding a recommendation contained in a report dated (k) made by (Name of Engineer making Report) [as to measures to be taken in the interests of safety at] [and/or] [as to recommendations as to the maintenance of] [and/or] [as to the time of the next inspection of] the reservoir; have decided [not] to modify that report. [Accordingly, I revise the certificate dated (k) which was given with reference to that report, in the following manner:-]   Signature of Referee   Date of Certificate

                   SCHEDULE 5   Regulation 10

Reports

In this Schedule references to an engineer’s findings and recommendations include—

(a)     confirmation that the undertaker has recorded the information required under section 11 of the 1975 Act;

(b)     particulars of any directions given by the engineer specifying the dates and times at which, or the manner in which information is to be recorded under section 11 of the 1975 Act;

(c)     details of any recommendations regarding alterations or additions to works or the installation of instruments or gauges for measuring leakage, deflections, settlement, uplift, pore pressures or similar matters;

(d)     details of any movement of the surrounding land observed which might affect the stability of the reservoir;

(e)     findings as to the adequacy and condition of the waste weir or overflow and any channels connected with it;

(f)      a statement of any alterations the engineer has observed which affect the level to which water may be stored or to the level of the overflow sills since construction or since last inspection;

(g)     a statement as to the adequacy of the margin between dam(s), reservoir walls or embankments level and overflow level;

(h)     findings as to the efficiency of the scour pipe or discharge culvert or other means of lowering the level of the water in, and any means of controlling the inflow of water to, the reservoir.

In these forms of reports, square brackets and the words within them are not to be included where they are inappropriate.

Reservoirs Act 1975 Report of the Result of an Inspection made under section 8 [Construction] [Alteration] of a Reservoir ·         Name and Situation of Reservoir, including National Grid Reference of its approximate centre ·         Name and Address of Engineer ·         Name of Panel of which Engineer is  member ·         Name and Address of Undertakers who appointed Engineer or confirmation that the Natural Resources Body for Wales appointed the Engineer, as appropriate ·         Date of Dates of Engineer’s Inspection ·         Engineer’s findings regarding the [construction] [alteration] of the reservoir, including any recommendations the engineer sees fit to make as to measures to be taken in the interests of safety. Signature of Engineer Date of Report

 

Reservoirs Act 1975 Report of the Result of an Inspection made under section 9 Re-use of Abandoned Reservoir ·         Name and Situation of Reservoir, including National Grid Reference of its approximate centre ·         Name and Address of Engineer ·         Name of Panel of which Engineer is a member ·         Name and Address of Undertakers who appointed Engineer or confirmation that the Natural Resources Body for Wales appointed the Engineer, as appropriate ·         Date of Dates of Inspection ·         Engineer’s findings regarding the re-use of the Reservoir including any recommendations the engineer sees fit to make as to measures to be taken in the interests of safety. Signature of Engineer Date of Report

 

Reservoirs Act 1975 Report of the result of an Inspection made under section 10 Periodical Inspection of a Large Raised Reservoir ·         Name and Situation of Reservoir, including National Grid Reference of its approximate centre ·         Name and Address of Engineer ·         Name of Panel of which Engineer is a member ·         Name and Address of Undertakers who appointed Engineer or confirmation that the Natural Resources Body for Wales appointed the Engineer, as appropriate ·         Date or Dates of Inspection ·         Engineer’s findings, including any recommendations the engineer sees fit to make as to the time of the next inspection or as to measures that should be taken in the interests of safety or as to the maintenance of the reservoir; and a note of any matters the engineer considers the supervising engineer needs to watch during the period before the next inspection of the reservoir under section 10 ·         A statement as to whether all of the safety measures recommended in the previous report have been taken; and, either recommendations to take any outstanding safety measures or an explanation of why a recommendation is no longer required Signature of Engineer Date of Report   Annex to Report (if required by section 26 for reservoirs completed before the 1930 Act came into force and not inspected under that Act)

 

Reservoirs Act 1975 Report made under section 14 Abandonment of Large Raised Reservoir ·         Name and Situation of Reservoir, including National Grid Reference of its approximate centre ·         Name of Panel of which Engineer is a member ·         Name and Address of Undertakers who appointed Engineer or confirmation that the Natural Resources Body for Wales appointed the Engineer, as appropriate ·         Date or Dates of Inspection of the Reservoir (if any) ·         Engineer’s recommendations as to the measures (if any) that ought be taken in the interests of safety to secure that the reservoir is incapable of filling accidently or naturally with water above the natural level of any part of the land adjoining the reservoir or is only capable of doing so to an extent that does not constitute a risk Signature of Engineer Date of Report

                   SCHEDULE 6   Regulation 11

Directions

The italicised letters in the form of directions in this Schedule indicate the information to be included as follows—

(a)     name of engineer;

(b)     address of engineer;

(c)     name of panel to which engineer is appointed;

(d)     name of undertakers;

(e)     name of reservoir;

(f)      situation of reservoir, with sufficient detail to identify it (including the National Grid Reference of the approximate centre of the reservoir);

(g)     level above Ordnance Datum to which water may be filled, excluding the allowance made for flood conditions;

(h)     level above Ordnance Datum to which water may be stored, excluding the allowance made for flood storage;

(i)      date of preliminary or interim certificate as appropriate;

(j)      conditions subject to which the reservoir may be filled with water or water may be stored up to the level specified;

(k)     date of report, certificate, direction as appropriate;

(l)      date of completion of works;

(m)   period recommended in the report within which the next inspection should be made;

(n)     date of inspecting engineer’s report;

(o)     name of inspecting engineer;

(p)     name of referee;

(q)     address of referee;

(r)      date of referee’s decision;

(s)      name of person appointing referee;

(t)      volume of water that makes a reservoir a large raised reservoir under the 1975 Act.

In these forms of directions, square brackets and the words within them are not to be included where they are inappropriate.

 

 

Reservoirs Act 1975 Direction under section 11(2) by [Construction Engineer] [Inspecting Engineer], as to the intervals and manner of recording specified information prescribed by regulations made under section 11(1) ·         I (a) of (b), being a member of the (c), appointed by (d) to [supervise the construction of] [inspect] the reservoir known as (e) situated at (f), direct that the following prescribed information must be recorded at the intervals and in the manner stated.   Information to be recorded Manner of recording the information Interval between records                           Signature of Engineer   Date of Direction     Notes 1. The matters to be recorded are any of those listed in the form of record prescribed by regulations made under section 11(1) of the Act. 2. Additional rows should be added to the table as necessary.

 

Reservoirs Act 1975 Direction under section 12(6) by Supervising Engineer, as to the periodic visual inspection by the Undertaker of a reservoir ·         I(a) of (b), being a member of the (c), appointed by (d) to supervise the reservoir known as (e) situated at (f), direct that the reservoir must be inspected not less than [daily][weekly][monthly][Quarterly][annually] for the purpose of identifying anything that might affect the safety of the reservoir, the interval commencing on (k).   Particular attention should be paid to the matters below as part of the inspection of the whole reservoir. Matters for particular attention                   Signature of Engineer   Date of Direction

 

Reservoirs Act 1975 Direction under section 12AA(4) by [Supervising Engineer] [Appointed Engineer], as to the testing of a flood plan   ·         I(a) of (b), being a member of the (c), appointed by (d) to [supervise][consult on the preparation of a flood plan under section 12A for] the reservoir known as (e) situated at (f), direct that the flood plan be tested as specified below, the interval commencing on (k).  A report of the test must be provided to assess the need for revision of the plan. Element of flood plan Manner of testing Interval between tests                                 Signature of Engineer   Date of Direction   Notes 1. Not all elements of the flood plan need to be tested at the same intervals.

 

Reservoirs Act 1975 Direction under section 12AA(7) by [Supervising Engineer] [Appointed Engineer], as to the revision of a flood plan   ·         I(a) of (b), being a member of the (c), appointed by (d) to [supervise][consult on the preparation of a flood plan under section 12A for] the reservoir known as (e) situated at (f), direct that the flood plan be revised as specified below.       Element of flood plan Revision required Timing                                     Signature of Engineer   Date of Direction   Notes 1. Not all elements of the flood plan need to be revised with the same urgency.

 

Reservoirs Act 1975 Direction under section 19(4A) by a Referee, as to the issue of a Certificate for the purposes of section 12AA(3)   ·         I(a) of (b), being a member of (c), having been appointed by (s) to investigate the complaint of (Name of undertakers), undertakers for the reservoir known as (e)  situated at (f), regarding the refusal of (Name of Engineer) to issue a certificate under section 12AA(3), as to the requirements of a direction under section 12A(2)(a) and (b) being satisfied; have decided after due consideration that the requirements of a direction under section 12A(2)(a) and (b) are satisfied.     Accordingly, I direct (Name of Engineer) to issue a certificate under section 12AA(3), as to the requirements of a direction under section 12A(2)(a) and (b) being satisfied, stating that the requirements are satisfied.   Signature of Referee   Date of Direction

SCHEDULE 7 Regulation 12

Information to be given in a notice under section 21(1) of the 1975 Act

1. Name and address of undertakers serving notice.

2. Name and situation of reservoir.

3. National grid reference of approximate centre of the reservoir.

4. Whether the undertakers intend—

(a)     to construct a new large raised reservoir; or

(b)     to bring a large raised reservoir back into use after that use has been abandoned.

5. The date when it is intended that construction will commence or the date when it is intended the reservoir will be brought back into use, as the case may be.

6. Name and address of the construction engineer or, in the case of re-use, of the engineer appointed for the purposes of section 9 of the 1975 Act.

7. The following information about the reservoir as it will be when constructed, or brought back into use as proposed—

(a)     category (i.e. whether impounding or non-impounding);

(b)     date(s) or approximate date(s) of completion of the dam(s), reservoir walls or embankments(s);

(c)     construction of the dam(s), reservoir walls or embankments(s) (i.e. whether constructed of earth, rockfill, gravity, buttress or by other means);

(d)     maximum height of the dam(s), reservoir walls or embankment(s) (in metres), measured from the lowest natural level of the surrounding land contiguous to it, to the top of the dam(s), reservoir walls or embankment(s), excluding the height of the wave wall;

(e)     the height of the dam(s), reservoir walls or embankment(s) (in metres) measured from the lowest natural level of the surrounding land contiguous to it to top water level;

(f)      the level of the top of the dam, the walls or embankment of the reservoir with reference to Ordnance Datum;

(g)     the top water level of the reservoir with reference to Ordnance Datum;

(h)     capacity (in cubic metres), measured from the lowest natural level of the surrounding land contiguous to it to top water level;

(i)      the water surface area at top water level (in square metres or square kilometres).