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Catchment Water Management Plan – VOLUME 3

Water Allocation Plan

Northern Adelaide PlainsPrescribed Wells Area

This report has been prepared with the assistance of the Northern Adelaide

Plains Catchment Committee for the Northern Adelaide and Barossa Catchment

Water Management Board.

December 2000

I Mark Brindal, Minister for Water Resources, hereby adopt this

Water Allocation Plan pursuant to section 104 of the Water

Resources Act 1997.

Hon Mark Brindal MP

Minister for Water Resources

Date: 22.12.2000

For further information contact:

Northern Adelaide and Barossa Catchment Water Management Board

1st Floor, 59 Commercial Road, Salisbury SA 5108

Telephone: (08) 8285 2033

Facsimile: (08) 8285 2133

Email: [email protected]

Web: www.catchments.net/nab

http://www.catchments.net/nab/contact.htm

Northern Adelaide and Barossa Catchment Water Management Plan – Volume 3

PAGE i

Contents

1. Northern Adelaide Plains Prescribed Wells Area 1

1.1 Underground Water Resources of the Northern Adelaide Plains Prescribed Wells Area 1

1.2 Natural Recharge Mechanisms 3

2. Assessment of Needs of Dependent Ecosystems 4

2.1 The Gawler River 4

2.2 Little Para River 4

2.3 Buckland Park 5

3. Assessment of Effect on Other Water Resources 6

4. Assessment of Capacity of Resources to Meet Demands 7

4.1 Demands 7

4.2 Current Status of the Tertiary Aquifer Systems 7

4.3 Capacity of Resource to Meet Demands 8

5. Water Allocation Criteria 10

5A. Water Allocation Criteria for Recharged Water 12

6. Transfer Criteria 14

7. Permits 16

7.1 Water Affecting Activities 16

7.2 Drilling, Plugging, Backfilling or Sealing of a Well 16

7.3 Repairing a Well 17

7.4 Draining or Discharging Water into a Well 17

7.5 Importation of Water 18

7.6 Use of Effluent 19

8. Monitoring 20

9. Miscellaneous 22

10. Glossary 23

Figures

1 Cross section of the Northern Adelaide Plains aquifers and confining layers

2 Northern Adelaide Plains Prescribed Wells Area

3 T1 Cone of Depression around Waterloo Corner and Penrice

4 T2 Cone of Depression around the Virginia/Angle Vale area


PAGE 1

1. Northern Adelaide Plains Prescribed WellsArea

The Northern Adelaide Plains Prescribed Wells Area covers approximately 800 km2 of an area

centred 30km to the North of Adelaide (Figure 2). The area was initially proclaimed under the Water

Resources Act 1976 by notice in the South Australian Government Gazette dated 13 May 1976 at

page 2459. Pursuant to clause 2(1) of the Water Resources Act 1997 (the Act), the proclamation in

1976 is in force as though it declared the wells in the Proclaimed Region to be prescribed wells under

the 1997 Act. The area is now known as the Northern Adelaide Plains Prescribed Wells Area. The

area contains relatively fertile soils underlain by a series of water bearing beds of sand, gravels and

limestone aquifers which are used as a source of irrigation water.

1.1 Underground Water Resources of the Northern Adelaide Plains PrescribedWells Area

The Northern Adelaide Plains are formed by Tertiary and Quaternary sediments up to 600 metres

thick which contain numerous aquifer systems. The sediments are of deltaic origin formed by the

accumulation of sediments from the surrounding hills. Figure 1 features a cross-section of the

resource showing the Tertiary and Quaternary aquifers and the flow of water in those aquifers.

1.1.1 Quaternary Aquifer Systems

The Quaternary sediments contain up to six thin aquifers comprising mainly of clay and silt with thin

layers of sand which form minor unconfined and semi confined systems. Measurements of

groundwater salinity recorded in the shallow upper aquifers (referred to as Q1 and Q2) are generally

high, ranging from 2000 mg/L to 15,000 mg/L towards the coast. Salinity in the deeper Quaternary

aquifers tends to decrease with depth and ranging from 1500 mg/L to 3000 mg/L in the (Q3)

Quaternary sediments. However, in some areas, the shallow sandy Quaternary aquifers (Q1 and Q2)

situated near the Gawler and Little Para Rivers generally exhibit low salinity ranging from 400 mg/L to

1500 mg/L. These salinities reflect the influence of winter recharge from the rivers. The Quaternary

aquifers are not generally used for commercial irrigation purposes because of low yields and salinity

problems.

1.1.2 Tertiary Aquifer Systems

The underlying Tertiary sediments contain several aquifer systems that exhibit significant variations in

thickness, lithology, salinity distribution and yield. There are two main deep aquifers that act as the

primary source of irrigation water in the region.

Water Allocation Plan – Northern Adelaide Plains Prescribed Wells Area

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• T1 Aquifer

The shallowest Tertiary aquifer, known as T1, is the main source of irrigation water in the area

south of Waterloo Corner. The top of the aquifer is approximately 60 metres below ground and is

composed of Dry Creek sands and Port Willunga limestone. It is wedge shaped with an average

thickness of 70 metres in the south, thinning out as it nears the Gawler River.

Underground water salinity ranges from 600 mg/L to 2000 mg/L with lower salinities recorded

near the Little Para River to the south. The aquifer is hydraulically connected to the overlying

Quaternary aquifer (Q4), which has a salinity ranging from 1820 to 4850 mg/L, and is separated

from the underlying aquifer by a layer of impervious clay to sandy, silty clay, which extends over

the entire region south of the Gawler River, although this is thin or intermittent in the vicinity of

Waterloo Corner.

• T2 Aquifer

The second underlying Tertiary aquifer known as T2 occurs throughout the entire region. It

consists of a large, water bearing layer of well-cemented lower Port Willunga formation limestone

which has a thickness between 80 and 120 metres. Salinity levels range from 600 mg/L in the

Gawler River area to greater than 3000 mg/L to the north and south. The T2 aquifer is generally

not used for crop irrigation purposes in areas south of Waterloo Corner due to high salinity levels

and the depth of the aquifer in that region.

• T3 and T4 Aquifers

Two other deeper water bearing aquifers (T3 and T4) have been identified in the area. However,

underground water salinity in these saturated sediments exceeds that in T1 and T2 and has been

as high as 80,000 mg/L, which is totally unsuitable for any form of crop irrigation use.


PAGE 3

Figure 1 - Cross section of the Northern Adelaide Plains aquifers and confining layers

1.2 Natural Recharge Mechanisms

The main source of recharge for the Tertiary aquifers of the Northern Adelaide Plains is from the

rainfall-fed fractured rock aquifers in the Mt Lofty Ranges to the east of the prescribed area. The

higher elevation of the Mt Lofty Ranges acts to pressurise water, which flows laterally in a westerly

direction through the fractured rock aquifers of the ranges into the Tertiary aquifers of the Plains

(Figure 1).

In the period prior to the major expansion of underground water irrigation in the region, the main

aquifers were sufficiently pressurised to ensure that most wells west of Port Wakefield Road were

free flowing (artesian) approximately 10 to 15 metres above ground level. However, levels began to

decline dramatically in the 1930s due to increasing irrigation activity. By the 1940s T1 and T2 were

no longer artesian and by the 1960s intensive pumping had resulted in the formation of a cone of

depression (the area around a pumping zone where the level of underground water is lowered by

pumping) around Virginia and the Little Para River.


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2. Assessment of Needs of DependentEcosystems

Information on the extent of underground water dependent ecosystems in the Northern Adelaide

Plains Prescribed Wells Area is extremely limited. There are no known ecosystems that are

dependent on the deep Tertiary aquifers of the Northern Adelaide Plains Prescribed Wells Area. It is

likely that ecosystems associated with the Gawler River and Little Para River and the estuarine

wetland of Buckland Park have a level of dependence on the shallow sandy Quaternary (Q1)

underground aquifers of the region.

2.1 The Gawler River

The underground water dependent ecosystems associated with the Gawler River environment

include riparian communities dominated by river red gums (Eucalyptus camaldulensis) and a diversity

of in-stream vegetation including Cyperaceae sp, Juncus sp and Typha. Other ecosystems

dependent on underground water include fauna communities living in the shallow sandy Q1 aquifers

(known as hypogean fauna) and watercourse sediments (known as hyporheic fauna) of the region.

2.1.1 Environmental Requirements for Dependent Ecosystems of the Gawler River System

Recent studies suggest that the riparian communities of the Gawler River system depend upon the

maintenance of the natural discharge regime whereby approximately 5000ML of watercourse water is

lost as groundwater recharge to the shallow sandy Quaternary (Q1) aquifer of the Gawler River.

These recharge events occur on a seasonal basis over three to four months during the winter period

and serve as a means of reducing underground water salinity. The available information suggests

that the riparian ecosystems require the water quality of the shallow sandy Quaternary (Q1) aquifer to

be maintained at present levels. The salinity of the shallow aquifer should therefore remain at

relatively low level, ranging from 400mg/L to 3000 mg/L. The volume of water associated with the

current flow regime should also be maintained at current levels as the minimum requirement for

groundwater dependent ecosystems associated with the Gawler River system.

2.2 Little Para River

The underground water dependent ecosystems associated with the Little Para River environment

include riparian communities dominated by river red gums (Eucalyptus camaldulensis) Acacia sp and

a diversity of in-stream vegetation including Cyperaceae sp, Juncus sp and Typha and Phragmites

sp. Other ecosystems dependent on underground water include fauna communities living in the

shallow sandy Q1 aquifers (hypogean fauna) and watercourse sediments (hyporheic fauna) of the

region.


PAGE 5

2.2.1 Environmental Requirements for Dependent Ecosystems of the Little Para System

The structure and diversity of the riparian communities of the Little Para System are similar to those

found in the Gawler River system. The underground water dependent ecosystems of the Little Para

River require the maintenance of the natural discharge regime whereby approximately 1200 ML of

surfacewater flow is lost as groundwater recharge to the shallow sandy Quaternary (Q1) aquifer.

These recharge events usually occur over the winter period. The available information also suggests

that these riparian ecosystems of the Little Para system require the water quality of the shallow sandy

Quaternary (Q1) aquifer to be maintained at present levels. The salinity of the shallow aquifer should

average less than 2,000 mg/L. The volume of water associated with the current flow regime should

also be maintained at current levels as the minimum requirement for groundwater dependent

ecosystems associated with the Little Para River system.

2.3 Buckland Park

Buckland Park is an estuarine wetland, which was artificially created by damming the deltaic mouth of

the Gawler River system (Figure 2). There is considerable variation in the filling and drying regime of

the wetland from year to year. The wetland is often filled during the winter period with flood flows

from the Gawler River. These flows have the effect of reducing salinity levels in the wetland. The

decrease in salinity allows the growth and development of a range of freshwater invertebrates and

aquatic plants including Muehlenbeckia sp, Halosarcia sp and Typha sp. The wetland system also

hosts a diversity of migratory and resident waterbirds. The number of waterbirds using the wetland

fluctuates seasonally and is linked to changes in wetland water levels.

2.3.1 Environmental Requirements for Dependent Ecosystems of Buckland Park Wetland

There is no information available on the extent to which underground water contributes to inundation

of the Buckland Park system. However, the hidden lateral flows of underground water from the

Gawler River system may assist with maintaining water quality during periods of freshwater

inundation. These seasonal flows are associated with watercourse water flows that occur over the

winter period and are necessary to reduce wetland salinity. The available information suggests that

the quality of water and the volume of hidden lateral flow associated with the Gawler River system

should be maintained at present levels as the minimum requirement for the ecosystems of the

Buckland Park system.


PAGE 6

3. Assessment of Effect on Other WaterResources

There is currently no evidence to suggest that the taking of underground water from the Tertiary

aquifers in the Northern Adelaide Plains Prescribed Wells Area has caused any detrimental impact to

surfacewater resources in the region. The bulk of underground water extractions in this area occur

during the summer period from the deeper, mostly confined, Tertiary aquifers (T1 and T2). There is

little, if any, hydraulic connection between the surfacewater resources and the main production

aquifers of the region. The underground water resources outside the Northern Adelaide Plains

Prescribed Wells Area experience pressure fluctuations as a result of heavy level of use within the

Northern Adelaide Plains Prescribed Wells Area over the summer period. There is no evidence to

suggest that these pressure variations are having a detrimental impact on the underground water

resources outside the prescribed area.

The best available information suggests that the present rate of underground water use from the

shallow Quaternary aquifers has no detrimental impact on surfacewater resources in the region.


PAGE 7

4. Assessment of Capacity of Resources toMeet Demands

4.1 Demands

4.1.1 Underground Water Extractions from the Aquifer Systems

Water users in the Northern Adelaide Plains Prescribed Wells Area rely heavily on the extraction of

underground water from the Tertiary aquifers for industrial use and crop irrigation purposes. The bulk

of the extractions occur from the T1 and T2 aquifers. The average use over the last 10 years is

18,000 ML per year which is pumped from over 1200 wells spread throughout the region.

The extraction rate has been fairly constant for the last decade. Most of the underground water

utilised in the Virginia/Angle Vale area is drawn from T2 aquifer. Total extractions from this aquifer

have been calculated at 13,500 ML per year on average. Most of the water (10,000 ML) is pumped

from the aquifer during the summer months.

Extractions from the T1 aquifer occur in several main pumping centres including the Waterloo Corner

region, where an average of 1500 ML to 2000 ML of underground water is used per year. T1 aquifer

is also used extensively for industrial purposes. A large industrial company located within the

Northern Adelaide Plains Prescribed Wells Area also draws approximately 1500 ML to 2000 ML per

year of low quality (saline) underground water for processing of its products.

An estimated 500 ML per year of underground water is extracted from the Quaternary aquifers (Q1-

Q4) within the prescribed area. The Quaternary aquifers are not normally used as a source of water

for commercial irrigation because of low yields. Most of the water extracted from the Quaternary

aquifers is used for stock and domestic purposes.

4.1.2 Demands of Ecosystems that Depend on the Resource

It has previously been stated that there are no known ecosystems that are dependent on the deep

Tertiary aquifers of the Northern Adelaide Plains Prescribed Wells Area. The quantity of water

required by ecosystems dependent on the Quaternary (Q1) aquifer is the quantity required to

maintain the present underground water levels of the aquifer.

4.2 Current Status of the Tertiary Aquifer Systems

The current total water allocation on water licences in the Northern Adelaide Plains Prescribed Wells

Area is 26,500 ML per year. The average use over the last 10 years has been 18,000 ML per year,


PAGE 8

however, in dry years, use has exceeded 24,000 ML. It is a matter of general policy that no additional

underground water has been allocated since the early 1970s.

Recent hydrogeological investigations have continued to identify two major problems associated with

the current level of underground water use in the region. The problems concern water level decline

and increasing underground water salinity levels.

The water level recorded in T1 aquifer has declined by 10 to 30 metres in the area around Waterloo

Corner over the last 30 years where a steep cone of depression has developed, mostly as a result of

intensive irrigation (Figure 3). The decline is in response to a number of factors including the intensity

of pumping during summer. The water level does not recover completely during winter, partly as a

result of pumping during the winter period.

The major pumping regions drawing water from T2 aquifer are centred in Virginia, Angle Vale and the

area north of the Gawler River. The extraction rates of underground water from these areas have

been relatively constant over the last 15 years. However, monitoring has shown that the aquifer

water level has declined by approximately 70 to 75 metres in the centre of the irrigation area over the

last 40 to 50 years. The cone of depression that exists in the T2 aquifer is characterised by a drop of

several metres during the heavy irrigation periods of summer and a slower incomplete recovery over

winter, causing the cone to progressively expand and spread laterally over a large portion of the

irrigated area until it reaches a new equilibrium (Figure 4).

Over the last 30 years, the average salinity recorded in the Tertiary aquifers of the Northern Adelaide

Plains has increased by 200mg/L in some parts of the T2 aquifer and up to 800mg/L in the T1 aquifer

near Waterloo Corner. The increases in salinity are related to the current rate of underground water

use from the Tertiary aquifers.

4.3 Capacity of Resource to Meet Demands

The capacity of the resource is presently insufficient to meet the current demands for water use in the

Northern Adelaide Plains Prescribed Wells Area without causing detrimental impacts on the

underground water resources of the area. The current level of underground water use in the Northern

Adelaide Plains Prescribed Wells Area is therefore in excess of what is considered to be an

acceptable safe yield because of the problems associated with the potentiometric surface (the

theoretical water level in an underground aquifer as determined by the pressure within that aquifer)

and underground water salinity.

The hydrogeology of the Northern Adelaide Plains aquifer system is extremely complex. The ability

to quantify an acceptable safe yield of underground water from the aquifer system is dependent upon

regular monitoring of underground water levels, extraction rates, salinity trends and a range of other

variables which can vary over time. The recent investigations on recharge mechanisms in the

Northern Adelaide Plains suggests that a single numerical value reflecting an estimated rate of

recharge does not represent a realistic measure of the volume of water that can be extracted from the

aquifer system without inducing unacceptable impacts on that system. The unacceptable impacts

would include increases in underground water salinity, losses of elastic storage, reduction in pressure

and water level decline to an unconfined situation.

The acceptable safe yield for the Tertiary aquifers of the Northern Adelaide Plains Prescribed Wells

Area lies within a range of predetermined potentiometric surface levels. The range can vary over

different periods (summer and winter), and in accordance with external influences such as the use of


PAGE 9

imported water (Bolivar reclaimed water) in the region. The limits to that range will reflect a yield

which can be sustained over a specific timeframe without causing unacceptable impacts on the

aquifer system or on the users who rely on the availability of good quality underground water.

The underground water levels need only be a few metres above the confining layer of each

production aquifer (T1 and T2) during the high demand period over summer provided that they rise to

an acceptable level in the aquifer(s) during the low demand winter period. The underground water

levels would need to rise to a point that would allow sufficient pressure recovery in the relevant

aquifer in order to minimise potential leakage from high salinity aquifers in the region (Q1, Q2, T3,

T4).

Regular monitoring will provide data that can be used for numerical modelling to predict an

acceptable safe yield of underground water use in the Northern Adelaide Plains Prescribed Wells

Area. The results of modelling will determine the extent of draw-down that can be tolerated over

summer and the rate of water level recovery that will be necessary over the winter period to maintain

an acceptable level of underground water use in the region.

In the absence of such modelling it is not possible to give an estimate of the volume of water that

represents an acceptable level of water use at this stage. However, it is clear that current use is

significantly above what can be considered an acceptable safe yield. The evidence shows that

underground water levels are continuing to decline and salinity is increasing in some areas of the

aquifer system.

At this stage it is not possible to predict the effect that the use of reclaimed water from the Bolivar

Reclaimed Water Treatment Plant will have on the capacity of the underground water resource to

meet demand for water in the area.


PAGE 10

5. Water Allocation Criteria

The following objectives and principles apply to the taking and use of water from the Northern

Adelaide Plains Prescribed Wells Area.

The Northern Adelaide and Barossa Catchment Water Management Board, in formulating these

objectives and principles, has considered:

• the present needs of the occupiers of land situated within the Northern Adelaide Plains

Prescribed Wells Area for water and their anticipated future needs

• the anticipated future capacity of land and the prescribed water resource within the Northern

Adelaide Plains Prescribed Wells Area for new uses

• the likely effect of the criteria for the allocation of the prescribed water resource on the value of

the land within the Prescribed Wells Area.

The present day uses of water by landholders in the Northern Adelaide Plains Prescribed Wells Area

largely include irrigation for horticultural production, commercial/industrial use, recreational water use

as well as stock and domestic use. The present needs for water by landholders is approximately

18,000 ML per year.

The use of water for stock and domestic purposes is expected to remain stable. Commercial

irrigation for horticulture will continue to place the greatest demands on the prescribed water

resources of the Northern Adelaide Plains.

The area of arable land within the Northern Adelaide Plains Prescribed Wells Area covers

approximately 16,000ha; however, at the present time only 4,500ha of land is used for horticultural

production. It can therefore be seen that the capacity of the land can sustain existing irrigation and

there is considerable potential for future irrigation development. The limiting factor to future irrigation

development will be access to water.

It is expected that the potential future demand for water can be met through the use of imported water

from the Bolivar reclaimed water scheme which can deliver approximately 22,000 megalitres of

reclaimed water for irrigation purposes to the region. Other options will include the use of water from

aquifer storage and recovery (recharged water) schemes in accordance with this plan.

The water allocation policies contained within this plan are unlikely to have a significant impact on the

value of land within the Northern Adelaide Plains Prescribed Wells Area in the foreseeable future.


PAGE 11

Objectives

1. Allocation and use of underground water in a sustainable manner.

2. Allocation expressed as a volume of water that may be taken and used.

3. Efficient use of water.

4. Maintenance of water quality.

5. Maintenance of underground water dependent ecosystems.

6. Maintenance of the integrity of the aquifers.

Principles

Basis of allocation

1. Water to be taken and used from the wells in the Northern Adelaide Plains Prescribed Wells Area

will be allocated:

(a) by the volume of water that may be taken and used

(b) for use for a specific purpose such as commercial/industrial, environmental, irrigation,

recreational, stock and domestic; and

(c) according to the aquifer from which the water allocation is to be extracted.

Water available for allocation

2. Water allocations from the Tertiary aquifers (T1 and T2) and the shallow Quaternary aquifers

(Q3, Q4) shall not exceed 26,500ML, being the total volume of water allocated at the

commencement of this plan.

3. The volume specified in principle 2 will vary in accordance with any variations to the water

allocations made under the Act.

4. Water shall not be allocated from the shallow Quaternary aquifers (Q1, Q2) if the taking and use

of that water is likely to have any adverse impact on:

(a) the integrity of the aquifer

(b) the quantity and quality of water in the aquifer and underground water dependent

ecosystems; and

(c) existing users of the resource.

5. Water shall only be allocated from the shallow Quaternary aquifers (Q1, Q2) if the underground

water has a salinity level greater than 3000 milligrams per litre (mg/L).


PAGE 12

5A. Water Allocation Criteria for RechargedWater

The following objectives and principles apply to the allocation of water drained or discharged to a well

in accordance with a permit under section 9(3)(c) of the Water Resources Act (“recharged water”).

Objectives

1. No negative impacts on the underground water resource, or the productive capacity of land from

the taking and use of water.



4. Allocation based on a percentage of water recharged.


Principles

Basis of Allocation

1. The basis for allocating recharged water will be:

1.1 an entitlement to take during a water use year, a percentage (generally not exceeding 80%)

of the volume artificially recharged in the previous water use year pursuant to a permit

issued under section 18 of the Act; or

1.2 (a) an entitlement to take during a water use year, a percentage (generally not exceeding

80%) of the volume artificially recharged in the previous water use year pursuant to a

permit issued under section 18 of the Act; and

(b) where any entitlements calculated in accordance with paragraph (a) in respect of the

preceding period have not been used, an entitlement to use those unused

entitlements.

Discussion

A ‘water use year’ is the period from 1 July in a calendar year to 30 June the following calendar year.

The ‘preceding period’ means the period nominated on the licence, not exceeding four years,

immediately preceding the previous water use year.


PAGE 13

This basis for allocation allows some flexibility in the use of recharged water in that, if the licence

allows, unused entitlements can be carried over for up to five years.

2. The percentage of recharge available should not exceed 80% except in those circumstances

where there is hydrogeological evidence which demonstrates that the extraction of up to 100% of

recharge water would not have a detrimental impact on the resource or on other users of the

resource.

Criteria for Allocation

3. Recharged water shall only be allocated where the proposed location and manner of use of the

recharged water is not likely to:

(a) have a detrimental effect on the underground water resource, including, but not limited to,

an accelerated increase in salinity or pollution

(b) have a detrimental effect on the productive capacity of the land, including, but not limited to,

creating perched water tables close to the surface or waterlogging

(c) cause unacceptable interference with the water supply from existing wells; and

(d) have a detrimental effect on any ecosystems.


PAGE 14

6. Transfer Criteria

The following objectives and principles apply to the transfer of licences and/or allocations in the

Northern Adelaide Plains Prescribed Wells Area.

Objectives

1. Minimal impacts on the underground water resource, or the productive capacity of land from the

taking and use of water.

2. Efficient use and management of water.

3. Sustainable use of the underground water resource.




Principles

1. Transfers of licences and/or allocations shall not be permitted where the taking and use of the

water transferred is likely to have any adverse impact on:

(a) the integrity of the aquifer

(b) the quantity and quality of water in the aquifer

(c) any underground water dependent ecosystems

(d) existing users of the resource; or

(e) the productive capacity of the land.

2. Transfers of licences and/or allocations shall not be permitted where the transferred water

allocation will be taken from a well in a different aquifer (T1,T2, Q3 or Q4), unless there is

hydrogeological evidence to demonstrate that there will be an overall benefit to the underground

water resource.

3. Transfers of licences and/or allocations shall not be permitted where the transferred water

allocation is from an area of high potentiometric surface to an area of low potentiometric surface,

unless there is hydrogeological evidence to demonstrate that any negative impact on the

underground water resource is negligible.


PAGE 15

Discussion

The potentiometric surface is the theoretical water level in an underground aquifer as determined by

the pressure within that aquifer. This principle provides that the transfer of a water allocation is not

generally permitted to move down gradient of a potentiometric surface.

4. Transfers of licences and/or allocations shall not be permitted where the proposed transfer or

variation will result in the taking of water from a well located in the shallow Quaternary aquifers

(Q1, Q2) where the salinity is less than 3000 milligrams per litre (mg/L).

5. Except where there is hydrogeological evidence to demonstrate that there is not likely to be any

adverse impact on the underground water resource, transfers of licences and/or allocations shall

not be permitted where:

(a) the proposed transfer or variation is from an area of low intensity pumping to an area of

high intensity pumping; or

(b) the proposed transfer or variation is from an area of high underground water salinity to an

area of low underground water salinity.


PAGE 16

7. Permits

Section 9 of the Water Resources Act 1997 provides that a permit is required for the various water

affecting activities listed in section 9(3) of the Act.

In addition, permits are required for:

(a) the activity listed in section 9(4)(i) of the Act where water use is at a rate which exceeds 1

kilolitre/year (see ‘importation of water’ below)

(b) the activity listed in section 9(4)(j) of the Act where water use is at a rate which exceeds 1

kilolitre/year (see ‘use of effluent’ below).

7.1 Water Affecting Activities

The following objectives and principles apply to all water affecting activities in the Northern Adelaide

Plains Prescribed Wells Area. They are additional to the objectives and principles applying to the

specific activities set out below.

Objectives

1. Protection of the quantity and quality of water resources and the maintenance of natural

hydrogeological systems.

2. Prevention of deterioration in the quality of underground water.

3. Protection and restoration of the natural character of underground water.

4. Protection of the ecological functions of water resources and dependent biological diversity.

7.2 Drilling, Plugging, Backfilling or Sealing of a Well

The following objectives and principles apply specifically to the activities of drilling, plugging,

backfilling or sealing of a well under section 9(3)(a) of the Act.

Objectives

1. The drilling, plugging, backfilling or sealing of a well in a manner which will protect the quality of

the underground water resource.

2. Protection of underground water resources from pollution, deterioration and undue depletion.


PAGE 17

Principles

1. The equipment, materials and method used in the drilling, plugging, backfilling or sealing of a well

should not adversely affect the quality of the underground water resource.

2. Aquifers should be protected during the drilling, plugging, backfilling or sealing of a well to

prevent adverse impacts on the integrity of the aquifer, including contamination of the

groundwater resource.

3. A well shall only be drilled where it will not cause, or will not be likely to cause, salt mobilisation or

a rising water table.

4. The headworks of a well for the draining or discharge of recharged water shall be constructed so

that recharge and draining or discharge operations can be metered without interference.

7.3 Repairing a Well

The following objectives and principles apply specifically to the activities of repairing, replacing or

altering the casing, lining or screen of a well under section 9(3)(b) of the Act.

Objectives

1. The repairing, replacing or altering the casing, lining or screen of a well in a manner which will

protect the quality of the underground water resource.

2. Protection of underground water resources from pollution, deterioration and undue depletion.

Principles

1. The equipment, materials and method used in the repair, replacement or alteration of the casing,

lining or screen of a well should not adversely affect the quality of the groundwater resource.

2. Aquifers should be protected during the repair, replacement or alteration of the casing, lining or

screen of a well to prevent adverse impacts on the integrity of the aquifer, including

contamination of the groundwater resource.

7.4 Draining or Discharging Water into a Well

The following objectives and principles apply specifically to the activities of draining or discharging

water directly or indirectly into a well (“artificial recharge”) under section 9(3)(c) of the Act.

Objectives

1. Draining or discharging water directly or indirectly into a well in a manner which does not

adversely affect the quality of underground water, the aquifer or any ecosystem that depends on

the underground water.

Principles

1. Subject to clause 3, water may be drained or discharged into a well for the purpose of aquifer

storage and recovery where the concentrations, levels or amounts of the substances, materials

or characteristics set out in clause 4 below, in the water to be drained or discharged, do not

exceed the concentrations, levels or amounts of those substances, materials or characteristics in

the native underground water.

2. For the purposes of clauses 1 and 3, the relevant concentrations, levels or amounts shall be

measured by sufficient representative samples of:


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(a) the water to be drained or discharged, collected either from an existing dam or directly from

the source; and

(b) native underground water collected from the proposed point of injection, or as near as

possible to the proposed point of injection, and from the same aquifer as that in which

storage is proposed.

where “sufficient representative samples” means suitable samples, collected with equipment

appropriate for the substance, material or characteristic to be measured and taken at suitable

locations and times to accurately represent the quality of the relevant water.

3. The draining or discharge of water directly or indirectly into a well may occur (despite clause 1)

where the concentrations, levels and amounts of the substances, materials or characteristics of

or in the water set out in clause 4 are not sufficient to degrade ecosystems dependent upon

underground water within the prescribed water resource or to reduce the suitability of the

underground water for other purposes for which it might reasonably be used.

4. For the purposes of clauses 1 and 3 above, the list of substances, materials and characteristics

comprises substances, materials and characteristics that may be reasonably expected to be

present in the water to be drained or discharged and have the potential to degrade the native

underground water and the ecosystems that depend upon the native underground water,

including where relevant (but not limited to):

(a) pH, TDS, turbidity, ammonia, nitrate, nitrite, total phosphorous, sodium, chloride, sulphate,

calcium, magnesium, bicarbonates, iron, total arsenic, total boron, total cadmium, total

chromium, total lead, total manganese, total zinc, total coliforms and faecal coliforms; and

(b) where the water to be drained or discharged comes from a source likely to contain

pesticides, Giardia, Cryptosporidium, volatile organic compounds and petroleum

hydrocarbons (including but not limited to water from land used for intensive agriculture or

industrial purposes) those substances, materials and characteristics

(c) trihalomethanes where the water to be drained or discharged has been treated by

chlorination.

5. The draining or discharging of water directly or indirectly to a well must not detrimentally affect

the ability of other persons to lawfully take from that underground water or damage any

ecosystem that depends on the underground water.

6. For the purposes of this plan the term “native underground water” means the underground water

in the relevant aquifer before any water has been drained or discharged to that aquifer by artificial

means.

7.5 Importation of Water

The following objectives and principles apply specifically to the activity of using water in the course of

carrying on a business in a catchment area at a rate that exceeds the rate prescribed by this plan

where the water has been brought into the catchment area by means of a pipe or other channel under

section 9(4)(i) of the Act (“use of imported water”). The prescribed rate is 1 kilolitre per year. The

relevant authority for this activity is the Minister responsible for the administration of the Water

Resources Act 1997.


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Objectives

1. Use of imported water in a manner that does not adversely affect water resources within the

catchment.

2. Ecologically sustainable use of imported water.

Principles

1. Use of imported water shall not cause a rise in the underground water level sufficient to

detrimentally affect a structure or ecosystem.

2. For the purposes of principle 1, structure includes, but is not limited to, a building, fence or wall.

3. Use of imported water shall not adversely affect the natural flow of water or the quality of

underground water.

4. Use of imported water shall not adversely affect the productive capacity of the land by causing

salinity, waterlogging or perched water tables or other such impacts.

5. Imported water shall not adversely affect water dependent ecosystems.

7.6 Use of Effluent

The following objectives and principles apply specifically to the activity of use of effluent in the course

of carrying on a business in a catchment area at a rate that exceeds the rate prescribed by this plan

under section 9(4)(j). The prescribed rate is 1 kilolitre per year. The relevant authority for this activity

is the Minister responsible for the administration of the Water Resources Act 1997.

Objectives

1. Use of effluent in a manner that avoids adverse impacts on the water resources within the

catchment, other natural resources and ecosystems that depend on water resources.

Principles

1. Use of effluent shall not cause a rise in underground water level sufficient to detrimentally affect a

structure or ecosystem.

2. For the purposes of principle 1, structure includes, but is not limited to, a building, fence or wall.

3. Use of effluent shall not adversely affect the natural flow of water or the quality of underground

water.

4. Dams used to store effluent should be constructed:

(a) to prevent leakage of the effluent downward through the soils

(b) to prevent overflows from the dam to the surface of the land surrounding the dam; and

(c) to prevent overflow from the dam into a watercourse.


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8. Monitoring

This section of the plan provides for the regular monitoring of the capacity of the prescribed water

resource to meet the demands for that water on a continuing basis.

It is proposed that monitoring of the resource will involve:

1. Monitoring of the underground water levels in the main production aquifers (T1 and T2) and in the

Quaternary aquifer system over the summer and winter period.

2. Monitoring of an observation well network of approximately 90 wells completed in the Quaternary

and Tertiary aquifer systems, comprising the following:

• 30 observation wells in the Quaternary aquifers, which are currently used to monitor

recharge from surface drainage and any hydraulic connections with the underlying Tertiary

aquifers

• 20 observation wells in the T1 Aquifer

• 35 observation wells in the T2 Aquifer

• five wells in the deeper highly saline T3 and T4 aquifers.

3. Monitoring a range of other variables including but not limited to:

• underground water levels

• underground water salinity

• volume of water extracted from aquifers.

4. The monitoring program will also incorporate information provided by all licensees and permit

holders through the provision of annual irrigation reports. These reports will include information

on:

• area under irrigation

• the type of crop irrigated

• volume of irrigation water applied to the land and time of irrigation

• source of irrigation water (T1,T2 Q1,Q2), imported water, recharge water

• the exact location of the well

• irrigation water salinity.


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Discussion

It is proposed that the full observation network will be monitored every three months. The data

collected from the network will, amongst other things, be used to develop potentiometric surface

maps, which will identify underground water levels within the aquifers. These levels will be mapped

at different times including the high use summer period and the low use winter period. The

information on potentiometric surface levels will be used in conjunction with information from the

Annual Irrigation Reports to assist in assessing the capacity of the resource to meet demands for

underground water use in the Northern Adelaide Plains Prescribed Wells Area. The information from

annual reports will be provided back to water users in the form of a report on trends in water use,

water quality and water quantity.


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9. Miscellaneous

In preparing this plan, the Northern Adelaide and Barossa Catchment Water Management Board has

had regard to the following:

1. The matters referred to in section 6(2) of the Water Resources Act 1997

2. The benefits of consistency with:

• relevant management plans under the Coast Protection Act 1972

• relevant Development Plans under the Development Act 1993; including

⇒ Development Plan Playford (City)

⇒ Development Plan Gawler (CT)

⇒ Development Plan Port Adelaide Enfield (City)

⇒ Development Plan Salisbury (City)

⇒ Development Plan Light (DC) (Metro)

• relevant environment protection policies under the Environment Protection Act 1993;

including “South Australian Reclaimed Water Guidelines: Treated Effluent”. EPA April 1999

• relevant plans of management under the National Parks and Wildlife Act 1972

• relevant district plans under the Soil Conservation and Land Care Act 1989

• guidelines relating to the management of native vegetation adopted by the Native Vegetation

Council under the Native Vegetation Act 1991.


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10. Glossary

Deltaic - Sediments formed by deposition at the 'delta', orthe portion of a river where it meets the sea.

Horticulture - The use of land for market gardening,viticulture, floriculture, orchids, wholesale plant nurseriesor commercial turf growing.

Mg/L - Milligrams per litre. In the case of groundwaterresources, it is a measure of salinity. The value ofdissolved salts in mg/L can also be referred to as 'partsper million'.

ML - Megalitre, or one million litres. An Olympic sizeswimming pool contains approximately one and a halfmegalitres.

Potentiometric Surface - A surface describing thepressure in a groundwater aquifer. The height at thesurface at a point represents the level the water wouldrise to in a well at that point.

Quaternary - Sediments that are between 1 and 2 millionyears old.

Tertiary - Sediments that are between 2 and 65 millionyears old.

Water Resources - The total amount of water that isavailable to supply the needs of all water users, includingwater-dependent ecosystems, irrigators and other humanconsumers. This includes water in watercourses, lakes,surfacewater (including stormwater), and effluent.


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Figures

water allocation plan · 2015. 4. 27. · northern adelaide and barossa catchment water management...

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