managing the groundwater resources of the earnscleugh terrace aquifer

Managing the groundwater resources

of the Earnscleugh Terrace Aquifer

OTAGO REGIONAL COUNCIL WORKSHOP – 18 March

Welcome / overview Policy presentation: aim, key concepts, process Science presentation: aquifer hydrology Q & A session Small group session Conclusion / Where to from here Tea & coffee

Today

Setting a

maximum allocation volume & aquifer restriction levels

for the Earnscleugh terrace aquifer

in the Water Plan

Project aim

Total volume of groundwater that may be taken from an aquifer by resource consents.

Measured in m3/year. To avoid aquifer depletion/compaction and

groundwater contamination, ensure surface water outflows.

Further allocation is available if combined consented takes < MAV

What is a maximum allocation volume?

Set in Schedule 4A of the Water Plan - takes into account hydrology, environmental, social economic, cultural, considerations

OR

Set as 50% mean annual recharge (interim/default MAV)

How is the maximum allocation volume determined?

Permitted vs. consented takes

Existing consents vs. applications for new takes

Groundwater takes not allocated as primary allocation (surface water)

Does the maximum allocation volume affect me?

Aquifer levels at which restrictions apply to groundwater takes

Takes usually restricted by 25%, 50% or 100% To maintain groundwater levels in localised

areas of high demand or during droughts No default set in the Water Plan Determined based on local environmental,

socio/economic, cultural considerations

What are aquifer restriction levels?

Consented takes

Community water supplies (Schedule 3B)

Permitted takes under Rule 12.2.2.2

When does an aquifer restriction level affect me?

RMA process

Workshop #2 (Optional)Discuss suggested management option

Workshop #1 (Today)Explain Water Plan basicsDiscuss science – technical recommendationListen community aspirations and values

Changes put into effect

Consultation process

Consultation key

stakeholders, incl. Iwi

Notify proposed plan change

Consultation draft

EarnscleughTerrace AquiferSimon East, Groundwater Scientist

Earnscleugh Terrace Aquifer boundary

Earnscleugh Terrace

Geology map

Earnscleugh Terrace cross section

Groundwater contours

Groundwater wells and take permits

Consumptive takes• 8 takes• Assessed maximum annual

take of 1.01 Mm3

• Actual use may be as low as 30%

Partially consumptive takes• 2 takes• Assessed maximum annual

take of 31.8 Mm3

• Possibly as much as 75% of water returned to the aquifer

• Actual use may be as low as 50%

Non-consumptive takes

Earnscleugh gold mine

Earnscleugh gold mine

Monitoring well locations

G42/0119 groundwater level monitoring

1994 1999 2004 2009 2014

-25

-24

-23

-22

-21

-20

Dept

h to

wat

er (m

)

G42/0190 groundwater level monitoring

1994 1999 2004 2009 2014

-12

-11

-10

-9

-8

-7

Dept

h to

wat

er (m

)

Why are groundwater levels declining?

• Increased groundwater pumping?

• Less rainfall?• Lower surface water flows?• Changes to irrigation?

Rainfall trend and groundwater level

1994 1999 2004 2009 2014

-11

-10

-9

-8

-7

-250

-200

-150

-100

-50

0

50

100

150

200

250

Groundwater level

Rainfall trend

Dept

h to

wat

er (m

)

Rain

fall

trend

Recharge and discharge

Water balance component Recharge(Mm3/year)

Discharge(Mm3/year)

Rainfall recharge 0.35Fraser Irrigation Scheme excess 0.55

Losses from the upper Fraser River 24.60Water race losses 3.40

Losses from Omeo Creek ?Range front recharge ?

Losses from the Clutha River ?Drainage into the lower Fraser River 16.20

Groundwater pumping 0.15Drainage into the Clutha River from springs 4.00

Direct drainage into the Clutha River 8.5Totals 28.9 28.9

Water balance

Surface water interaction

Losing river

Gaining river

Maximum allocation volume (MAV)• Policy 6.4.10A sets the default MAV as 50% of the

mean annual recharge (MAR)• Water race leakage not included as it is only a

temporary source of recharge• Range front, Omeo Creek and Clutha River

recharge not included at this stage as they haven’t been fully assessed

Source Volume (Mm3/year)Rainfall recharge 0.35

Fraser Irrigation Scheme excess 0.55Losses from the upper Fraser River 24.60

Total MAR 25.00

MAV (50% of MAR) 12.75

Current allocation

Consumptive takes1.01 Mm3/year

Partially consumptive takes31.82 Mm3/year

Default MAV12.75 Mm3/year

Estimated assessed maximum allocation32.83 Mm3/year

Available allocation0.00 Mm3/year

Options for management

• Accept the default MAV (50% of MAR)

• Develop a tailored MAV:• Consider a higher MAV by undertaking further

investigations to determine additional recharge components

• Consider a lower MAV based on the maximum likely irrigation requirement for the zone or for the protection of other values

• Consider a groundwater restriction level to provide protection from groundwater level decline

Community input into the allocation process

Community involvement in identifying values and aspirations is an integral part of the process of setting allocation limits.

Combined with the science input, community involvement helps to achieve the best outcome.

Small Group Discussions

How do you use water from the aquifer?Have low groundwater levels ever affected you?

How often does this happen? How were you affected?What is important about the aquifer?

To you personally. For the local economy, environment, and community (social/cultural importance).

How would you like to see water from the aquifer being used in the future? 

Are there any future growth opportunities? Are there any risks to this growth happening?

Small Group Discussions

Report Back

Further Feedback• Provide any further feedback by 1 April 2014

• Email: policy@orc.govt.nz

• Post: 70 Stafford Street, Private Bag 1954, Dunedin

• Phone: 0800 474 082

• Workshop materials, feedback forms will be put on the

website: www.orc.govt.nz