Toowoomba North Basalts Groundwater Status Review 2020 - Contents of this presentation - Department of Natural Resources ...

Toowoomba North Basalts
Groundwater Status Review 2020
                                                   Steven Williams,
                                                   Water Services,
                                                   Toowoomba

                           Contents of this presentation
                           1.   Key messages
                           2.   Map of the area
                           3.   Review groundwater levels
                           4.   Proposed Limitations
                           5.   Opportunities for further discussion

Groundwater Status Review 2020
Key Messages
• There are 186 water licences totalling a volume of 8,575.6 ML
• Below average rainfall across the area with 243mm recorded at the Bell
  Police Station BOM gauge in 2019 compared to an average of 690mm.
• Slight reprieve with above average rains in January and February 2020.
• Generally across the northern basalt area, longer-term aquifer storage
  has declined to a level nearing lowest on record.
• Recent rains may have reduced the short-term demand on groundwater.

Toowoomba North Basalts –
• Total of 20 monitoring        Location of monitoring bores
  bores located in
  Toowoomba North Basalts
  which are dipped quarterly

• Generally two prominent
  aquifers in area:
   • formations above 30m
      (weathered/fractured)
   • formations between
      30m – 70m (semi
      confined)

• Aquifers do not continue
  laterally across whole area
  and the lower formation is
  not present in some areas.

Groundwater Status Review 2020

• Limitations are based upon a number of considerations
• Information of sustainable yield of the aquifer such as:
     • Long-term storage depletion
     • Expected recovery time after rainfall and recharge events
     • Comparison of current water levels to aquifer intake zones (i.e. areas of
       higher permeability such as fractures/weathered layers)
•   Water level trends
•   Water demand and extraction
•   Forecast seasonal conditions
•   Balancing access to the resource for multiple stakeholders (e.g.
    irrigators, town water supply, stock and domestic users)

Groundwater Status Review 2020

• Due to the varying depositions and aquifer characteristics within the basalt
  formation, the Toowoomba north basalts have been assessed across four
  separate areas to gain a better understanding of aquifer trends. These are:
   1. Dalby – Jimbour area (upper aquifer above 30m)

   2. Bell area (lower semi-confined aquifer ~30m – 70m)

   3. Oakey area (upper aquifer above 30m)

   4. Highfields area (lower semi-confined aquifer)

• The monitoring bore hydrograph that was selected for each area shows a typical
  aquifer response within the catchment.

RN 42231450 Kaths Rd (north Kaimkillenbun)
Area 1 Dalby – Jimbour
SWL (March 2020): -16.55m             Note:
                                      Measurement Units – metres
                                      RN = Registered Number
Depth of bore: 26m                    SWL = Standing Water Level
                                      WL = Water Level
Aquifer: 14.8m to 18m

WL trend: Steep decline with little
to no recovery since 2010/11
floods.

WL change since Jan 2019:
-0.41 m

RN 42231536A Koondai Rd (North of Bell)
Area 2 – Bell area
SWL (March 2020): -9.37 m

Depth of basalt: 49.90m

Aquifer: 47.7m to 48.0m

WL trend: Slow decline with small
response from February rain.

WL change since Jan 2019: -0.2m
to Jan 20 but recovered +0.1m to
March 20.

RN 42231306A Kingsthorpe-Bourke Rd
Area 3 – Oakey area
SWL (March 2020): -19.11m

Depth of basalt: 16.8m

Aquifer:   14.2m to 16.8m

WL trend: Very sharp decline with
levels reaching lowest in
recorded history. Below main
aquifer bed.

WL change since Jan 2019:
-1.14m.

RN 42231223 Borghardt Rd (Highfields State School)
Area 4 - Highfields
SWL (March 2020): -31.88m

Depth of bore: 100m

Aquifers: 46.4m to 49.8m
          83.2m to 88.8m

WL trend: Declining

WL change since Jan 2019:
-2.21m to Jan 20 with a recovery
of +0.29m to March 20.

Groundwater Status Review 2020
Summary
• Generally across the basalts, longer-term aquifer storage has declined in
  both upper and lower aquifers.
• The upper aquifers generally take between 3 – 6 months to stabilise and
  rise when the area receives above average rainfall with the lower aquifers
  taking anywhere from 18 – 24 months.
• Water levels across the north basalts are fast approaching the perforated
  sections of monitoring bores in many areas if not already in the perforated
  sections.
• The patterns seen on water level hydrographs are directly related to
  rainfall, groundwater extractions and natural discharge. Both, the upper
  and lower aquifer water levels are susceptible to climatic variations and
  influence from surrounding pumping.

Groundwater Status Review 2020

Proposed Limitations
• Current groundwater limitations are 70%
• Proposed to continue the limitations for the 2020-21 water year:
       • 70% of the nominal entitlement on your water licence.
       • Pumping times: 8 hour period over 4 days (Monday, Tuesday,
           Wednesday and Friday (total 32 hours).
• Licensees can apply for an Individual Notice (IN) to either install a meter, or
  demonstrate a need to have different pump days/hours (max 32 hours).
• Until licensees receive an IN they must comply with the general limitations
  notice.
• Existing IN holders need to reapply every year.
• New limitations notice release date - late June 2020.
• Limitations do not apply to take for Stock and Domestic purposes.

To request additional information or make a time to discuss your specific situation
                                                   please call the department on:

                                                               Phone - 4529 1394

                                                     The department would value
                                                              your feedback on the
                                                      limitations consultation via a
                                                     short feedback survey on the
                                                                           website.

                                                                        Thankyou