Upper and Lower Namoi River

Upper and Lower Namoi River 
Drought Stage

Stage 1 - Normal management

Stage 1 normal operations recovering. Upper Namoi – de-escalated from Stage 4 critical to Stage 3 severe on 23 March 2020 and then to Stage 2 recovering on 1 May 2020. Returned to normal operations in mid-January 2021.

Stage 1 - Normal management

Stage 1 normal operations. Lower Namoi – de-escalated from Stage 4 critical on 23 March 2020, and then from stage 3 severe to recovering in November 2020. Returned to normal operations in mid-January 2021.

Storage Levels
  • Keepit Dam increased to 64% (275 GL) by 15 April 2021 from almost empty 1% (holding 3 GL of active capacity) at the start of 2020.
  • Split Rock Dam increased to 28% (116 GL) in mid-April 2021 compared to 1% (holding 3 GL of active capacity) at the start of 2020.
  • The Namoi Valley experienced the lowest inflow between 2017 and 2019 (worst drought) since 1918.
Allocations
  • The first general security allocation in the Lower Namoi since August 2017 was made in September 2020 of 4.2% with small monthly increases to end of December 2020 and then increasing to 39.3% in early February 2021 and then 82.6%in mid-March 2021.
  • The 2020/21 water year started with zero for general security, 100% for town and domestic and stock and 90% for high security.
  • Upper Namoi started the 2020/21 water year on zero general security allocations, until a 50% allocation was made on 22 April 2020. Suspension of carryover water was lifted on 25 February 2020. In mid-January 2021 general security allocations were increased to 100%.
  • Zero for general security in Lower Namoi for all of 2019/20 and all carryover water suspended until 25 February 2020 when suspension lifted.
  • Reduced high security allocations for both the Upper and Lower Namoi Valleys for most of 2019/20 until full high security allocations announced on 22 April 2020, however water was being provided through river flows.
Actions
  • Water transferred from Split Rock to Keepit Dam during 2018 and 2019.
  • No releases made to Lower Namoi water users during 2019 and for most of 2020.
  • First release since December 2018 was made in March 2020 to only supply some domestic and stock users immediately below the dam. Access for the rest of the river was only available from run of the river flows (not regulated releases) until December 2020 when a block release commenced. With improvement in Keepit storage, block release was cancelled and orders were able to be met from downstream flows from January 2021.
  • Normal releases have been occurring in the Upper Namoi.
  • Natural inflows caused by rainfall in late March 2019 were restricted to town, domestic and stock and high security access only. Some useful flows reached Walgett in April. Restrictions on access repealed on 6 May 2019.
  • Temporary water restrictions (section 324 order) were placed on general security users on 6 December 2019 in the Upper Namoi, restricting access to all water in accounts to  secure town water supplies for Manilla township. This restriction was lifted on 25 February 2020.
  • Restrictions on access to inflows applied during January and February 2020 across the Northern Basin limiting access to critical needs. Flows reached Walgett and entered the Barwon-Darling River from 9 February. These restrictions ended late February, with some limited access to certain areas during this period where flows had exceeded target levels.
  • Releases from Split Rock Dam re-commenced from April 2020, once two years reserve for town water supply was available in the storage.
  • Two solar aerators installed in Keepit Dam in 2019.
  • Pian Creek replenishment flow provided in February/March 2020 and in August 2020.
  • Fish refuge pools mapped and fish rescues were undertaken during December 2019.
Issues
  • Because of low water levels boating access to Keepit Dam was limited in 2019.
  • Low flows downstream of Keepit Dam and high temperatures contributed to fish deaths in January 2019 and further deaths throughout the system in November 2019 because of very low water availability.
  • Fish deaths around Narrabri, Gunnedah, Carroll and Boggabri in late January/early February 2020 as a result of short sharp rise in river flows.
Outlook
  • The aim is to build reserves in headwater storages, with tributary flows meeting current orders where possible.
  • General security users were advised in December 2020 that restrictions would be applied in the Upper Namoi to protect town supplies if Split Rock Dam fell to 15 GL. However subsequent rainfall in the catchment had increased storage volume to 107 GL by mid-January 2021 and town water supplies are secure for at least the next two years.