Risk of Spill Information for the Campaspe system

Monday 11 October, 2021

The risk of spill in the Campaspe system at 10 October 2021: 5%

This value represents the percentage of years that spills occur from GMW’s share of Lake Eppalock taking into account the current storage volume, storage releases, inflows and evaporation from the storage using the historic data available.

Note: 10% or lower is the threshold for a declaration that would return water quarantined in spillable water accounts to allocation bank accounts.

Volume needed to fill Lake Eppalock at 1 September 2021: 140,007 ML

The current volumes in Campaspe system spillable water accounts can be found at the Victorian Water Register

Ranked historic inflow to Lake Eppalock: July - September

Ranked historic inflow to Lake Eppalock: July - September
Ranked historic inflow to Lake Eppalock: July - September. Inflow for the July - September 2021 period is indicated by the red line: 73,367 ML

Description and Tabulation of the Graphical Content Ranked Inflow to Lake Eppalock: July - September

A bar graph titled Ranked historic inflow to Lake Eppalock: July – September is on the page above. X axis label “% Probability of Exceedance” which spans 99% on the left to 1% on the right. Y axis label is “3 month inflow – units megalitres (ML)”. Significant highlighted data in the graph is the inflow for the July – September 2021 period is indicated by the red line: 73,367 ML.

Each % probability of exceedance is reported from 99% to 0%. The general nature of the information presented is low inflow values of less than 10,000 megalitres have a high probability of occurrence. Less than 10% probability of inflows above 217,738 megalitres.

Tabulation of data from the image of the graph above.
% Probability of Exceedence 3 month inflow in megalitres (ML)
99% 0
90% 8,078 
80% 17,968 
70% 30,532 
60% 44,990 
50% 65,597 
2021 73,367
40% 94,228 
30% 130,626 
20% 165,599 
10% 217,738 
1% 369,210

Ranked Historic inflow to Lake Eppalock: October - December

Ranked historic inflow to Lake Eppalock
Ranked historic inflow to Lake Eppalock: October to December. The volume difference at Lake Eppalock between full supply and the storage volume on 1 October is indicated by the green line: 140,007 ML.

 

Description and Tabulation of the Graphical Content Ranked Historic inflow to Lake Eppalock: October - December

A bar graph titled Ranked historic inflow to Lake Eppalock: October – December is on the page above. X axis label “% Probability of Exceedance” which spans 99% on the left to 1% on the right. Y axis label is “3 month inflow – units megalitres (ML)”. Significant highlighted data in the graph is the difference between the full supply volume of Lake Eppalock and the volume at 1 October 2021 is indicated by the green line: 140,007 ML.

Each % probability of exceedance is reported from 99% to 1%. The general nature of the information presented is low inflow values of less than 10,000 megalitres have a high probability of occurrence. Less than 10% probability of inflows above 95,832 megalitres.

Tabulation of data from the image of the graph above.
% Probability of Exceedence 3 month inflow in megalitres (ML)
99% 0
90% 1,568 
80% 4,388 
70% 6,748 
60% 10,578 
50% 14,631 
40% 22,458 
30% 33,476 
20% 50,473 
10% 95,832
Current airspace  147,283 ML
1% 276,256 

 

Notes for charts:

There are 128 years of historic inflow data available for Lake Eppalock (inflow data for the period before the construction of the dam are based on modeled inflows). The first chart displays the volume of inflow to Lake Eppalock for the period 1 July to 30 September in each of those 128 years. The volumes of inflow shown are ranked in order from lowest to highest with the red line representing the volume of inflow recorded for the period in the current water year (2021).

The second chart displays the volume of inflow to Lake Eppalock for the period 1 October to 31 December in each of the 128 years of historic data. The volumes of inflow shown are ranked in order from lowest to highest. The volume difference at Lake Eppalock between full supply and the storage volume on 1 October is indicated by the green line.

Probability of exceedance: Probability that the volume of inflow will be equal to or greater than a specified volume in any given year.

Additional notes:

  • The volumes in spillable water accounts can change due to seasonal determination increases.
  • The information provided here for the Campaspe system does not take into consideration the storage sharing arrangements at Lake Eppalock between GMW and Coliban Water.
  • Current year inflows are based on operational data.