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25 JUNE, 2020

FOLH would like to acknowledge the support of the Otago Regional Council who have ratified 2 key actions requested by FOLH in their submission on the ORC 2020-2021 Operating Plan.

 

2. Managing lake water inflows and outflows

 

ORC, FOLH and their respective science advisors agreed that targeted augmentation of Mill Creek with cool, low nutrient water from the Arrow River irrigation scheme would benefit lake health at relatively low cost and with little risk. Further to this, the Lake Buoy would be able to measure the effect of this intervention and provide feedback on how and when to augment the water.   ORC agreed that this would be a useful management action and built 80% of required infrastructure at Millbrook Resort to allow this to happen.

 

ORC identified the Lake Hayes outlet culvert as a limiting factor in this project and FOLH supports ORC’s initiative to review the specs of the culvert with a view to upgrading the culvert to avoid the recent lake flooding issues that have been identified by FOLH. This single culvert replaced 2 smaller culverts which when installed replaced a bridge that had been at the Lake Hayes outlet, allowing stream to flow unconstrained.  In the 1960s, lake levels were controlled by the natural lake outlet profile. 

 

Lake level does affect lake health, as shoreline flooding releases large amounts of soil phosphorus and erodes lake shores. All this was researched and described in the 1995 Lake Hayes Management Strategy, which described optimal lake height, lake level variation and culvert design. Considering the substantial time elapsed since the ORC built the infrastructure for flow augmentation from the Arrow River, it is heartening to know that ORC’s proposal to review the outlet culvert should be relative simple to carry out because most of the relevant data will be collated as part of the 1995 Strategy update. 

 

1. Updating and reinstating the
1995 Lake Hayes Management Strategy 

 

The issues addressed in the comprehensive Lake Hayes Management Strategy (1995) remain largely unchanged today. However, to bring it up to date, data from the current ORC catchment nutrient study needs to replace the old nutrient load information. Similarly, the catchment land use information needs to be updated to reflect the move away from agriculture to tourism-based activities, resorts, golf courses and residential development. Most of the work needed to update this document has already been completed - it just needs to be professionally compiled. The 1995 Strategy was widely supported by stakeholders and, therefore, could easily be readopted once updated.

 

The Lake Hayes Management Strategy is not an operational plan but a contextual framework for all the initiatives which together will lead to the recovery of Lake Hayes. In hindsight, had we carried on with it in 2003 the lake would already be well down the track to recovery by now. The sad thing is that while so much discussion and debate has been going on about the state of the lake, no positive actions have been undertaken lake or catchment since then.

 

To get things moving, FOLH identified 2 initiatives in the 1995 Strategy, which, if implemented, could begin some positive actions to improve the lake health.

30 MARCH, 2020

The water quality monitoring buoy installed last year in Lake Hayes by the Otago Regional Council has provided valuable information about the dire water quality conditions that recently resulted in the death of a number of brown trout in the lake.

Water quality over recent years has deteriorated, resulting in a major reduction in trout numbers. The few trout that survive struggle with poor water quality in summer and the recent observation of numerous dead trout in the lake highlights the stresses that trout in the lake must now endure.

 

A flood in Mill Creek due to heavy rains in early February 2020 carried high loads of sediment and nutrients into the lake.  

  

Subsequently, calm, warm weather provided the perfect conditions for cyanobacteria (also known as blue-green algae) to bloom in the lake – visitors to the lake will have noticed a thick green scum on the lake surface. The lake was then officially closed to recreation for a period of time due to the risk of toxin production by the cyanobacteria. A consequence of these conditions in the lake resulted in very high pH, and low dissolved oxygen concentrations, at a time when the water was very warm. These conditions put great stress on the trout population, and unfortunately dead trout began to be observed on the lake shore.  

For over 10 years, the Friends of Lake Hayes have been lobbying the Otago Regional and Queenstown Lakes District Councils to come up with a plan to restore the water quality of Lake Hayes to an acceptable level. We think four tasks are required to accomplish this:

 

  1. Reinstating the 1995 Lake Hayes Management Strategy. 

  2. Completing a science-driven integrated lake and catchment management plan, which should sit within the Otago Regional Council’s Water Plan.

  3. Updating the rules in the Queenstown Lakes District Plan requiring best management practice in relation to land use in the catchment.

  4. Encouraging improvement in lake water quality by improving the sediment and nutrient retention of the catchment by, for example, restoring previously drained wetlands.  

 

The Friends of Lake Hayes have started this process by identifying land for replanting and restoring wetlands around Mill Creek. It is the intention that this plan is community driven and is supported by all stakeholders.

Dead Trout found at the south west end of Lake Hayes, just off the raupo beds on March 13, 2020.

A flood in Mill Creek due to heavy rains in early February 2020 carried high loads of sediment and nutrients into the lake.  

Cyanobacteria bloomed in February 2020 causing the lake to be closed to swimming again.

12 MARCH, 2020

We have heard some great news that a well-known NZ bird watcher and photographer, John Kyngdon has spotted a very rare Marsh Crake at Lake Hayes.

The Marsh Crake is one of New Zealand’s most secretive birds, largely because it inhabits dense wetland vegetation, rarely ventures into the open and usually only calls at dawn or dusk and through the night. Marsh Crakes primarily feed on invertebrates and seeds of aquatic plants.

Photo copyright John Kyngdon.

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