Environment Waikato News
21st July 2008
The latest Algal counts can be found here
16th November, 2007
The lake level (weir operation) consent under review by Environment Waikato (EW) has been concluded. The lake level /weir operation will remain unchanged for the next three years. This was conveyed to the club by a courtesy phone call from EW, thanks. That's OK for the Yacht Club, with a couple of reservations. Firstly, that the level in the winter will not be dropped too low that will hamper the Winter Trailer Yacht Series and secondly that the "Summer" level will be attained by the 1st October each year (the level at 1st October 2007 was about 20mm lower than that minimum required after alteration of the weir was not made till the 17th September, to late to achieve the required level; we have photographic evidence on each Sunday throughout September). We wait for an improvement in 2008.
The Blue Green algae count on the EW web site is up at 123,000 cells per ml, a level much higher than is usual (dated 25/29 October). Concerned and surprised at this level, on the 6th November the Club took a water sample and had it counted at NIWA. The results showed a blue-green count of 14,600 cells per ml, more in line with levels that are typical at the lake early in the summer. This huge variation in result (we have experienced this before) certainly makes one wonder about the sampling procedures and more so how the counts should be interpreted. NIWA sent a copy of their report directly to EW, we have a copy in the Clubhouse for all to see. The low-level hazard is set at 15,000 and medium starts at 100,000cell/ml. Counts can go well into the millions as unfortunately sometimes is seen in some of the north Waikato lakes.
What's happening with Waikato Lakes?
1st November 2007. Huntly Civic Centre.
That was the title of a community information day supported by Environment Waikato (EW) and eight other players in the area. A small public notice placed in a Hamilton community paper attracted my attention and I duly booked my place. (I did wonder why a clearly identifiable lake user like the Ngaroto Sailing Club did not receive direct notification! This tactic has happened before, for example the recent call for submissions to the Ngaroto management plan was notified in a similar way by the Waipa District Council! Sharp eyes are required.) I wonder why? What's the real agenda?
The program included:
- General impacts on lakes, CBER, University of Waikato
- Farming impacts on the environment, EW
- Koi Carp, University of Waikato
- Community initiatives around lakes, NZ Landcare Trust and EW
- Freshwater Mussel Research, NIWA
- Tainui co-management, Tainui
- Regional requirements, EW
- District approach, Waikato District Council
An advertised keynote address by Peter Buckley (under the banner of President, Federated Farmers, Waikato and now Chairman of Environment after the recent election) followed an extended Tainui welcome and lunch. I have to say that the President or Chairman whatever hat he was wearing (was impossible to tell which if any) has a long, long way to go. No aspirations or policy of either on the environment, but a rambling account of his own lowland peat farm and adjacent wetland. Watch for an improvement there is a vast potential for sure. I hope it can be realised!
The audience of around 80 odd people contained many from the allied organisations listed in the agenda plus good number of other interested parties.
So what did I learn that might have some relevance to Lake Ngaroto?
Peter Buckley reckoned that a 35-acre wetland he owned was worth over a million dollars (he had had an offer by a keen duck shooter). Wetlands are therefore very valuable; I was very pleased to know that. I hope that goes on to mean that those degraded areas of wetland will receive urgent, positive and a practical level of management to improve them.
That ground water is likely to contain much of the nitrogen that is a key driver of poor water quality. In small catchments (in contrast to that of Lake Taupo or Rotorua) that ground water is likely to take just 4 or 5 years to flow through to the lake (Taupo and Rotorua 50 years plus). So responses in a small catchment lake can be expected to occur quite quickly! Let's make a start! I can't say any local examples were quoted. I say get cracking so as to make a difference!
Gross sediment infilling has occurred and has adverse effects on lakes, including making them shallower and when combined with wind substantially reduce water clarity, contain substantial amounts of phosphate fuelling plant and algae growth. Large settlement traps are thought to be effective. Local examples with good monitoring of effectiveness appear to be lacking. Lake Ngaroto surely would be a good site for applied experimentation!
Koi Carp feed among the sediment on lakebeds, stirring it up reducing the water clarity especially in shallow lakes. Wind on top of this leads to low clarity levels stifling aquatic plant growth. Examples from the management of fish populations were quoted from North America and Australia, from over 50 years ago, with good effect. Is rocket science needed to start here?
Freshwater mussels (as we occasionally see at lake Ngaroto) are certainly rare now, but were once in better water conditions a common food source.
EW has a lake level setting process that included minimum water levels being attained in the summer (when peat is most at risk of drying and degradation). They stated that these levels are achieved 80 to 90 percent of the time. (Lake Ngaroto was clearly not included in the data set, I wonder why? The answer is clear; it frequently fails to reach the required summer levels due to poor weir management! October 2007 was another example!
Farms are required to have a Nutrient Management Plan. Some conditions were given but I didn't hear anything about any special conditions that might be applied in sensitive catchment areas. Wouldn't that be an obvious step?
At Ngaroto we have two very clearly identifiable recreational water use clubs (rowing and sailing) where water quality is critical to their success. I concluded that EW is likely to be the key organisation to lobby. We need to up the anti through the employee and political routes, and make a difference to Lake Ngaroto.
Ross Wren