Our Stories

Upper Catchment Data between 17/06 and 20/07/2020

What a beautiful frosty morning! Dean, Kaden, Jonathan, and I scrambled over the fence and up the catchment. At each site we collected data and gathered water samples. At 3a the water was sluggish and cold with a significant amount of sediment present, be careful how you collect the samples! We are testing the water not the water and sediment. There are sheep grazing the pasture.

Map of the sites 3A, 3 and 3C in the upper catchment

Then we followed the sheep up the catchment dropped off bottles at 3B and continued up to 3C, scrambled under the fence and did the business at 3C, much less sediment.

The bottom or substrate at 3B, rocks and smaller gravel covered with a thin layer of sediment. The large rock on the foreground is about 70cm across. Many small snails, mayfly nymphs and koura present.
This is looking down the catchment from beside 3B. There is no protection of the banks other than pasture grass.

June 16th – 20th 2020 – Site 3B John McGlashan

Frosty calm start to the day.

In the 20th May, air temp increased from 6.5oC at 9.14 through to 11.1oC by midday, no wind but a slight build up by midday to 17.2 kph from NNE

No rain fall.

High wispy cloud, blue sky and around 20% CCV.

1mm of rainfall over the previous 5 days, no rainfall but the ground is damp and boggy.

Looking eastwards from Site 3B

June 17th 2020 – Site 5 OGHS

Our team of Cara, Harriet and Ayla braved the increasingly cold weather at Site 5. With the north easterly breeze providing just enough waves to lap over the top of our gumboots we braved the cool water to check the depth, temperature, oxygen and salinity. Dissolved oxygen and salinity values were consistent as were the wet socks from the previous monitoring due to a significant increase in the water’s depth. A summary of nutrients is included below.

Bird life comprised mostly swans, paradise ducks, mallard/grey ducks and scaups. Swans in particular were present in large numbers. A solitary pukeko was spotted by Ayla.

June 3rd 2020

Murray Vickers and I set off from the vehicle at Edwin’s farm at 1.00 on June the 3rd to take some measurements at Site 6. I needed Murray to help as we had to open and shut the farm gate!! The day was cool and overcast so you needed your parka and gumboots.

The walk over the fence to the stream was through thick wet vegetation (next time bring hedge clipper or hungry goats) and muddy stuff. The ground is very wet.

Follow the yellow line!
This is looking down the stream. The bottom or substrate is thick sediment and you’re feet will disappear. The weed is steadily taking over much of the open water.



Commentary from Full Monitoring on August 22nd 2018

Weather station: Temperature was cool 9.1-9.4oC. Wind speed fluctuated between 17.2-7.2 km/h, and direction changed from SSW to WSW.

No significant rainfall over the last three days

Site 1


High water level, strong ripples, clear water, strong breeze, slight showers, 90% cloud cover (ccv)

Seagrass still covered by sediments or a layer of alga, some patches looked cropped by swans, a lot of bs poo close to the shore, Canadian pondweed (cpw) pieces common floating on the surface and caught in the bucket sweep.

Bucket sweep-1 dead common bully, 2 water boatmen, abundant Amphipods, one water flea, multiple small snails, 3 Physa snails.

70-80 BS, 20+ Black-backed gulls, 3 Paradise ducks.

Site 2

Cold wind from the south, complete cloud cover, small chop on water surface.

Good growth of seagrass, cpw growing well inside the patches of seagrass, all covered with a layer of dark green alga.

Bucket sweep- 30 Amphipods, abundant Daphnia in the water column, 8 small snails.

Site 3

Water clear, much lower than last visit, cold south wind.

Site 4

Overcast, light rain, light wind, cold.

Small random patches of Milfoil and weak growth of seagrass

Bucket sweep-15 Amphipods, 3 shrimp, 2 larger Amphipods (different species ??), 12 Blood worms/Chironmous, 6 small snails and 3three segmented worms/pink colour.

Site 5

Very windy and rainy and yuk! Low water levels and lots of bird feet marks in the ground.

Weak growth of Seagrass

Bucket sweep-3 shrimp, and some small snails.

DATA COMMENTARY. We are comparing our data with July 25th.

  • 164 Black Swans on the upper lagoon, including 164 cygnets..SPRING!!
  • Water levels lower
  • Water temperature slightly lower
  • DRP –slightly lower in the upper lagoon, lower in the stream
  • NNN-lower in the stream but still significant and lower in the lower lagoon
  • Chlorophyll a – slight decrease at all sites but good signs of biological activity
  • E coli- The stream and Site 5 in the lower lagoon exceed our guideline values.

Commentary from Full Monitoring (FM) at Tomahawk Lagoon (TL) on July 25th 2018.


Air temperature ranged from 6.5 oC at 10.39 to 8.8 oC at 2.00. A cool day.

The wind was starting to build through out the day, 6.4km/h -9.7 km/h at 2.00.

Wind direction ENE

No rainfall during the day, 16 mm rain fell over the previous 4 days.

Site 1

10:40 am

65%ccv, light breeze, slight ripple, water very clear, cold day.

Abundant sea grass covered with silt, some pieces of Canadian pondweed.

Water boatman observed swimming in the weed along with many water fleas (Daphnia sp)

Abundant amphipods, one caddis fly larvae, abundant small snails and two Physa snails.

21 Black swans including 3 cygnets. Observed feeding very close to the hall.

Site 2

12:20 pm 

Sunny,cold wind from the east, ripples on clear water, very clear!!!

Abundant and healthy sea grass and pieces of Canadian pond weed.

Lots of Daphnia, abundant Amphipods and small snails, 2  Dytiscid beetles or water beetles.

Many birds all recorded on the e bird site.

Site 3

12:40 pm

Clear sky and cold wind, stream high and cloudy. No stock in the paddock.

Site 4

13:25 pm 

Continuous ripples, nor’easter wind, no clouds, very clear water, cold, relatively few birds.

A piece of Milfoil floated passed by, some weak patches of seagrass growing.

Our bucket sweep-12 shrimps, 3 amphipods, 2 small snails and 6 bloodworms (Chironmous midges).

Site 5

11:15 am

Moderate amount of water, very cold, breezy, a bit cloudy.

Weak patches of seagrass.

Bucket sweep-abundant Amphipods, few small snails.

DATA COMMENTS compared with 27th June.


Water levels have remained high due to rainfall on previous days


Site 4 and 5 show a slight decrease in salinity most likely due to extra freshwater falling and flowing through the catchment.


Water is very clear esp at S1 and 2 and cold.


DRP remains at quite a high concentration in the upper lagoon.


NNN remains high at most sites but very high in the stream flowing into the lagoon.


E. coli levels lower at all sites, S5 still exceeds guideline values.

Low water temperatures will slow down the bacteria growth and reproduction.


Algal levels have increased in the lower lagoon.


Bird numbers high in the upper lagoon, this is due to the significant growth of Seagrass in the upper lagoon.

Updated 4/09/2018