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Figure 10.6: Comparison of Trophic Level Index water quality variables between lakes in pasture catchments and lakes in natural catchments, 2004–2006

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Notes:

  1. Total nitrogen concentrations are much higher than total phosphorus concentrations, but nitrogen values have been scaled down by 100 in this graph for the purposes of presenting information on both nutrients together.

  2. mg/L = milligrams per litre.

Data source: Ministry for the Environment, in press c.

Text description of figure

Bar graph comparing water quality variables for lakes in pasture versus natural catchments.  Key feature is that nutrient levels are higher and visual clarity lower in lakes in pasture catchments.

 

Parameter

Natural catchment (39 monitored lakes)

Pasture catchment (55 monitored lakes)

Total nitrogen 
(mg/L) 

0.00174 (scaled for graph)
0.174 (actual)

0.00733 (scaled for graph)
0.733 (actual)

Total phosphorus
(mg/L) 

0.0083

0.051

Algae (Chlorophyll a)
(mg/L) 

0.0017

0.0094

Visual clarity (m)

6.4

1.2