Annual report 2006-2007 - Taranaki Regional Council

Site E: Kahouri Stream (KHI000400)
This site in the Kahouri Stream at the Flint Road bridge was located nearly 800 metres below
the confluence of the tributary stream from the stockcar grounds catchment, and 2.7 km
downstream of site C. A moderately high community richness of 27 taxa was found at this
site, slightly higher than the long term median richness (Table 2) but similar to that recorded
at the nearest upstream site (C). The community was characterised by one ‘highly sensitive
taxon (Deleatidium mayfly), five ‘moderately sensitive’ taxa (Coloburiscus and Austroclima
mayflies, elmid beetles, Archichauliodes dobsonfly and Aphrophila cranefly), and two
‘tolerant’ taxa (Aoteapsyche caddisfly and orthoclad midges).
MCI value
140
120
100
80
60
40
20
0
Number of taxa and MCI values in the Kahouri Stream below Flint
Road bridge (KHI000400)
Jan-88
Jan-89
Jan-90
Jan-91
Jan-92
Jan-93
Jan-94
Jan-95
Jan-96
Jan-97
Jan-98
Jan-99
Jan-00
Jan-01
Jan-02
Jan-03
Jan-04
Jan-05
Jan-06
Jan-07
MCI value M edian M CI to date
No. of taxa M edian no. of taxa to date
Figure 7 Number of taxa and MCI values in the Kahouri Stream at site E (KHI000400)
As was the case with the community upstream at site C, the high proportion of ‘sensitive’
taxa (62% of total richness) was responsible for the MCI score of 104 units, slightly higher
than the long term median value (Figure 2). It was also slightly higher than the score
recorded 2.7 km upstream at site C despite the distance between these two sites and the
documented natural deterioration in communities in a longitudinal direction (eg: 2.6 MCI
units/km in ringplain streams (TRC, 1999)). This site actually recorded the highest MCI
score of this survey.
The increased abundance of a number of ‘sensitive’ taxa from site C to site E resulted in the
significant increase of 1.2 SQMCIS unit over this stream reach (Stark,1998). The SQMCIS
value at site E (6.0 units) was the highest recorded at this site to date, and significantly
higher than the median value from the eight most recent surveys (Table 2) at this site
(Stark,1998).
These results indicate that the cumulative discharges from the various industries situated in
the Kahouri Stream catchment upstream of Flint Road had not recently had significant
detrimental impacts on the biological communities of the stream, particularly considering
the relatively low flow conditions over the summer period. The downstream trend in
SQMCIS scores (Figure 3) followed the trend in historical median scores through this reach
of the Kahouri Stream.
Site F: Kahouri Stream (KHI000457)
This site, immediately upstream of the Stratford Power Station (elevation: 270 m asl), was
located about 2.2 km downstream of site E. A moderately high community richness of 26
10
70
60
50
40
30
20
10
0
No. of taxa