River and stream water quality and ecology - Greater Wellington ...

River and stream water quality and ecology in the Wellington region: State and trends
Table 4.11: Summary of meaningful trends (ie, p1%
per year) in NNN, Amm N and TN concentrations (mg/L) recorded at RSoE sites
over July 2006 to June 2011. MASS=median annual Sen slope (mg/L/yr)
calculated using the Seasonal Kendall test. The arrow indicates the direction of
the trend
Site Site name Median n MASS
Raw data Flow-adjusted data
Rate of
change
(%/year)
Trend n MASS
Rate of
change
(%/year)
Nitrite-nitrate nitrogen (NNN)
RS05 Otaki R at Pukehinau 0.038 60 -0.003 -8.7 ↓ 60 -0.004 -10.5 ↓
RS08 Ngarara S at Field Way 0.255 60 -0.054 -21.0 ↓ Not assessed (no flow data)
RS15 Porirua S at Glenside 1.000 60 -0.058 -5.8 ↓ No trend
RS16 Porirua S at Wall Park 0.990 60 -0.044 -4.5 ↓ No trend
RS24 Mangaroa R at Te Marua 0.484 60 -0.029 -6.0 ↓ No trend
RS25 Akatarawa R at Hutt Confl. No trend 60 -0.008 -8.0 ↓
RS28 Wainuiomata R at Manuka Trk 0.075 58 -0.006 -8.3 ↓ 57 -0.006 -7.7 ↓
RS30 Orongorongo R at Orongo. Stn 0.056 59 -0.014 -25.5 ↓ 53 -0.015 -28.7 ↓
RS31 Ruamahanga R at McLays 0.025 60 -0.002 -6.9 ↓ No trend
RS32 Ruamahanga R at Te Ore Ore 0.397 60 -0.037 -9.4 ↓ No trend
RS33 Ruamahanga R at Gladstone Br No trend 60 -0.038 -9.5 ↓
RS36 Taueru R at Castlehill No trend 60 -0.010 -14.5 ↓
RS37 Taueru R at Gladstone 0.910 59 -0.120 -13.2 ↓ Not assessed (no flow data)
RS39 Whangaehu R 250 u/s confl. 0.965 60 -0.214 -22.2 ↓ Not assessed (no flow data)
RS46 Parkvale S at Weir No trend 57 -0.130 -10.5 ↓
RS49 Beef Ck at Headwaters 0.024 60 -0.003 -12.4 ↓ Not assessed (no flow data)
RS50 Mangatarere S at SH 2 No trend 59 -0.051 -4.1 ↓
RS52 Tauanui R at Whakatomotomo 0.012 59 -0.001 -8.8 ↓ 59 -0.001 -12.3 ↓
Ammoniacal nitrogen (Amm N)
RS08 Ngarara St at Field Way 0.03 60 -0.007 -26.7 ↓ Not assessed (no flow data)
RS18 Karori S at Makara Peak 0.01 60 -0.001 -10.6 ↓ No trend
Total nitrogen (TN)
RS07 Mangaone S at Sims Road Br 2.60 60 -0.188 -7.2 ↓ 60 -0.117 -4.5 ↓
RS08 Ngarara S at Field Way 1.00 60 -0.100 -10.1 ↓ Not assessed (no flow data)
RS15 Porirua S at Glenside No trend 60 -0.057 -4.4 ↓
RS17 Makara S at Kennels No trend 60 -0.034 -5.6 ↓
RS27 Waiwhetu S at Wainui Hill Br 0.80 59 -0.049 -6.1 ↓ 59 -0.040 -4.9 ↓
RS29 Wainuiomata R u/s of White Br 0.38 59 -0.036 -9.4 ↓ No trend
RS32 Ruamahanga R at Te Ore Ore 0.56 60 -0.049 -8.9 ↓ No trend
RS33 Ruamahanga R at Gladstone Br No trend 60 -0.046 -6.8 ↓
RS35 Mataikona trib at Sugar Loaf Rd 0.19 59 -0.025 -13.2 ↓ Not assessed (no flow data)
RS37 Taueru R at Gladstone 1.47 59 -0.151 -10.3 ↓ Not assessed (no flow data)
RS39 Whangaehu R 250 u/s confl. 1.70 60 -0.197 -11.6 ↓ Not assessed (no flow data)
RS44 Totara S at Stronvar 0.15 58 -0.026 -17.2 ↓ 58 -0.020 -13.1 ↓
RS45 Parkvale trib at Lowes Res. 4.80 47 -0.298 -6.2 ↓ No flow data
RS46 Parkvale S at Weir No trend 57 -0.116 -6.1 ↓
RS54 Coles Ck trib at Lagoon Hill Rd 0.23 50 -0.012 -5.4 ↓ Not assessed (no flow data)
WGN_DOCS-#1100598-V3 PAGE 49 OF 160
Trend
Despite a number of ‘impacted’ sites showing improvements, such as Ngarara
Stream at Field Way (which now meets the ANZECC (2000) lowland TV for
Amm N, Figure 4.18), in many cases the overall median values of NNN and
TN are still elevated when compared against their respective ANZECC (2000)