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

River and stream water quality and ecology in the Wellington region: State and trends
Makara Peak, Kaiwharawhara Stream at Ngaio Gorge and Waiwhetu Stream at
Wainuiomata Hill Bridge), respectively. With the exception of dissolved
copper and zinc at the Kaiwharawhara Stream site, all of these same sites also
exceeded their site-specific, hardness-modified TVs.
Maximum concentrations of dissolved copper recorded at two sites exceeded
the hardness-modified USEPA (2009) guideline for acute toxicity on one
occasion: the Porirua Stream at Glenside and the Porirua Stream at Wall Park
(Table 4.4). Maximum concentrations of dissolved zinc also exceeded
hardness-modified USEPA (2009) acute toxicity thresholds at four sites: Karori
Stream at Makara Peak (on four occasions), Porirua Stream at Wall Park (two
occasions), Waiwhetu Stream at Wainuiomata Hill Bridge (two occasions), and
Mangapouri Stream at Bennetts Road (one occasion).
Table 4.4: Summary of dissolved copper, lead and zinc concentrations (mg/L)
measured at ten RSoE sites, based on monthly sampling between July 2008 and
June 2011 (n=36). Median values in bold exceeded ANZECC (2000) chronic
toxicity (95% level of protection) TVs and underlined median values exceeded
site-specific, hardness-modified TVs. Maximum concentrations that exceeded
USEPA (2009) hardness-modified acute toxicity guidelines are also in bold font
Site
Mangapouri S
at Bennetts Rd
(RS02)
Ngarara S at
Field Way
(RS08)
Waikanae R at
Greenaway Rd
(RS10)
Porirua S at
Glenside
(RS15)
Porirua S at
Wall Park
(RS16)
Karori S at
Makara Peak
(RS18)
Kaiwharawhara S
at Ngaio Gorge
(RS19)
Hutt R opp.
Manor Park GC
(RS21)
Hutt R at Boulcott
(RS22)
Waiwhetu S at
Wainui Hill Br
(RS27)
Dissolved copper Dissolved lead Dissolved zinc
Med Min Max
n