NewLarned Zealand et al.—Low-elevation Journal of Marine river and water Freshwater quality inResearch, NZ 2004, Vol. 38: 347–366 347 0028–8330/04/3802–0347 © The Royal Society of New Zealand 2004 Water quality in low-elevation streams and rivers of New Zealand: recent state and trends in contrasting land-cover classes SCOTT T. LARNED1 ecosystems and human health. Water quality state MIKE R. SCARSBROOK2 varied widely within land-cover classes: E. coli and 1 dissolved nitrogen and phosphorus concentrations in TON H. SNELDER the pastoral and urban classes were 2–7 times higher NED J. NORTON1 than in the native and plantation forest classes, and BARRY J. F. BIGGS1 median water clarity in the pastoral and urban classes 1National Institute of Water and Atmospheric was 40–70% lower than in the native and plantation Research Limited forest classes. Water quality state in the pastoral class P.O. Box 8602 was not statistically different from that of the urban Christchurch, New Zealand class, and water quality state in the plantation forest email:
[email protected] class was not statistically different from that of the native forest class. Significant trends in low-eleva- 2National Institute of Water and Atmospheric tion rivers were limited to four parameters: flow Research Limited (trending down in all instances), and temperature, P.O. Box 11 115 clarity, and conductivity (trending up in all in- Hamilton, New Zealand stances). The trends in flow, temperature, and clar- ity were apparent at the national scale, and within the pastoral class. The magnitudes of these trends Abstract River water quality in New Zealand is were very low, corresponding to changes of £0.5%/ at great risk of impairment in low elevation catch- year in parameter medians.