Whangamata Harbour – contaminant loads and estuarine and coastal water quality, summer 2001

Four surveys of the loads of contaminants in the catchment of Whangamata Harbour were made during January-March 2001. Contaminant loads were calculated from measurements of stream flow and contaminant concentrations at sites on six streams and two stormwater outfalls flowing into the harbour. Purpose: To gain more knowledge of water quality in the Whangamata harbour and catchment following concerns about the health of the harbour.

31 sampling sites including inflowing waterways, Wentworth Valley, Waikiekie estuary, Moanaanuanu estuary, coastal waters. Survey dates: 11 January 2001, 8 February 2001, 22 February 2001, 9 March 2001 Variables measured: Flows, ammoniacal-nitrogen (amm-N), dissolved inorganic nitrogen (DIN), dissolved reactive phosphorus (DRP), Escherichia coli bacteria (Ec), Enterococci bacteria (ent), faecal coliform bacteria (fc), nitrate and nitritie nitrogen (NNN), salinity (S), water temperature (T), total Kjeldahl nitrogen (TKN), total nitrogen (TN), total phosphorous (TP), turbidity (turb).

Whangamata harbour and catchment

Sampling Sites: all NZNS 260, sheet T12 Otuwheti Stream @ SH 25 – 633 438 Wentworth River @ footbridge – 645 387 Waikiekie Stream @ SH25 – 638 414 Kaupeka Stream @ SH25 – 634 423 Okauanga Stream @ Link road – 638 397 Te Wheiti Stream @ SH25 – 636 418 Achillies stormwater – 646 388 Hetherington stormwater – 648 407 Wentworth Valley (WV) abobe camp – 603 357 WV ford – 610 360 WV near quarry – 620 375 WV above golf course – 637 381 WV Wairoa Stream – 614 372 WV Wairangi Stream – 617 374 WV Drain near quarry – 621 376 WV Muddy stream – 626 382 WV Drain through farm – 634 383 WV Drain near Widdison Place – 638 379 WV Drain near landfill – 636 379 Waikiekie estuary (WE) large pohutukawa – 640 416 WE stream mouth – 642 418 WE mid-bay mangroves – 644 416 WE off Moana Point – 646 414 WE off southern point – 648 412 Moanaanuanu estuary (ME) upstream of link road bridge – 646 387 ME downstream of bridge – 645 393 ME downstream of small island – 647 395 ME near large pohutukawa – 643 398 ME upstream end of main arm – 642 402 Wharf – 657 406 Ebb-tide delta – 660 402

January – March 2001

Field collection of water quality data using standard field measurements and techniques, and standard laboratory measurements used. Frequency of collection: 4 sample periods

Short sampling period. Sites C2 and S4 should not be compared as sampled at different times. Gaps in collection: Not reported Data quality: Standard field and laboratory procedures followed. Attribute accuracy: Standard field and laboratory procedures followed. Completeness: About 15% of the harbour catchment was unmonitored (7.2 km2) and the flow of water and contaminant loads were estimated. No attempt was made to estimate the contaminant loads to the harbour from the many unmonitored urban stormwater outfalls.

report appendices, electronic, maps Digital Format: MS Excel

Publicly available Sensitivity/Confidentiality: No restrictions

Completed