Dr Daniel Collins is a hydrologist at NIWA. He formed the Waiology blog to bring together commentary on New Zealand's freshwater systems. The blog features commentary from numerous contributors.

Estuaries on the receiving end of catchment runoff - Waiology

Nov 06, 2013

By Judi Hewitt Estuaries are the transition between fresh water and the open coast, sheltered water that is neither fully saline nor fresh. The New Zealand coastline contains 441 estuaries, whose environmental characteristics are recorded in the Estuarine Classification database. Estuaries support a wide range of human activities and values and are an integral part of the cultural identity of New Zealanders. Ecosystem services (services that humans value) that estuaries provide range from food, recreation, high value real estate and cultural identity to cleansing contaminants from water before it enters the coast. The diversity of estuarine services, and the ability of estuaries to maintain them, is reliant to a large degree on a suite of ecosystem processes, the diversity of habitats within estuaries and the pressures that each estuary is under from human activities. Estuaries are frequently thought of … Read More

Water quality – What about the fish and the anglers? - Waiology

Oct 31, 2013

By Neil Deans New Zealand is blessed with an abundance and multitude of freshwaters which provide the habitat for an equally diverse array of species, including both native and introduced fish and wildlife. Some of these have intrinsic value; others are also valued because they provide food or recreational pursuit, or are indicators of a healthy environment. (Credit: G. Krewitt.)Anglers and game bird hunters have had a statutory interest and involvement in what lives in our freshwaters for over 150 years since Acclimatisation Societies (from which Fish and Game NZ was formed in 1990) were first established. While their early emphasis was on transplanting species here from elsewhere the primary focus of anglers and hunters for over 50 years has been on the protection of the habitats where these animals reside. Wetlands were appreciated by duck hunters … Read More

Effects of water quality on freshwater fish - Waiology

Oct 29, 2013

By David Rowe The presence and abundance of fish in our rivers depends on many factors, water quality being one. Water temperature, the amount of oxygen dissolved in the water, acidity (pH), ammonia concentration, and suspended sediment level can all influence the suitability of water for fish. When changes in land-use occur in river catchments, or pollutants enter waterways, one or more of these key variables can change such that the water quality deteriorates and fish are affected. Permissible limits for the water quality variables therefore need to be identified to avoid such effects and knowledge of the responses of fish species to water quality is essential for setting these limits. Freshwater fish have different tolerances to water quality, so that changes in water quality may translate to changes in the relative abundance of different species. (Upland bully, … Read More

Bugs in the system: How do we make sense of recreational water quality? - Waiology

Oct 23, 2013

By Gary Bedford When it comes to recreational use of freshwater, are we swimming in mixed messages? Fairfax reported that ‘More than 60 per cent of monitored rivers in New Zealand are unsafe for swimming according to Environment Ministry figures’. Dr Mike Joy from Massey University reportedly stated that 95% of New Zealand’s lowland rivers fail the bathing standard due to pathogens. And the Consumer organisation claims that gradings applied to bathing spots are more meaningful than actual water quality analyses[1]. To add to the confusion, monitoring is not undertaken or reported consistently inter-regionally or at a national level. If a site fails to meet the bacteriological standard, that doesn’t actually mean it is ‘unsafe’. And there’s a degree of ignorance, and/or political grandstanding, over how good or bad NZ’s freshwater recreational spots actually are. So … Read More

Pipes, ponds and beyond: Measuring and managing urban stormwater quality - Waiology

Oct 21, 2013

By Jonathan Moores and Jenni Gadd In keeping with urban areas throughout the world, New Zealand’s cities were established next to streams, rivers, lakes and harbours. As well as water supply, these waterways provided for transport, trade and recreation. Paradoxically, however, there is substantial evidence that urban development is harming these very same waterbodies. Parts of Auckland’s harbours, for instance, suffer from increased rates of sedimentation, toxic metal accumulation, reduced ecological health and a growing unsuitability for recreation [PDF]. These effects are at least partly due to discharges of urban stormwater. A stormwater treatment pond, Auckland’s North-western Motorway (J. Moores).Until the late 20th century stormwater management focused on drainage and flood control and stormwater was piped and discharged to the nearest waterway with no treatment. Stormwater was considered to be chemically benign, like rainfall. Now we know … Read More

An overview of the water quality in New Zealand rivers - Waiology

Oct 18, 2013

By Rob Davies-Colley The quality of water in rivers and downstream lakes and estuaries strongly affects how we can use it and what value we place on it. And to define water quality, it is imperative to make long-term, national measurements. Much information on the water quality of New Zealand rivers at national scale has come from monitoring at 77 sites in the National Rivers Water Quality Network (NRWQN) operated by NIWA for 25 years. A much larger number of water quality sites is operated by regional councils, though almost all have been running for shorter periods. The 77 river water quality monitoring sites in the National Rivers Water Quality Network (NRWQN) operated by NIWA. The sites are mostly located close to flow monitoring sites.Important attributes that together define water quality include: constituents important to aquatic life that vary … Read More

A primer on water quality - Waiology

Oct 16, 2013

By Clive Howard-Williams Society is increasingly concerned over water quality. The means by which this is maintained and enhanced while growing an economy is a major challenge for governments in many places. Here I introduce some underlying concepts around water quality that Waiology followers will need to appreciate when they look at the forthcoming series of blogs. What is good water quality? “Good” water quality depends on what the water is for (B. Diggles).Rather than just being a set of defined scientific numbers, water quality is rather a perception defined by communities and it varies from place to place and between communities. What is seen as poor water quality by some may be adequate for others. Generally however, good quality is usually recognized as water that is safely drinkable, swimmable and from where food may be gathered and … Read More

Un-muddying the Waters: Series on NZ water quality - Waiology

Oct 14, 2013

By Daniel Collins The state of our waters is a hot button topic. Water quality has become an election issue from Southland to Northland, from towns to nation, and it is often in the news. Swimming water quality and implications of the proposed Ruataniwha water storage and irrigation scheme in Hawke’s Bay are cases in point. Sediment plume from Hinemaiaia Stream into Lake Taupo (D. Rowe).What is at stake varies from place to place, but in general it is our health, wealth and well-being, which include industrial activity and the environment’s natural character and ecosystem services. These high stakes are reflected in public surveys. In a 2010 report from Lincoln University, water pollution and other freshwater issues were identified as the most important environmental issues facing New Zealand. While respondents generally thought our waterways were at least in … Read More

There’s more to whitebaiting than catching fish - Waiology

Sep 02, 2013

By Julia Bradshaw George Wood canned whitebait at Hokitika from 1893 until at least the 1920s. (Photo: Hokitika Museum, #4578)Unlike the rest of New Zealand, on the West Coast the season for catching whitebait starts on 1 September and the build-up has been noticeable during the last week. Distinctive huts have appeared along the sides of rivers, motor-homes are noticeably more common and there are more strollers than usual along the river-banks. They are keeping an eye out for shoals of whitebait, a sign that the season will be a good one. Catching whitebait has always been an important part of West Coast life. Tangata whenua had sophisticated and clever ways of catching mata (whitebait), all of which were copied by early Pakeha. Scoop nets, pot nets and trenches (stands) in use today can be easily traced back … Read More

Conservation and management of New Zealand whitebait species - Waiology

Aug 29, 2013

By Jane Goodman A bucketful of Giant kokopu (Photo: Emily Funnell).New Zealand’s whitebait fishery consists of the young of five migratory galaxiid species – inanga (Galaxias maculatus), koaro (Galaxias brevipinnis), banded kokopu (Galaxias fasciatus), giant kokopu (Galaxias argenteus) and shortjaw kokopu (Galaxias postvectis). Smelt (Retropinna retropinna) are also present in catches from some rivers along with the young of other fish species such as eels and bullies. (See Amber McEwan’s earlier blog.) Four of the five galaxiid whitebait species (inanga, koaro, giant kokopu and shortjaw kokopu are ranked in the New Zealand Threat Classification System (Townsend et al. 2008) as ‘at risk – declining’; banded kokopu are listed as not threatened (Allibone et al. 2010). Threat status is assigned according to the number of mature individuals (i.e. breeding adults), area of occupancy of the smallest area essential … Read More