Our fresh water 2017 – Expert reaction

UPDATED: The Ministry for the Environment and Statistics New Zealand have released the latest national report about the state of freshwater.

Our fresh water 2017 measures the quality of New Zealand’s waterways, including water quality, biodiversity and cultural health.

Nitrogen levels at over half of monitored river sites are getting worse, according to the report and 72 per cent of the 29 native fish species monitored are either threatened with or at risk of extinction.

The SMC gathered expert reaction to the report, please feel free to use these comments in your reporting. The report is available on the MfE website.

Professor Jenny Webster-Brown, director, Waterways Centre for Freshwater Management, University of Canterbury, comments:

“The data compiled in the MfE report conclusively confirms that the overall quality of our freshwater environment is declining … rapidly. This is consistent with all recent reports and research on our freshwater systems … there is little evidence to the contrary.

“In the last 10 years we have begun to address the problem through policy changes and law amendments, but a greater investment of time, funding and effort is needed in action and innovation before we will be able to halt and, if possible, reverse this trend.

“Consistent, rigorous monitoring data is vital to understand the freshwater environment’s response to pressure but, on its own, will simply continue to chart the decline of water quality, quantity and ecosystem health.

“The report highlights the ongoing and escalating problem of nitrogen leaching from land into the waterways. This compares with apparently improved control of phosphorous, from the same source, likely due to more fencing and planting of riparian strips on agricultural streams.

“Nitrogen control is a more difficult problem to solve, particularly with the legacy of high nitrate in groundwater in agricultural regions of NZ, but this should act as an even greater incentive to find/fund solutions and ways to manage high nitrate concentrations (for example, in drinking water) in the meantime.

“The report also highlights the poor state of urban streams, something which is easily overlooked in the rush to blame dairy farmers for all of our freshwater problems.

“There are already solutions available for preventing contamination of urban streams, a problem shared by all cities, and yet we still cling to the same systems of stormwater control and choice of problematic building materials that have led to these issues …. and over-use urban water supplies that would otherwise recharge these systems.   

“Obstacles to uptake of sustainable urban water technologies need to be identified and removed.

So, by all means, collect more data to address the data gaps identified in the report … this is essential. However, it is vital that we also invest in, and otherwise provide incentives for, actions that will protect our freshwaters and change this scenario for the better.”

Dr Chris Daughney, division director – environment and materials, GNS Science, comments:

The report emphasises the ‘legacy effects’ on groundwater, i.e. that it takes a long time for our impacts to be seen in groundwater and also for it to recover. What do we know about our impacts on groundwater, past and present?

“Human activities have affected groundwater quality at about 40% of long-term monitoring sites across New Zealand. At these sites, the main sign of human impact is in the form of nitrate concentrations that are above the natural baseline (i.e. the concentrations that are expected in the absence of human impact). At many of these sites the observed nitrate concentrations are not far above the natural baseline, but at some sites (about 5% of the total number of long-term monitoring sites), the nitrate concentrations are much higher than baseline and can even exceed the drinking water standard.

“We can use our in-house expertise at GNS Science to evaluate the age of the groundwater that we are testing. We can see that, for groundwaters that were recharged prior to about 1880, the nitrate concentrations tend to be low and at baseline levels. For groundwaters that were recharged from about 1880 to about 1955, the nitrate concentrations increased slightly in some parts of NZ. For groundwaters recharged since about 1955, the nitrate concentrations in some monitoring sites have exceeded baseline by a significant margin.

“Through this work, we have inferred that the increase in nitrate concentration from baseline to slight elevation around 1880 corresponds with the start of the meat export industry in NZ, whereas the transition to even higher nitrate concentrations at some sites after 1955 corresponds with the onset of industrialised agriculture.”

Of monitored groundwater quality sites, 55 per cent were ‘indeterminate’. Do we have sufficient data to detect trends in groundwater quality?

“‘Detecting’ trends means that the change over time is statistically identifiable by some particular test. In other words, there will always be some trend in groundwater quality, but our statistical test may not be able to detect it.

“The ability of a statistical test to detect a trend depends on how many measurements we have over time (a longer time series record makes it easier to detect the trend). Trend detection also depends on the rate of change that is occurring (the faster the change in groundwater quality, the fewer measurements we need to detect it). And trend detection is also affected by the variation in the dataset (if the data are quite noisy around the long-term trend then it is more difficult to detect the trend statistically).

“All this said, the main message is that we need to continue our on-going long-term monitoring of groundwater quality across NZ, so that we can identify trends as robustly and as quickly as possible.”

How could we improve our understanding of these water resources, both in terms of quality and volume?

“Short answer: more monitoring and scientific investigation. The fact is that groundwater resources are very important for NZ, but they remain poorly understood. For example, 3D geological models of aquifer systems are important for groundwater management. These models tell us how much groundwater is likely to exist in the aquifer, where the groundwater is found and what flow paths it might take through the aquifer. So far we only have such 3D geological models for about 30% of NZ’s aquifers. And that’s just one type of information we need to more effectively understand our groundwater systems.”

Dr Mike Joy, freshwater ecologist, Massey University, comments:

“Our Freshwater Report 2017 from the Ministry for the Environment definitely shows an improvement in honesty on their water chapter in the recent state of the environment report. However, there are still some really obvious attempts shift focus away from agricultural impacts.

“Once again waterways in urban catchments are given the same prominence as pastoral even though urban make up less than 1% of river length and pastoral are 40%.

“First I’ll go through their key findings in the media release to demonstrate some of the biases.

• Nitrogen levels: the report says 55% are getting worse and 28% getting better, but that’s for all sites. If, as would be logical you look at landcover classes separately (figure 11) then looking at pasture sites then of the sites that showed a trend then 72% got worse and 28% better.
• Phosphorus is a non-issue because the algae can in most cases get all the phosphorus they need to cause problems from the sediment where levels are high, so don’t need it from water which is where it is measured.
• For E. coli the report inexplicably switches from 20-year record (for other parameters) to 10 years and as would be expected after removing most of the data then most (52%) of sites have no trend because of this lack of data. However, of the significant trends left then for pasture catchments, 60% got worse and 40% better (for urban one site got worse).  This sounds a bit different to the 22 times higher in urban and 9.5 in urban reported.

“In the detail of the main report, a number of issues arise, apparently from a lack of freshwater ecological knowledge. In the section on nitrogen then figures are present using the banding from the National Policy Statement.

“This approach is flawed for two reasons: 1). As far as I’m aware the limits are still subject to public submissions so could and should be changed and 2). Nitrate toxicity is a red-herring because we know that fish or invertebrates cannot die twice.

“Much lower levels of nitrate (actually in the A band) are well known to have algal blooms at that cause fish deaths through oxygen depletion, so the amount of nitrogen that is toxic to them is a non-issue and only occurs in laboratory experiments and not real-life.

“The ANZECC guideline level is around 0.5 mg/l about one tenth of the toxic limit, thus using these toxic limits is disingenuous.

“Next, the section on algal blooms starts with the statement that 83% of the length of rivers is not expected to have prolonged algal blooms. This statement misses the point because just one day of a bloom is just as lethal to fish and other life as any longer length of time, once again they can’t die more than once.”

Ken Taylor, Director, Our Land and Water National Science Challenge, comments:

“I agree with the overall conclusions of the report about the state of our water quality. We’ve had a beneficial shift in thinking around water quality which means that no-one is now denying that there’s a problem.

“We no longer have to demonstrate there’s a problem, there’s plenty of information to show that there is, now we need to focus on finding the solutions to the problem.

“All over the country, there are communities working hard to come up with solutions to work sustainably within environmental limits.

“There is already research underway to understand the way that pressures on the land impact on our water quality. One of the roles of the Our Land and Water, National Science Challenge is to look at finding the solutions to these issues that already exist.

“One of the problems with the report is that it only presents half the story, the bad news half not the good news half.

“In many cases the report points to a lack of data which is unfortunate because there is a lot of available data on these issues which could have been included, this means this picture we’re being presented is only a partial one.

“The report is constrained by the Environmental Reporting Act, which limits what can be reported on to the current state and trend of environmental pressures, it doesn’t discuss the levels of response which are already going on to counteract these issues.

“We’re already seeing promising responses at a community level, in policy and in scientific research working towards offsetting the issues we’re dealing with now.”

NOTE: Ken was part of the technical advisory group for the report and is a member of the Land and Water Forum.

Dr Joanne Clapcott, freshwater ecologist, Cawthron Institute, comments:

“I was primarily involved with the TAG to provide input on the stream sediment section and feedback on the overall presentation of the report.

“The TAG gave their time and expertise to this free of charge as we want to ensure the public has the best possible information about the state of freshwater in New Zealand.

“The Our fresh water environment 2017 report provides a robust assessment of the degraded state of New Zealand’s freshwaters. However, it’s important to note we are limited as we can only report on topics with available data.

“There’s a clear need to collect more data and better measure the ecology of freshwaters. Our biodiversity is at risk and we need to adopt better methods to assess biodiversity based on the innovative technologies available today.”

Professor Richard McDowell, Chief Scientist, Our Land and Water National Science Challenge, comments:

Dr Scott Larned, manager – freshwater research, Niwa, comments:

There has been a big public focus on ‘swimmability‘ but what are some of the other big issues facing our freshwater ecosystems?

“Yes, there are several big issues. Some of the biggest are wetland loss and degradation, nutrient enrichment in lakes, estuaries and lowland rivers, invasive non-native species (particularly aquatic plants and algae), potential effects of river flow alteration due to diverting flood flows to storage (a potential problem at this point, with inadequate data), potential decline and loss of rare native species, and high contaminant levels (including dissolved metals) in urban streams.”

Were there any trends found in the latest data that were of particular concern?

“There is a real mixture of improving and degrading trends in water quality, and this applies to all of the major land-cover classes (pastoral, urban, natural and plantation forest). The general trend of greatest concern is the gradual increase in nitrate-nitrogen at many (but not all) pastoral and urban river monitoring sites.

“This general pattern may be partly due to the ‘legacy effect’ of nitrate that was leached from land years or decades ago and is now emerging from groundwater into surface water. It’s a concern because it’s very difficult to reduce nitrate levels in groundwater, and because the current trend may continue far into the future due to the legacy effect.”

Several data gaps have been identified, what areas do you think we need to spend more effort to better understand?

“Good question. In general, the freshwater domain report focuses on patterns. These include patterns in space, like broad differences in water quality in urban, agricultural and native forest areas, and patterns in time, like temporal trends in water quality and fish abundance.

“What we need most, in addition to patterns, are cause-and-effect relationships. We need to identify causes to understand why some water quality variables are getting worse in some areas, and other variables are improving. The most valuable causal data would be detailed land use data. These data are not available at national scales, so we rely on land-cover data instead, which doesn’t provide cause-and-effect relationships.

“To make this need more tangible, here is an example. There is a widespread improvement underway in river phosphorus concentrations in agricultural areas. This could be due to stock exclusion, better fertiliser management, better effluent management, better erosion control, or some combination.

“If we have good information about the causes for the improvements in river phosphorus, we can encourage specific practices, and provide evidence that investments in fencing, effluent treatment, etc. are good investments.

“Other big gaps include wetland monitoring, which is minimal at present and mostly focused on the extent of wetlands, not their conditions. More lakes and groundwater sites need to be monitored to assess national state and trends. And more rivers in undeveloped catchments (like the DOC estate) need to be monitored to provide baseline conditions.

“Those baselines are needed to identify the effects of global change without the confounding effects of local land use. Baselines are also needed for restoration targets.

“More work on the health risks of cyanobacteria is needed. Cyanobacteria and faecal pathogens are both part of the swimmability proposals, but our knowledge of health risks due to contact recreation near cyanobacteria is pretty minimal.

“For water quantity, the biggest gap is measured abstraction data (also called ‘metered takes’). The current analyses are based largely on consented takes, which are potential, not actual. Other gaps in water quantity reporting concern interactions between surface water and groundwater, including how abstraction of one affects the quantity of the other.

“For ecosystems and habits, the biggest gaps include physical habitat monitoring, fish, periphyton and cyanobacteria monitoring, and estuary monitoring.  Regional councils are starting to expand their monitoring programmes to include these areas, but it will be several years before there is adequate data for accurate assessments.”