Aquatic publication review (36)

Why does water cost money? Because treating it for consumption is an expensive process, and also quite energy-intensive. Before complaining about the price of water, it’s worth reading analyses on the energy requirements of its various treatment processes. And it will become all the more expensive the more scarce it becomes, to which the lack of adequate protection of water and water-dependent ecosystems will certainly contribute.

Did you know that only 17 percent of the world’s peatlands are under protection? This is worrisome, especially since the ecological state of the waters still leaves much to be desired – long time series analyses indicate that, while waters that were in poor and bad condition have improved over the past decade, at the same time those in very good and good condition have lost quality. We also return to the question of whether beavers are useful environmental engineers or pests – the results of a study by Scottish scientists provide further arguments for appreciating these mammals.

1 Magni M., Jones E. R., Bierkens M.F.P., van Vliet M.T.H., (2025). Global energy consumption of water treatment technologies. Water Research, 277, 123245

Seemingly obvious, yet not everyone realizes that providing people with clean and safe water for consumption is a rather energy-intensive process. The needs in this regard are poorly quantified on a global scale. A team of researchers from Utrecht has attempted to estimate the energy consumption needed to treat water using different technologies for three processes – conventional treatment of water drawn from groundwater and surface water, desalination and wastewater treatment.

The authors made a meticulous analysis of various technologies, their energy intensity and spatial and temporal variability (for available data from 1945-2019) worldwide. It turns out that globally, in one year alone (2015), these processes required 379-1159 TWh (1.36-4.17 EJ) of energy, which corresponds to between 1.8 and 5.4 percent of total global electricity consumption. Of this, 189-331 TWh was consumed in desalination processes, 85-279 TWh for wastewater treatment and 105-549 TWh for conventional drinking water treatment. The highest consumption was in the Middle East and North Africa (where desalination dominates), Western Europe (wastewater treatment) and South Asia (conventional drinking water treatment), where the listed processes account for 19, 2 and 5 percent of electricity consumption in these regions.

The results of the research make it possible to forecast future energy demand for water treatment technologies and to better understand the link between water demand and the energy required to obtain it. It is useful to be aware of such relationships before asking why water is getting more expensive.

2. Austin K.G., Elsen P.R., Coronado E.N.H., et al. (2025). Mismatch between global importance of peatlands and the extent of their protection. Conservation Letters, 18:e13080

A month ago (February 2) we celebrated World Wetlands Day, and I think we are all aware of how important these ecosystems are for water retention and carbon sequestration. A review of the issue of conservation of these valuable areas on a global scale, published in Conservation Letters, indicates, unfortunately, a very low level of their protection.

An analysis of data on the global distribution of peatlands (Peat-ML map, compiled on the basis of peat soils lying to a depth of at least 30 cm) and protected areas revealed that globally, only 17 percent of peatlands are under legal protection, a much lower percentage than for other ecosystems of particularly high conservation value, such as mangroves, salt marshes and tropical forests. Only 11 percent of boreal peatlands and 27 percent of temperate and tropical zone peatlands are under legal protection. Moreover, in these zones, almost half of such ecosystems, despite being located in protected areas, are still subject to moderate and sometimes even strong human pressure (more than one-fifth of all peatlands worldwide, with regions in Europe and on the east coast of the US being the most vulnerable).

The authors of the text pay special attention to the need to strengthen the protection of peatlands. In addition to this, it is also necessary to restore peatlands that have already been degraded, which involves altering water flows in the wetlands and re-wetting the drained peat. Conservation measures do not necessarily mean banning use, but rather aim to ensure their proper (sustainable) use.

3 Lyche Solheim A., Thrane J.-E., Mentzel S., Moe J.S., (2025). Harmonized biological indicators for rivers and lakes: Towards European assessment of temporal trends in ecological quality. Ecological Indicators, 171, 113207

One of the many benefits that EU countries have achieved after a quarter-century of implementation of the Water Framework Directive is access to long-term monitoring data series with a similar range of parameters. The requirement to capture the ecological status of individual groups of organisms in the form of standardized ecological quality ratios (EQRs ranging from 0 to 1) makes it easier to compare states and track multi-year trends not only across countries, but across the EU.

A team of scientists affiliated with the European Environment Agency (EEA) presented in the journal Ecological Indicators an analysis of trends in ecological condition based on consistent time series of normalized EQR values from 2015-2021. They looked at four quality elements: phytobenthos and benthic macroinvertebrates in rivers, and phytoplankton and macrophytes in lakes, using examples from 2,500 rivers and 700 EU lakes. For each analyzed quality element (group of organisms to be assessed), the time series were grouped according to their initial state (i.e., ecological quality in 2015).

Positive trends, indicating improvement, were found for those quality elements that initially showed poor or poor condition overall, i.e. phytobenthos and benthic invertebrates in rivers, and phytoplankton and macrophytes in lakes. Conversely, negative trends were indicated for all groups of organisms with very good or good initial condition (although these changes were statistically significant only for phytobenthos and invertebrates). These preliminary results show the potential of ecological quality indicators in assessing the effectiveness of European water policy. At this point, the study shows that what was good has deteriorated and what was poor has improved, so everything tends to average out. However, the study’s authors point out that longer time series will be needed to more reliably assess trends in the ecological quality of water bodies.

4. White H. L., Fellows R., Woodford L., et al. (2025). The impact of beaver dams on distribution of waterborne Escherichia coli and turbidity in an agricultural landscape. Science of The Total Environment, 968, 178871

There has been a lot of talk about beavers in the media recently, mainly because of extremely different interpretations of the effects of their hydroelectric activities on humans and the environment. Advocates of these useful mammals are provided with further arguments for their protection by a paper by Scottish ecologists from the University of Stirling, which appeared in Science of the Total Environment. The authors examined the impact of European beaver(Castor fiber L.) structures, comprising a sequence of 14 dams and associated beaver ponds, on the variability of Escherichia coli concentrations and water turbidity in a watercourse flowing through agricultural land. Based on a two-year study (August 2017-July 2019), they showed that while the dams were a source of E. coli and turbidity increases, the ponds acted as clarifiers and sinks for these pollutants in this system.

To confirm these findings, the researchers conducted an in-situ experiment in 2023 involving the introduction of manure (25 l) into two closely spaced, comparable streams, one of which was modified by beavers and the other not (control). Analysis of pollutant concentrations along these streams showed that the presence of beaver ponds reduced E. coli concentrations by more than 95 percent compared to the control stream. This study shows that dams affect microbial contaminants and can significantly reduce the amount of contaminants reaching downstream receivers. Beaver dams (or their analogs) could support environmental management strategies in agricultural systems as part of nature-based solutions (NBS).

[1] https://doi.org/10.1016/j.watres.2025.123245
[2] https://doi.org/10.1111/conl.13080
[3] https://doi.org/10.1016/j.ecolind.2025.113207
[4] https://doi.org/10.1016/j.scitotenv.2025.178871