CREW Newsletter Nov 2020
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A journey along the River Dee, NE Scotland
CREW manager Dr Rachel Helliwell and Partnership chair Prof Marc Stutter hiked, biked and canoed their way for three days from the Pools of Dee high in the Cairngorms to the sea at Aberdeen harbour. Besides capturing the beauty of the catchment, the film shot by the pair summarises the main pressures on Scotland’s water environment, such as climate, land use and changes in demographics.
“It was a great adventure”, Rachel says. “We wanted to describe the catchment from the source to the mouth – how the river changes along its course, how the various pressures on the river change along that journey.
The film covers a range of issues and provides an update on how academia, public bodies and the water industry are working together as a ‘Hydro Nation’ to overcome these challenges. “In the mountains we discussed climate change and the impact of less snow on river flows and temperatures, then as we cycled through the middle reaches of the catchment we addressed topics such as forestry and land management, and in the lower reaches we discussed the importance of agriculture, increased development in response to population pressures, and flooding,” she explains.
“We really want to get across the different perspective gleaned from travelling along the river at a slow pace and inspire a curiosity in the Dee and its catchment.”
Marc adds: “The river essentially has three zones, which mapped quite neatly onto the three days we spent travelling it, using three different modes of transport. We were keen to show the connections between the top and bottom of the river – and that issues at the bottom of the catchment depend very much on what happens at the top.”
The pair hope that the video will serve as a great teaching tool to showcase the importance of sound catchment management, and hopefully appeal to the public too. The film, titled “Journey along the River Dee, NE Scotland” is available to watch on YouTube here: https://www.youtube.com/watch?v=d1vtLVAPx7o&feature=youtu.be&app=desktop
Private water supplies and the potential implications of climate change
Review of the likely impacts of climate change (amount, frequency and distribution of precipitation), and the resilience of private water supplies
Climate change is affecting Scotland’s weather patterns, which in turn impacts the quantity, distribution and frequency of precipitation. This study will review existing data and studies from Scotland and other countries or regions in broadly comparable climatic zones. Outputs from this project will help to inform new policies and provide evidence to existing policies that seek to ensure that communities and households have reliable and sustainable access to drinking water supplies.
Private water supplies (PWS) are those supplies that are not provided by Scottish Water, and instead are the responsibility of their owners and users. PWS source their water from either surface or groundwater. There are over 22,000 PWS in Scotland serving nearly 4% of the population. Quantity can be problematic for both groundwater and surface water supplies, with some reducing in flow or drying up completely particularly during the summer months. Some supplies run dry every year.
Climate change over the coming decades is expected to continue to bring increasingly variable weather, including drier and warmer summers. Little is known about how dry periods will impact private water supplies. An understanding on the impacts is required so that the Scottish Government can consider policies to ensure that communities in remote and rural areas, which are typically served by private water supplies, have access to water supplies that are less vulnerable to changes in river flows (e.g. low flows in summer months), and declining water tables and associated impact on spring flows.
The policy drivers behind this project are as follows. PWS must meet the requirements for Drinking Water Quality as set out in the Drinking Water Regulations (The Water Intended for Human Consumption (Private Supplies) (Scotland) Regulations 2017). The standards are derived from the EU Drinking Water Directive which is in turn derived from advice from the WHO. Sufficient water quantity is a basic condition for adequate living standards in line with the Sustainable Development Goal 6 (SDG: Access to water and sanitation for all). Supplies are classified into regulated (Type A) and exempt (Type B) supplies. Regulated are typically supplies serving more than 50 people, more than 10m3 or those that supply a commercial or public premises (including rented and tied accommodation). There are some 2500 regulated and 20,000 exempt supplies in Scotland.
Research question(s) to be answered through this project
Phase 1: What are the likely impacts of future changes in the amount, frequency and distribution of precipitation and the resilience of private water supplies (PWS)? What recommendations can be provided to policy-makers to enhance the resilience of PWS?
Phase 2: What can be deducted from climate change projections (modelling data) regarding changes in precipitation? How will different regions in Scotland be affected? How will it affect regions where PWS predominate?
Evaluating an upland NFM hydrometric network: implications for future monitoring
This project sought to assess the hydrometric network of the River Knaik catchment (37 km2) in Perthshire in terms of fitness for purpose and quality of the data collected to date for evaluating Natural Flood Management (NFM) measures. Rainfall and stream gauges were installed to measure the hydrological response to land use changes brought about by NFM. This evidence was needed to evaluate NFM in the catchment and inform future schemes.
The project found that the locations of the sensors to monitor hydrological change were appropriate given the planned NFM measures (peatland restoration, reduced sheep stocking density and tree planting). However, owing to technical problems and maintenance issues, the data quality was not sufficient to evaluate the effectiveness of measures for mitigating flood peaks.
Based on this assessment, options for redeploying the monitoring network elsewhere, alternative monitoring approaches and improving the current network were outlined. Of wider relevance to the practice of NFM hydrometric monitoring, this assessment highlighted the importance of long-term monitoring for reliable evaluation, the need for long term funding commitment (e.g. supporting staff to download and maintain the equipment) and technical input from a hydrologist. A research summary is provided below.
Tracking SARS-CoV-2 via Municipal Wastewater
Sampling wastewater from a community can be a relatively straightforward way to determine if specific agents are being excreted by that population. As SARSCoV-2, the causative agent of COVID19, can be present in the faeces of infected people, then it may be possible to determine if a community has infected individuals by monitoring the wastewater or other sewage samples for the presence of the virus. The most sensitive method for detection of the virus is to amplify sections of its RNA genome, a practice that is now applied to respiratory tract swabs worldwide to determine whether people are infected. This three-month project had two main objectives:
(1) to test methods to concentrate, extract and amplify viral RNA from different wastewater samples to work out whether the virus can be detected;
(2) to add a safe ‘control’ virus into wastewater samples to compare the efficiency of methods between different laboratories and to account for losses during processing to help determine exactly how many SARS-CoV-2 viral particles were in the wastewater sample.
A key point is that this project was not assessing whether any detected SARS-CoV-2 RNA represented the presence of infectious viral particles. The focus was to develop a detection tool for the virus in communities that could help to identify infected populations. The project compared several published methods for viral extraction from wastewater and then looked at other sewage plant samples such as ‘sludge’ and ‘cake’ as well as some of the outflow water that is released into the environment. The main results were as follows:
(1) A safe control virus was compared against SARS-CoV-2 as a way to measure detection efficiency from different types of samples. This control virus behaved in a very similar way to the pandemic virus and is now being supplied to other laboratories as a safe way to test any concentration and extraction methods. We used both this virus and SARS-CoV-2 to measure the efficiency of the methods trialled.
(2) SARS-CoV-2 virus was detected in certain wastewater samples collected during the initial wave of the pandemic in Scotland. The different methods tested offer different pros and cons. The two main methods, spin filter columns and PEG precipitation can both work, but both can have high losses of virus. Columns are quite expensive and may be subject to supply problems, whereas precipitation can more easily handle larger volumes, but requires a high-speed spin step needing more specialised equipment.
(3) Direct extraction from more solid samples such as ‘sludge’ and ‘cake’ does not require a concentration step and while this was more sensitive, it was only possible to test a small number of samples, so further work is needed to confirm this.
(4) No SARS-CoV-2 RNA was detected in the outflow water during the tests, whilst given that primary sludge is treated (e.g. pasteurized, heat-dried, alkali-lime treated), as per legislative requirements, concentration of viral RNA in the solid phase should pose no further risk to human health.
In summary, wastewater and other samples from wastewater plants can be used to determine the presence of SARS-CoV-2 in the local population. The sensitivity of this approach needs to be evaluated, but it offers the potential to monitor populations with much lower levels of sample processing than testing of individuals. More work is required to translate levels of viral RNA in wastewater to the level of infection within the community. While more samples need to be evaluated, SARS-CoV-2 virus was not detected in outflow water released from a wastewater plant receiving wastewater containing the virus. Infectivity was not assessed, but the low levels of SARS-CoV-2 RNA detected are unlikely to represent an additional threat to the health of individuals that work with wastewater taking standard precautions in their work environment.
Slender Naiad (Najas flexilis) Habitat Quality Assessment
Slender Naiad (Najas flexilis) is a rare aquatic plant species of European conservation importance.The species is believed to be under increasing threat in its Scottish stronghold. However, the factors that affect the health of N. flexilis populations in Scotland are not fully understood, such as, why does the species disappear, and where and why it fares well in some sites. In addition, more needs to be known about what actions can be taken to ensure that the habitat quality needed to support populations of the plant is either maintained or restored. Thus, this project was commissioned by CREW to review the existing knowledge and available information on the habitat requirements of N. flexilis from Scotland and other countries where the species is native. The aim is also to identify what data are already available, where they are, and how to access them.
The now published report highlights that much of the sensitivity of N. flexilis to the known threats of, eutrophication, competition with other plants and the mild acidification of circumneutral lakes can be related to its physiology as an obligate user of CO2; N. flexilis plants being unable to metabolise bicarbonate for photosynthesis. This physiological restriction puts limits on its distribution, particularly with respect to the pH and alkalinity of the lake, and is the reason that N. flexilis is typically found in circumneutral waters, with C-limitation of growth likely to be present at pH <5.5 and pH>8. This physiological requirement may be the reason for the favourable habitat being associated with machair and with anecdotal evidence of populations in lakes around groundwater springs – which are normally high sources of free CO (Falkowski and Raven, 2007). In terms of acidification, lower pH levels below 6.5 may be detrimental to reproductive performance of N. flexilis, before lower pH levels <5 start impacting growth rates through CO2-limitation. In relation to eutrophication, nutrient enrichment leads to increases in phytoplankton, epiphyte and aquatic plant growth. This has the potential to lead o C-limitation for obligate CO2 users during daytime if pH levels rise above 8. This is likely to be exacerbated by grassland or forestry improvements if liming of the land leads to increased pH of circumneutral lakes (but beneficial in acid lakes). The result of both eutrophication and alkalisation is a strong competitive advantage for aquatic plants that use bicarbonate. This is especially true for plant species that can tolerate and survive the combination of low light and increased ratio of bicarbonate to CO2 such as Elodea spp. Whether or not invasive nonnative species, such as Elodea, have impacted N.flexilis populations indirectly, through reducing CO2 availability, or directly, through competition for deeper, low-light habitat is unknown; a combination of both direct and indirect impacts may be involved. This report is the output of the first phase of the project, and a second report will be published in early 2021, including information on which lochs in Scotland provide the most favourable conditions for Slender Naiad, and possible sites for potential re-introduction in the future.
Understanding the link between phosphorus and ecological impact
Factoring ecological significance of sources into phosphorus source apportionment: Phase 2
Phosphorus (P) source apportionment is an important tool for prioritising mitigation strategies and assessing compliance as part of River Basin Management Planning process within the EU Water Framework Directive. However, the methodology for P source apportionment in rivers is subject to significant errors and uncertainty as annual total P loads are assumed to correlate with ecological impact, despite a wealth of evidence to demonstrate other factors such as seasonality and P bioavailability that affect the processes and mechanisms responsible for the transport of P from source to river systems (Stutter et al., 2014).
In 2014 CREW delivered a descriptive methodology of how modelled Total Phosphorus (TP) loads could be modified to take account of their impact on ecology (Phase 1). This project (Phase 2), evaluated the relevance of the method developed in Phase 1 to derive ‘ecologically significant source apportionment’ and examined potential factors affecting ecological status based on the regulatory data. Data from 45 Scottish streams were examined to identify a relationship between diatom response (a key ecological indicator for water body status) and other factors including: nutrients, soluble reactive phosphorus (SRP) loads from different sources, land cover proportions and hydrological catchment characteristics. The main findings and recommendations of Phase 2 are available below in the Executive Summary and Main Report.
Retrofitting Sustainable Urban Drainage Systems to industrial estates
Industrial estates are a well-recognised cause of pollution and Sustainable Urban Drainage Systems (SUDS) have been identified as an important option to address the pollution risk. This study aimed to investigate the potential for retrofitting SUDS on industrial estates to try to reduce pollution of watercourses. The project focused primarily on source control SUDS, or SUDS on an individual property bassis, as well as conveyance types of SUDS.
The principal research site was Houston Industrial Estate, Livingston, which has over 100 businesses and includes major, extensive factory premises, as well as intermediate-size factory premises and many small industrial units typically managed by a landlord or agent. In addition, one sector of the estate has been redeveloped since the statutory requirement to use SUDS technology was established in Scotland. This allowed the project to assess the maintenance of the SUDS installed at that time as well as the SUDS awareness of those businesses.
Research methods included an initial SUDS awareness survey, verification visits and detailed follow-up with several premises to explore opportunities and barriers to retrofitting SUDS in their specific circumstances, and a breakfast seminar and focus group for participating businesses.
The study identified three broad classes of barriers to retrofits: cost, time and space. A number of opportunities were identified, including a need for education and engagement with businesses, including support to grasp opportunities as well as understand requirements. An Executive Summary and Summary report are available below.
On request from Scottish Water, the Centre of Expertise for Water (CREW) funded a pilot project that aims to determine whether SARS-CoV-2 viral RNA can be detected in municipal wastewater from Scottish communities and whether the detection of SARS-CoV-2 viral RNA in municipal wastewater has the potential to be used to track community infection. Dr Alex Corbishley led the research from the University of Edinburgh's Roslin Institute and CREW engaged the Scottish Environment Protection Agency (SEPA) to ensure that the methods developed could ultimately be adopted by SEPA as part of their national (Scottish) programme of surveillance and analysis. CREW invited experts such as Dr Michael Gormley (Heriot Watt University) to join the project Steering Group and informed the Scottish Government of key developments to ensure project outcomes are shared widely.
CREW funding and coordination allowed for a rapid response to the research need to develop an assay to help tracking SARS-CoV-2 via municipal wastewater. The CREW project team used this opportunity to develop networks (and funding proposals) within the UK and internationally to work collaboratively towards finding a solution to this complex issue.
Dr Alexander Corbishley of the University of Edinburgh’s Roslin Institute, said:
“Detecting viral genetic material in waste water is relatively easy, however the challenge is measuring how much genetic material is present accurately and relating that to disease levels in the community. The support from CREW has allowed us to use our expertise in disease monitoring to inform SEPA and Scottish Water’s efforts to develop a Scottish wastewater monitoring programme”.
See BBC Scotland coverage here: https://www.bbc.co.uk/news/uk-scotland-53109139
Private Water Supplies and the local economic impacts in Scotland
There are approximately 22,000 private water supplies in Scotland serving a population of nearly 197,000 people
Many of these are also micro- and other businesses which rely on these supplies for their existence: frequently
providing services to a broader public as visitors and tourists particularly in remote rural areas of the country.
This study provides evidence of the impact private water supply reliance has upon social and economic
infrastructure; business development; costs of clean water; land management and stewardship and support needs.
It also highlights indicative issues within three sectors (tourism, dairy farming and forestry) that are likely to be
more widely pertinent.
The findings reveal the complexity of private-supply arrangements and infrastructure, and the considerable
gaps to be bridged to ensure future rural social and economic sustainability, system effectiveness, and to
reduce localities’ vulnerabilities.