Lough Neagh Water Quality Dashboard - FAQ
Frequently Asked Questions -
1. The Viewer
1.1 What data does the Viewer display?
The viewer displays environmental data (for multiple physico-chemical parameters) collected from nine monitoring locations, at approximately 50cm below the water surface in and around Lough Neagh.
Sites include:
- Three buoy stations located at:
- Rea’s Wood (North East Lough)
- Washing Bay (South West Lough)
- Lower Bann (North East Outlet)
- Six river locations, positioned in each of the Lough’s major inflowing tributaries (Rivers Six Mile Water, at Antrim town, River Main at Shane’s Castle estate, Moyola River at Waterfoot, Ballinderry River at Mullan, River Blackwater at Maghery, and Upper Bann at Portadown).
1.2 What data is available?
Buoy Stations monitor the following parameters:
- Water temperature (°C)
- Dissolved oxygen (% Saturation)
- Blue Green Algae - Phycocyanin (Relative Fluorescence Units, RFU)
Data are displayed in interactive graphs and are also available for download.
The data for the following parameters are available for download only:
- Turbidity (Nephelometric Turbidity Unit, NTU)
- Specific conductivity (Microsiemens, µs/cm)
River Stations monitor:
- Water temperature (degree Celsius, °C)
- Dissolved oxygen (percentage saturation, % Saturation)
Additional information about each parameter can be accessed via the info buttons on the graphs.
1.3 How can I find and use satellite images of Lough Neagh?
Once the Viewer is open, click on the "Data Downloads and FAQs" tab at the bottom of the screen. At the bottom of the page is a link to the Copernicus Satellite Imagery Viewer. Instructions on its use can be found in the "About" section of the Copernicus website.
1.4 How often is the data updated?
- Lough Buoy Stations: Data is collected continuously and updated every 30 minutes via telemetry, with a 7-day lag.
- River Stations: Data is downloaded monthly from the river locations and uploaded manually to the viewer.
1.5 What is telemetry?
Telemetry is the automatic measurement and wireless transmission of data from remote sources in Lough Neagh.
1.6 How is the data used?
This data is shared through the Lough Neagh Science Platform. It supports scientists, researchers, and environmental organisations in monitoring water quality, developing predictive models, and informing decision-making.
1.7 What is the optimal way of viewing information?
The Lough Neagh Platform is optimised for desktop viewing to ensure the best user experience, please access it through a desktop or laptop computer.
2. Maintenance, Calibration
All monitoring equipment is maintained monthly and calibrated when required. During these procedures, minor variations or gaps in data may occur.
2.1 Does DAERA offer data analysis services?
The Department of Agriculture, Environment and Rural Affairs (DAERA) provides this data for public use but does not offer analysis or interpretation services on the raw data, other than that in official publications.
2.2 How reliable is the data?
Remote sensors are widely used in monitoring water quality. They provide high-frequency data at a low cost. However, the data they produce is used as part of investigative monitoring and not official government statistics. Data is referred to as being "non-validated".
Measurements are subject to environmental influences and may fluctuate.
- Each sensor's accuracy is detailed in the metadata.
- Monthly calibration ensures consistent performance.
- Users are encouraged to review and screen data before use.
Non-validated data should be used for indicative trends only.
2.3 When I view downloaded data the date format is inconsistent
The instrumentation records date and time in US, not UK format. If opening in programmes such as MS Excel, the programme may have issues transforming it automatically to a UK format. For example: It may transform some data to a text format instead of date format.
Programmes such as MS Excel provide an option under the “data” heading to allow importing “from a text/csv” file. This allows users to “transform data” manually. By right clicking in the Date column the option to “change type” can be selected, and a “date/time” option can be selected. The “locale” can be selected as UK rather than US.
This should import the data with the correct date formats.
3. Current use of the Viewer and its data
3.1 Is the data used by Government?
This monitoring forms part of a broader investigation into water quality issues in and around Lough Neagh. By understanding both inflows and conditions within the Lough, authorities can:
- Improve decision-making
- Coordinate monitoring across agencies
- Encourage collaboration between environmental stakeholders
The data is reviewed regularly to determine water quality issues in particular catchments and the Lough itself. This includes, if a potential pollution incident is identified from the data, it is reported to the NIEA Emergency Pollution Hotline (contact 0800 80 70 60 or emergency-pollution@daera-ni.gov.uk) for investigation and appropriate action by the relevant authorities.
DAERA will follow up significant issues, with further investigative monitoring deployments planned in the Lough Neagh Catchment.
3.2 How does DAERA use the data?
As part of the Lough Neagh Action Plan, DAERA uses data from the Lough Neagh Science Platform to support better decision-making and encourage positive environmental actions.
This data helps with:
- Understanding how Lough Neagh and its surrounding river catchments behave in our source to sea approach.
- Studying blue-green algal growth patterns to understand when and why they occur
- Exploring ways to manage nutrients and assess the impact of different interventions
- Coordinating monitoring programmes and sharing knowledge through education and outreach
3.3 Can the data indicate the presence of harmful algae.
Increased levels of phycocyanin fluorescence are usually indicative of blue-green algal growth, some of which may produce toxins.
Confirming the presence of harmful algae and toxins is not possible through this viewer, it must be undertaken by laboratory analysis. Actual sightings and photographs of suspected algae should be reported and verified via the blooming algae app (Bloomin’ Algae | UK Centre for Ecology & Hydrology)
Please Note: Data are generated from single points within the Lough and surrounding conditions may vary. This viewer should not be used as a standalone decision-making tool for water safety, advice from other bodies should also be sought and adhered to.
3.4 Does the data indicate if it is safe to swim or enter the water?
Please consult the NI Bathing Water Quality Dashboard for advice on water quality at bathing waters.
3.5 Does my drinking water come from Lough Neagh?
For information on drinking water and blue-green algae, including where your drinking water comes from, visit NI Water’s website ‘About your water’
3.6 Can other events appear similar to harmful algal growth?
To understand the growth of algae it is best to view data changes over multiple months, especially through a growth season. This will indicate the range of variation in each parameter. Infrequent short increases of phycocyanin fluorescence Intensity which may appear significant when viewing weekly or monthly data must be viewed in context. Short term peaks may not be indicative of a significant bloom. They may be due to material impacting the sensor or unusual light reflectance in the water column.
Significant increases in dissolved oxygen may often accompany excess algal growth but can also be caused by several natural factors including wave action, plant growth and growth of non-harmful algae.
3.7 What does a typical bloom look like?
There is no single fluorescence (RFU) value that defines an algal bloom in scientific literature.
RFU may values vary:
- in different environmental conditions,
- between different compositions of blue-green algal species
- may also vary between different brands of sensor, and.
- where the bloom is in a growth phase or a decomposition phase.
A noticeable bloom occurred across the Lough in August 2025. During the bloom phycocyanin readings were elevated significantly above winter levels. The majority of values recorded were between 5 and 20 RFU over several weeks, with occasional spikes of over 50 RFU. However, future blooms values may differ based on the factors mentioned above.
The following are key points when assessing bloom development, extent and movement:
- Sensors measure RFU values 50cm below the surface.
- Blooms are mobile and both move laterally across the lake and vertically through the water column.
- More accurate bloom assessments can be achieved by cross-referencing sensor data with satellite imagery (link available in the DATA Download and FAQs section of the portal).
3.8 Are there published studies measuring phycocyanin fluorescence?
Links to studies include.
Exploring the Use of Fluorometric Sensors to Monitor Harmful Algal Blooms in Lakes
Performance evaluation of phycocyanin probes for the monitoring of cyanobacteria - PubMed
3.9 Why are there drops in Dissolved Oxygen(DO)?
Instrumentation placed in rivers and lakes to monitor environmental variables can occasionally produce erroneous data due to factors such as biofouling, high sediment loadings, extreme high and low flow conditions, sensor blockage, or equipment malfunction. Although efforts are made to identify and remove these anomalies, some deviations from expected DO levels may persist and warrant further investigation. Low dissolved oxygen events will remain on the platform and until the further investigations are complete. Where erroneous data is proven, it will be removed.
In certain cases, sharp drops in DO may be linked to pollution coming from upstream sources, such as discharges. These pollutants may travel in concentrated plumes that pass by the sensor. It’s important to note that the readings from one sensor do not always reflect the conditions across the whole river. Depending on the amount and type of pollution, the overall impact on the river’s health may be minimal.
Excessive macrophyte growth can have a considerable impact on diurnal Dissolved Oxygen levels, particularly during the summer period with nighttime troughs and daytime peaks.
Where data indicates oxygen level concerns, these are reported to the NIEA Emergency Pollution Hotline (contact 0800 80 70 60 or emergency-pollution@daera-ni.gov.uk) for further investigation.
3.10 Can temperature readings be impacted by a site's location?
River and lake water can freeze in cold weather, although this is uncommon in fast-moving rivers in Northern Ireland. Freezing may damage sensors. Should this occur sensors will be replaced and the data removed.
Sensors placed in shallower water near the riverbank can be affected by air and land temperatures during more extreme weather conditions. For example, in winter freezing air temperature may cool the edges of a river more than the centre of the river. In summer, warmer air may see river edges warm more quickly than the deeper parts of the channel.
These readings therefore reflect conditions at the sensor’s location and not the average temperature across the whole river.
3.11 Why are oxygen levels above 100%?
Sometimes, rivers and lakes can have unusually high levels of oxygen—this is called supersaturation. It can happen naturally during warm, sunny weather when plants and algae grow quickly and produce extra oxygen through photosynthesis. Rain and wind can also boost oxygen levels by mixing air into the water.
3.12 Why do some rivers have lower oxygen levels?
Prior to entering the Lough several of the rivers slow significantly. Slow-moving water tends release sediment and nutrients and may have lower levels of dissolved oxygen. These rivers are less subject to wind mixing and turbulence to become aerated and warmer temperatures in these areas also reduce the water’s ability to hold oxygen.
Human activities, such as sewage discharge, agricultural runoff, and industrial waste can also reduce dissolved oxygen levels.
3.13 Is the water level of Lough Neagh controlled?
The level of Lough Neagh is controlled by infrastructure at the lake’s outflow see here for more details - Lough Neagh levels | Department for Infrastructure
3.14 Why are there data gaps?
Specialist equipment is placed in rivers and lakes to monitor metrics like temperature, oxygen levels, and other water quality parameters. The natural environment may impact the data collected in several ways, such as:
- Natural build-up on the sensor (biofouling)
- Blockages or technical faults
- Routine maintenance or calibration
- Battery or sensor loss
Some sensors are more prone to these impacts than others. Where these cases are identified, data is removed from the viewer. Occasional data gaps are therefore normal and expected.
3.15 How can the data be used?
The data collected from Lough Neagh is shared through the Lough Neagh Science Platform, where it helps scientists, researchers, and environmental groups study water quality and develop useful tools like models and forecasts.
Sharing this information also supports better decision-making, helps coordinate monitoring efforts, and encourages collaboration between different organisations working to protect our water environment.
Should you wish to use the data please reference Viewer appropriately using the metadata supplied.
4. Future development of the Viewer
More datasets will be added in the coming months, reflecting ongoing research and monitoring efforts across the public sector.
All data comes from a constantly changing natural environment, and is published as “non-validated”, i.e. it is not official government statistics.