Lough Neagh Water Quality Dashboard - FAQ

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

Monitoring of cyanobacterial breakthrough and accumulation by in situ phycocyanin probe system within full-scale treatment plants - PMC

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.

 

5. The Dashboards

5.1 What data do the Dashboards display?

There are currently two Dashboards, which can be accessed via the tabs at the foot of the screen.  They provide water quality data from Loug Neagh and its surrounding catchment.  One dashboard provides high frequency near-real time data, the other monthly water chemistry and algal data. Further details are provided below.

5.1.1 Main Map &In-Situ Probe Data Dashboard 

This dashboard displays high frequency near real-time environmental data (for multiple physico-chemical parameters) collected from nine monitoring locations.  The data is recorded every 30 minutes. 

Three in-Lough buoy stations are located at:

Rea’s Wood (North East Lough)

Washing Bay (South West Lough)

Toome  (North East Outlet)

These probes are suspended from the buoys at a depth of approx. 50 cm below the surface.

Six river stations are 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).

The river probes are fixed to the banks.  As a result, depths at which readings are taken will vary as river levels rise and fall.

5.1.2 Chemistry & Algal Shore Data Dashboard

This dashboard displays water chemistry and algal data collected from nine nearshore monitoring locations.  Water Samples and in-situ measurements are taken once a month at a depth of not more than 1 metre.

The sites are located at Ballyronan, Bartin’s Bay, Cranfield, Derryadd, Moore’s Point, Rea’s Wood, Stanierd’s Point, Toome Bridge, and Washing Bay.  They provide a detailed understanding of nearshore conditions around the Lough.

Chemistry sampling commenced at eight of the sites in Feburary 2025 and the FluoroProbe® sampling started in May 2025.  Sampling at Derryadd commenced in 2026.

5.2 What data are available?

5.2.1 Main Map &In-Situ Probe Data Dashboard 

Near real-time buoy stations monitor the following parameters at a high frequency:

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.

Near real-time data for the following parameters are also available, but 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.

5.2.2 Chemistry & Algal Shore Data Dashboard

These nine nearshore sites are sampled once a month for both water chemistry and algae. 

The following water quality determinants are sampled. 

ALK	Alkalinity	milligram per litre	EEA_3153-02-4
BOD	Biochemical Oxygen Demand	milligram per litre	EEA_3133-01-5
CHLR A	Chlorophyll a	micrograms per litre	EEA_3164-01-0
CL MG	Chloride	milligram per litre	16887-00-6
COLOUR	Colour (after 0.45µm filter)	HAZEN UNITS
COND	Conductivity	µS/cm	EEA_3142-01-6
DO	Dissolved Oxygen	milligram per litre	EEA_3132-01-2
DO %	Dissolved Oxygen % Saturation	Percentage Saturation	EEA_3131-01-9
N TOT	Nitrogen, Total	milligram per litre	EEA_31615-01-7
NH3	Ammonia (Non-ionised)	milligram per litre	EEA_31613-01-1
NH4-N	Ammonia, Total	milligram per litre	14798-03-9
NO2-N	Nitrite	milligram per litre	14797-65-0
NO3-N	Nitrate	milligram per litre	14797-55-8
P(SOL)	Phosphorus, Soluble Reactive (SRP)	milligram per litre	14265-44-2
P(TOT)	Phosphorus, Total (TP)	milligram per litre	7723-14-0
PH	pH Value	pH UNITS	EEA_3152-01-0
SS	Suspended Solids	milligram per litre	EEA_31-02-7
TEMP	Temperature	Degrees Celcius	EEA_3121-01-5
TON	Total Oxidised Nitrogen	milligram per litre	EEA_3161-02-2

At each of the nine nearshore monitoring sites, FluoroProbe® measurements are collected alongside water chemistry samples. The fluorometer uses light of different wavelengths to identify major phytoplankton (algal) groups and estimate their concentration in the water. Measurements are collected monthly to track changes in phytoplankton communities over time.

The chart presents data on the main groups measured, including blue-green algae, cryptophytes, diatoms and green algae.

5.3 How can I find and use satellite images of Lough Neagh?

Click on the "Resources & FAQs" tab at the bottom of the screen.  Resources include links to further sites such as the Copernicus Satellite Imagery Viewer. This viewer is not operated by DAERA. More details on it and instructions on its use can be found in the "About" section of that Copernicus website.

5.4 How often are the data updated?

Lough Neagh Buoy Stations: Data are collected continuously and updated every 30 minutes via telemetry, with a 7-day lag.

River Stations: Data are downloaded monthly from the river locations and uploaded manually to the Dashboard.

Water chemistry and FluoroProbe® data: Published as it becomes available. Algal composition and concentration data will be presented shortly after analysis is undertaken. Due to the laboratory analyses and checking required for water chemistry, results can take up to two months before being published.

5.5 How are the data used?

These data are shared with the public through the Lough Neagh Dashboards and are part of the Science Platform envisaged by the Lough Neagh Report and Action Plan.  The Dashboards support scientists, researchers, and environmental organisations in such ways as, monitoring water quality, developing predictive models, and informing mitigations and decision-making. 

5.6 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 using a desktop or laptop computer. 

6. Technical Information, Maintenance and Calibration

All field monitoring equipment is maintained monthly and calibrated when required. During these procedures, minor variations or gaps in data may occur.

The FluoroProbe® is routinely maintained and calibrated in accordance with the manufacturer's recommendations. This includes monthly cleaning and routine maintenance, as well as manufacturer factory recalibration at a minimum of every two years.  Periods of maintenance, calibration, or instrument checks may occasionally affect data availability or result in temporary gaps in the dashboard.

Water chemistry samples are analysed by the Water Chemistry Laboratory of the Northern Ireland Environment Agency.  In this UKAS Accredited Testing Laboratory, analyses are completed in accordance with established in-house analytical procedures which have been validated to meet requirements of ISO 17025 and relevant legislation. 

6.1 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. 

6.2 How reliable are 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 are used as part of investigative monitoring and not official government statistics. 

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.

All probes are designed to operate within a specified measurement range and environmental conditions. During more extreme events, some background instrument parameters may become unreliable. For example, where the chlorophyll concentrations exceed 500 µg/L the fluoroprobe data is less accurate but indicative of concentrations of algae over 500 µg/L. In more extreme cases, especially in relation to high frequency monitoring, datasets become unreliable and data is redacted completely.

6.3 Why may the downloaded date format be inconsistent?

The high frequency buoy instrumentation records date and time in US, rather than the UK format.  When data are opened in programmes such as MS Excel, they may have issues transforming date and time automatically to a UK format.  For example: Some dates may be converted to text rather than to a UK 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.

6.4 What probes are used?

Each dashboard displays data obtained using specifically designed probes.  Please be aware that probes operate in a dynamic environment. 

6.4.1 Main Map & In-Situ Probe Data Dashboard 

The near real-time lake data are gathered using AquaTROLL 600 and AquaTROLL 800 probes. These in-situ devices have multiple sensors which record Temperature, Dissolved Oxygen, Specific Conductivity, Turbidity and Phycocyanin. (Water Quality Multiparameter Sondes | Multiprobes)

The river data are gathered using a PME MiniDOT. It records Temperature and Dissolved Oxygen only. (miniDOT® Logger | Dissolved Oxygen Sensor & Logger | PME)

These probes record high frequency data.

6.4.2 Chemistry & Algal Shore Data Dashboard 

The FluoroProbe® is a highly sensitive measuring instrument for the analysis of chlorophyll with algae class determination. FluoroProbe® measurements are collected monthly. (FluoroProbe (Chlorophyll) - bbe moldaenke)

The water chemistry analyses are undertaken in the laboratory following monthly field sampling.

6.5 What is telemetry?

Telemetry is the automatic measurement and wireless transmission of data from remote sources, in this case it relates to transmission of data from  Lough Neagh. 

7. Current use of the Dashboards and their data

7.1 Are the data used by Government?

This investigative 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
• Better 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.  If the data indicate a potential pollution incident, then it is reported to the NIEA Incident 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.

7.2 How does DAERA use the data?

DAERA uses data from the dashboards 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.

7.3 Can the data indicate the presence of harmful algae.

Data, such as algal composition, concentration and Increased levels of phycocyanin fluorescence, will provide indications of blue-green algal growth, some of which may produce toxins. However, these dashboards cannot confirm the presence of toxins, this requires additional tests and analysis. 

It should be noted that the FluoroProbe® data will give a reasonable indication of potentially harmful blue-green algae at the time and date the sample is taken.  However, currents and weather conditions continuously influence algal movements.

Actual sightings and photographs of suspected blue-green algae should be reported and verified via the blooming algae app (Bloomin’ Algae | UK Centre for Ecology & Hydrology). You can see confirmed locations of blue-green algae in Northern Ireland using the Blue-Green Algae Confirmed Locations Viewer (Blue-Green Algae - Confirmed Locations).

Please Note: Data are generated from individual points within the Lough and surrounding conditions may vary.  These data should not be used as a standalone decision-making tool for water safety.  Advice from other public bodies should also be sought and followed.

7.4 Does the data indicate if it is safe to swim or enter the water?

Please consult the NI Bathing Water Quality Dashboard (NI Bathing Water Quality Dashboard) for advice on water quality at bathing waters. 

7.5 Is my drinking water impacted by algae in Lough Neagh?

Drinking Water Inspectorate provide information on drinking water and blue-green algae (Drinking Water and Blue-Green Algae | Department of Agriculture, Environment and Rural Affairs).

NI Water also provide details via their website (bga | About your water | Northern Ireland Water) 

7.6 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.

The dashboards provide information in high frequency near real-time on phycocyanin and lower frequency algal composition data.  This provides a broad understanding of what is happening and where.  The nine nearshore sites provide details of the algal composition and concentration.  These datasets should be considered in combination with other available data to provide a more accurate understanding of the conditions in the Lough. 

Please note that the graphs have adaptive axes, so check actual values. For example, infrequent short increases of phycocyanin fluorescence intensity may appear significant when viewing weekly data.  However, it is recommended to view data from several months and compare data with previous blooms to best understand the data context.

It should also be noted that substantial short-term peaks lasting a few minutes 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. 

7.7 What does a typical bloom look like?

There is no single fluorescence (RFU) value that defines an algal bloom in scientific literature. Nor is there a FluoroProbe® level or algal composition that  officially indicates a bloom. 

RFU values may vary: 

• in different environmental conditions;
• between different compositions of blue-green algal species;
• between different brands of sensor, and;
• where the bloom is in a growth phase or a decomposition phase. 

However, for comparison and understanding, a noticeable growth  began in August and continued into September 2025.  During the bloom phycocyanin readings from the in-Lough buoys were elevated significantly above winter levels.  The majority of values recorded were between 5 and 20 RFU over several weeks at 50cm below the surface, with occasional spikes of over 50 RFU. 

FluoroProbe® data indicates significant variation between the nine nearshore sites where blue-green algae were the dominant group and values ranged from 12 µg/L up to 70 µg/L in summer months.  In comparison, the blue green algae concentration at Moore’s Point in November 2025 was 0.22 µg/L and in December 2025 it was 3.5 µg/L.

Please note, future blooms’ values and compositions may differ based on the factors mentioned above. Blooms are mobile and move both 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 Resources & FAQs section of the portal).

7.8 Are there published studies measuring phycocyanin fluorescence?

Links to studies include.

• Exploring the Use of Fluorometric Sensors to Monitor Harmful Algal Blooms in Lakes
• Monitoring of cyanobacterial breakthrough and accumulation by in situ phycocyanin probe system within full-scale treatment plants - PMC
• Performance evaluation of phycocyanin probes for the monitoring of cyanobacteria - PubMed

7.9 Why are there occasional 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 DO 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 is important to note that the readings from one sensor may not reflect the conditions across the whole river.  Depending on the amount and type of pollution, the overall impact on the river’s health will vary.

Excessive macrophyte growth can have a considerable impact on diurnal DO levels, particularly during the summer period with nighttime troughs and daytime peaks.

Where data indicates oxygen level concerns, these are reported to the NIEA Incident Hotline (contact 0800 80 70 60 or emergency-pollution@daera-ni.gov.uk) for further investigation.

7.10 Can temperature readings be impacted by a site's location?

River and lake water can freeze in cold weather, although this is uncommon in moving water in Northern Ireland.  Freezing may damage sensors.  Should this occur sensors will be replaced and the erroneous 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 temperatures may cool the edges of a river more than the centre of the river.  In summer, hot conditions may see shallow 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.

7.11 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. 

7.12 Why do some rivers have lower dissolved oxygen levels?

Prior to entering the Lough several of the rivers slow significantly. Slow-moving calm water will deposit sediment and nutrients to the river bed, enhancing summer plant and algal growth.  Subsequent plant and algal death and decay may lower dissolved oxygen.  Such rivers are also less turbulent minimising natural aeration processes. 

Warmer temperatures may reduce the water’s ability to hold oxygen, especially in the absence of plant and algal growth.

Human activities, such as sewage discharge, agricultural runoff, and industrial waste may also reduce dissolved oxygen levels.

7.13 Is the water level of Lough Neagh controlled?

The level of Lough Neagh is controlled by the Department of infrastructure at the lake’s outflow. More details are available at the following link.  (Lough Neagh levels | Department for Infrastructure) 

7.14 Why are there data gaps?

In the “Main Map & In Situ Probe Data” Tab data is recorded from specialist equipment 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.  Occasional data gaps are therefore normal and expected.

In the "Chemistry & Algal Shore Data" tab, data gaps are less likely but may occur due to adverse weather conditions or extreme algal bloom events that impact sampling activities or laboratory analyses.  Where possible, follow-up sampling is undertaken. In  the unlikely event that is it not possible to retake a sample, no value will be entered into the table or graphs (i.e.left blank). Where possible, all water chemistry sampling for a location will be undertaken on the same date.  However, FluoroProbe® and water chemistry samples may occasionally be collected on different dates, so please check the dates when examining data. No sampling was undertaken at the Derryadd site in 2025. 

7.15 How can the data be used?

The data collected from Lough Neagh is part of the wider Lough Neagh Science Platform which is being developed as part of the Lough Neagh Report and Action Plan.  These dashboards will help 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 the dashboard appropriately using the metadata supplied. 

 

8. Future development of the Data Dashboards

The addition of further datasets is planned, reflecting ongoing research and monitoring efforts across the public sector.  Some will be included as new tabs in the GIS dashboard, others will be added to the resources pages as links.

All data come from a constantly changing natural environment, and is published as “non-validated”, i.e. They are part of an investigative monitoring programme and are not official government statistics.