Reduction of diffuse pollution

Leading beneficiary: Latvia University of Life Sciences and Technologies

Supporting beneficiaries: Latvia University of Life Sciences and Technologies, LSFRI Silava, Latvia’s State Forests, University of Latvia, Farmer’s Parliament, Latvian Environment, Geology and Meteorology Centre

The LIFE GoodWater IP objective “Reduction of diffuse pollution” supports implementation of the Water Framework Directive by reducing nutrient pollution from agriculture, forestry and aquaculture and by improving ecological conditions in selected water bodies. 

In the LIFE GoodWater IP project, “Reduction of diffuse pollution” combines seven activities:

• A1 – assessment of nutrient pollution from agriculture and development of green infrastructure and sustainable drainage solutions;
• A2 – assessment of nutrient pollution from forestlands and development of green infrastructure and environmentally friendly drainage solutions;
• A4 – assessment, modelling and development of recommendations for improving the ecological status of Lake Sauka;
• C4 – assessment and reduction of aquaculture pressures and development of recommendations for integration into River Basin Management Plans;
• C5 – practical measures to reduce agricultural nutrient pollution, including river restoration, sustainable drainage systems, wetlands and buffer strips;
• C6 – practical forestry measures, including riparian buffer zones, sedimentation ponds and peak-flow control;
• C8 – implementation and evaluation of a nature-based solution to reduce nutrient loads entering Lake Sauka

2020: baseline studies and identification of pollution pressures

The project began by establishing monitoring systems and assessing nutrient pollution in agricultural catchments, forestland and Lake Sauka. Water-quality measurements were combined with information on land use, agricultural production, drainage networks and local pollution sources.

In agricultural areas, the work focused on Slocene, Aģe, Auce and Ēda. Monitoring and geospatial analysis helped identify the river sections, tributaries and drainage systems with the highest nutrient concentrations. In forestland, the Tora River catchment within the Aģe basin was selected for more detailed study.

At Lake Sauka, hydrobiological, hydrochemical and hydromorphological investigations were launched to assess ecological status and nutrient inflows. Aquaculture monitoring also started, covering nutrient discharges, sediments, fish health, biodiversity and pharmaceutical substances.

The main result of 2020 was the establishment of a scientific baseline for selecting appropriate measures and evaluating their future effects.

2021: selection of demonstration sites and technical solutions

During 2021, monitoring was expanded and the first detailed assessments were completed. The project used the results to identify priority areas and prepare site-specific recommendations.

In agricultural areas, the proposed solutions included constructed wetlands, sedimentation ponds, buffer strips, controlled drainage, saturated buffers, grassed waterways and woodchip bioreactors. The recommendations were discussed with landowners and adapted to local conditions.

In forestland, the project selected locations for a riparian buffer zone, sedimentation ponds and a peak-flow control structure. Preparatory work began at the Tora demonstration sites.

Lake Sauka research continued, although some fieldwork and modelling activities were delayed by COVID-19 restrictions. Despite these delays, the project continued collecting the information needed for a lake ecosystem model and future management recommendations.

2022: from assessment to implementation readiness

In 2022, the project moved from general assessment to detailed technical preparation. Agricultural and forestry solutions were refined together with designers, landowners, municipalities and responsible authorities.

The first complete recommendations for sustainable and environmentally friendly drainage systems were prepared. Technical designs were developed for sedimentation ponds, constructed wetlands, peak-flow control and other nutrient-retention measures.

At Lake Sauka, the multi-year assessment produced a detailed picture of the lake’s ecological condition and the main nutrient inflows. This work provided the basis for selecting a practical intervention in an inflowing agricultural drainage ditch.

The Initial Monitoring Report was completed at the end of 2022. It established the reference conditions against which future changes in nutrient concentrations, ecological quality and biological indicators could be assessed.

2023: first major demonstration measures

In 2023, the project entered the practical implementation stage. The first large-scale rural sustainable drainage and river-restoration measures were completed in the Aģe and Slocene catchments.

Works included river restoration, sedimentation ponds, constructed wetlands, fish-spawning areas and measures to reduce sediment and nutrient transport from agricultural land. Around 12 km of green-infrastructure and environmentally friendly drainage measures had been implemented by the end of the reporting period.

Preparations also advanced for additional measures in the Auce and Ēda catchments, including controlled drainage, saturated buffers, bioreactors and further constructed wetlands.

Research on Lake Sauka was largely completed. The ecological assessment, ecosystem model and management recommendations confirmed that the most significant nutrient pressures were linked to diffuse agricultural runoff. As a result, Actions A4 and C8 were reassigned from point-source pollution to the diffuse-pollution objective.

Aquaculture recommendations were also finalised, providing proposals for reducing fish-farm impacts and improving integration of aquaculture measures into future River Basin Management Plans.

2024: expansion across all four demonstration catchments

• In 2024, implementation expanded across Slocene, Aģe, Auce and Ēda. New wetlands, sedimentation systems, drainage measures and restored river sections were completed or brought into construction.
• In the Ēda catchment, a surface-flow constructed wetland was established and part of the riverbank was restored. 
• In the Auce catchment, riverbed and bank restoration was completed over several kilometres, supported by a wetland and sedimentation pond designed to reduce nitrogen concentrations.
• A major buffer-strip demonstration was established along the Kalva watercourse. The 10-metre-wide and 5-kilometre-long strip created a continuous nutrient-retention zone between agricultural land and the watercourse.

Forestry measures also reached an advanced stage. A peak-flow control structure and several sedimentation ponds were constructed, while the riparian zone along the Tora River was diversified and managed to improve nutrient retention, flow regulation and ecological conditions.

For Lake Sauka, the constructed-wetland design was completed and approved, enabling the transition from research and planning to construction.

2025: consolidation, monitoring and policy uptake

By the end of 2025, the project had created a broad demonstration network of agricultural and forestry measures. The cumulative results included 27.35 km of river restoration and environmentally friendly drainage measures at 27 agricultural demonstration sites.

Monitoring continued to evaluate whether the measures were reducing nutrient loads and improving ecological status. Positive developments were observed at several sites, although longer monitoring series are still needed to separate the effect of project measures from seasonal and climatic variation.

The Lake Sauka constructed wetland remained under implementation. Once completed, it is expected to reduce nutrient transport from agricultural drainage water before it enters the lake.

The project also achieved important policy-level progress. Buffer strips and constructed wetlands were incorporated into agricultural support systems, allowing the demonstrated approaches to be replicated outside the LIFE project areas. In 2025, a national procedure for supporting constructed wetlands was adopted, creating the possibility of financing additional projects through the CAP (Common Agricultural Policy) Strategic Plan.

For agriculture and forestry, the project has demonstrated a range of nutrient-reduction methods and approaches. 

Results achieved by the end of 2025:

• restoration of rivers over a total length of 27.35 km, including 15.29 km during 2024–2025;
• sustainable and environmentally friendly drainage measures at 27 demonstration sites in the Slocene, Aģe, Auce and Ēda water bodies;
• establishment and management of a 10 m wide and 5 km long buffer strip along the Kalva watercourse;
• inclusion of buffer-strip establishment and management in support schemes under the European Agricultural Fund for Rural Development and the CAP Strategic Plan 2023–2027;
• construction of one peak-flow control structure and three sedimentation ponds in forest drainage systems;
• establishment of approximately 2 km of riparian buffer strips in forestland.