Recommended management measures to improve river quality have been defined

Although the overall hydromorphological quality of the rivers in the surveyed part of the Salaca basin is good and high, this does not mean that no management measures are needed. The objective of the Water Framework Directive is not only to improve the ecological quality but also to avoid deterioration of the existing quality, which is particularly important also in the context of climate change. Also, the Nature Restoration Law sets an identical objective. Its basic principles are to restore ecosystems that are in poor condition and not to degrade those that are in good condition. In Natura 2000 sites, including the Nature Park “Salaca River valley” and freshwater habitats, the principles of maintaining the existing area and good quality of habitats are determined.

A total of 11 management measures have been identified, covering both river and riparian area:

• Removal of obstacles
• Removal of beaver dams
• Beaver population control
• Removal of wood debris
• Eradication of poachers
• Reduction of river overgrowth
• Control and eradication of the invasive species Heracleum sosnowskyi
• Control and eradication of the invasive species Impatiens glandulifera
• Control and eradication of other invasive species
• Removal of white alder
• Other measures.

The management measures were grouped and prioritized according to their expected positive impact on the hydromorphological and ecological quality of the rivers, with priorities from 1 to 5. The rivers of Salaca River basin, although located in the same region, are very diverse in terms of hydromorphological typology, impacts and pressures. The prioritization of management actions considered the impacts and the potential for improving river quality. Therefore, the same management measure may be prioritized differently for different rivers.

As first priority, or mandatory action, is the removal of obstacles. Restoring the longitudinal continuity of the river is the basis for good river quality. The second priority is the reduction of the overgrowth, the removal of important beaver dams and wood debris. The third and fourth priorities are to reduce the impact of wood debris, control of various invasive species, removal of beaver dams and beaver population control. The fifth priority, administrative measures, was given to measures aimed at improving laws and regulations, such as additional control of poachers.

Overall, the most common measure is removal of wood debris, selected in 43 river sections or 26% of the surveys. This measure has been identified for the river Glāžupe, Jogla, Iģe, Korģe and Korģīte, Pužupe, Svētupe and Salaca. In the Salaca, however, falling trees affect only a small stretch of the river and its removal is more related to preventive flood control.

Measures to reduce overgrowth were identified only in the Jaunupe and Salaca, in a total of 24 sections. The removal of overgrowth is mainly necessary to restore the ecological quality of the river rapids, with particular emphasis on the restoration of salmonid spawning grounds.

Removal of beaver dams is needed in 17 river sections, mainly in the Korģe and the Glāžupe. Seven river sections require beaver population control measures, mainly in the Iģe and Korģe. It should be noted that removing beaver dams without controlling their population is low efficient measure. In Korģe, most of the measures are related to reducing beaver population, which is particularly important in fast-flowing salmonid waters. In contrast, the sections surveyed in the Svētupe showed signs of beaver activity, but very few dams themselves, indicating that management measures have been implemented in the past.

Dams and various obstacles made of stones were found in 14 river sections – in the Glāžupe, Iģe, Jogla and Svētupe. The removal of all of them was given the highest priority. Obstacles restrict the longitudinal continuity of the rivers and makes significant pressure on the hydromorphological and ecological quality of the rivers. Obstacles in clean, unpolluted rivers, where the eutrophication load is low, can have a significant impact on the river ecosystem and therefore the removal of obstacles is given the highest priority.

Different measures have been identified for the control of the invasive Heracleum sosnowskyi in 6 sections and for the control of the Impatiens glandulifera in 15 sections. Both species are predominantly found along the banks of the Salaca River. Removal of white alder has been applied to one stretch of the Glāžupe River. “Other measures” were identified in 11 river sections and include downstream dam mitigation, appropriate buffer zone between the riverbanks and agricultural land, as well as litter removal.

In total, 106 river sections, or 63% of the total number of river sections surveyed, had at least one management measure identified. It should be noted that not all management measures recommended by the experts can be implemented within the LIFE IS SALACA project due to financial reasons, but they will be included as necessary management measures in the process of elaboration of the nature management plan for the nature park “Salaca River Valley”.