Preliminary assessment of the environmental status of river systems

Anne Guri W. Steindal of Multiconsult puts the spotlight on aquatic environmental conditions. Read about Multiconsult’s painstaking work in conjunction with upgrades to the E18 in the latest edition of the local business journal Agdernæring.

20. January 2016

Importance of environmental status

In recent years, there has been growing interest in the environmental status of the water around us – from groundwater to water in streams, rivers, lakes and fjords. This is partly due to growing awareness of the importance of the natural environment and its impact on us, but it also reflects stricter national and European regulations, which aim to ensure holistic management of our water resources.

The main aim is for all water resources to have a good environmental status by 2021.

New highway being built

The E18 highway between Arendal and Tvedestrand is being upgraded, and the County Governor has ordered that the environmental condition of the river systems around the planned new route be monitored.

Since April, Multiconsult have therefore been studying the river systems affected by the western section of the new road – the Mørfjær, Songe and Barbu river systems – to assess their environmental condition before construction work begins.

This preliminary assessment involves surveying the abundance and variety of fish, amphibians, algae and benthic organisms in the river systems, as well as taking water samples to determine the physical and chemical state of the water (such as pH and levels of particles, nutrients, metals, oil compounds, etc.).

Important information

Preliminary assessments are important because they give an idea of how vulnerable/robust the river systems are with respect to external factors, e.g. whether they are home to particularly valuable species or ones that are highly susceptible to changes in water conditions. This makes it possible to decide what action must be taken to enable the fish and other river inhabitants to remain and thrive as much as possible during and after the construction of the road.

The assessments also provide important information about the “normal state” of streams, rivers and lakes, as well as about the expected variations in water levels, particle content and chemical conditions over the course of a year. This makes it easier to monitor the water quality while the road is built and operated, and to take action if abnormal readings occur.

Preliminary results

To date, the assessments have shown that these river systems and their surrounding areas are home to very valuable natural assets. For instance, amphibians have been found in many tarns and small lakes, and it turns out that sea trout and eels can be found far up all of the streams and rivers. There are also salmon in the Barbu river system, but they are blocked by a dam in the Barbudalen valley. The common rudd, which is considered a pest fish, is spreading in the river systems, threatening trout and other fish.

We have learned a great deal about annual changes in water ecology and chemistry. In general, the chemical status of all of the streams and small lakes appears to be good, although there is somewhat too much iron and organic matter, which in many cases may have natural causes.

This important job of monitoring water quality will continue right until the road is completed.