Half of the Finnish peatlands have been drained in order to improve forest growth. Nowadays
new forest ditches are hardly being made, but the existing ditch networks require maintenance
work every 20–40 years. This means more than 10 000 km of ditches being dug open and
deeper every year. This causes changes in the ecological and chemical status of water bodies.
Since 2011 the Water Act has required the project leader to send a prior notification of
ditching projects to the regional environmental supervisory authority. According to the Water
Act, a notification should include e.g. an assessment of environmental impacts. The aim of
this article is to find out how effectively this assessment obligation functions. This article
scrutinizes firstly the legislation concerning the regulation of environmental impacts of ditch
network maintenance, and secondly the practical functioning of the notification process. The
empirical part is based on questionnaire that was sent to the regional environmental supervisory
authorities and on evaluating 80 forest ditching notifications.
The results show that legislation does not set a clear framework for impact assessment.
Also, notifications rarely fulfill the obligation to assess and notify the impacts. In practice
the notifications either include no assessment at all, or the assessment is that “there are no
significant impacts”. The assessment task is thus left solely to the supervisory authority, which
is usually able to estimate the impacts of a single project based on the received information, but
the practices differ remarkably in different supervisory authorities. Their possibilities to assess
the cumulative effects of several ditching or other projects are, however, minimal. Cumulative
effects may cause severe deteriorating especially in fragile small waterbodies such as rivulets
and ponds. Authorities should have better resources and legislative support to be able to assess
cumulative effects. Also a more effective implementation of the general obligation to minimize
negative environmental effects could help in minimizing the negative environmental effects of
ditch network maintenance projects.