Legal and political context

Content taken from the dossier “From the European Nitrates Directive to green algae plans in Brittany: contributions from INRAE scientists”.

The first green tides appeared in Brittany in the 1970s, associated with a marked increase in nitrate concentrations in Breton rivers, a phenomenon that was to become more marked until the end of the 20th century: from 5 mg/l in 1960, the average nitrate level rose to 53 mg/l in 1994. At national level, nitrate pollution led to the promulgation of the European Nitrates Framework Directive in 1991, the coercive measures of which were translated into a series of plans and programmes in Brittany.

In 1991, Europe adopted the so-called “Nitrates” Directive (91/676/EEC), with the dual aim of “reducing water pollution by nitrates and eutrophication from agricultural activities” and “preventing the spread of such pollution”. To achieve this, it imposes a series of action and monitoring measures on Member States. At the heart of these regulations is the introduction of action programmes centred around “vulnerable zones” where water supplies are likely to be polluted by nitrates. It also provides a framework for agricultural practices, regulating spreading periods and setting the amount of nitrogen that can be applied annually from livestock effluent at a maximum of 170 kg/ha. This directive is translated into French law by a national action programme (PAN), which sets out the common base applicable to all “vulnerable zones”, and regional action programmes (PAR), which specify or reinforce the measures to be applied depending on the regional context. A few years later, the Nitrates Directive was incorporated into the Water Framework Directive (2000/60/EC), requiring EU Member States to achieve good status for coastal waters by 2027 at the latest. In Brittany, a region particularly hard hit by water pollution caused by nitrates and eutrophication, this European policy led to the introduction of plans to combat green algae (PLAV) in 2010. PLAV 1 (2010-2016) and PLAV 2 (2017-2021) target eight bays particularly affected by the green algae phenomenon, as well as their catchment areas. Coordinated and run jointly by the State and the Regional Council, these plans are drawn up and implemented in conjunction with scientists, representatives of farmers and environmental associations. They aim to improve public health and the health of the coastline by developing two aspects: firstly, by improving the collection and disposal of green algae, and secondly, by preventing and limiting agricultural nitrogen leakage. From the Nitrates Directive through to the PLAV, plans and programmes have supported changes in farming practices.

1994-2013 : Key programmes to combat eutrophication in Brittany:

• Bretagne Eau Pure programme (1994-2006): a programme to restore water quality involving the European Agricultural Guidance and Guarantee Fund, the Ministry for the Environment, the Loire-Bretagne Water Agency, the Conseil Régional de Bretagne and the four départements of Brittany. It involved setting up contractual action programmes on the river systems most affected by water pollution.
• Prolittoral programme (2000-2006): a regional and interdepartmental programme to combat green tides, coordinated by CEVA with scientific support from Ifremer. Maintaining the same partnership as Bretagne Eau Pure, Prolittoral consists of 3 parts: preventive, curative and transversal.
• Major Project 5 (2007-2013): a State-Region Brittany project contract coordinated by the State (DREAL) and the Loire Bretagne Water Agency, which has taken over from the Bretagne Eau Pure and Prolittoral programmes.

Scientific requirements and contributions from INRAE

Content taken from the “From the European Nitrates Directive to green algae plans in Brittany: the contributions of INRAE scientists” dossier

Since the 1970s, researchers at INRAE have been studying nitrate flows from agricultural fields to catchment areas and their impact on the biological balance of aquatic environments. Agro-hydrological models have been developed to provide a better understanding of nitrate flows and to help local players implement regional policies.

At national level, nitrate pollution led to the promulgation of the European Nitrates Framework Directive in 1991, the coercive measures of which have been translated into a series of plans and programmes in Brittany. For more than 40 years, INRAE teams have been working in Brittany to understand the processes governing nitrate flows, from the plot to the catchment scale, and to support those involved in the field.

With the deployment of plans to combat green algae in Brittany (PLAV), scientists have gradually moved from the position of experts providing advice to that of mediators supporting the various stakeholders by sharing scientific knowledge on the subject. These years of experience have led to the creation of a dedicated training course for new elected representatives who are going to become involved in the PLAV, capitalising on the knowledge of former elected representatives and on scientific knowledge.

In Brittany, scientists from INRAE, Ifremer, CNRS, the Centre d’étude et de valorisation des algues (CEVA), etc., have supported and monitored these developments at both local level, through collaborative research projects, and national level, through expert appraisals. The terrestrial component, developed by INRAE, has focused in particular on modelling nitrogen flows in agricultural plots and adapting practices.