Working group 3 defined four key topic areas to deal with during the period June 1998 to December 2000.

Each key topic area will be dealt with by an organizing committee that will be responsible for collection and assessment of the present state of knowledge on phosphorus losses at the catchment scale in the participating countries, and for preparing and organizing a working group meeting where the main introductions and discussions will focus on one of four defined key topic areas.

The four organizing committees will use the contact persons from each of the participating countries in working group 3 to establish the present state of knowledge on the four key topic areas. Each committee will meet once every year to compile the information collected and prepare results, etc. for the working group meeting they are responsible to organize.

Each of the four planned working group meetings will be the final platform for scientific discussions, conclusions and recommendations on each of the four key topics defined. Each organizing committee will finalize their specific key topic with a report not later than 3 months after the working group meeting.

Identify appropriate methodologies to quantify dissolved and particulate phosphorus loss from catchments and the contribution of the total phosphorus loss, which is derived from agricultural areas.

• Laboratory analysis procedures
• Runoff measurement technologies
• Sampling procedures and technologies
• Source apportionment procedures
• Retention in freshwater systems

The organizing committee shall consider any spatial and temporal resolution problems that may influence the choices of methodologies to quantify phosphorus losses at the catchment scale.

Members of the organizing committee are:

Niels Vagstad, Norway (chairman)
Jürg Gelbrecht, Germany
Antonio Paz-Gonzales, Spain
Ilone Borlund, Finland
Stedus Ferrary, Italy
Brian Kronvang, Denmark

The organizing committee shall organize the second working group 3 meeting to be held in Berlin in early 1999.

 Objective

Identify the current loss of dissolved and particulate phosphorus from small agricultural and non-agricultural catchments (< 2500 ha) and investigate the possibilities to develop ´smart´ empirical models based on existing data.

• Collect and assess export coefficients for dissolved and particulate phosphorus loss from small agricultural and non-agricultural catchments in the participating countries. The collected data should preferably be for a fixed time period.

• Investigate the existence of data as hydrology, catchment properties and agricultural practices on the catchment level for use in the development of ´smart´ empirical functions.
• Assess existing lumped empirical phosphorus models.
• Investigate the usefulness and constraints in developing ´smart´ empirical functions and their possible use at different scales

The organizing committee shall consider any spatial and temporal resolution problems that may influence the use of empirical models to estimate and predict phosphorus losses.

 Members of the organizing committee are:

Robin Hodkinson , England (chairman)
Hradetzky, Austria
Ken Irvine, Ireland
Hans Olav Eggestad, Norway
Jeroen de Klein, The Netherlands
Sirco Peltonen, Finland
Brian Kronvang, Denmark

The organizing committee shall organize the third working group 3 meeting to be held in Cambridge/Dublin in autumn 1999.

Identify the methodologies that can be applied to point out and quantify the importance of different source areas, pathways and sinks for dissolved and particulate phosphorus losses at the catchment scale.

• Assess the importance of different phosphorus pathways in small agricultural catchments which differs in hydrology and catchment properties.
• Investigate the possibilities and constraints in using concentration-discharge relationships when dealing with catchment responses to hydrological events for P-losses.
• Investigate the advantages and constraints in using different kinds of ´fingerprinting´ techniques to identify sediment and particulate phosphorus source areas and quantify the importance of different pathways.
• Investigate the usefulness of applying different kinds of catchment surveys for identification and quantification of phosphorus source areas and pathways at the catchment scale.
• Investigate the usefulness of conducting comparative studies of phosphorus loss at the field and catchment scale.

The organizing committee shall consider any spatial and temporal resolution problems that may influence the use of different methodologies to identify source areas for phosphorus and quantify phosphorus losses along different pathways at the catchment scale.

Members of the organizing committee are:

Daniel Schaub, Switzerland (chairman)
Roz Jackson, England
Gerard Govers, Belgium
Brian Kronvang, Denmark 

The organizing committee shall organize the fourth working group 3 meeting to be held in Basel/Zürich in early 2000.

 Objective

 Identify possible management strategies that can be implemented at the catchment scale to combat diffuse phosphorus pollution and assess the advantages and disadvantages of applying deterministic models to estimate and predict phosphorus loss from agricultural areas, phosphorus transport in watercourses and phosphorus storage at the catchment scale.

• Outline the different management strategies (source and transport) that can be applied at the catchment level to combat diffuse phosphorus losses.
• Identify and assess existing deterministic models that can be applied at the catchment scale to estimate and predict phosphorus losses from agricultural areas.
• Outline the need of input data for different deterministic models and resolution problems related to the use of such models on different scales.

 Members of the organizing committee are:

Coen Roest, The Netherlands (chairman)
Michael Rode, Germany
William Magette, Ireland
Wouter Schiettecatte, Belgium
Ilona Barlund, Finland
Renan Goetz, Switzerland
Stefano Ferraris, Italy
Brian Kronvang, Denmark

 The organizing committee shall organize the fifth working group 3 meeting to be held in Wageningen in autumn 2000.