EPTB Vilaine

An old story

With large activities…

IAV was created in 1961 between 3 counties :

Loire Atlantique, Morbihan, Ille et Vilaine

Vilaine marshes dynamic

Flood prevention

Develop new farmland

Restore navigation

5 63 53 5

4 44 4

A tool to serve the counties

Goals quickly completed with water

supply (Férel plant was inaugurated in

1972) and later with maintenance of

the waterway (1989)

Some key dates

1961 à 1970

Building of the Arzal dam

1972

Water supply plant

1989

Concession of the waterway

1995

First « environmental contributions »

1998

IAV is designated as SAGE operator

2003

Official approval of SAGE Vilaine

2007

EPTB Vilaine

2010

Reviewing of Sage Vilaine

Status

Public Administrative Institution with legal

and financial autonomy

« Etablissement Public Territorial de

Bassin » (waterboard) of the Vilaine

catchment area since 2007

Board :

12 County Conselors (3x4)

1 chairman

2 vice-chairmen

Average budget :

• Investment budget : 6/10 M€

• Operating budget : 12/14 M€

• Conties contributions + subsidies

• 45 Employees

Actions and issues

1- Context/goals

Management of the water

reservoir : water supply,

navigation, flood prevention

Prevent the conjunction of

Vilaine flooding and high tide in

Redon

Arzal dam : keystone of

hydraulic regulation

Minor side hydraulic structures on

Isac et Trévelo

2- Recent and ongoing actions

Maintenance of the waterway

Upgrades of the Arzal dam

Design of a new lock at the

Arzal dam (DROP project)

Original role:

Flood prevention

Development of

agriculture

Commercial navigation

Current role :

Main objectives :

Water supply and flood

prevention

Secondary objectives :

Navigation

Maintain a good balance in

the Vilaine estuary and

marshes

Fish migration

3- Issues

Keep a high standard of

performance in water level

management

Equipments reliability

Make our management more

« visible » and

understandable for public and

users

1- Context/goals

Complex environment with

frequents usage conflicts

Upsets induced by the dam

achievement

Siltage connected to « water

supply » usage

IAV is « in the heart of the

landscape »

2- Recent and ongoing actions

Efficient dialogue within an

Estuary Steering Committee

Building of a ship designed

for specific dredging

operations

3D hydro-sedimentary and

hydro-dynamic modelling

Transfer of mussel culture

installations

3- Issues

Think in terms of sustainable

development …

Work on social acceptance of

development operations

Weight the pros and cons

before embarking on

important dredging programs

1- Context/goals

Founding and statutory mission

of IAV, enhanced by the SAGE

et EPTB status

Expertise at the whole

catchement area scale.

Coordination, assistance to

local organizations

Management of the structuring

projects.

2- Recent and ongoing actions

Hydraulic modelling

Global understanding

Simulation of scenarios : local

protection, flood reservoirs,

structures management…

Reducing vulnerability

Risk Awareness

Put flood marks

Crisis management

Assistance to local

communities

Construction programs

Flooding areas (Chateaubriant)

Dike restauration (Moisdon)

InterReg programs : Wave

3- Issues

Enhance risk awareness

Work on reducing

vulnerability

Develop cost/benefits

analysis for important

construction programs

1- Context/goals

One of the 2 biggets plants in

Britanny : an average of 17

Mm3/year

Towards Morbihan 25%

Towards Ille et Vilaine 5%

Towards Loire Atlantique 70%

Key role of regional regulation

In winter : 30 000 m3/day

In summer : 90 000 m3/day

2- Recent and ongoing actions

New contract of public service

delegation covering the period

2009/2023

Restructuration of the plant to

enhance the process (COT,

micropollutants) : 2016/2020

New feeder towards Rennes :

2017/2020

3- Issues

Maintain the key role of

regional regulation

Improve the process to keep

the plant « up to date » and

to anticipate new

regulations/pollutants

Management of the reservoir

during periods of

drought/water scarcity

1- Context/goals

European framework + EPTB

(Waterboard) status : key role

on water and aquatic

environments

Some remarkable aquatic

environments on the basin

Wetlands locally very important

for water quality

Vilaine is a major axis for fish

migration

2 – Recent and ongoing actions

Monitoring of the Arzal dam

fishpass (strong eel expertise

on the basin)

Natura 2000 operator on the

Vilaine marshes : write the

targets document

Coordination of the of rivers

and wetlands inventory at the

basin scale

Cartography of primrose – local

works of primrose uprooting

3 – Issues

Keep a high level of expertise

Work on local acceptance of

glass eel fishery regulation

Improve the hydraulic

regulation of Vilaine marshes :

not only flood prevention and

water supply, but also

environment issues,

navigation… : Arzal dam

becoming a multi users

hydraulic structure

Context

Multi users area : water supply,

flood prevention, agriculutre,

navigation…

Current lock causes salt

intrusions penalizing water

supply

Siphons to prevent salt

intrusions : losses of huge

amounts of fresh water (300

000 m3/day)

Water scarcity :

-restrictions in the use of lock :

conflict with boaters

-Preventive rise in water levels

to increase the capacity of

storage : conflict with farmers

Project

New lock anti salt intrusions

No need of siphons to prevent

salt water intrusions : no

losses of fresh water

Water scarcity :

- No restrictions in the use of

lock : no conflicts with boaters

- No need of preventive rise in

water levels : no conflict with

farmers

Problems :

-Be sure of the efficiency of the

project

-Cost of the project : 20 M€

Institution d’ Aménagement de la Vilaine

EPTB Vilaine