1. Running conclutions from workshop on GEP/Water Storage
Prepared by Peter Pollard

2. Continuity for fish Inclusion in libraries Nearly all countries
Upstream and downstream continuity important
Emerging good practice
Bypass channels, lifts, ladders
Fish ramps possibly for smaller dams
Screens if risk of entering turbines
Trap/release or stocking if other options not feasible
Expected frequency
Normally expected
Main reasons not required
Natural barriers to fish
No fish habitats
Downstream continuity - uncertainty about impact on non-migratory fish
Scale of impact addressed
Variable depending on ecological importance
Typically around 1 to 2 km (range 0.5 to 10 km)

3. River flow: upstream of re-charge & downstream of abstraction
Inclusion in libraries
All countries include flow mitigation
Flow mitigation considered ecologically important
Emerging good practice
Mitigation adapted to site characteristics (eg considering habitat &/or ecological criteria; etc)
Includes a low maintenance flow component typically in range Q92 to Q97 (few cases up to Q60 +)
Includes an additional variable/dynamic component
For long-distance migrators, includes suitable flow timed to trigger/support upstream & downstream migration
Optimising river morphology if not possible to restore adequate flow
Expected frequency
Normally expected
Reasons not required
No flow impact - sufficient water for good status released
Significant impact on water use – particularly maintenance low flow component
Scale of impact addressed
Variable typically 1 to 2 km (range 0.1 to 10 km)

4. Hydro-peaking: downstream of re-charge
- extreme and rapid fluctuations in flow leading to effects like fish stranding, wash out
Inclusion in libraries
Most countries with large hydropower schemes
Emerging good practice
Reduce rate at which discharge ramped down
In-channel structures to reduce velocities & provide shelter
Low flow to damp down effect
Re-locating discharge
In-channel balancing reservoirs
External balancing reservoir (only possible if space available)
Fish stocking – generally only (but not always) if other options not possible or fully effective
Expected frequency
Moderately common
Most commonly ramping down; in-channel structures stocking
Reasons not required
Water use not hydropower
Scale of effect small – eg size of peak compared with river

5. Lake level Inclusion in libraries
Majority countries include mitigation
Ecological impact varies with water use & lake shape
Emerging good practice
Maintain connectivity to feeder streams (if interrupted)
Balance levels with inflows from other reservoirs (only possible in few cases)
Limiting level variation in ecologically sensitive periods by reduced abstraction
If level variation only modest, protection of shore zone habitats
Protecting parts of reservoir - embayment
Fish stocking – if other options not possible
Expected frequency
Mostly not very common – experience currently limited
Reasons not required
No ecological impact – eg use does not produce significant level variation
Potentially significant impact if limiting abstraction
Impact addressed
Level changes range < 1 to > 3m.
Too little variation in level
Depends on sensitivity – eg lake shape

6. Ponded river Inclusion in libraries
Majority of countries with large rivers and barrages – normally for hydropower schemes, navigation & flood defence
Emerging good practice
Bypass ponded area and barrier to create flowing habitat
Raising bed to increase flowing habitat
Re-connecting oxbows etc
In-channel habitat improvements (if compatible with other uses eg flood protection) – most effective where still some flow or in combination with other mitigation creating flowing habitat.
Expected frequency
Common in some countries
Most common so far are improving in-channel & riparian habitat & re-connecting oxbows.
Reasons not required
No ecological impact – no uses producing ponded rivers or length of ponded river small
Impact on water use if lowering dam or creating a bypass channel [Other measures no impact on use]
Impact addressed
Typically 1 to 2 km (range 0.5 to 10)

7. Continuity for sediment
Inclusion in libraries
Many but not all have mitigation for sediment continuity
Most think important – except possibly break up of bed armouring)
Possible emerging good practice
Mechanical break up of armouring
Mechanical removal sediment accumulations
Reintroduce sediment mobilising flow
In-channel structures to increase flow to move sediments
Re-introduce sediment downstream of small intakes
Re-introduce sediment downstream of large dams
Remove bank fixation to enable sediment erosion
Expected frequency
Mostly very little used but some experience in some countries
Reasons not required
No ecological impact eg because impacted length short
Introducing re-mobilising flows some impact – impact on use of occasional flushing flows likely to be low
Impact addressed
Typically 1 to 2 km (range 0.5 to 10)

8. Temperature Inclusion in libraries
A minority of countries (7) have mitigation in library
Recognised that can be an important impact – greatest in common with hydro-peaking
Possible good practice
Multiple intakes
Syphoning
Managing lake level in sensitive periods (ie so intake is near lake surface)
Expected frequency
Not very common – very little experience although some in Norway
Reasons not required
No ecological impact – water use does not involve release of deep water from reservoir or length affected short
Impact addressed
Typically 1 to 2 km (range 0.5 to 10)

9. How to select measures from the library

10. 1. Rule out if the impact missing on the water body
2. If library has > 1 measure options to address an impact, rule out those that would not be the most ecologically beneficial given site characteristics
Carry out process in an open and transparent way
3. Rule out if improvement delivered by the best measure would be ecologically insignificant
4. Rule out if there would be a significant impact on the use

11. Would the remaining measures provide for some ecological continuum
(eg better than bad status)?
Minimum across Europe?
Yes No
Would taking measure be disproportionately costly?
Yes No
GEP once all measures in place
Set less stringent objective

12. Not relevant to type of use
Ruling out mitigation measures
Step 1: Is there an impact to address?
Not relevant to type of use
Site characteristics
Already mitigated
eg already working fish pass; river flow already provided
eg hydro-peaking impact only from hydropower
No impact
Impact too small
eg natural barriers to fish; lake shape
eg < 0.5 to 10km

13. Impact on water use: emerging good practice
Identify appropriate scale at which impact on use is judged (where benefits arise)
Scheme level
eg mitigation that would have a very large impact on scheme? (eg lake water level mitigation where draw down very large)
Only few water bodies – isolated schemes
National or supply level
water supply zone for drinking water
electricity grid network or national for hydropower
Make decision-making process open and transparent
Engage stakeholders through public consultation
Make impact on use threshold/criteria clear – provide certainty
Work with stakeholders to find ways to minimise impact on water use
Prioritise improvements through RBMP
Set out what can be done without impact on water use
If necessary, prioritise improvements to maximise environmental benefit

14. Current state of play
Few countries set out threshold/criteria for impact on use (4 France for hydro & only 1 for water supply. France translated into flow law)
For hydropower, typically thresholds around > 2 to 3% reduction in total output.
For hydropower, consider importance of different benefits (eg providing for peaks in demand)
For water supply, creating a negative supply/demand balance (after leakage reduction etc)

15. Test for alternatives
In general, alternatives to water uses not identified
Only example – recharging karst aquifers in winter to provide water supply
Test should not be overcomplicated
Rule out if no environmentally significantly better option
Collect more information from Member States on this topic?

16. What are we trying to compare?
Common standard for GEP
Process for deciding what GEP is

17. Starting distance from good status
Significant impact on water use threshold
How close to good status
and =

18. Starting distance from good status
Significant impact on water use threshold
How close to good status
and =
National priorities /role of use
(eg importance of hydropower)
Starting conditions
(eg is drinking water supply zone water rich or water scarce? scope to reduce leakage; etc)
Original level of mitigation
Site characteristics (eg lake shape etc)
Impact scale judged relevant
(0.5 to 10 km)