Hydropower Good Practice Guidelines
This response is made on behalf of the following organisations:
Angling Trust/ Fish Legal
Atlantic Salmon Trust
Buglife- The Invertebrate Conservation Trust
Institute of Fisheries Management
Marine Conservation Society
Salmon and Trout Association
The Rivers Trust
Wild Trout Trust
We believe that, alongside water and energy efficiency, increasing the uptake of
sustainably sourced renewable energy technologies is essential for environmental
and climate protection, by reducing greenhouse gas emissions and decarbonising
the power sector in order to avert the worst impacts of human-induced climate
Like with the assessment of any new proposed development, minimising potential
harm to the natural environment is essential, as is climate protection, so it is
important the right renewable technologies are installed in the right places in rivers
around the UK.
We believe that hydropower can play a part, albeit relatively small in the England and
Wales, provided that steps are taken to ensure no adverse effects to our aquatic
ecosystems occur, including to hydro-geomorphology, in-stream substrate, fish,
invertebrates, associated flora and the flows required to support them. However, it
should be recognised that the contribution of individual schemes in lowland areas
with low gradients and flows will be minimal.
In addition, so that the aquatic environment can adapt to climate change, we must
ensure these ecosystems are as naturally resilient as possible. The UK (and other
Member States) must also ensure the EU Water Framework Directive (WFD) and
Habitats Directive (HD) are fully complied with and the legal requirements of the
WFD to achieve good ecological status (or good ecological potential) in rivers are
We believe that it is important to:
1. Keep our rivers flowing and wetlands wet; amend or revoke those water
abstraction licenses that damage lakes and wetlands
2. Restore rivers from source to sea; regenerate rivers, lakes and wetland in
partnership with local communities.
There is a risk that these objectives could be compromised if potential run-of-river
hydropower schemes are installed without proper regard for the aquatic environment.
We believe that there are five key criteria to achieving sustainable run-of-river
An independent Environmental Impact Assessment must be carried out for all
hydropower applications at the specific site, and assessed within the
Aquatic biodiversity connection corridors should be in place to ensure that
there is minimal impediment to natural up and downstream movements of fish
and invertebrates past all hydropower schemes.
There should be minimal effect on natural water flows or levels that adversely
affect the aquatic environment in its natural state.
Vulnerable species should be prevented from entering the turbines and
directed to the by-wash channel by appropriate screening.
Post-scheme monitoring to ensure that these steps are being implemented
and are effective should be carried out. This monitoring should be carried out
on the full range of flora and fauna within the affected river reach. If
monitoring indicates the scheme is having a detrimental impact on the
environment the scheme would be stopped until the issue is resolved, or
removed if no solution can be found.
Consultation question 1
Are there other effects (both positive and negative) which should be
considered on a cumulative basis?
For fish, we believe the cumulative impacts of multiple fish passes as well as weirs,
both upstream and downstream, should also be considered. Fish passes are not
100% effective, so in order to improve ecological status of our fisheries in
accordance with the Water Framework Directive (WFD), we need consider the use of
fish passes in the catchment as a lesser alternative to removing the barrier/weir
altogether. Cumulative impacts are particularly important for fish species which
migrate long distance, such as salmon, sea trout and eels; for example, five fish
passes, each 85% effective, would reduce the number of fish able to access
spawning areas above them by 66%.
The cumulative effects of any ecological impacts in flow-reduced sections of river
also need to be considered, as well as the obvious ones of mortality (direct and
indirect) resulting from inadequate screening, migration delay/predation and turbine
Where immovable obstructions are present, the positive effects of improved fish
passage when provided by developers should also be assessed.
Consultation question 2
We would value your comments how these cumulative effects should be
considered and assessed.
We believe the Government should require the Environment Agency (EA) to produce
coordinated catchment strategies. These should include removal of existing barriers,
hydropower development opportunities and fish passage opportunities. It makes no
sense for the environment for the EA to continue to permit on a first come, first serve
basis. The potential cumulative impacts of the hydropower cannot be adequately
managed in this way. We must enforce the precautionary principle if the scientific
evidence is not available.
If there is any chance of producing so called ‘win-win’ scenarios, current barriers to
fish migration, along with hydropower opportunities, must be assessed together. We
believe without doing so the EA cannot ensure modifications, such as hydropower
developments, are not breaching the no-deterioration requirements of the WFD. We
cannot and should not continue to manage each pressure on our rivers in isolation.
Consultation question 3
Can you suggest ways in which additional protection can be provided for weir
pools (where they have been identified as having special importance)?
On many impounded rivers, weirpools afford the only truly diverse habitat, providing
not only spawning opportunities for many rheophilic species, but also flow-dependent
invertebrates and macrophytes. The text adequately describes the issues, but the
Guide then makes no attempt to provide an appropriate solution. It correctly
highlights the importance of moderate flows to maintain the morphology, and it is the
frequency and periodicity of these flows which is lost with the proposed regime (as
Table 2) of leaving a minimal “hands off” flow and allowing the turbine to take the
remainder up to the mean flow or more.
The first step is to identify those weirpools at risk. This should be a quick and easy
task for EA Area staff based on local knowledge, supplemented by relevant angling
and conservation organisations where possible. Those weirpools will almost
invariably be those that provide habitat diversity in an otherwise uniform impounded
Protection should be relatively straightforward with the following potential options:
1. A proportional distribution of flow, above a “hands-off”, between turbine and
2. A “stepped” residual flow.
3. A residual flow of 40-60% of the mean flow (see Q4 response below)
Consultation questions 4
a. Would you propose any changes to the flow tables for low head schemes?
4b. Please provide your reasons and any supporting evidence
Despite the assurances asserted in the current Guidelines, the abstracted flow
regimes do not take proper account of ecological and fisheries issues. The
“scenarios” in Section 4 do adequately describe the issues for the common types of
hydropower schemes, yet the Guidelines fail to translate these to the “flow table”
Flow controls many, if not all, of the biotic and abiotic processes within rivers, yet the
Agency’s attitude is that hydropower is non-consumptive. However, for any reach of
river deprived of water, whether a weirpool or several km of river, it is very much
consumptive, and any abstraction should be assessed accordingly. The same
standards should therefore be applied as a default.
Current expert scientific opinion highlights the importance of leaving a naturalistic
flow regime – consisting of high, moderate and low flow events – in any reach
depleted of water. The type of flows prescribed by the “flow table” – a “hands-off”
quantity and turbine take up to the mean – has been demonstrated in peer-reviewed
scientific papers to adversely effect the biomass and density of fish in the depleted
reach as well as change the structure of the population.
The examples of hydrographs and flow duration curve presented in Figures 2 & 3 are
of an extreme “flashy” low baseflow river. An example using a more typical moderate
baseflow river would be more representative. This confirms concerns about the over-
simplistic approach to using ‘look-up tables’.
There have been a large number of attempts to define minimum flows. Those which
may provide a naturalistic flow regime, and therefore should be the defaults, are:
1. A proportional flow split above a “hands-off” allocation. If the depleted reach is
the principle fish migration route, then that should always have a majority
2. A system widely adopted in the US and adopted by Germany; the “Montana
method” (Tennant 1976). This specifies a “hands-off” flow of between 40 and
60% of the annual mean. 40% provides “good” instream habitat, 50%
“excellent” and 60% “outstanding”.
Consultation question 5
What are your views on including a requirement to ensure fish passage around
all new weirs?
WFD prescribes that Good Ecological Status (GES) or Good Ecological Potential
(GEP) depends on free upstream and downstream movement for all species of fish.
The Guidelines should comply with the known anticipated legislative changes.
Any new weirs should include provision for all-species fish passage. However, this
question should never arise as the presumption should be against the construction of
new, or increased, impoundments.
The provision of technical or naturalistic fish passes is never the best solution for fish
passage as they rarely prove to be 100% efficient or cause no delay, whether
upstream or down (see for example Hydropower Generation in the context of the EU
WFD). Therefore the default principle for all obstructions should be their removal,
resulting in free passage for fish, invertebrates and sediments and improvement to
the upstream morphology. Where removal is not possible for valid reasons, any
development on or adjacent to them should include a facility to allow unrestricted
passage of all fish species.
Consultation question 6
Are these revised screening and by wash requirements adequate for the
protection of fish as part of the design of hydropower schemes? Y/N
Please provide your reasons and supporting evidence
Crossflow turbines, a variety of impulse turbines, are correctly described as causing
virtually 100% mortality to fish. Why, therefore, is their screening requirement seen
as different to the other types of impulse turbine? If 3mm is necessary for other
impulse turbines, then it should be for Crossflow. Any other option is illogical.
Screening for propeller and Francis turbines should be based on the size of fish at
risk, not on the migration size of smolts. To have a differentiation between Regions is
confusing and nonsense. The default screening size for larger propeller/Francis types
should be 10mm throughout, or 9mm where there is a predominance of male silver
eels. For smaller turbines of these types, 6mm screens should be the default. The
guide rightly describes the impact of the small “polymer” variant of Francis turbines
as being similar to Crossflow turbines and will therefore also require 3mm screens.
Under and breast shot waterwheels require similar screening to larger
propeller/Francis turbines, as may 4 or 5 blade Archimedean screws depending on
the results of current testing. Until the potential impact of Archimedes screw turbines
with more than 3 blades has been thoroughly tested and independently verified they
should be treated as other damaging turbines.
All developments, including waterwheels and Archimedean screws, require an
Table 3b provides for physical bar screens to prevent access to turbines by upstream
migrating fish. As waterwheels and Archimedean screw turbines are as dangerous as
other types of turbines, it is illogical to exempt them from this requirement. Therefore
a similar sized screen would be required to prevent fish entering the turbine, and
therefore will require the same, or smaller, size of screens upstream to prevent
trapping fish between the turbine outflow and the downstream screen. It is also
essential to prevent upstream migrants from entering tailrace cul de sacs, by
screening, regular shutdowns or channel design.
The screen orientation, approach velocities and bywash as described in 9.3 and 9.5,
are acceptable and schemes not complying with this should be rejected.
Consultation question 7
New weirs: Do you agree with this? Y/N
Please provide your reasons and any supporting evidence
We wish to see clarification of the distinction between lowland rivers and upland
streams, with clear reference to river type (size, gradient, fish zone) to avoid
We agree with the EA presumption against the creation of new weirs solely for
hydropower on lowland rivers. Any new weir is likely to affect adversely the river
geomorphology and ecology with a risk of deterioration in Ecological Status, contrary
to the requirements of the WFD.
For the same reason we would presume against the creation of new weirs on upland
streams for high head schemes, unless it could be demonstrated that the effect
would be undetectable or totally mitigated. Weirs have been shown to cause long-
term changes in the river fauna (including invertebrates and periphyton), where the
changes in flow regime result in the formation of dynamically fragile fauna
communities (Artimage, 2006).
Consultation question 8
Do you agree with our general approach towards raising weirs as of
hydropower schemes? Y/N
Please provide your reasons and any evidence to support them
We would be against raising any weirs, unless it could be demonstrated that the
effect would be undetectable or totally mitigated.
Scenario 1 (weir raised to compensate for drop in water level as a result of the
proposed scheme) is acceptable provided it does no more than compensate, i.e. the
upstream water level is not raised. However, when the turbine is not operating at full
capacity, the upstream water levels will be higher than previous, and this aspect
should need careful consideration.
Scenario 2 (weir raised by more than Scenario 1 to increase generating capacity) is
unacceptable. Raising the water level will increase the length of the impounded reach
with adverse effects on the geomorphology and ecology with a risk of deterioration in
Ecological Status, contrary to the requirements of the WFD. It may also reduce the
efficiency of any fish pass or the ability of fish to pass directly over the obstruction.
Consultation question 9
Do you have any suggestions for criteria which might be helpful when
assessing more than one application for hydropower schemes on the same
weir or impoundment?
Multiple schemes on one weir pose a number of problems:
How is the ‘available water’ allocated?
Who has prior call on any allowable abstraction above a Hands Off Flow?
Who is liable if a Hands Off Flow or other licence condition is breached?
Who would be the defendant in any case taken by interested parties whose
legitimate interests were damaged?
Who is liable if the part of the weir owned by one person is damaged by a
scheme on the part owned by another?
How is the potential divided attraction flow to upstream and downstream
migrating fish towards offtakes/outfalls instead of the desired route to be
prevented? It is more difficult even than single schemes.
Given the difficulties posed by these questions there is no sense in allowing more
than one development especially as it effectively splits the generating potential with
no overall renewable energy benefit. In principle this is no different from the means
by which water available is shared for consumptive abstractions along a river, ie first
come first served. The EA’s regulatory responsibilities are not well served by it
attempting to act as a broker between potential developers.
Consultation question 10
Do you agree with this approach to the permitting of high head schemes?
Please explain with evidence what other model/criteria we should use.
High head schemes are normally in the upper reaches of river catchments, and as
they may be above natural obstructions impassable to fish, they are invariably
treated as of little ecological value. However, they often contain genetically unique
brown trout populations, some of which will contribute to downstream populations.
They also contain invertebrate communities, also important to downstream
populations, via drift. Impounding these fast flowing upland streams can adversely
affect the composition of the invertebrate fauna.
New obstructions, even low ones, may compromise free movement of these fish and
must always include provision for fish passage as a default. These schemes often
have very long depleted reaches, and therefore the default flows described in the
tables are unsuitable. A flow regime following the Montana/German model (as
previously described) of a residual flow of 40% of the mean flow should be the
default to protect the river ecology, including fish and invertebrates.
Consultation question 11
a. Under what circumstances should environmental monitoring (pre and post
scheme) be required in association with the development of a hydropower
We believe pre and post environmental monitoring should be required to gain
information on all schemes where we do not already have sufficient information to
show no/minimal impact of the scheme on the surrounding ecosystem and
associated species. At the moment we do not believe this information exists for any
scheme designs, and therefore we seek an extensive programme of monitoring to
reduce this uncertainty. This should include the requirement for catchment wide
environmental assessment where cumulate impacts apply.
b. What aspects of the environment should be monitored?
A full Environmental Impact Assessment (EIA) should be required, including an
assessment of the aquatic ecological impacts.
c. Who should fund this monitoring?
The cost of monitoring should be incorporated into the cost of the scheme, therefore
The Government and its associated bodies, e.g. the EA and Defra, should fund the
catchment planning and cumulative impact research. It should not be funded from
rod-licence or fisheries Grant Aid revenue.
Consultation question 12
Please let us know of any further points that you feel have not been captured in
this consultation. If it relates to a specific piece of text it would be useful if you
could cross reference it. If not please identify the issue clearly and provide any
The presumption of the guidelines is that if schemes are compliant then they will be
“fast-tracked” for licensing and will require no post-scheme monitoring. Therefore, the
default position must be that the guidelines are fit for purpose and be at least
ecologically neutral. The present iteration is therefore not acceptable. Any variation
from the guidelines must be fully justified.
Run-of-river hydropower schemes will never produce more than a negligible
contribution to the Country’s energy needs or energy security. Nor, with its reliance
on large subsidies, should it be treated as sustainable development. It should only be
considered where it can be clearly demonstrated that it can be done so without
ecological damage and be compliant with the WFD. Considering its insignificance, it
is improbable that any damage could be compliant with the conditions specified in
Article 4.7 of the WFD.
All run-of-river hydropower schemes should include an exit / end of life strategy in the
consent, whereby it is ensured that the river reaches and weir pools are returned to
former condition in the event of cessation of operation for whatever reason.