Information that two of the Beavers located in the Forest of Dean have been removed due to a virus they carry.
However it seems they may well be replaced shortly.!!
Phosphate
Monitoring
For a number years now the river Wye, at various
times of the year, has suffered Eutrophication, commonly known by anglers as
‘algae bloom’ and manifests itself in very heavily clouded water and generally
associated with cessation of catches. Eutrophication occurs when
a body of water becomes overly enriched with minerals and nutrients which
induce excessive growth of plants and algae. This process may result in oxygen
depletion of the water body. Eutrophication is almost always induced by the
discharge of nitrate or phosphate-containing detergents, fertilizers, or
sewage
into an aquatic system.
This
Eutrophication seems to have exploded with the massive increase in chicken shed
developments along the Wye and its tributaries. WSA propose gathering of data
in the form of water sampling to examine whether there is evidence in support
of this hypothesis.
Phosphates are
naturally occurring minerals. These minerals are mined to get phosphorous
required for the production of fertilizers. Orthophosphates found in natural water
provide a. good estimation of the amount of phosphorus.
The natural background levels of total
phosphorus are generally less than 0.03
mg/L [ppm]. The natural levels of phosphate usually range from 0.005 to 0.05 mg/L [ppm]. Many bodies of
freshwater are currently experiencing increases of phosphorus and nitrogen from
outside sources.
A current, but as yet approved, planning
application for chicken sheds near Builth Wells on the Cnithio Brook a
tributary of the Wye affords the opportunity to carry out sampling on a before
and after basis. NRW have identified some requirements to satisfy the
protection of flora and fauna [see 18_0475_FUL-NRW-115193]. WSA have objected
to this application [see WSA Comments
for Planning Application 180475FUL] but fully expect it to go ahead.
Phosphates do not pose a human or health risk
except in very high concentrations. Large streams may react to phosphate only
at levels approaching 0.1mg/L [ppm], while small streams may react to levels of
0.01mg/L [ppm] or less. In general, concentrations over 0.05 will likely have
an impact while concentrations greater than 0.1 mg/L will certainly have impact
on a river.
Rainfall can cause varying amounts of phosphates
to wash from farm soils into nearby waterways.
Phosphate will stimulate the growth of phytoplankton and aquatic plants
which provide food for fish. If an excess of phosphate enters the waterway,
algae and aquatic plants will grow wildly, choke up the waterway and use up
large amounts of oxygen. This condition is known as eutrophication or
over-fertilization of receiving waters. This rapid growth of aquatic vegetation
eventually dies and as it decays it uses up oxygen. This process in turn causes
the death of aquatic life because of the lowering of dissolved oxygen
levels. The
ideal dissolved oxygen concentration for many fish is between 7 and 9 mg/l; the optimal DO for adult brown trout
is 9-12 mg/l. Most fish cannot
survive at concentrations below 3 mg/l of dissolved oxygen
Aquatic life uses may be hampered when the
entire water body experiences daily fluctuations in dissolved oxygen levels as
a result of plant respiration at night.
For protection of
ecological health phosphate levels should be <0.05mg/L [ppm].
Phosphate levels as
little as 0.15mg/L [ppm] are considered sufficient to trigger algal blooms in
surface waters.
WSA propose monitoring the Cnithio Brook at a
suitable site downstream of the planning proposal both before its operation and
during.
A simple 5 minute sampling process will use
hand held devices to measure orthophosphates, dissolved oxygen, water
temperature and water levels.
Equipment required to carry out this sampling
will cost circa £600 for which we have funds available.
Typical Equipment
Phosphate
Tester
Disolved
Oxygen Probe
Digital Thermometer
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