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#7716 Río Izoria, Valle de Aiala, Álava, Spain

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Spain, Álava, Ayala

The Izoria River is a small stream that flows into the Nervión River and the latter into the Cantabrian Sea. It takes its origin in the Sierra Salvada in the town of Orduña, Vizcaya, Spain.

Here lives the exciting cyprinid Phoxinus bigerri, native to rivers in the north of Spain, as well as in the Ebro River Basin and the Adour, in France. It shares habitat among others with Parachondrostoma arrigonis and the Austropotamobius italicus, the “signal crab”.

The stream is surrounded by trees and shrubs on both banks, namely Viburnum lantana, Acer campestre, Crataegus laevigata, Tyla platyphilos, Cornus sanguinea and Crataegus azarolus.

Submitted by
Asier Murga Arteta
GPS
43.0541344, -3.0439744
Geographical region
Southern Europe
Drainage Basin
Valle de Aiala
River catchment
Water body type
Stream
Water body name
Río Izoria
Water body part
Waterfall
Water body course
Middle course
Water body: tributary of
River
Tributary name
Río Nervión

Videos above and below water

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
High
Concentration of sediments
Medium
Water temperature
It ranges from 5°C in winter, and in summer to 21 °C
Water flow/curent
Strong

Chemical parameters

pH
8.0
Conductivity
178
GH
KH
7.0 mg/l
Dissolved Oxygen

Substrate in nature

Sand
Grey
Pebble/Gravel
Mixed
Stone
Mixed
Stone form
Irregular
Silt/Mud
Grey
Leaves
None
Driftwood
None
Submerged terrestrial vegetation
Yes

Aquatic Biotope

Date of collecting
May 30, 2023
Collecting area
Below waterfall
Water depth
1,0m
Air temperature
22 °C
Sunlight
Partial shade

Environment

Environment
Untouched
Surrounding area

This biotope is a cool and humid place, surrounded by green fields and many trees.

There is some livestock and agriculture in the area, but in general the river is healthy because from its source to here is only about 20 km, and in between there are hardly any people or any factory that could pollute the river.

As always, the biggest danger of this biotope is the human being. I have seen some people taking water for irrigation, that can be a problem especially in summer, although this river has never dried up completely.

On the water there are wild ducks, out of the water you can see wild boars and “corzos”, a species of deer.

Underwater landscape

The recreated area is a natural pool that receives a continuous supply of water through a small waterfall of approximately 60 cm in height, located in the upper part of the pool.

This pool is located a few kilometers from the source, in the medium-upper section of the river. On the journey to get here, the waters do not pass through industrial or inhabited areas, so they are quite healthy in terms of water quality.

The swimming pool is approximately 8m wide and 8m long. Maximum depth 1.8m. Altitude of 254m above sea level.

The water appears transparent although with a greenish tinge due to the presence of algae covering the limestone rocks at the bottom and is well oxygenated by the strong current.

The waterfall never lacks water. Under the stones you can see a dark colored muddy silt type bottom. From its source, the water passes through areas rich in limestone, which influences its parameters (hardness and pH), hardening and alkalinizing it.

Fishes:

  • Parachondrostoma arrigonis (Cyprinidae)
  • Phoxinus bigerri (Cyprinidae)

Crustacean:

  • Procambarus clarkii (Astacidae)
  • Pacifastacus leniusculus (Astacidae)
  • Austropotamobius italicus (Astacidae)

Aquatic vegetation:

  • Aufwuchs
Threats to ecology

The Río Izoria, from its headwaters to the estuary, transports loads of nutrients, sediments (gravel, sand, clay, silt) and organisms to the coastal environment, like many other rivers.

The draining of rivers threatens the sustainability of their biological richness and fisheries productivity – hence the importance of recovering the ecological flow of rivers to ensure their connection with the Cantabrian Sea.

River floods are necessary to reshape the substrate and rejuvenate the river’s riparian vegetation.
Furthermore, all flora and fauna near the river depend on it.

Riparian zone

Trees near the aquatic habitat
- Smilax aspera (Smilacaceae)
Trees near the aquatic habitat
- Crataegus azarolus (Rosaceae )
Trees near the aquatic habitat
- Crataegus laevigata (Rosaceae)
Trees near the aquatic habitat
- Tlilia platyphylos (Malvaceae)
Trees near the aquatic habitat
- Cornus sanguinea (Cornaceae)
Trees near the aquatic habitat
- Acer campestre (Sapindaceae)
Trees near the aquatic habitat
- Viburnum lantana (Adoxaceae)