History of The River Lea trail

The River Lea industrial trail is in the Lea-Artibai district. This landscape, protected as a Monument Site in 2015, was our version of Silicon Valley at the end of the 17th century and is made up of assets and landscapes of high heritage value linked to shipbuilding and forge & milling in the pre-industrial era.

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A bit of history

  • Arriving at the municipality of Munitibar, we can start a fantastic walking or cycling route through one of the most beautiful industrial landscapes in Bizkaia, the path that follows the Lea River for 23 km to its mouth in Lekeitio. On this route, alongside the water, you will have a unique opportunity to discover and enjoy peaceful, little-known places steeped in history.

  • The Lea River is short but intense. It rises on the northern slope of the Oiz massif in Munitibar and runs through the municipalities of Aulesti, Gizaburuaga and Amoroto at the other end and flows into the sea between Mendexa and Lekeitio. Although archaeological remains and evidence of its rich activity since Roman times can be found in the surrounding area, it was undoubtedly the 16th and 18th centuries that brought splendour and wealth to the region.

    The hydraulic mills, iron production, shipyards and seafaring industry in the area were at the forefront of Europe. Our own version of Silicon Valley, where the industrialist and engineer Pedro Bernardo Villarreal de Bérriz was the enlightened figure who, with his “Treatise on Hydraulic Machines for Mills and Forges”, developed new techniques and scientific and engineering innovations that led to a revolutionary improvement in living conditions for the population.

  • The industrial landscape of the Lea River reflects the surrounding nature and the remains of abundant hydraulic installations that are still preserved along its entire length, which can be enjoyed on a comfortable and peaceful walk. This route is a perfect example of how interesting elements of our industrial heritage can be showcased in a natural setting with exceptional scenic value.

  • As early as the 14th and 15th centuries, innovative ironworks were installed on this river to obtain iron from its ore, where the force of the water moved bellows and hammers, as well as traditional grain mills. Many dams and weirs were built to divert the river water to these facilities, most of which are still in place today and are evidence of the technological advances implemented by Villarreal de Bérriz.

    Several examples stand out, such as the straight gravity dams and arch-type dams, which illustrate the evolution in the design and optimisation of materials and improvement in production.

  • In addition to these infrastructures, as you reach the mouth of the Lea on the Cantabrian coast, it is worth visiting the Marierrota tidal mill. This is a seawater mill, similar to river mills, although what set it apart was a large masonry dyke and a dam that filled at high tide and emptied at low tide, which set the mill machine in motion. The old mill has been restored and now houses an interpretation centre. It is open to visitors at weekends during the summer.

  • At the end of the Lea River, there are some very interesting traditional riverside shipyards, such as those of Mendieta, Eguiguren and Achurra. In the river estuary, between Isuntza Beach and San Nicolás Island, part of the Malecón Lazunarri remains. This hydraulic infrastructure was built in the 18th century to divert the mouth of the estuary, preventing the formation of a sandbar caused by the strong drift of sand, which hindered the access of boats upstream and blocked the fishing port.

  • The shipyards are located on both banks of the Lea River, on artificial platforms on the sandy shores. These traditional complexes have no enclosed spaces and are highly versatile. They consist of a masonry platform supporting the assembly slipway structure, where the tarred crossbeams were laid to form the keel of the future boat; wooden gangways used to raise and lower the vessel; and single- or multi-bay buildings with wooden walls and posts supporting exposed wooden truss roofs, covered with tile or sheet metal in a double-pitched configuration, together with stone floors and access roads.

    The shipyards, most of which were privately owned, were dedicated to the construction of fishing boats and coastal vessels, such as pateches (small coastal cargo vessels), pinazas (light pinnace-type vessels), and venaqueras (inshore workboats). They are buildings from the late 19th and early 20th centuries, although there is evidence of shipyards existing in earlier periods at the site where some of them are located.

  • The most significant points along the Lea River industrial route are:

    BENGOLA Ironworks, Energía Natural Renewable Energy Interpretation Centre (Munitibar)

    At this interpretation centre, you will find what are, to date, the earliest pieces of evidence of the application of hydraulics to metallurgy in the Basque Country. Specifically, these are the remains of two ancient phases of the ironworks, the first of which dates back to approximately the end of the 13th century, the base of an iron-reduction furnace and the base of a small trip hammer. In the next phase, at the end of the 15th century or the beginning of the 16th century, a new ironworks was established next to the old one, from which the remains of the hammer and the furnace were recovered. This complex has been turned into a museum and the remains can be visited. At this interpretation centre, you can also enjoy the Renewable Energy Park. This is an educational space that showcases the main characteristics of natural and renewable energies (wind, solar, geothermal, hydraulic,etc.).

  • BENGOLEA Ironworks (Gizaburuga)

    This is undoubtedly one of the most important ironworks in Bizkaia and among the most important in the world in the first half of the 18th century. It is a complex hydraulic installation located in the Okamika neighbourhood of Gizaburuaga. A large double ironworks consisting of a huge charcoal store, several areas for collecting iron ore and wrought-iron blooms, storage sheds, three flour mills, a reservoir and a two-arched bridge. A single column supported the entire roof. It is one of the most complex ironworks in the Basque Country, although it is currently abandoned. The owner of the estate, Pedro Bernardo Villarreal de Berriz, renovated most of its facilities in the early 18th century. The Bengolea dam is unusual: unlike the reservoirs in the area, it has a single central buttress (prismatic pier) and a straight upstream face.

  • MARIERROTA Tidal Mill (Mendexa)

    Marierrota is a tidal mill located at the end of the Lea Trail, at the mouth of the river between the beaches of Isuntza and Karraspio, which uses the tidal cycle to create a head of water to turn the millstone. It was built in 1555 with the aim of replacing river mills during times of drought. The masonry dyke that created the water basin is still preserved, and when the tide went out, this reservoir set the milling machinery in motion. The mill building, which was demolished in the 1980s, has been rebuilt and now houses a Biodiversity Interpretation Centre where visitors can learn about the marshland and the activity that took place in Marierrota for more than five centuries.