At first glance, the site might only offer a peaceful painting: a reservoir lake bordered by pine forests, a water and sky horizon upon which birds slide. But behind this postcard hides an intriguing detail: A concrete flower rests upon the water; eight petals converge toward a central well. This “daisy” is not an architectural fantasy: it constitutes the Sarno dam’s spillway, the cornerstone of its hydraulic safety. According to the local narrative, its configuration – eight petals linked by a well of around six-meters in diameter – is supposed to be unlike anything else in the world. A technical achievement that converses with the whims of water.

When winter rain swells the reservoir of the Sarno dam, which is nestled at the foot of the Tessala Mountains, water reaches its maximum level. It then crosses the threshold of this singular daisy. The eight concrete petals draw a circular labyrinth and artificially extend the crest line. The water whirls in this winding path before it dives into the central well – a hydraulic “tulip” that sweeps it downstream, dissipating its energy into a masterful choreography.

This arrangement associates a morning-glory type of spillway with a labyrinth overflow. Unlike the famous “Glory Hole” of the Monticello in California – a simple, circular funnel –, the Sarno daisy plays on geometry. Its petals increase the transit capacity while limiting the footprint. A technical gesture paired with a rare aesthetic, which earns it its poetic nickname.

A daily vital resource

The Sarno dam came into being between 1947 and 1954, in a colonial Algeria keen on ensuring its water supply. Built upon the Sarno stream, a tributary of the Mekerra, it is part of a well-established technology: An earthen dam with an upstream layer of asphalt concrete, ensuring the impermeability of the embankment.

The dam, operational since 1954, has become part of the national hydraulic assets, which is managed nowadays by the National Agency of Dams and Transfers (ANBT). Its current useful capacity, slightly reduced by natural sedimentation, comes close to 21.25 million cubic meters – a data point confirmed by official monographies.

Beyond its spectacular image, the dam plays a strategic role in potable water supply. Located at about 15 kilometers from Sidi Bel Abbès, it primarily serves Sidi Hamadouche and its surroundings, but its networks extends to several municipalities according to demand and to periods of water stress.  

An ecological gem to preserve

The numbers are eloquent: Following recent rainfall, the fill rate came close to 90%, which translates to about 20 million cubic meters. In order to secure this resource, a treatment plant was put into operation. It contains two water purification lines with a capacity of 25 liters per second each. A crucial reinforcement in a region where each drop counts.

The Sarno site is not limited to its civil engineering features. It also forms a true ecosystem: a shimmering body of water, lush riparian forests, and pine groves climbing the slopes. A local botanical survey recorded 77 terrestrial plant species, spread across 72 types and 42 families, dominated by Asteraceae and Lamiaceae. A subtle yet tangible biodiversity.

However, the dam remains exposed. Pollution alerts due to wastewater discharges have been reported, accompanied by occasional fish die-offs. A stark reminder: Without vigilance, this ecological corridor risks suffocation under human pressure. Watershed-scale sanitation measures are needed to preserve this natural as well as hydraulic asset.

A geometric singularity

Does calling the Sarno daisy “one of a kind” belong to the realm of local myth or is it a technical reality? The labyrinth overflow principal – a folded crest that increases the length of outflow – does exist elsewhere. Likewise, morning-glory type spillways, such as that of the Monticello dam, discharge high waters through a vertical funnel.

However, the combination of both, embedded into an embankment dam from colonial Algeria, with this floral signature with eight petals? Here resides the rarity. No other documented construction seems to have adopted this geometry. The originality does not lie in the invention of the concept, but in its execution: a marriage between technical efficiency and visual grace.

At a time when territories are rediscovering their hydraulic assets, Sarno possesses a tangible framework for its valorization. Classified as a touristic expansion zone, the area of the dam covers 53 hectares, 11.7 of which are exploitable. The Directorate of Tourism and Crafts of the wilaya outlined a key infrastructure project: A vacation village, a family leisure park, a relaxation zone that highlights the site’s landscape.

These facilities could turn Sarno into a weekend destination, generating economic opportunities while preserving the integrity of the structure. One could imagine interpretive panels explaining flood hydraulics, a secure viewpoint overlooking the concrete flower, and a themed trail for observing migratory birds.

The equation is delicate, yet doable: Blending local tourism, technical pedagogy and environmental exemplarity. For if accommodation infrastructure is necessary, it should not obscure what is essential – rigorous monitoring of water quality, control of pollutant discharges, and raising awareness among residents. Between controlled development and ecological protection, the daisy of Sidi Hamadouche could become a regional emblem: One of water better shared, better protected, better told.

A management in need of modernization

Beyond its hydraulic functions, the dam illustrates the challenges of modern administrative management. Like many public infrastructures, it is part of a broader effort toward digitization and the simplification of procedures: Access authorizations, development projects, additions to technical files. This modernization, though sometimes slowed by delays, aims to streamline interaction between citizens, project initiators, and managing authorities — a crucial issue for any asset enhancement initiative.

Seventy years after its impoundment, the Sarno daisy continues to protect. It limits flood flows, secures potable water supply, and hosts a discreet biodiversity. It is also a reminder that engineering, when it surpasses pure functionality, can caress beauty.

In a world where infrastructure tends to melt into the landscape, Sarno dares to showcase its structure. Its eight petals of concrete do not wish to disappear: they highlight the beauty of the place. A lesson in both humility and pride, for those who still believe that water, this vital resource, deserves constructions that are worthy of it. Because between the power of water and human intelligence, the most beautiful work is that which manages to be both lasting and inspirational.

Hydraulic profile of the daisy.