The urban development of the Former Pignatelli Reservoirs in Zaragoza is the result of a public competition organized by the Zaragoza City Council to incorporate this urban void into the city’s fabric, extending the existing Pignatelli Park. The Pignatelli Reservoirs were built in the late 19th century in response to the need to supply water to the southern part of the city of Zaragoza from the Imperial Canal. Within the site, covering 30,000 m², there were four large open-air water reservoirs measuring 125 × 40 m and 4 m deep, with a total storage capacity of 80,000 m³ among the four. In addition, there were other structures dedicated to water treatment and storage, which have been preserved and integrated into the development: the caretaker’s house, the underground filtration vault, and the cistern where clean water was stored, a space consisting of 33 brick groin vaults. The project is conceived as a hydraulic system that organizes the different parts of the proposal. It is a space that emphasizes the identity of water as the medium that gave rise to the Reservoirs, where the former need for water supply is transformed into a contemporary recreational use of water, so that the site does not lose its original identity and character. The traces of the former reservoirs are transformed into three differentiated areas, each with a distinct manifestation of water, in which it always plays the leading role.

First reservoir: the pond. A body of water measuring 99 by 41 meters, conceived as a new leisure space for the city of Zaragoza. A landscape where programs related to water are developed, such as piers, navigable areas, and water sports. Two differentiated zones are proposed. The central area, occupying most of the basin, is a navigable water surface with a depth of 50 cm. At its center, 800 nozzles release misted water, cooling the urban environment. Along the perimeter, a band alternates platforms overlooking the central area with smaller ponds. These ponds, with a natural character, include aquatic vegetation and fauna, enhancing the park’s biodiversity.

Second reservoir: the banded garden. This space adopts a more domestic scale, ideal for leisurely use. The garden is organized into bands of varying width, including the following areas: – Landscaped zones with wild meadow vegetation at the northern and southern ends, acting as a transition between walkways and children’s play areas. – Two large children’s activity areas with silica sand paving. – Walkways paved with handmade brick, similar in appearance and tone to that used in the construction of the retaining walls of the former reservoirs. – A central square where, once again, vegetation and water take center stage. Two rectangular areas with water jets integrated into the brick paving create playful water effects of varying height, cooling the atmosphere during warm months. At the center, six raised planting beds are arranged, each with seating around its perimeter and shrub and flowering vegetation inside. – Flanking the central square are two metal structures that allow climbing vegetation to grow, forming green walls that provide shade. The entire space is densely planted with deciduous fruit trees, alternating species and arranged according to a grid.

Third reservoir: the amphitheater. A topography is created to shape this space as an amphitheater. The planted surface is modeled, integrating four main walkways and multiple access points to the different seating areas arranged within. The trees, planted in a natural and varied manner, are large in scale with high canopies, creating a space reminiscent of a large hypostyle hall. Water once again plays a leading role, with a pond containing water-lily-type aquatic vegetation located at the lowest point of the amphitheater. The stage platform appears to float above the pond, like a true water theater. A canopy with a metal structure and folded metal sheet roofing, featuring a large cantilever, covers the stage, emphasizing one of the park’s main areas.

In order to stitch together the three main areas, a network of walkways is provided, organized longitudinally and transversely. The two north and south longitudinal paths run the full length of the park. They feature a central band of exposed aggregate concrete with Calatorao aggregate, and two side bands paved with crushed Jaulín stone. Large deciduous trees are integrated into these side bands. The four transverse paths connect the longitudinal ones and separate the three main spaces. They include deciduous trees of smaller scale than those along the longitudinal paths and continuous paving of crushed Jaulín stone, extending the side bands of the longitudinal paths.

The first transverse path establishes a connection with the existing Pignatelli Park. To ensure continuity of the green area, one of the site’s opportunities is utilized: its change in elevation, ranging from 0 m to 5.75 m. Part of the historic retaining wall is restored and reinforced, incorporating a continuous railing that unifies the different sections. This railing integrates metal tension cables that allow climbing vegetation to grow, creating a new green wall. Along the wall, several distinctive elements appear: the park entrance sign, the main staircase connecting to the northern longitudinal path opposite the caretaker’s house, and a stepped viewing area with a metal canopy cantilevering over the Pignatelli Park walkway.

Throughout the development, the use of local materials is prioritized, reducing the ecological footprint. A large portion of the pavements used are porous, promoting direct infiltration into the ground. In addition, by understanding the park as a large hydraulic system, special attention is given to the treatment of runoff water as a design tool. The project seeks to relieve the sewage network by channeling rainwater into underground gravel infiltration trenches which, thanks to two wells, allow for the gradual infiltration of water into the soil.

Ultimately, the project aims to transform the original infrastructures and processes of the reservoirs, linked to water storage, into recreational and cultural urban infrastructures with water-related urban programs .