Yellowish or cloudy water reported in parts of Angra do Heroísmo and Praia da Vitória is being attributed to suspended material entering the supply system after the first intense autumn rains. Municipal services are flushing the network and adjusting treatment as the island’s springs return to more normal flows.
After months of summer dryness, rain does more than change the color of the Terceira landscape. Beneath the ground, springs respond as well. Their flow can increase suddenly, carrying organic matter and other suspended material into the water system. According to Angra do Heroísmo councilman Paulo Lima, that seasonal transition explains the yellowish and cloudy water recently appearing from some taps in Angra do Heroísmo and Praia da Vitória.
The phenomenon commonly occurs around October, when the first significant rains follow the dry season, but municipal officials say it has been more pronounced this year. During the prolonged dry period, some springs reached particularly low production levels. The abrupt return of rainfall then caused a rapid increase in flow, carrying suspended material through the system and temporarily altering the water’s appearance.
Municipal technical services are monitoring conditions and have intensified flushing operations throughout the distribution network. Additional discharges are being carried out at network endpoints, progressively renewing the water from upstream to downstream. Lima says the quality at the springs has already improved significantly; the immediate task is therefore to replace the water still circulating through the distribution system so that its usual transparent appearance can gradually return.
Treatment is also being adjusted. The municipality has increased the amount of sodium hypochlorite used for disinfection, although Lima explains that much of the additional product is presently being consumed in oxidizing organic matter remaining in suspension. Consequently, adding more hypochlorite does not necessarily produce an equivalent increase in residual chlorine throughout the network.
The situation extends beyond Angra because water systems on an island do not always follow municipal boundaries. Angra do Heroísmo has two delivery points supplied from the Cabrito spring, which also provides water to some areas of Praia da Vitória. The municipality therefore continues to monitor both the springs and the distribution network while flushing operations proceed.
For residents, the change is immediately visible because few public services are as intimate as water: it enters the kitchen, the shower, the glass placed on the table. Municipal officials describe the present episode as a natural seasonal occurrence intensified by an unusually dry preceding period and expect the appearance of the water to normalize progressively as spring flows stabilize and the network is renewed.
On an island, even what emerges from a household tap carries the memory of the landscape. After a long dry summer, the first rains have reached Terceira’s underground waters. For a few days, the springs are carrying traces of that transition with them.
Based on a story in Diário Insular-José Lourenço, director. The photo is from DI.