Alojas NAI Wastewater Treatment Plant, Alojas pagasts, Latvia

Alojas NAI is a wastewater treatment plant located in Alojas pagasts, Limbažu novads, Latvia. It served a small population of 608 people before its operational status was listed as closed. The plant's address is Osīši, Limbaži , Aloja, Alojas pagasts, Limbažu novads, LV-4064. As a secondary treatment facility, Alojas NAI provided biological treatment to reduce organic matter and suspended solids. For small agglomerations in Latvia, such plants typically operate under national regulations aligned with the EU Urban Waste Water Treatment Directive (91/271/EEC), which requires appropriate treatment before discharge. The plant had a designed capacity of 2010 m³/day, indicating it was built to handle a larger load than its actual discharge volume of 116.04 m³/day. The treated effluent from Alojas NAI was discharged into the local watershed, which ultimately drains into the Baltic Sea via the Gauja River basin. The Baltic Sea is a sensitive marine environment with limited water exchange, making nutrient removal important for preventing eutrophication. The closure of this plant may have shifted wastewater management to a nearby facility, affecting local water quality.

Alojas NAI discharged into the Gauja River basin, which flows into the Gulf of Riga and then the Baltic Sea. The Baltic Sea is a brackish, semi-enclosed sea with high ecological sensitivity to nutrient pollution. The Gauja River supports diverse aquatic life and is an important migratory corridor for fish species. The plant's closure may reduce local nutrient loads but could increase pressure on receiving waters if wastewater is redirected.