ForRiver is a project by Forus Oy aimed at enhancing the ecological state of Finland's rivers and achieving carbon sequestration through river liming.

The world's rivers transport large amounts of organic and inorganic carbon to the oceans. A significant portion (1.9–2.3 PgC/year) of the dissolved inorganic carbon, however, does not remain in the water but is released into the atmosphere as carbon dioxide, with only part of the carbon being stored in stable forms (e.g., bicarbonate) in the oceans. For this reason, the carbon dioxide concentration (pCO₂) in rivers is typically much higher than in the atmosphere. In Finland, rivers are in some areas highly acidified due to soil characteristics (especially acid sulfate soils) and human activities (e.g., agriculture and drainage).

Adding limestone (CaCO₃) to a river increases the alkalinity of acidic waters, enhancing the river's ability to transport carbon in stable forms rather than as carbon dioxide. The goal of adding limestone is to facilitate carbon sequestration by utilizing carbonate weathering reactions. Limestone introduced to river water chemically breaks down under the influence of water and carbon dioxide. The reaction produces calcium ions and bicarbonate as end products.

Adding limestone to river water neutralizes acidity and raises the water's pH. This improves living conditions for fish, supports ecosystems, and reduces the harmful effects of metals and heavy metals by promoting their binding and precipitation.