Acid rain causes acidification of lakes and streams and contributes to damage of trees at high elevations and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, including irreplaceable buildings, statues, and sculptures that are part of our nation's cultural heritage. Prior to falling to the earth, SO2 and NOx gases and their particulate matter derivatives, sulphates and nitrates, contribute to visibility degradation and harm public health.

The ecological effects of acid rain are most clearly seen in the aquatic, or water, environments, such as streams, lakes, and marshes. Acid rain flows to streams, lakes, and marshes after falling on forests, fields, buildings, and roads. Acid rain also falls directly on aquatic habitats. Acid rain primarily affects sensitive bodies of water, which are located in watersheds whose soils have a limited ability to neutralize acidic compounds (called "buffering capacity"). Lakes and streams become acidic when the water itself and its surrounding soil cannot buffer the acid rain enough to neutralize it. In areas where buffering capacity is low, acid rain also releases aluminium from soils into lakes and streams; aluminium is highly toxic to many species of aquatic organisms.

Acid rain harms and kills individual fish, which reduces fish population numbers, and could completely eliminate entire fish species from a water body, and decrease biodiversity. Both low pH and increased aluminium levels are directly toxic to fish. In addition, this may cause chronic stress that may not kill individual fish, but will lead to lower body weight and makes fish less able to compete for food and habitat.

Some types of plants and animals are able to tolerate acidic waters. Others, however, are acid-sensitive and will be lost as the pH declines. Generally, the young of most species are more sensitive to environmental conditions than adults. At pH 5, most fish eggs cannot hatch. At lower pH levels, some adult fish die. Some acid lakes have no fish. The chart below shows that not all fish, shellfish, or the insects that they eat can tolerate the same amount of acid; for example, frogs can tolerate water that is more acidic (has lower pH) than trout.

Trees are an extremely important natural resource. They provide timber, regulate local climate, and forests are homes to wildlife. Acid rain can make trees lose their leaves or needles. The needles and leaves of the trees turn brown and fall off. Trees can also suffer from stunted growth; and have damaged bark and leaves, which makes them vulnerable to weather, disease, and insects. All of this happens partly because of direct contact between trees and acid rain, but it also happens when trees absorb soil that has come into contact with acid rain. The soil poisons the tree with toxic substances that the rain has deposited into it.

Acid rain and the dry deposition of acidic particles contribute to the corrosion of metals and the deterioration of paint and stone (such as marble and limestone). These effects seriously reduce the value to society of buildings, bridges, cultural objects (such as statues, monuments, and tombstones), and cars.

Dry deposition of acidic compounds can also dirty buildings and other structures, leading to increased maintenance costs.