With increased industrialization and development, many of the nation's eastern trout rivers were dammed, polluted, or allowed to silt up, raising water temperatures and killing off the native brook trout. Smallmouth bass were often introduced to northern rivers now too warm for native trout, and slowly became a popular gamefish with many anglers. Equally adaptable to large, cool-water impoundments and reservoirs, the smallmouth also spread far beyond its original native range. Later, smallmouth populations also began to decline after years of damage caused by overdevelopment and industrial and agricultural pollution, as well as a loss of river habitat caused by damming many formerly wild rivers in order to form lakes or reservoirs. In recent years, a renewed emphasis on preserving water quality and riparian habitat in the nation's rivers and lakes, together with stricter management practices, eventually benefited smallmouth populations and has caused a resurgence in their popularity with anglers.