The amount of thermally altered habitat is not known. However, based on the extent of water impoundments, riparian canopy alteration, heated discharges, and channel changes, the affected habitat area is likely large. The reduction of natural stream flows by removal of water for out of stream uses is a significant concern where it impairs water quality and salmonid habitat. Reduced flows result in increased water temperature, reduced flushing of systems and may exacerbate other water quality problems. Studies show that excessively reduced flows provide less habitat for fish and may result in increased aggression, competition, or predation.
Altered flows can also affect fish migration.
Elevated pH levels that may adversely effect salmonids have been observed in some coastal streams. The bacteria water quality standard is designed to provide an indicator of potential human health problems from fecal contamination. It is of particular concern in coastal estuaries for the shellfish industry because there are federal FDA limits that must not be exceeded in shellfish growing waters. Bacteria, as measured by this water quality standard, is not considered to be a factor for decline of salmonids. Toxics Toxic substances can adversely affect aquatic life and aquatic habitat.