COMMON LIMITING FACTORS in WRIA 22-23 and their impact to physical processes and salmon

Water Quantity

Physical Process Effects

Low summer flows are typically a result of an altered hydrology (landscape manipulation that allows rapid surface runoff).  In non-glacial systems summer flows are maintained by groundwater connectivity, wetland discharges, and precipitation.   The combination of altered hydrology and the removal of instream structure contribute to channel incision and disconnection from floodplains and adjacent wetlands which results in the inability to store water for summer flows.  High peak flows also contribute to accelerated bank erosion and movement of substrate downstream.   Low summer flows are susceptible to becoming too warm, low in dissolved oxygen, and have a higher concentration of other pollutants, all of which affect salmonid survival.