Limiting Factors are defined as physical, biological, and ecological conditions that: (1) limit the ability of the ecosystem to sustain native plant and animal populations and to accommodate natural disturbances like floods; (2) limit the quality or availability of habitat that supports all the different life stages of Kootenai River white sturgeon (which is endangered) and other native species; and (3) limit the ability of the ecosystem to sustain the local tribal culture, subsistence needs, and economy. Limiting factors can be addressed by active restoration or changes in management.
Stream morphology refers to the form and structure of streams, so morphological limiting factors are factors that have altered natural and historical processes shaping the form and structure of the river. They include: the river's response to altered hydraulics, the river's response to altered sediment transport, the loss of channel and floodplain connection, reduced channel boundary roughness (smooth banks lacking vegetation or woody debris), and bank erosion.
Riparian vegetation includes the plants that grow rooted in the water table of a nearby wetland area such as a river, stream, reservoir, pond, spring, marsh, bog, meadow, etc. Hence riparian area limiting factors are factors that have altered the native vegetation community. They include: a lack of surfaces to support riparian vegetation recruitment, a lack of outer bank vegetation, frequent scour and deposition of floodplain surfaces, an altered hydroperiod (the length of time during the growing season when water is available in the rooting zone), invasive plant species, a lack of native plant diversity and seed sources, a lack of nutrient sources for primary productivity, and altered carbon balance (due to depletion of wetland systems).
These are factors that have changed the aquatic environment. They include: insufficient water depths for Kootenai sturgeon migration, insufficient water velocities for successful Kootenai sturgeon spawning, a lack of coarse substrate for egg attachment, a lack of cover for juvenile fish, a lack of pool‐riffle complexity, a simplified food web from lack of nutrients, insufficient pool frequency, a lack of fish passage into tributaries, a lack of off‐channel habitat for rearing, and altered water quality.
River and floodplain management have affected several aspects of the ecosystem. These factors include: a dam-controlled flow regime, a dam-controlled sediment regime, a dam-controlled thermal regime, a dam-controlled nutrient regime, bank armoring, levees and diking districts, transportation corridors, and floodplain land uses.