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| The
Portneuf River |
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| Geography |
Discharge |
Floods |
Groundwater |
Water
Quality |
| Threats to the Portneuf | |
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Threats to ecosystems in this watershed
are characteristic of
forces
that threaten ecosystems throughout much of the western United States.
Changes in land use over the past two centuries have modified the
distribution and abundance of plants and animals, influenced the
availability, quality, and use of surface water and groundwater, and
changed important ecological forces such as the frequency of fire. Stormwater Runoff Rainstorms and snowmelt can cause water to flow over paved areas into storm sewers. In cities, where there are large expanses of pavement, this can result in large inputs of sediment, trash, and chemicals into streams and rivers, and a significant negative impact on water quality. Unfortunately, Pocatello has many storm sewers that empty directly into the Portneuf River. One effective way to reduce inputs into the river is to collect runoff in vegetated basins. These basins will slow the water down, allowing much of the trash and sediment that the water has collected to fall out of the water column and be retained in the basin. Vegetation and soil in the basin will capture many of the chemicals in the water, which can include fertilizer, pesticides, and herbicides that were applied to lawns and gasoline and oil that leaked out of cars and trucks. Many of those chemicals will be either taken up by plants or broken down by microbes in the soil, keeping them out of the river where they could harm aquatic plants, insects, and fish. Erosion Large scale erosion, whatever the cause, poses a serious threat to rivers and streams in the western United States. In large rivers, like the Columbia, deposition of sediment that was washed into the river can require large scale dredging operations to keep navigation channels open. One of the most important impacts in smaller streams and rivers, like the Portneuf and its tributaries, is that gravel beds can be buried in silt, destroying their utility as spawning and overwintering habitat that is critical for native fishes. Bacteria High concentrations of disease-causing organisms can make it unsafe to swim, wade, or fish in streams or rivers. Poential sources of bacteria in the Portneuf River include livestock, wildlife, failing septic systems, and urban animals such as dogs, cats, and pigeons. |