Efforts to Protect our Water


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The Portneuf River
Geography	Discharge	Floods	Groundwater	Water Quality

Protecting Water Quality

    Just as human activities have had serious negative impacts on our local ecosystems, we have in the past decade made great strides in learning how to protect, and even restore, important components of the ecological web that supports us.

Wetlands
   We have gained a much better understanding of the importance of wetlands, and the ways that they clean water. Wetlands are sometimes described as ‘nature’s kidneys’ because their plants and microbes remove a variety of pollutants from water that moves through them. Constructed wetlands are being used, either alone or in combination with other treatment technologies, to improve water quality. The Fairview Constructed Wetland System is an excellent example of a constructed wetland. This system treats irrigation return flows from a small watershed on the west side of American Falls Reservoir, removing sediment, nutrients, and bacteria from water before it reenters the Snake River.

Idaho Fish and Game Wetland Conservation Strategy

Reducing Inputs From 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.

South First Street Constructed Wetland
In 1998 the City of Pocatello built a stormwater retention basin between South First Street and the Union Pacific railroad yard. The basin, about 1 ha in area, collects water from storm sewers in an area that includes much of Idaho State University. Once in the retention basin, stormwater percolates through the soil and into the aquifer. Silt and trash that would otherwise have been deposited directly into the Portneuf River are retained in the basin. Nutrients, including fertilizer that washes off lawns, are removed from the water by plants growing in the basin.
Water enters the basin in the northwest corner and flows into a deep section that serves as a settling area. Much of the heavier sediment settles out in this area, which will be dredged when it begins to fill. During larger storm events water flows into the remainder of the basin, which was planted with several wetland plant species. As of 2003, the dominant wetland plant species in much of the basin was three-square bulrush (Schoenoplectus pungens). Smaller patches were planted with Nebraska sedge (Carex nebrascensis), Baltic rush (Juncus balticus), and cattail (Typha latifolia) in 2001. Some of these plants have survived, but it remains to be seen if they will spread within the basin.

Gathe Road Stormwater Retention Basin
In 2002 the City of Pocatello built a stormwater retention basin on the east side of Gathe Road, near North City Park. This basin will collect water flowing off the hills on the west side of Gathe Road and allow the water to percolate through a layer of vegetation and into the groundwater. The lower part of the basin was planted with Nebraska sedge (Carex nebrascensis), Baltic rush (Juncus balticus), and cattail (Typha latifolia), and the sides of the basin were planted with Great Basin wildrye (Elymus cinereus).

Edson Fichter Nature Area Wetland
In 2003 the Idaho Department of Fish and Game began construction of a filtration basin in the Edson Fichter Nature Area. The goal of this project is to reduce the amount of sediment in the Portneuf River, leaving the water clearer and improving habitat quality for native fish. Water will be pumped from the Portneuf River into the basin, which was excavated in an area that was part of the historic floodplain. Much of the sediment load in that water will drop out of the water within the basin. Some of the water will flow through an outlet back into the river channel, and some will percolate through the bottom of the basin and into the aquifer adjacent to the river.