The Snake

The dusty greens, grays and golden browns of southern Idaho unfurl from the edges of the Snake River and spread across the arid landscape. The river slithers into canals that water thirsty fields of potatoes, onions and sugar beets. It tumbles over falls and is shadowed by some of the steepest canyon walls on its journey west to the Columbia.

In times past, salmon spawned by the millions in this river while bony-plated sturgeon swam its depths. The last 100 years have taxed the resilience of this river born of the crashing waters of the Bonneville Lake Flood. Dams for irrigation and electricity have supported human activity but have slowed and silted the waterway. Chemical fertilizer and other pollutants have tainted the water and fed the overgrowth of aquatic weeds.

For people floating down the Snake and boating in its reservoirs, they may not yet know about the changes ramping up to improve water quality under the Snake River Stewardship Program (SRSP), one of the largest watershed restoration programs in the United States.

TFT began working with Idaho Power Company in 2016 on the SRSP.

“The SRSP is unique among TFT projects because of its 50-year program life,” said David Primozich, conservation director. “Our next longest programs are Oregon water quality trading projects at 20 years. We think these robust timelines are essential for delivering measurable improvements to the environment.”

Work in 2019 included field teams maintaining and monitoring five previously implemented project sites and transitioning one site from passive restoration to an active planting site. Back in the office, teams continued to develop and test the database and data collection tools that allow SRSP staff to track and manage the program. Additionally, Idaho Power moved forward with permitting the Rippee Island floodplain enhancement project, which will be built in 2021.

Also last year, the states of Idaho and Oregon certified the company’s water-quality plan for the Snake River — a key milestone in the renewal of the federal license for the operation of three dams in Hells Canyon, which provide about 70% of IPC’s hydropower electricity.

While the SRSP is still in a research phase, we’re assisting Idaho Power with building the systems and running multiple pilot projects to test permitting, implementation, and maintenance techniques. Attention to the details of site selection, planning, training local contractors, and documenting performance now will ensure the program will launch smoothly once it receives its final approval.

Restoration actions from the research phase thus far include 8 acres of floodplain enhancement, 37,000 native trees and shrubs planted, and 1,450 tons per year of sediment prevented from washing off fields into the river.

“The Snake River is crucial to providing clean energy to our customers,” said Brett Dumas, environmental affairs director at Idaho Power. “We’re committed to the actions that will improve its water quality.”

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A hydropower dam is initially licensed by the Federal Energy Regulatory Commission (FERC) at the time of construction, it must then be periodically relicensed for continuation of the existing project. One component of the licensing/relicensing process is an examination of the potential environmental impact of the dam on the river ecosystem and function, and a mitigation plan to address any impacts. As part of the relicensing of the three-dam Hells Canyon Complex, Idaho Power Company plans to implement the Snake River Stewardship Program (SRSP), a watershed-scale restoration plan for offsetting temperature impacts.

Section 401 of the federal Clean Water Act requires state certification for a license issued by a federal agency for an activity that may result in a discharge into waters of the U.S., such as a hydropower dam. This requirement allows each state to have input into federal projects that may affect its rivers and streams and to ensure the projects will comply with state water quality standards. For the Hells Canyon Complex, both Idaho and Oregon Departments of Environmental Quality must review and grant 401 certification.

Oregon and Idaho Departments of Environmental Quality jointly set water quality targets for the 2,500 square miles of the impaired Snake River-Hells Canyon subbasins. The Snake River-Hells Canyon Total Maximum Daily Load (TMDL) contains temperature load allocations for point sources and nonpoint dischargers, like the Hells Canyon Complex. The load allocation assigned to the Hells Canyon Complex is exceeded during the fall; Idaho Power must address elevated water temperatures below Hells Canyon Dam. An increased thermal load in the water can negatively impact the rearing and spawning habitat of cold-water fish. In order to offset its portion of the heat load in the TMDL, Idaho Power will implement the multi-project SRSP as part of a Temperature Management and Compliance Plan. Meeting the requirements of the Snake River-Hells Canyon TMDL for temperature is part of Section 401 certification.

The Shade-a-lator module, a unit of the HeatSource model, is used to calculate temperature improvements as a reduction in thermal loading from the sun to the river due to riparian (streamside) vegetation. Riparian trees block the sun, increasing the shading of the stream. Riparian revegetation creates thermal improvement that are quantified in units of kilocalories per day. Riparian revegetation projects are proposed for more than 100 miles of streambank along 10 tributaries of the Snake River. The proposed riparian revegetation projects will restore many of the natural riparian functions that are currently missing from the Snake River tributaries. Over time, these revegetated riparian areas will not only shade the streams, but will also contribute large wood and other organic material to the stream, stabilize streambanks, increase cold-water patches, and increase water storage.

Geospatial analysis and existing models are used to calculate temperature improvements as a reduction in thermal loading from changes in river surface area. These actions create thermal improvements that are quantified in units of kilocalories per day. The proposed instream actions will increase sinuosity and complexity of the shallow, slow-moving Snake River. Actions at multiple project sites include narrowing and deepening the river channel by enhancing floodplains and wetlands and constructing or enhancing islands. Constricting the width of the channel will increase water velocities and sediment transport along the riverbed around the project sites. This in turn will help to keep the gravel riverbed free of fine sediment – good for both cold-water fish habitat and hyporheic exchange. Hyporheic exchange refers to the mixture of water in the river channel with adjacent shallow groundwater, creating cold patches in the river.

In addition to instream and riparian improvement projects for temperature, the SRSP includes a third set of actions to address sediment and phosphorus transport. By upgrading to pressurized irrigation systems in relevant upstream agricultural areas, sediment and phosphorus runoff from agricultural land practices will be reduced. These voluntary reduction actions would protect the ongoing effectiveness of the instream restoration projects in downstream reaches of the Snake River.

Yes. The area is home to numerous sensitive species, including trout, whitefish and sturgeon, as well as the endangered Physa snail. The Mid-Snake River suffers from various issues that compromise water quality and wildlife habitat. These include: lack of streamside vegetation; slow-moving water due to wide, shallow channels; nutrient and sediment loading from agricultural runoff; excess aquatic vegetation growth; and low oxygen levels. Restoring the river’s natural functions will have a significant positive impact for native species.

The proposed watershed restoration program will have widespread environmental benefits in the Snake River and tributaries. Conversely, a structural solution such as a temperature control structure (TCS) in Brownlee Reservoir, an alternative that has been proposed by other stakeholders, would provide no upstream benefits, limited downstream benefits for temperature, and could adversely impact downstream resources.

The SRSP is designed as a compliance program for 401 certification of Idaho Power Company’s Hells Canyon complex. It will extend for the term of the new license, which is expected to be 40 to 50 years, and address water temperature issues and river-channel function between the Hells Canyon Complex and Swan Falls Dam.

There are three components to the SRSP.
1. The instream restoration actions, including narrowing and deepening the river channel, and creating inset floodplains and emergent wetlands will be located in the Middle Snake River from Walters Ferry to Homedale. The first construction actions will take place around Bayha and Wright Islands.
2. The riparian habitat improvement actions, including restoring native vegetation for shade along key streambanks, will take place along 100 miles of 10 major tributaries of the Snake River. The first plantings will likely take place in the Powder River subbasin.
3. The upland irrigation improvement actions, including implementing best management practices for irrigation, will take place numerous locations along the Snake River where agricultural runoff is a significant contributor to poor water quality. The first upgrades are taking place in the Grand View area.

Yes. The stewardship program will create a river channel with sections that are deeper and have faster-flowing water, to inhibit the growth of unwanted aquatic plants and provide better cold-water conditions for fish. The associated wetlands and floodplains that will be created will enhance wildlife and bird habitat. When completed, the channel modifications will make it easier for boat navigation in the Middle Snake River, and public land will remain accessible.