Mapping the Impacts of Salmon Runs on the Nez Perce Tribe
Utilizing the power of GIS can help the Nez Perce retain their way of life -- Wild Pacific Salmon.
For centuries, the Nez Perce tribe has sustained themselves on wild Pacific Salmon. So integral have the salmon become to their way of life, they are often regarded as the "Salmon People."
After the construction of four dams on the lower Snake River and one dam on the Clearwater River in the 19th Century, the Nez Perce are now challenged with declining numbers of wild Chinook, Coho, and Sockeye salmon. Prior to the existence of the dams, an upward estimate of 18 million wild salmon reached Nez Perce territory in Idaho every year 1 . As of the 2022 salmon run seasons, only 2,087 Sockeye, 19,258 Coho, and 124,562 Chinook reached the Lower Granite Dam, the most upstream dam on the Snake 2 . Most of these fish were hatchery fish, not wild. What implications do the declining salmon numbers have on the Nez Perce? And are there feasible solutions?
The Salmon People
The importance of salmon to the Nez Perce goes beyond the nutritional component.
Salmon People 3
"The four concrete barriers on the lower Snake River have had, and continue to have, a devastating impact on the fish and on tribal people." -- Shannon Wheeler, chairman of the Nez Perce tribal executive committee
Mapping the Challenge
Utilizing GIS capabilities to visualize threats to wild Pacific Salmon.
Historically occupying approximately 19 million acres across the Snake, Clearwater, and Salmon River basins, the Nez Perce now reside on 770,000 acres of reservation land, mostly along just the Clearwater River. A loss of territory and fishing grounds in these watersheds reduced Nez Perce access to salmon well before the dams were even built 3 .
As anadromous fish, Pacific Salmon must traverse hundreds of miles of stream from their headwater spawning locations to the ocean. After a few years at sea, they make the voyage again, this time swimming upstream back to their spawning waters in order to breed.
For salmon to reach Nez Perce grounds, they must pass through the waters of the mighty Columbia, Snake, and Clearwater Rivers. This distance equates to nearly 900 miles of freshwater streams for the salmon to reach interior Idaho.
Within the span of a few decades, several dams were constructed along the Snake and Clearwater Rivers. These dams now act as a significant impedance and barrier to migrating Chinook, Sockeye, and Coho salmon.
All four dams located on the Snake River -- Ice Harbor, Lower Monumental, Little Goose, and Lower Granite -- have fish passageways that assist the salmon in maneuvering the concrete obstacles. Still, these dams obstruct the natural flow of the Snake and limit mobility of the salmon.
The Dworshak Dam, located high up on the Clearwater River within Nez Perce territory, does not have a fish passageway system. For the few lucky salmon that make it to this point past the several dams downstream (including several along the Columbia River), there is no further upstream travel.
Ice Harbor
Ice Harbor was the first of the four dams constructed on the lower Snake River in 1961. While all four dams have a fish passageway, they still act as significant barriers to salmon migration.
Lower Monumental
Lower Monumental was constructed in 1969.
Little Goose
Little Goose was constructed in 1970.
Lower Granite
Lower Granite is the youngest (1975) of the four dams on the lower Snake River, and the final obstacle for salmon to reach their spawning waters near Nez Perce lands.
Dworshak
Constructed in 1972 at a height of 717 feet, the Dworshak Dam has no fish passageway for salmon migrating the Clearwater River.
Since the inaugural year of each dam, adult salmon counts have been conducted for each species, including Chinook, Sockeye, and Coho. This data provides valuable insight to salmon population trends for the past 50-60 years throughout the Snake River (since there is no fish passageway at Dworshak, there is no fish count data available for the Clearwater River).
The following charts were created in ArcGIS Pro with data retrieved from the Columbia Basin Research DART 2 (Data Access in Real Time).
Ice Harbor Salmon Counts
Adult salmon counts for Chinook, Sockeye, and Coho seem to indicate that populations have improved over the decades.
Lower Monumental Salmon Counts
However, these graphs alone do not distinguish between wild salmon and salmon that originate from hatcheries.
Little Goose Salmon Counts
Even with fish hatchery production increasing the salmon populations, these figures are far below the historical estimates of millions of wild salmon prior to the development of the dams.
Lower Granite Salmon Counts
As long as the dams exist, it is highly unlikely that the Nez Perce will ever experience salmon runs similar to what their ancestors of hundreds of years ago did.
Wild vs. Hatchery
Here is a sample year (2020) with data that differentiates between wild and hatchery salmon 4 . As we can see, hatchery Coho outnumber wild Coho by roughly 5x, and hatchery Chinook outnumber wild Chinook by 10x.
This 2020 hatchery escapement report, provided by the Washington Department of Fish and Wildlife, is also representative of other years, where wild salmon species are increasingly shown to be in peril.
*Note, there were no figures provided in the escapement report for hatchery Sockeye in the Columbia River Region. For other regions, such as the Puget Sound Region, hatchery Sockeye still drastically outnumber wild Sockeye.
Analyzing a Potential Solution
Conducting GIS analysis on a hypothetical scenario.
While increasing hatchery production of salmon is currently the primary solution, propositions of removing the four dams along the Snake River have gained popularity in recent years 5 . By eliminating these dams, even though they have fish passageways, the Snake River could experience a significant rebound of wild salmon populations. But what about the Clearwater River, and the towering Dworshak Dam that has no fish passageway?
This analysis is based on the scenario that the Dworshak Dam is removed and the Clearwater River is restored to its free-flowing condition. Removing dams, especially of this size, is a costly and controversial option. Dworshak produces hydroelectricity, a significant source of power for the region. There are many additional factors when considering the removal of a dam, but it can be done (the restoration of the Elwha River is a fantastic example). In the case of restoring healthy salmon populations to the Nez Perce, it might be the only option.
Upstream from the Dworshak Dam, a new watershed can be created in order to determine the area that salmon are currently unable to reach.
However, within this watershed, there are more dams that further restrict salmon access.
The Elk River Dam and Deer Creek Dam are two dams within this newly created watershed that restrict salmon mobility.
The upstream watershed of the Deer Creek Dam is small -- only 2.27 square miles.
The upstream watershed of the Elk River Dam is a bit larger -- 42.16 square miles.
These two watersheds need to be removed from the larger watershed, since salmon will not be able to reach those waters with the removal of the Dworshak Dam.
The remaining Dworshak watershed is 2,397.63 square miles in size, and full of freshwater habitat that is perfect for salmon spawning.
These are the major streams that would be accessible for the salmon with the removal of the Dworshak Dam.
This does not even include the small creeks and tributaries, which are also great for salmon spawn locations.
In total, there is a potential 809 linear miles of additional freshwater streams that would open up to the salmon with the removal of the Dworshak Dam.
This is a significant increase in habitat area for the salmon, as well as accessible fishing grounds for the Nez Perce.
Nez Perce Impacts
What does all this mean for the Nez Perce?
The Nez Perce are then faced with two options as possible solutions in their fight to restore healthy salmon populations. One option is to continue the trend of increasingly relying on hatchery fish to maintain the meager populations that currently exist in the rivers. Unfortunately, this option has shown unpromising and underwhelming results. With the best years only barely approaching 200,000 salmon, and most of those coming from hatcheries, this option leaves little on the table for the Nez Perce.
The second option is to breach the dams. This is not a simple task; alternate resources must be available for the hydroelectric energy, barge transportation, and agriculture irrigation that are dependent upon the dams. The Nez Perce, in collaboration with surrounding tribes and regional politicians, are fighting for this option to become a reality in the near future. Without the removal of the dams, they claim, wild salmon will soon be extinct from the Snake River.
For the foreseeable future, the Nez Perce will have to continue to live with the existence of the five dams along the Snake and Clearwater Rivers, as well as the diminishing existence of wild salmon. Their nourishment, and cultural identity, will conitnue to be threatened.
From left to right: Sockeye salmon; the Clearwater River before Dworshak; harvesting salmon roe at the Nez Perce Tribal Hatchery
If you want to learn more, or take action to help, here are some great resources to check out: