Idaho’s precious Snake River is essential to thriving ecosystems, economies, and communities from the sparkling waterfalls of Swan Valley in the east to the depths of Hells Canyon in the west. While the Snake River is a keystone in the lives and livelihoods of Idahoans, this magnificent river is in perilous condition. Overallocated and heavily polluted, the river is too contaminated for safe recreation in some locations and runs entirely dry in other stretches.
You may have heard that the Idaho Conservation League is working to clean up this river and make it fishable and swimmable once more. But what does this actually mean? In this blog, we’ll begin to break down the basics of pollution science, explain the key terms our program staff use in their day-to-day advocacy, and discuss what these terms mean in the context of the Snake River.
The background
Before we can dive into the “how,” we tackle our Snake River work, it’s important to understand the “why.”
Water management is divided into two categories: quality (how clean is the river) and quantity (how much water is in the river). While these categories may make things simpler from a management perspective, they don’t reflect the reality that everything about water is connected. The Snake River is a prime example of how water quality and quantity are linked and need to be simultaneously addressed to restore the river to a better condition.
The state of Idaho manages the Snake as “two rivers.” The “upper Snake” is upstream of Milner Dam (located between Twin Falls and Burley in south-central Idaho) and the “lower Snake” is everything downstream of Milner. More water rights exist than water is available in a typical year, causing the Snake to run dry annually at Milner Dam and be at lower than ideal flows elsewhere.
The river’s difficult overallocation situation is compounded by wastewater pollution. You may have heard the phrase,“the solution to pollution is dilution.” The massive volume of the Snake River historically has diluted wastewater from cities and agriculture. But what happens when there isn’t enough water to dilute all of this wastewater in the first place?
This is the tricky situation Idaho’s Snake River finds itself in—and where our work begins to restore it.
Talk like an expert: key terms
Our Snake River program staff engage daily with difficult questions of how to best care for the river while supporting the communities that rely on successful water management (both quantity and quality). These are some of the essential terms for those conversations.
- Nutrient Pollution: The contamination of water bodies, such as rivers, by excessive “nutrients”, primarily nitrogen and phosphorus, often originating from agricultural runoff.
What does this mean for the Snake River? Nitrogen and phosphorus are fertilizers. Rooted macrophytes (a common type of aquatic plant) and algae (including toxic algae) thrive in the river with that extra boost of fertilizer. Excessive aquatic plant growth can throw off the natural balance of the river ecosystem. And that’s not to mention what these pollutants can do to the groundwater. Which leads us to our next term:
- Aquifer: An underground body of permeable rock that stores groundwater.
What does this mean for the Snake River? The Eastern Snake Plain Aquifer is one of the most impressive sources of groundwater on the continent, if not the world. Southern Idaho’s porous, volcanic rock creates an ideal aquifer beneath this region, which holds as much water as Lake Erie. Unfortunately, the same phosphorus and nitrogen pollution that can run off directly into the river from farm fields and large dairies can also percolate into the aquifer and contaminate our groundwater supplies. For Idahoans who rely on this groundwater, they face the potential health risks associated with elevated levels of nitrate.
- Point Source Pollution: Pollution that can be traced back to a specific source, such as a wastewater treatment plant’s discharge pipe, where pollutants enter a water body. This type of pollution is regulated under the Clean Water Act, with all point sources required to get a discharge permit from the Idaho Dept. of Environmental Quality.
What does this mean for the Snake River? To improve water quality in the Snake River, we must ensure that the major point source polluters have appropriate permit limits regulating their discharge of phosphorus and other pollutants into the river, and that these polluters are following these regulations. This includes various municipal wastewater treatment plants (the biggest being for the City of Twin Falls) and the numerous fish farms that line the Snake River near Hagerman. In the last decade, certain point sources have made significant strides toward reducing their phosphorus pollution while others still have clear room for improvement.
- Nonpoint Source Pollution: Pollution that comes from diffuse sources, like runoff from agricultural fields, making it challenging to pinpoint a single origin. Nonpoint source pollution is not regulated under the Clean Water Act, leaving it harder to control.
What does this mean for the Snake River? Roughly 85% of the phosphorus load in the Snake River is attributed to nonpoint source pollution. Thus, to clean up the Snake we must make significant reductions in this sector. Given that these nonpoint sources are not effectively regulated, ICL advocates for funding to incentivize practices on agricultural lands that will reduce nitrogen and phosphorus pollution.
- Total Maximum Daily Load (TMDL): The maximum amount of a specific pollutant that a water body can receive while still meeting water quality standards—you can think of it as a pollution “budget” for a section of river.
What does this mean for the Snake River? In order for the Snake River to be restored to a healthy, swimmable, and fishable river, we need stringent pollution budgets for the river. For the last five years, ICL has been closely engaged on the revision of the Mid-Snake TMDL for Total Phosphorus, which covers the section of river from Milner Dam to King Hill. This particular TMDL is being revised to correct flaws in the prior TMDL that led to over-inflated phosphorus allocations to the various point and nonpoint sources discharging into that stretch of river.
- Best Management Practices (BMPs): Conservation practices and techniques that farmers and landowners can implement to reduce water pollution from agricultural activities, such as buffer strips and cover cropping.
What does this mean for the Snake River? Because nonpoint pollution sources (e.g. agricultural field runoff) are not regulated under the Clean Water Act, BMPs offer a win-win solution that protects the best interests of Idaho, from bolstering our economy to protecting our environment. To learn about some of the farmers in Idaho who have implemented BMPs on their fields, check out our Farm Series. ICL will continue to advocate for additional funding to incentivize BMPs in the Snake River watershed to help curb nitrogen and phosphorus pollution.
If you have any questions, feel free to email Josh Johnson, ICL’s Central Idaho Director, at jjohnson@idahoconservation.org. You can also stay up to date on the latest Snake River news by signing up for our bi-monthly Snake River Campaign updates. We’ll let you know what’s going on, how you can help, and how together, we can save the Snake River.