Around 5pm on Monday, May 4th 2015 a semi hauling two pup trailers full of fertilizer slid and tipped one trailer on Hwy 191, about 14 miles south of Big Sky, spilling substantial amounts of fertilizer.
The accident occurred directly on and over the Taylor Fork bridge, a primary tributary to the Upper Gallatin River. Our primary concern was that discharging a vast quantity of fertilizer into any waterbody can create a toxic environment for local fish and water quality.
The fertilizer granules – confirmed as monoammonium phosphate – are commonly used in farming to supply crops with nitrogen and phosphorus nutrients that prompt strong plant growth. However, when dissolved in water in a concentrated volume (such as a spill into a small creek) monoammonium phosphate can create a toxic mess that can temporarily alter local water quality and even cause a fish kill.
In response we went down to inspect the area, sample the fertilizer granules, inspect the clean-up, and verify that no significant amount of fertilizer entered the Taylor Fork and nearby Gallatin River. 
As our photographs show, there was slim likelihood of any substantial volume of fertilizer making its way into the Taylor Fork or nearby Gallatin River. We inspected the bridge itself and found two small culvert drains (discharging directly into the Taylor Fork) with plenty of fertilizer granules adjacent and draining into stormwater runoff. 
However, the drains only measure approximately four inches in circumference, and the bridge had an almost 180 degree grade, meaning while an unknown amount of fertilizer was discharged into the Taylor Fork, it is highly unlikely that any significant quantity entered the waterway and downstream Gallatin. 
We also inspected the roadside grasses and found an old silt sock Best Management Practice (BMP) along the southeastern ground leading to the Taylor Fork. Very little granules traveled up to the silt sock (approximately 6′ downhill), nor did we find any evidence of any fertilizer traveling farther than a few feet from the road on either side of Hwy 191 for the full breadth of the accident. 
Long-haul trucking of fertilizer, let alone hazardous or toxic substances, is a threat to the Gallatin River, its important fisheries, and its communities. The Gallatin was lucky in this instance with minimal discharges to the River; other past accidents, not so much. Southwest Montanan’s need to begin a dialogue about the threats posed by long-haul trucking on Hwy 191: as our region continues to experience new growth and develop, we need to be proactive in giving our region’s most important resources – our waterways – the protection they deserve.
We will be reaching out to stakeholders and listening to everyone’s thoughts on how we should move forward to protect the Gallatin, united by our common belief in the value of clean water and the unique, special importance of a clean, free-flowing Gallatin River. If you are concerned about the issue of long-haul trucking on Hwy 191 and its threats to the Gallatin River please contact us – we want to hear from you! 