Threehorn Wartyback Mussel (Obliquaria reflexa), one of the 38 species present in the St. Croix. (USFWS photo)As the state of Wisconsin looks into charges over the April incident in which a sand mine near Grantsburg spilled fine sediment into the St. Croix for several days, a couple river experts recently chimed in with their views.
Jill Medland, environmental coordinator for the St. Croix National Scenic Riverway, explains why sand is bad for the river, including fish and mussels:
What’s so bad about sediment? Well, while it is still in suspension, it makes the water cloudy. If you were a fish, a sudden sediment discharge would be akin to finding yourself in a dust storm. It makes it hard to see and hard to breath. Sediment can clog fish gills and scratch their eyes and skin making them vulnerable to infection.
But that is just the beginning. As sediment settles out of the water, it can damage fish spawning and mussel beds. Small-mouth bass, a favorite game fish, needs clean sand and gravel bottoms for spawning. In many places along the St. Croix, a clean sand and gravel riverbed is the natural condition and it supports a good small-mouth bass fishery. Add more sand, silt, and clay to the system and you’ve altered it to something the smallmouth bass can no longer use.
Deb Ryun, executive director of the St. Croix River Association, offered thanks to the hiker who discovered the spill, the public agencies that responded, and even the mining company:
Thank you, Don, the citizen who was out on a park trail and noticed a stream that was heavy with silt. He cared enough to take a few pictures and seek help. When I got the pictures, I passed them on to Burnett County Land and Water Department. My late-in-the-day inquiry was answered long after normal business hours – so much for government workers not being engaged or caring. Before noon the next day, there was an onsite visit to the stream by the county, and another agency had an airplane track the sediment plume to its source. They then followed the stream and did some ground-truthing, and met with managers of the mining operation. They made temporary recommendations and scheduled follow-up visits. The final thank-you goes to the mining company. While it isn’t ideal that the spill happened, my understanding is that they took quick action to take care of the immediate problem.
Meanwhile, another mine proposal by the company which operates the Grantsburg mine is being considered in Scandia, Minnesota. The city has recently posted the Final Environmental Impact Statement, and the city council will vote on its adequacy at a meeting on September 24.
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