Unnatural Data - Spring 2023
Impact of Increased Snowfall on River Levels
We’ve all been wondering the same thing—will the increased snowfall this winter cause flooding in the spring and help to lessen ongoing drought conditions? According to the National Weather Service, several factors go into determining spring flood risk, including snowpack, frost depth, river ice, soil moisture, antecedent river levels, and spring precipitation. In the case of the Big Sioux River Watershed, soils were quite dry, and river levels were low going into the winter due to drought conditions. Although there is currently an above-average snowpack, if we see average spring snowmelt and precipitation, we can expect to see a below-normal flood risk due to the low river levels and dry soil. However, if we are to see a rapid snowmelt or a heavy precipitation event, there is a higher likelihood of flooding in some areas of the watershed.
Over 60% of the entire Missouri River basin is currently classified as being in a drought. Even with mountain snowpack accumulating at average rates and plains snowpack at above-average rates, experts say that drought conditions will continue to persist. In the winter, above-normal precipitation is not a significant amount of water, so we will need multiple episodes of soaking rainfall or melting snow to considerably improve drought areas.
Potential for Fish Kills This Spring
Fish kills made news headlines this winter with a sizable winterkill at the James River dam in Huron that went viral on TikTok. A winterkill occurs when heavy snow covers a frozen lake or river, blocking the sunlight from reaching the waterbody for a sustained period of time. Without sunlight, plants cannot photosynthesize and produce oxygen, leading to a decline in oxygen levels and a subsequent fish kill. A winterkill is more likely to occur in a lake or stream where water levels were low going into the winter due to a dry summer and fall. A periodic winterkill is not always a bad thing, however. In waterbodies with less than desirable fish species, such as carp, a winterkill can help to thin the population, allowing gamefish species to rebound in the following years.
Will we see more fish kills this spring? There is a high likelihood that we will see more fish kills this year due to low water levels in the fall and heavy snow cover this winter. As snow and ice begin to melt, keep an eye on local waterbodies for fish kills lining the streambanks. If you find a fish kill, we recommend contacting your local conservation officer or stream and lake association.
Salt Deicer: A Chronic Water Polluter
Days of below-freezing temperatures and a snowy winter are a recipe for the overuse of deicing salts on icy roads, sidewalks, and driveways. But did you know that using more salt will not yield better results and will only further pollute our waterways? Just 12 oz. of salt, about as much as would fill a coffee mug, is enough to treat a 20-foot-long driveway or about 10 squares of sidewalk. When excess salt enters our waterways, chloride levels increase, becoming toxic for fish, amphibians, and aquatic bugs and plants. In addition, water polluted by road salt is denser than freshwater, which causes it to settle at the bottom of lakes. When this chemical stratification occurs, the lake can no longer mix naturally, leading to a bottom layer of the lake devoid of oxygen and all aquatic life.
So, what can you do?
Remove all snow from the area first, and only apply salt in areas where it is needed for safety.
If there are excess salt grains on dry surfaces, sweep them up and save the salt to reapply later in the season.
Educate your family and friends on the importance of limiting their use of deicing salts. It takes just one teaspoon of salt to permanently pollute five gallons of water.