After a slow start to the snowy weather, the mountains are experiencing a pattern of snow storm after snow storm. This recent storm has even left snow resorts closing because of too much snow. As a result, the state's snowpack is well above the average levels of where it typically is for middle January. The Colorado River Basin is currently 146-percent (137-percent in the headwaters) and the South Platte watershed is at 146-percent. The southwest corner of the state- the Gunnison, Animas, and San Juan watershed is around 160-percent. While the Yampa and White river is around 133-percent. The Arkansas and Rio Grande basins are hovering around 150-percent.
But what does this mean for our rivers?
If the snow melts too rapidly, it could cause severe flooding in places of the state and, something that Colorado rarely sees, our reservoirs may be filled up too soon from too much water, according to an article by 9news. "Our goal is to be at 100-percent full for our reservoirs, once runoff season is over,” Travis Thompson, spokesperson for Denver Water said. “So, we're always adjusting levels to try and make sure that happens. Sometimes if you do see too much, we may have to do some releases earlier in the year to try, whether it's preventing too much water at that time."
However, if we have a cooler spring and the snow is able to melt at a slower rate, it could mean great things for our rivers and fish as the dissolved oxygen increases and in return, increasing the quality of our aquatic ecosystems.
The total amount of snowpack is essential to Colorado’s freshwater ecosystems because it serves as frozen water storage. Trout species, as well as the bug life and standing stock in every ecosystem, require watersheds to be at normal levels in order to flourish. Dissolved oxygen (DO) is fundamental to aquatic life. With higher levels of snowpack, there is more capability for dissolved oxygen in water due to higher water levels and colder temperatures. Cold water can hold more DO than warm water. Higher DO levels are achieved when water levels and flow rates are high and where the water is aerated in the rapids.
Most species of trout requires 5-6 times more DO when water temperatures reach 75 degrees compared to when they are at 41 degrees. “Species that cannot tolerate low levels of DO – mayfly nymphs, stonefly nymphs, and beetle larvae – will be replaced by a few kinds of pollution-tolerant organisms, such as worms and fly larvae. Nuisance algae and anaerobic organisms (that live without oxygen) may also become abundant in waters with low levels of DO,” according to Brian Oram with the Water Research Center. Fish reproduction can also be hampered if there is not sufficient snowpack because eggs and fish in immature stages require much higher DO content in water.
The current levels of snowpack could be great for our rivers and trout this summer, but that would require a slower runoff to avoid possible floods in the case of a fast melting period.
For more information about how snowpack affects Colorado's rivers, check out the article Snowpack and Our Rivers by Danielle Adams.