Snowpack and Our Rivers
Posted by CTU Communications Intern on February 17, 2016 in Arkansas, Basin Updates, Conservation, Dolores-San Miguel, Gunnison Basin, Habitat, Leadership, Lower Colorado-Roaring Fork, North Platte-Poudre-Thompson, Press/PR, Rio Grande Basin, San Juan-Animas, South Platte, Trout, Upper Colorado-Fraser-Blue-Eagle, Water Quality, Yampa-White
By: Danielle Adams
For Colorado, the snowpack levels don’t only affect recreation, they affect our way of life. While the accumulation may wreck havoc on commutes, the snow provides Colorado with some much needed moisture during the hotter, dryer months.
Thanks to a strong El Niño winter, the buildup of snow accumulation throughout the state has increased each basin’s snowpack to above average.
Snowpack is a seasonal accumulation of slow-melting snow, which becomes compressed in layers by its own weight over time. As there is more snow accumulation in a region, the snowpack becomes more dense. The denser the snow, the more water storage capability it has–a hard layer will have around a 40% water to 60% air ratio.
According to Denver Water, collection in the Upper South Platte watershed is 126% of normal and the Upper Colorado River watershed is 118% of normal. If snowfall can continue to build snowpack in the coming months watersheds across the state will be in much better shape than previous years. In an article by CBS Denver, Noah Newman with CSU’s Colorado Climate Center said, “March is our biggest month for snowfall. If we don’t see the expected March snow then these numbers will go down.”
The total amount of snowpack is essential to Colorado’s freshwater ecosystems because it serves as frozen water storage. The accumulation of water in the river basins and watersheds across the state is in direct correlation with the amount, and melt-rate of the basin’s snow total.
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.
So what do low levels of snowpack mean for us on a conservation level?
There are a few things to keep in mind in the event that snowfall patterns slow, and snowpack fails to develop as extensively as predicted. As the spring and summer months draw nearer, lower snowpack levels brings strained trout populations. In these circumstances, trout will be trying even more desperately to conserve energy in order to utilize less oxygen. This means, that even with all steps taken to properly handle a fish, under these already stressful environmental factors, the fish has less of a chance for survival. In order to keep our fish populations strong and growing even under preexisting environmental stress, catch and release tactics must be carried out even more delicately than usual.
Next time you’re stuck in traffic due to a snowstorm and the stress levels are rising, keep in mind that the snow is good for our waters and trout. The higher levels of snowpack mean higher watershed levels and lower water temperatures, leading to higher levels of dissolved oxygen- making bugs and fish, and ultimately the angler happier.
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