Every year, streams and rivers are fed in the spring by fresh cold water given off by the melting snowpack. Since the 1950s, snowpack for spring snow melt in the mountains of the U. S. Northwest is declining, and this trend is projected to continue as the climate warms further this century. While precipitation has increased throughout the 1900s-2000s, temperature increases have had the overpowering affect on the snowpack (Hamelt 4559).
Reduced snowpack and early snow melts in areas such as the Rockies, Sierras, and Cascades is likely to hurt hydropower during parts of the year, and to place other stresses on the region’s water supply (Serreze 35). Rivers that rely on the snowpack melt later in the spring such as the Columbia River or the Colorado River are losing large portions of their usual spring snow melt (Stewart 1). Growing demand and decreasing supply has the Colorado River running dry before the flow makes it to supply the water deprived areas of Mexico.
Runoff from winter snowpack accounts for about 70 percent of the annual water supply for more than 30 million people living in the western United States, nearly 10% of the U. S. ’s population (doi. usgs). This rapid change in the snowpack decreasing yields and melting earlier in the season has a domino effect on all aspects of the region. Agriculture, fresh water supply, wildlife, landscape and hydropower are all seeing direct results from the warmer winter months changing western North America’s snowpack. The snowpack is a necessary piece of nature.
The yearly recurrence of winter mountain snowfall is a critical backbone for water resources in western North America. The mountain snowpack provides natural storage of fresh water from the cold season until it gradually melts during the spring, replenishing rivers and aqueducts. Western North America relies heavily upon this fresh water source. A huge amount (sometimes more than 70%) of stream flow in the western United States begins as melting mountaintop snowpack. The climate of western United States receives more precipitation in the winter.
Although this water is stored directly in groundwater and soil, snow accumulation is the leading method by which winter precipitation is held for the dry summer months (Mote 30). When these areas experience milder temperatures in the winter, this stored resource is released to early for its use during the summer months. The already low flows of late summer are projected to decrease further due to both earlier snowmelt and increased evaporation and water loss from vegetation. Image 1. Columbia River in the state of Washington. Agriculture is a very important sector in economies across western North America.
California is one of our nation’s leading producers in fruits and commodities such as wine. States such as Colorado still have agriculture but run most of their revenue through livestock, which still remains water demanding. However, these cannot be properly run without the help of irrigation. The region does not receive enough consistent precipitation nor does it have great natural sources of freshwater for agriculture. Large fresh water sources such as the Colorado River lose one third of their flow to agriculture in the region. Arizona has 25 percent of its water provided by the Colorado River.
Of this water, 80 percent of it is used for agriculture. The river is responsible for providing 15 percent of U. S. crops and about 13 percent of their livestock (CRWUA). Some areas of California could only have access to 30 percent of the water ordered for farming this year as stated in April 2012 by the Business Journal. Therefore, this water is taken along great distances from rivers supplied by the spring melt of the snowpack. As far as a fresh water supply, the northwestern area of North America is not in as much trouble as the southwest.
The southwest relies heavily on lakes, streams, and rivers that are refilled every spring by the northwestern snowpack. Less snowpack and earlier snow melts means when the northwest region does not refill water bodies when they are most needed. When they do receive precipitation during the mild winter and warm months, that water may be lost directly to the environment/vegetation when it use to be accumulated snow then melted in the spring (Cayan 82). At this rate, the western states are in trouble for losing a large portion of their current fresh water supply.
Studies through the University of San Diego in 2009 claim there’s a 50% chance that the reservoir created by the Hoover Dam, Lake Mead, could run dry by 2021. “Under conservative climate change scenarios in the West, Barnett and Pierce found decreases in runoff could short the Colorado River by about 400,000 acre feet of water 40% of the time by 2025. That’s equivalent to the amount of water needed to supply 0. 4-0. 8 million households (Stark, USA Today). ” Mexico already has seen in the past few decades the rapid decline of water coming from the Colorado River, the nation’s seventh-longest river (See Image 2).
Although the coastline provides potential for creating freshwater from the ocean, the process would be far too expensive, especially when compared to the current source. Image 2. The Colorado River can be found dry in Mexico. Photo was taken at the Gulf of California, also known as Sea of Cortez (National Geographic). On a similar note, due to these bodies of water having less flow, the surrounding wildlife is suffering. Forest fires in the northwest region are expected to be a more common occurrence due to less water available in the summer months.
As a whole, tree growth will slow down and become more susceptible to insect infestation, which will also hurt their timber industry (Global Climate Change 136). However, the small population of trees that once had longer cold winter periods will show an increase in growth due to a slightly milder climate and more water instead of what was previously snow on the mountaintops. Although human development is the main cause for historically low levels of salmon, early snowpack melts are adding to the stresses.
Winter-time snow melts will wash away eggs or small salmon not mature enough to swim against the stream which usually didn’t come until spring (Global Climate Change 137). When these melts come early, it also means less water will be coming from a melt in the spring. Warmer air creates warmer water which will promote more disease and parasites, affecting all types of northwestern coldwater fish species such as trout and steelhead. If air temperature exceeds the threshold of 70 degrees Fahrenheit for the August average, water conditions become dangerous for coldwater fish.
As studies suggest, stresses on coldwater fish will be increasing within the next decades (see Figure 1). Figure 1. Air temperature increases are to add dangerous stress levels to coldwater fish populations such as salmon and trout (Global Climate Change Impacts in the U. S. ). As a direct result of less available water in the summer months, wildlife downstream will be severely be damaged. Southern riparian zones of the Colorado River, vegetation grown along the borders of the river, are a small portion to be affected but contain some of the area’s most diverse species.
Towards the end of the river, the Colorado River Delta supports 358 species of birds (Shanahan 75), the endanger jaguar, and the critically endangered vaquita harbor porpoise with only a couple hundred remaining making it one of the rarest mammals in the world (Alles 1). From the forests of the Rocky Mountains to the Mohave Desert, 1,600 species of plants live off of the Colorado River watershed (Benke 488). Modifying the river has led to the extinct of 4 fish species, in a region where 42 of the fish species are endemic (Benke 493).
Today, only ten percent of water makes it to the delta from what once did. Invasive plants, such as salt cedar and cattails, now dominate the delta, a landscape of seemingly endless mud flats where forests used to stand (Zeilinski, Smithsonian Mag). Image 3. Only found in the Colorado River Delta, the Vaquita Harbor Porpoise is one of the rarest mammals in the world, with less than 300 currently alive (photo from arkive. org). Another factor to consider with change in water flow through the region is the effect it has on the landscape.
During the early 20th century, western North America began modifying the Colorado River’s path, building dams and diverting the flow hundreds of miles to places such as Los Angeles, San Diego, and Phoenix (Zeilinski, Smithsonian Mag). The damming and diverting of the Colorado can be seen as an engineering feat or annihilation of the environment. Drought has severely deprived the river within the last few years. At the edges of Lake Mead, there are marks as high as 130 feet above the current surface where the water levels use to be within the last 80 years. Water resource officials say some of the reservoirs fed by the river?will never be full again (Zeilinski, Smithsonian Mag). ” Due to this region’s growing need for water and diminishing supply, drastic measures have been made to the landscape and environment. The creation of Lake Powell engulfed the beauty of Glen Canyon in addition to causing erosion in the Grand Canyon (Mark, Earth Island Institute). Bob Wilkinson, a professor at UC Santa Barbara is quoted saying: “It’s not about sustaining where we are at now, because the situation is already pretty bad.
It’s about restoration. We have to meet our needs while putting more water back into natural systems. ” A more current concern is landslides on steep rocky cliffs. With the increase in rainfall instead of snowfall in the winter, there will be an increase in saturated soils. With this increase will follow more common landslides (see image 4). This will become a growing issue as landslides destroy developed lands and become a hazard near any tampered with steep cliffs (Global Climate Change 138). Image 4. Landslide at California’s Yosemite National Park (Yosemite. a. us) A final topic that has a crucial impact from the change in snowpack behavior is hydroelectric power. Ross Dam provides nearly 70 percent of the region’s power and 20 percent of Seattle’s electricity (Cambridge, Global climate change impacts in the U. S. ). Ross Dam is located in the state of Washington, but near the Canadian border. In fact, Ross Lake extends over 20 miles into Canada. This Dam relies heavily on the snowpack and a steady melt from the snowpack in the spring to maintain power production.
If the water comes too early or the precipitation never makes it to the Dam, they can face problems producing electricity during the summer months. The Columbia River contains 14 hydroelectric dams, making it the largest power producing river in North America. With the Colorado River, it consists of over 20 major dams that also provide a majority of power to the region. The Hoover Dam on the Colorado may be the most famous in North America. It was originally the world’s tallest dam as well as the world’s largest hydroelectric power producer (Bureau of Reclamation).
It is responsible for the growth of Las Vegas to the world renowned city that it is today. These three examples give the timing of the snowpack release a large responsibility on being able to provide ample power to their regions throughout the summer months. Image 5. Lake Mead held back by the Hoover Dam along the Colorado River (usbr. gov) The water supply from spring and summer snowmelt runoff supports agriculture, urban areas, recreation, power and the ecological health regional water bodies. Water supply in the western region of North America and springtime runoff predictions are necessary for water use planning and flood management.
With the recent hardships with the snowpack falling short of the populations demand, the growing Sunbelt region is faced with a difficult issue to overcome in the near future. Although in the last 50 years trends have been showing a decrease in the snowpack and earlier melt times, this year the state of Washington is at 137% of their average snowpack level, which is great news for their spring and summer month’s economy (Washington Snow Survey Program). As populations around the world are rapidly growing, fresh water has become one of the scarcest resources.