When I started my job with CFWE a year ago, I knew relatively little about Colorado’s water.  I grew up in Ohio, where rivers only seemed to make the news when they flooded or caught fire.  But in Colorado, I began to hear the saying, “Whiskey is for drinking, water is for fighting.”  So, I started learning about what made water in the West – and Colorado – so prized.  Here’s a short summary of the major themes this non-Westerner has learned in a year. 

Water is Scarce

Colorado is part of the region once called the “Great American Desert.”  Statewide, the average annual precipitation is only 16 inches.  In contrast, Iowa receives 32 inches and Florida receives more than 50 inches!  If all of Colorado received its 16 inches evenly, water planning would be straightforward.  But from year to year and region to region, the amount varies wildly.  The mountains might receive 50 inches of precipitation, while the San Luis Valley receives just 7 inches annually.

A Good Water Year Depends on Snow

Winter is crucial for Colorado’s water, since the majority of the state’s precipitation comes from snow.  Most of this falls in the mountains, accumulating during the winter and melting during spring and summer.  This snowmelt feeds Colorado’s rivers, providing approximately 80% of their water.  Little snow in the winter can mean drought in the summer.

Colorado Must Save Water for Future Use

River levels peak in spring and summer, and then all that water runs away.  Survival during the dry seasons requires some human ingenuity.  Colorado has over 1800 reservoirs to capture and store water for later use.  This is an ancient practice:  Colorado’s earliest residents built reservoirs, such as those found at Mesa Verde.

Supplying water for people, businesses, and farms across the state requires a vast infrastructure network.  Since Colorado doesn’t receive a lot of rain, it is very difficult to grow crops relying only on precipitation.  Instead, farmers need to irrigate their fields, relying on groundwater, river water, and complex irrigation systems to do so.  Competition for limited water requires a clear system of law.

The Oldest Water Claims Get First Dibs

Colorado’s challenges of climate and geography shaped its system of water law.  In the eastern United States, only those with land adjoining a stream had a right to use the stream’s water.  This system is known as riparian law.  In Colorado, users of water often live far away from the source of the water, so riparian law is impractical.  Colorado adopted the system of prior appropriation, in which those with senior (older) rights to water have the right to use it before junior (newer) rights holders in times of water shortages.  This system is summed up as “first in time, first in right.”

Private persons, public agencies, and businesses can hold rights to use Colorado’s water.  The water itself, however, is always owned by the public.

Water Goes to the Atlantic or Pacific – Except When It Doesn’t

A drop of water falls on the Continental Divide.  If it rolls to the west, it will end up in the Pacific Ocean.  If it rolls to the east, it will make its way to the Atlantic Ocean.  If Nature were left to its own devices, this would be true.  But Coloradans have different needs.

The Rocky Mountains and the Continental Divide run down Colorado, dividing it into the mountainous Western Slope and the plains of the Front Range.  The Western Slope has more water – but the Front Range has a larger population.  Under the prior appropriation doctrine, the user of water does not need to live near the water source.  Since more people live in the eastern half of the state, human engineering carries water from the west to the east, across (and sometimes under) the Continental Divide.  Water originally bound for western rivers heads east instead.  These transbasin diversions are often points of contention between the Western Slope and the Front Range.

Water Flows Out, Not In

Colorado is highly unusual in that most of its water originates within the state and then flows out, rather than flowing in from other states.  Colorado is known as the Headwaters State, since it is the origin of four major rivers – the Rio Grande, the Colorado, the Arkansas, and the Platte.  But Colorado cannot use all of its watery bounty.  Its rivers flow through 18 other states and the Republic of Mexico.  These states often battle with their own water shortages, making the flows from Colorado crucial.  But which state owns what portion of the river water?

Colorado Shares Its Rivers With Other States

Many Western states also follow the doctrine of prior appropriation – the oldest claims on the water get to use it first in times of shortage.  But how do these claims apply across state boundaries?  As California grew rapidly in the late nineteenth century, many of the states that shared its rivers worried they would be squeezed out of water – and their own opportunities to grow.  So the Western states drew up interstate compacts, agreements that divide water between the states.  Now, Colorado must always send certain amounts of water downstream to other states, even in dry years, to honor these compacts.

Water Will Always Be An Issue

Colorado’s water woes are not going away.  The state continues to grow – population is increasing, especially along the Front Range, and new businesses are competing for water.  Meanwhile, climate change threatens river and precipitation levels.  Will Colorado have less water to share amongst more people?  Colorado’s water will continue to need defenders and caretakers.

If you had to explain Colorado’s water issues to a non-Westerner, what would you include?  What water issues do you think makes Colorado unique?