Water in Colorado: Climate, Hydrology and Uses Dr. Gigi Richard Faculty Director, Water Center at CMU Professor, Geosciences River Cañon - Nestler Water in Colorado: Climate, Hydrology and Uses

2015 Water Year Oct Sept OctNovDecJanFebMarAprMayJunJulAugSep Water year is named for the year in which it ends

How to define “normal”? = 30 years = 30 years We often compare to the average of a recent 30-yr period “The new normal” = warmer, drier, lower streamflow Warmer, drier and lower streamflow than 1970s

Colorado’s Water Supply

Image credit: Colo. Foundation for Water Education A “Headwaters” State Interstate Compacts

Importance of the Colorado River Water for nearly 40 million people Metropolitan areas have a combined metro gdp of $1.7 trillion (12th largest economy in the world) International treaty w/ Mexico and interstate compact between seven states Irrigates 2.2 million hectares of land (15% of US crops & 13% of livestock) Generates more than 4,200 MW of electricity Recreation & tourism A “ribbon of green” – riparian areas in the Southwest make up less than 3% of the landscape, but provide critical resources for over 75% of wildlife from US Bureau of Reclamation, 2012, Colorado River Basin Study

What is climate? Described by the long-term temperature and precipitation regime at a location What’s the difference between weather and climate? If you don’t like the weather: Wait five minutes! If you don’t like the climate: Move! Location! Changes very slowly Very predictable

Grand Junction  9.4 in/yr Grand Junction  9.4 in/yr Colorado Average Precipitation  15.5 in/yr Boulder  20.7 in/yr Denver  15.5 in/yr Fort Collins  16.1 in/yr Boulder  20.7 in/yr Denver  15.5 in/yr Fort Collins  16.1 in/yr

Aridity  Drought Aridity is a permanent climatic condition in a region, whereas drought is a temporary lack of moisture

Colorado’s climate varies spatially and temporally Monthly temperature and precipitation, avg Blue bar = mean monthly precip, in (right axis) Red line = mean daily max T for each month Blue line = mean daily min T for each month From Climate Change in Colorado: A Synthesis to Support Water Resources Management and Adaptation, produced by Western Water Assessment, Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder for the Colorado Water Conservation Board, Aug 2014

Climate & Hydrology of the Colorado River Basin 34% of watershed receives < 10 in/yr 84% of watershed receives < 20 in/yr 34% of watershed receives < 10 in/yr 84% of watershed receives < 20 in/yr Most of the runoff is produced by only 15% of the drainage area

Colorado River at CO-UT State Line 2011 Flood 2011 Flood Yampa River at Deer Lodge

Colorado River at CO-UT State Line 2012 Drought 2012 Drought

Maps from Streamflow data from usgs.gov 2013 Drought? Flood! Variability in timing and distribution of precipitation result in variable streamflow and availability of surface water supply

GEOL Introduction % of the Population 80% of the Water What do we do when we don’t have water when and where we need it?

From High Country News Glen Canyon Dam, 1963 Lake Powell 27 million ac-ft storage capacity Hoover Dam, 1935 Lake Mead 29 million ac-ft storage capacity Photo by Peter McBride Photos by Peter McBride All-American Canal Photo from Nasa.gov Colorado River Aqueduct Los Angeles & San Diego Central Arizona Project

Oct Natural Variability Filling Lake Powell 1983 Flood Controlled Variability

Blue Mesa Dam completed 1966

Resulting impacts Pre-dam Mean Annual Flood 82,700 cfs Post-dam Mean Annual Flood 30,000 cfs Hydrology Sediment supply & channel morphology Ecological – riparian & aquatic Water Quality From VanSteeter & Pitlick 1998 Data from usgs.gov

How do we use water in Colorado? Irrigation 89% Irrigation 89% Data from Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 pp.

How does Colorado’s water use compare with other states? Figure from Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 pp.

Irrigation withdrawals by state, 2010 #1 CA #1 CA #2 ID #2 ID #3 CO #3 CO Data from Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 pp.

Groundwater Withdrawals in Colorado, mgd 157 mgd 1 mgd 141 mgd Data from Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 pp. 130 mgd

Surface Water Withdrawals in Colorado, mgd 702 mgd 441 mgd 559 mgd 355 mgd Data from Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 pp. 438 mgd 413 mgd 409 mgd

Total Freshwater Withdrawals in Colorado, mgd 462 mgd 579 mgd 703 mgd 563 mgd Data from Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L., and Linsey, K.S., 2014, Estimated use of water in the United States in 2010: U.S. Geological Survey Circular 1405, 56 pp.

Thank you Yampa River, June 2011, G. Richard