Colorado River DeltaColorado River Delta

SWES 574SWES 574

Fall 2003Fall 2003

W.J. WardW.J. Ward

Rodriguez, C. A., Flessa, K. W., Tellez-Duarte, M. A., Dettman, D. L., and Avila-Serrano, G. A.(2001b). "Macrofaunal and isotopic estimates of the former extent of the Colorado River estuary, upper Gulf of California, Mexico." Journal of Arid Environments, 49, 183-193.

Outline Four Time Periods Outline Four Time Periods

Pre-Hover Dam (late 1800’s to 1932)Pre-Hover Dam (late 1800’s to 1932)

Post Hover Dam (1932 to 1996)Post Hover Dam (1932 to 1996)

Current focus on Colorado DeltaCurrent focus on Colorado Delta

FutureFuture

Colorado River FactoidsColorado River Factoids Area drains over 242,000 square miles on Area drains over 242,000 square miles on

its 1,450 mile course its 1,450 mile course Colorado flow rate max 7000 m3s-1 Colorado flow rate max 7000 m3s-1

creating deposits 5 km thick in some areas. creating deposits 5 km thick in some areas. (average annual flow 60 year period (1906-(average annual flow 60 year period (1906-65) is 15.09 million acre-feet 65) is 15.09 million acre-feet

Colorado is saltiest carrying 9 million tons Colorado is saltiest carrying 9 million tons per year. Salinities were 32-35 l range now per year. Salinities were 32-35 l range now 35 – 45 l range35 – 45 l range

Flow irrigates over 1,000,000 acres in the Flow irrigates over 1,000,000 acres in the United States and 500,000 acres in Mexico United States and 500,000 acres in Mexico

Source: Worster, 1985, & (Hoover Dam Web Site Hoover Dam Historyhttp://www.usbr.gov/lc/hooverdam/)

Colorado Delta FactoidsColorado Delta Factoids Colorado river flowed into the Gulf of Colorado river flowed into the Gulf of

California forming a bay 50 miles wide. California forming a bay 50 miles wide. Each year the river deposited 140,000 Each year the river deposited 140,000 acre feet of silt (214 sq. miles coved in 1 acre feet of silt (214 sq. miles coved in 1 ft. of soil) ft. of soil)

Colorado Delta was once 3000 sq. miles. Colorado Delta was once 3000 sq. miles. Now ½ that size Now ½ that size

The Salton Basin received flow from the The Salton Basin received flow from the Colorado river eight (8) times from 1824 to Colorado river eight (8) times from 1824 to 1904 1904

45 species in the United States segment of 45 species in the United States segment of the Delta are now listed as endangered, the Delta are now listed as endangered, threatened or sensitive threatened or sensitive

(Hoover Dam Web Site Hoover Dam Historyhttp://www.usbr.gov/lc/hooverdam/)

Aldo Leopold called the Delta “ a vast gallery forest of cottonwood, (Populus fremontii) and willow (Salix gooddingii) in the north interspersed with wetlands containing cattail (Typha domengensis) and common reed (Phragmites australis) in low areas and mesquite bosques (Prosopis glandulosa & Prospis pubescens) in higher terraces”. The endemic salt grass, Distichlis palmeri, dominated the estuarine zone. Beaver, jaguar and deer were in abundance and Egrets flocked in such numbers as to make the ground appear white in 1920.

Glenn, E. P., Zamora-Arroyo, F., Nagler, P. L., Briggs, M., Shaw, W., and Flessa, K.(2001). "Ecology and conservation biology of the Colorado River Delta, Mexico." Journal of Arid Environments, 49, 5-15.

Typical Colorado Delta Marsh – Early 1900’s

Colorado river flooded town of Yuma in 1852, 1890, 1905, 1916, 1920. The river port of La Paz was left on high ground in 1868 by the Colorado river changing it’s course. Floods have occurred 1884, 1905, 1909, 1916, 1917, 1923, 1926, 1937, 1939, 1941, 1952, 1957, 1962, 1964, 1965, 1967. 1884 flood was 30.1 million acre-feet with discharge of 300,000 cubic feet per second.

Fort Yuma after Railroad

Interagency Committee (1970). "Lower Colorado Region Comprehensive Framework Study; app. 9, Flood Control." U. S. Pacific Southwest Inter-Agency Committee, 103.

Sykes, 1937, Freshwater fish and saltwater fish at the mouth of the gulf were diminished in numbers as to almost be nonexistent. Bird life and many mammals such as raccoon and beaver were so diminished to have practically disappeared. (Sykes, 1937, The Colorado Delta.

Zamora-Arroyo, F., Nagler, P. L., Briggs, M., Radtke, D., Rodriquez, H., Garcia, J., Valdes, C., Huete, A., and Glenn, E. P.(2001). "Regeneration of native trees in response to flood releases from the United States into the delta of the Colorado River, Mexico." Journal of Arid Environments, 49, 49-64.

Current Colorado River Flow

Today much of the area between channels is a vast monoculture of Tamarix ramosissima

Bivalue mollusk Mulinia coloradoensis reduced to only small areas where they can still be found. Total living clams reduced by 95 % due to increased salinity and lower nutrients from sediment flows. Salinities were 32-35 l range now 35 – 45 l range. Rodriguez, C. A., Flessa, K. W., and Dettman, D. L.(2001a)."Effects of Upstream Diversion of Colorado River Water on the Estuarine Bivalve Mollusc Mulinia coloradoensis.“Conservation Biology, 15(1), 249-258 .

Changes in downstream water total flows, seasonal timing of flows, short-term fluctuations in flows, extreme high and low flows, & water quality such as temperature, nutrient load, turbidity, and dissolved gases, can dramatically change biodiversity.

Biodiversity ChangesBiodiversity Changes Meander cutting and abandonment of river Meander cutting and abandonment of river

channels leads to a geomorphologically channels leads to a geomorphologically diverse floodplain, and consequently the diverse floodplain, and consequently the development of highly complex forest.development of highly complex forest.

Channel incision or lowering the channel Channel incision or lowering the channel

bed causing water table to decline greater bed causing water table to decline greater than 1.5 m can greatly impact cottonwood than 1.5 m can greatly impact cottonwood trees.trees.

Populus fremontii survived 1 cm sediment Populus fremontii survived 1 cm sediment deposit by the time it reached 2 cm tall deposit by the time it reached 2 cm tall (approx. 2 weeks); Tamarix ramosissima at (approx. 2 weeks); Tamarix ramosissima at 4-6 cm tall (approx. 5 weeks). However, 4-6 cm tall (approx. 5 weeks). However, Tamarix ramosissima exhibited some Tamarix ramosissima exhibited some survival after complete burial of 1-2 cm. survival after complete burial of 1-2 cm.

Future FocusFuture Focus 80-120 m3s-1 flow rates on the 140 80-120 m3s-1 flow rates on the 140

km stretch between Morelos Dam km stretch between Morelos Dam and the Gulf is sufficient to bring the and the Gulf is sufficient to bring the river out of its existing cannel and river out of its existing cannel and inundate the floodplain. A 3- month inundate the floodplain. A 3- month spring release is sufficient to spring release is sufficient to germinate tree seedlings. Native germinate tree seedlings. Native trees, once established, can survive trees, once established, can survive at least 4 years between floods by at least 4 years between floods by utilizing alluvial water tables that are utilizing alluvial water tables that are 1-2 m below the surface along this 1-2 m below the surface along this stretch of the riparian corridor. stretch of the riparian corridor.

Zamora-Arroyo, F., Nagler, P. L., Briggs, M., Radtke, D., Rodriquez, H., Garcia, J., Valdes, C., Huete, A., and Glenn, E. P. (2001)."Regeneration of native trees in response to flood releases from the United States into the delta of the Colorado River, Mexico.“ Journal of Arid Environments, 49, 49-64.

ReferencesReferences Cohen MJ, Henges-Jeck C, Castillo-Moreno G, “A preliminary water balance for the Cohen MJ, Henges-Jeck C, Castillo-Moreno G, “A preliminary water balance for the

Colorado River delta, 1992-1998”, J Arid Environ 49 (1): 35-48 Sep 2001Colorado River delta, 1992-1998”, J Arid Environ 49 (1): 35-48 Sep 2001 Garcia-Hernandez J, Hinojosa-Huerta O, Gerhart V, et al.,”Willow flycatcher Garcia-Hernandez J, Hinojosa-Huerta O, Gerhart V, et al.,”Willow flycatcher

(Empidonax traillii) surveys in the Colorado River delta: implications for (Empidonax traillii) surveys in the Colorado River delta: implications for management”, J Arid Environ 49 (1): 161-169 Sep 2001management”, J Arid Environ 49 (1): 161-169 Sep 2001

Glenn EP, Zamora-Arroyo F, Nagler PL, et al., “Ecology and conservation biology of Glenn EP, Zamora-Arroyo F, Nagler PL, et al., “Ecology and conservation biology of the Colorado River delta, Mexico”, J Arid Environ 49 (1): 5-15 Sep 2001the Colorado River delta, Mexico”, J Arid Environ 49 (1): 5-15 Sep 2001

Hayes, Rachel, “The Colorado River Delta: Bordering on a Sustainable Future”, Hayes, Rachel, “The Colorado River Delta: Bordering on a Sustainable Future”, Borderlines 38, vol. 5, no. 8, Aug. 1997Borderlines 38, vol. 5, no. 8, Aug. 1997

Kowalewski M, Avila Serrano GE, Flessa KW, Goodfriend GA, “Dead delta's former Kowalewski M, Avila Serrano GE, Flessa KW, Goodfriend GA, “Dead delta's former productivity: Two trillion shells at the mouth of the Colorado River”, Geology; productivity: Two trillion shells at the mouth of the Colorado River”, Geology; December 2000; v.28 no.12 p.1059-1062December 2000; v.28 no.12 p.1059-1062

Pitt J, Luecke DF, Cohen MJ, et al.,”Two nations, one river: Managing ecosystem Pitt J, Luecke DF, Cohen MJ, et al.,”Two nations, one river: Managing ecosystem conservation in the Colorado River delta”, Nat Resour J 40 (4): 819-864 Fall 2000 conservation in the Colorado River delta”, Nat Resour J 40 (4): 819-864 Fall 2000

Stromberg JC,”Restoration of riparian vegetation in the south-western United States: Stromberg JC,”Restoration of riparian vegetation in the south-western United States: importance of flow regimes and fluvial dynamism”, J Arid Environ 49 (1): 17-34 Sep importance of flow regimes and fluvial dynamism”, J Arid Environ 49 (1): 17-34 Sep 2001 2001

Vandersande MW, Glenn EP, Walworth JL,”Tolerance of five riparian plants from the Vandersande MW, Glenn EP, Walworth JL,”Tolerance of five riparian plants from the lower Colorado River to salinity drought and inundation”, Journal of Arid lower Colorado River to salinity drought and inundation”, Journal of Arid Environments (2001) 49: 147-159Environments (2001) 49: 147-159

Varady RG, Hankins KB, Kaus A, et al.,.”.. to the Sea of Cortes: nature, water, culture, Varady RG, Hankins KB, Kaus A, et al.,.”.. to the Sea of Cortes: nature, water, culture, and livelihood in the Lower Colorado River basin and delta – an overview of issues, and livelihood in the Lower Colorado River basin and delta – an overview of issues, policies, and approaches to environmental restoration”, J Arid Environ 49 (1): 195-209 policies, and approaches to environmental restoration”, J Arid Environ 49 (1): 195-209 Sep 2001 Sep 2001