Colorado River Delta - Revision history

JeffreyJLukas at 20:00, 14 August 2025

2025-08-14T20:00:48Z

← Older revision		Revision as of 16:00, 14 August 2025
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	''Page credits:''		''Page credits:''

	*~~Co-author~~: Jeff Lukas, Wiki Team		*Author: Jeff Lukas, Wiki Team
	*Reviewer: Jennifer Pitt, Colorado River Program Director, Audubon		*Reviewer: Jennifer Pitt, Colorado River Program Director, Audubon

	Last update: July 2025		Last update: July 2025

JeffreyJLukas at 20:00, 14 August 2025

2025-08-14T20:00:26Z

← Older revision		Revision as of 16:00, 14 August 2025
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	</references>		</references>

	Page credits:
			''Page credits:''

	*Co-author: Jeff Lukas, Wiki Team		*Co-author: Jeff Lukas, Wiki Team

JeffreyJLukas at 19:59, 14 August 2025

2025-08-14T19:59:33Z

← Older revision		Revision as of 15:59, 14 August 2025
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	Page credits:		Page credits:

	Co-author: Jeff Lukas, Wiki Team		*Co-author: Jeff Lukas, Wiki Team
	Reviewer: Jennifer Pitt, Colorado River Program Director, Audubon		*Reviewer: Jennifer Pitt, Colorado River Program Director, Audubon

	Last update: July 2025		Last update: July 2025

JeffreyJLukas at 19:58, 14 August 2025

2025-08-14T19:58:39Z

← Older revision		Revision as of 15:58, 14 August 2025
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	Co-author: Jeff Lukas, Wiki Team		Co-author: Jeff Lukas, Wiki Team
	Reviewer: ~~Tanya Petach~~, ~~Wiki Team~~		Reviewer: Jennifer Pitt, Colorado River Program Director, Audubon

	Last update: ~~April~~ 2025		Last update: July 2025

JeffreyJLukas at 19:57, 14 August 2025

2025-08-14T19:57:11Z

← Older revision		Revision as of 15:57, 14 August 2025
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	<ref name="h-h">Hinojosa-Huerta, O., Soto-Montoya, E., Gómez-Sapiens, M., Calvo-Fonseca, A., Guzmán-Olachea, R., Butrón-Méndez, J., et al. (2013). The birds of the Ciénega de Santa Clara, a wetland of international importance within the Colorado River Delta. Ecological Engineering, 59, 61-73. https://www.sciencedirect.com/science/article/abs/pii/S0925857413001092</ref>		<ref name="h-h">Hinojosa-Huerta, O., Soto-Montoya, E., Gómez-Sapiens, M., Calvo-Fonseca, A., Guzmán-Olachea, R., Butrón-Méndez, J., et al. (2013). The birds of the Ciénega de Santa Clara, a wetland of international importance within the Colorado River Delta. Ecological Engineering, 59, 61-73. https://www.sciencedirect.com/science/article/abs/pii/S0925857413001092</ref>

			</references>

			Page credits:

			Co-author: Jeff Lukas, Wiki Team
			Reviewer: Tanya Petach, Wiki Team

	~~</references>~~		Last update: April 2025

JeffreyJLukas: /* The Delta today */

2025-07-21T20:16:55Z

The Delta today

← Older revision		Revision as of 16:16, 21 July 2025
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	===The Delta today===		===The Delta today===
	Despite the much-degraded condition of the Delta’s ecosystems, covering less than 10% of their original extent, they remain important habitat to diverse populations of birds and other animals, including several federally listed endangered or threatened species (in U.S. and/or Mexico): Yuma Ridgway’s Rail (Rallus obsoletus yumanensis), Southwestern Willow Flycatcher (Empidonax traillii extimus), Yellow-billed ~~cuckoo~~ (Coccyzus americanus), and desert pupfish (Cyprinodon macularius). The Delta is also an important oasis for migrating birds on the Pacific Flyway; over 250 species use the Cienega de Santa Clara alone, and over 350 species have been documented across the Delta.<ref name="h-h"/> The Delta also remains important to the cultural heritage of the Cucupá and other Mexican people who live in towns and villages along the lowermost river and around the Delta.<ref name="sonoran"/> Many of these local communities have joined the restoration efforts.		Despite the much-degraded condition of the Delta’s ecosystems, covering less than 10% of their original extent, they remain important habitat to diverse populations of birds and other animals, including several federally listed endangered or threatened species (in U.S. and/or Mexico): Yuma Ridgway’s Rail (''Rallus obsoletus yumanensis''), Southwestern Willow Flycatcher (''Empidonax traillii extimus''), Yellow-billed Cuckoo (''Coccyzus americanus''), and desert pupfish (''Cyprinodon macularius''). The Delta is also an important oasis for migrating birds on the Pacific Flyway; over 250 species use the Cienega de Santa Clara alone, and over 350 species have been documented across the Delta.<ref name="h-h"/> The Delta also remains important to the cultural heritage of the Cucupá and other Mexican people who live in towns and villages along the lowermost river and around the Delta.<ref name="sonoran"/> Many of these local communities have joined the restoration efforts.

	Future efforts to restore and maintain riparian and wetland habitat in the Delta could face even greater challenges from hydroclimatic conditions. A continuation of the Upper Basin hydrology seen from 2000-2024 would likely preclude any releases of surplus water from Lake Mead and Morelos Dam into the Delta, as occurred in the 1980s and 1990s, and additional warming will further stress the vegetation in the Delta trying to hang on between environmental releases. Minute 323 expires in 2026, and any subsequent agreements will need to accommodate the uncertain contours of the [https://coloradoriverscience.org/Water_law_and_policy#Development_of_new_guidelines_for_post-2026_operations Post-2026 Colorado River operations].		Future efforts to restore and maintain riparian and wetland habitat in the Delta could face even greater challenges from hydroclimatic conditions. A continuation of the Upper Basin hydrology seen from 2000-2024 would likely preclude any releases of surplus water from Lake Mead and Morelos Dam into the Delta, as occurred in the 1980s and 1990s, and additional warming will further stress the vegetation in the Delta trying to hang on between environmental releases. Minute 323 expires in 2026, and any subsequent agreements will need to accommodate the uncertain contours of the [https://coloradoriverscience.org/Water_law_and_policy#Development_of_new_guidelines_for_post-2026_operations Post-2026 Colorado River operations].

JeffreyJLukas: /* The Delta before the early 1900s */

2025-07-21T20:13:19Z

The Delta before the early 1900s

← Older revision		Revision as of 16:13, 21 July 2025
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	Prior to the construction of dozens of large dams on the mainstem and tributaries, the Colorado River carried million tons of sediment annually to its lowest reaches<ref name="dorsey" />, building a broad alluvial plain from the [[Salton Sea]] to the Gulf of California.<ref name="ross" /> At the southern end of this plain, close to sea level and the Gulf, the Colorado River branched out into multiple distributary channels, creating over 3,000 square miles of freshwater, brackish, and saltwater wetlands: the Colorado River Delta. This shifting mosaic of verdant wetlands was sustained by the river’s inflows, which intermingled with seawater carried upstream by the tides<ref name="briggs"/>.		Prior to the construction of dozens of large dams on the mainstem and tributaries, the Colorado River carried million tons of sediment annually to its lowest reaches<ref name="dorsey" />, building a broad alluvial plain from the [[Salton Sea]] to the Gulf of California.<ref name="ross" /> At the southern end of this plain, close to sea level and the Gulf, the Colorado River branched out into multiple distributary channels, creating over 3,000 square miles of freshwater, brackish, and saltwater wetlands: the Colorado River Delta. This shifting mosaic of verdant wetlands was sustained by the river’s inflows, which intermingled with seawater carried upstream by the tides<ref name="briggs"/>.

	[[File:CO_Delta_Map.png\|thumb\|~~700px~~\|Figure 1. Satellite ~~image~~ of the Colorado River Delta region overlain with major geographic features. The dashed blue line shows the approximate course of the Colorado River)]]		[[File:CO_Delta_Map.png\|thumb\|600px\|Figure 1. Satellite imagery of the Colorado River Delta region overlain with major geographic features. The dashed blue line shows the approximate course of the Colorado River, which today flows only intermittently below Morelos Dam, mainly from irrigation return flows and also periodic environmental releases. (Imagery: Google Earth)]]

	Thousands of Cucupá (now also known as Cocopah or Kwapa) people lived on the higher ground of the Delta, farming corn and other crops in seasonally flooded fields and fishing in the channels and the lagoons.<ref name="kelly" /> European visitors to the Delta from the 1500s onward remarked on the power of the tides and the confounding physiography of multiple channels and soft sediments that hindered upstream travel by boat and by foot.<ref name="sykes" /> It was not until the early 1900s that visitors, most famously Aldo Leopold, began to document what the Cucupá had long known about the Delta: Its dynamic landscape of wetlands supported numerous and diverse plants and animals. The Delta, Leopold wrote, held “a verdant wall of mesquite and willow…a hundred green lagoons…fleets of cormorants” and many other birds, beavers, and jaguars.<ref name="isak" /> The Delta’s waters hosted an equally prolific aquatic fauna, including billions of endemic Colorado delta clams.<ref name="smith" />		Thousands of Cucupá (now also known as Cocopah or Kwapa) people lived on the higher ground of the Delta, farming corn and other crops in seasonally flooded fields and fishing in the channels and the lagoons.<ref name="kelly" /> European visitors to the Delta from the 1500s onward remarked on the power of the tides and the confounding physiography of multiple channels and soft sediments that hindered upstream travel by boat and by foot.<ref name="sykes" /> It was not until the early 1900s that visitors, most famously Aldo Leopold, began to document what the Cucupá had long known about the Delta: Its dynamic landscape of wetlands supported numerous and diverse plants and animals. The Delta, Leopold wrote, held “a verdant wall of mesquite and willow…a hundred green lagoons…fleets of cormorants” and many other birds, beavers, and jaguars.<ref name="isak" /> The Delta’s waters hosted an equally prolific aquatic fauna, including billions of endemic Colorado delta clams.<ref name="smith" />

JeffreyJLukas at 19:44, 21 July 2025

2025-07-21T19:44:11Z

← Older revision		Revision as of 15:44, 21 July 2025
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	Prior to the construction of dozens of large dams on the mainstem and tributaries, the Colorado River carried million tons of sediment annually to its lowest reaches<ref name="dorsey" />, building a broad alluvial plain from the [[Salton Sea]] to the Gulf of California.<ref name="ross" /> At the southern end of this plain, close to sea level and the Gulf, the Colorado River branched out into multiple distributary channels, creating over 3,000 square miles of freshwater, brackish, and saltwater wetlands: the Colorado River Delta. This shifting mosaic of verdant wetlands was sustained by the river’s inflows, which intermingled with seawater carried upstream by the tides<ref name="briggs"/>.		Prior to the construction of dozens of large dams on the mainstem and tributaries, the Colorado River carried million tons of sediment annually to its lowest reaches<ref name="dorsey" />, building a broad alluvial plain from the [[Salton Sea]] to the Gulf of California.<ref name="ross" /> At the southern end of this plain, close to sea level and the Gulf, the Colorado River branched out into multiple distributary channels, creating over 3,000 square miles of freshwater, brackish, and saltwater wetlands: the Colorado River Delta. This shifting mosaic of verdant wetlands was sustained by the river’s inflows, which intermingled with seawater carried upstream by the tides<ref name="briggs"/>.

	[[File:CO_Delta_Map.png\|thumb\|700px\|Figure 1. ~~CAPTION. SOURCE~~.)]]		[[File:CO_Delta_Map.png\|thumb\|700px\|Figure 1. Satellite image of the Colorado River Delta region overlain with major geographic features. The dashed blue line shows the approximate course of the Colorado River)]]

	Thousands of Cucupá (now also known as Cocopah or Kwapa) people lived on the higher ground of the Delta, farming corn and other crops in seasonally flooded fields and fishing in the channels and the lagoons.<ref name="kelly" /> European visitors to the Delta from the 1500s onward remarked on the power of the tides and the confounding physiography of multiple channels and soft sediments that hindered upstream travel by boat and by foot.<ref name="sykes" /> It was not until the early 1900s that visitors, most famously Aldo Leopold, began to document what the Cucupá had long known about the Delta: Its dynamic landscape of wetlands supported numerous and diverse plants and animals. The Delta, Leopold wrote, held “a verdant wall of mesquite and willow…a hundred green lagoons…fleets of cormorants” and many other birds, beavers, and jaguars.<ref name="isak" /> The Delta’s waters hosted an equally prolific aquatic fauna, including billions of endemic Colorado delta clams.<ref name="smith" />		Thousands of Cucupá (now also known as Cocopah or Kwapa) people lived on the higher ground of the Delta, farming corn and other crops in seasonally flooded fields and fishing in the channels and the lagoons.<ref name="kelly" /> European visitors to the Delta from the 1500s onward remarked on the power of the tides and the confounding physiography of multiple channels and soft sediments that hindered upstream travel by boat and by foot.<ref name="sykes" /> It was not until the early 1900s that visitors, most famously Aldo Leopold, began to document what the Cucupá had long known about the Delta: Its dynamic landscape of wetlands supported numerous and diverse plants and animals. The Delta, Leopold wrote, held “a verdant wall of mesquite and willow…a hundred green lagoons…fleets of cormorants” and many other birds, beavers, and jaguars.<ref name="isak" /> The Delta’s waters hosted an equally prolific aquatic fauna, including billions of endemic Colorado delta clams.<ref name="smith" />

JeffreyJLukas at 19:41, 21 July 2025

2025-07-21T19:41:09Z

← Older revision		Revision as of 15:41, 21 July 2025
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	===The Delta before the early 1900s===		===The Delta before the early 1900s===
	Prior to the construction of dozens of large dams on the mainstem and tributaries, the Colorado River carried million tons of sediment annually to its lowest reaches<ref name="dorsey" />, building a broad alluvial plain from the [[Salton Sea]] to the Gulf of California.<ref name="ross" /> At the southern end of this plain, close to sea level and the Gulf, the Colorado River branched out into multiple distributary channels, creating over 3,000 square miles of freshwater, brackish, and saltwater wetlands: the Colorado River Delta. This shifting mosaic of verdant wetlands was sustained by the river’s inflows, which intermingled with seawater carried upstream by the tides<ref name="briggs"/>.		Prior to the construction of dozens of large dams on the mainstem and tributaries, the Colorado River carried million tons of sediment annually to its lowest reaches<ref name="dorsey" />, building a broad alluvial plain from the [[Salton Sea]] to the Gulf of California.<ref name="ross" /> At the southern end of this plain, close to sea level and the Gulf, the Colorado River branched out into multiple distributary channels, creating over 3,000 square miles of freshwater, brackish, and saltwater wetlands: the Colorado River Delta. This shifting mosaic of verdant wetlands was sustained by the river’s inflows, which intermingled with seawater carried upstream by the tides<ref name="briggs"/>.

			[[File:CO_Delta_Map.png\|thumb\|700px\|Figure 1. CAPTION. SOURCE.)]]

	Thousands of Cucupá (now also known as Cocopah or Kwapa) people lived on the higher ground of the Delta, farming corn and other crops in seasonally flooded fields and fishing in the channels and the lagoons.<ref name="kelly" /> European visitors to the Delta from the 1500s onward remarked on the power of the tides and the confounding physiography of multiple channels and soft sediments that hindered upstream travel by boat and by foot.<ref name="sykes" /> It was not until the early 1900s that visitors, most famously Aldo Leopold, began to document what the Cucupá had long known about the Delta: Its dynamic landscape of wetlands supported numerous and diverse plants and animals. The Delta, Leopold wrote, held “a verdant wall of mesquite and willow…a hundred green lagoons…fleets of cormorants” and many other birds, beavers, and jaguars.<ref name="isak" /> The Delta’s waters hosted an equally prolific aquatic fauna, including billions of endemic Colorado delta clams.<ref name="smith" />		Thousands of Cucupá (now also known as Cocopah or Kwapa) people lived on the higher ground of the Delta, farming corn and other crops in seasonally flooded fields and fishing in the channels and the lagoons.<ref name="kelly" /> European visitors to the Delta from the 1500s onward remarked on the power of the tides and the confounding physiography of multiple channels and soft sediments that hindered upstream travel by boat and by foot.<ref name="sykes" /> It was not until the early 1900s that visitors, most famously Aldo Leopold, began to document what the Cucupá had long known about the Delta: Its dynamic landscape of wetlands supported numerous and diverse plants and animals. The Delta, Leopold wrote, held “a verdant wall of mesquite and willow…a hundred green lagoons…fleets of cormorants” and many other birds, beavers, and jaguars.<ref name="isak" /> The Delta’s waters hosted an equally prolific aquatic fauna, including billions of endemic Colorado delta clams.<ref name="smith" />
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	Future efforts to restore and maintain riparian and wetland habitat in the Delta could face even greater challenges from hydroclimatic conditions. A continuation of the Upper Basin hydrology seen from 2000-2024 would likely preclude any releases of surplus water from Lake Mead and Morelos Dam into the Delta, as occurred in the 1980s and 1990s, and additional warming will further stress the vegetation in the Delta trying to hang on between environmental releases. Minute 323 expires in 2026, and any subsequent agreements will need to accommodate the uncertain contours of the [https://coloradoriverscience.org/Water_law_and_policy#Development_of_new_guidelines_for_post-2026_operations Post-2026 Colorado River operations].		Future efforts to restore and maintain riparian and wetland habitat in the Delta could face even greater challenges from hydroclimatic conditions. A continuation of the Upper Basin hydrology seen from 2000-2024 would likely preclude any releases of surplus water from Lake Mead and Morelos Dam into the Delta, as occurred in the 1980s and 1990s, and additional warming will further stress the vegetation in the Delta trying to hang on between environmental releases. Minute 323 expires in 2026, and any subsequent agreements will need to accommodate the uncertain contours of the [https://coloradoriverscience.org/Water_law_and_policy#Development_of_new_guidelines_for_post-2026_operations Post-2026 Colorado River operations].


	~~[[File:FILENAME.png\|thumb\|700px\|Figure 1. CAPTION. SOURCE.)]]~~

	==Data and tools==		==Data and tools==

JeffreyJLukas at 18:33, 21 July 2025

2025-07-21T18:33:59Z

← Older revision		Revision as of 14:33, 21 July 2025
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	===[https://www.sciencebase.gov/catalog/item/5d655b2fe4b0c4f70ceeafa2 USGS Colorado River Delta Minute 319 monitoring data]===		===[https://www.sciencebase.gov/catalog/item/5d655b2fe4b0c4f70ceeafa2 USGS Colorado River Delta Minute 319 monitoring data]===
	This dataset includes compilation of vegetation indices, phenology assessment metrics, estimates of evapotranspiration, and change maps for seven reaches of the delta's 150-km long region, for almost a 20-year period from 2000-2019.		This dataset includes compilation of vegetation indices, phenology assessment metrics, estimates of evapotranspiration, and change maps for seven reaches of the delta's 150-km long region, for almost a 20-year period from 2000-2019.


	</onlyinclude>		</onlyinclude>

	==Additional resources==		==Additional resources==


	===Environmental Work Group reports for Minute 319 and Minute 323===		===Environmental Work Group reports for Minute 319 and Minute 323===
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	[https://ibwc.azurewebsites.net/wp-content/uploads/2024/05/FINAL-ENG-2019-Implementation-report-CLEAN-finalized-on-2024-03-05.pdf Minute 323 - 2019 Implementation Report]		[https://ibwc.azurewebsites.net/wp-content/uploads/2024/05/FINAL-ENG-2019-Implementation-report-CLEAN-finalized-on-2024-03-05.pdf Minute 323 - 2019 Implementation Report]

	===Hydrologic monitoring in the Colorado River Delta - Sonoran Institute===		===[https://storymaps.arcgis.com/stories/2c96aabde941470eae53d318930339d4 Hydrologic monitoring in the Colorado River Delta - Sonoran Institute]===

			A very detailed StoryMap documenting an environmental flow through the Delta in 2021 and the restoration and monitoring activities before and during the flow.


	~~===[URL_Resource2 Name_Resource2]===~~

	==Notes==		==Notes==