Tamarisk Can Water be Saved?? 35 th Annual Colorado Water Workshop, WSC July 22, 2010 Tim Carlson Research & Policy Director Tamarisk is a non-native phreatophyte that can dominate riparian lands Distribution Tamarisk covers approximately 1.6 million acres of riparian lands within the western United States Courtesy of Fred Nibling, Bureau of Reclamation Tamarisk has a Reputation for consuming large amounts of water BOR & USGS Tamarisk Assessment Peer reviewed Papers 7-States Colorado River Basin Tamarisk Assessment ET Peer Panel Is there an opportunity to save water? 2 Studies, 2 Different Approaches BOR & USGS Report7-States Report CW & Willows use same amount of water ~ 3/yr. On upper terraces of floodplain, tamarisk will use more water than native xeric plants (e.g., bunch grasses, sage, rabbitbrush, etc.). Difficult to measure savings. Demonstration projects advocated. Impacts to wildlife Mixed. CW & Willows use same amount of water ~3/yr. On upper terraces of floodplain, tamarisk will use more water than native xeric plants (e.g., bunch grasses, sage, rabbitbrush, etc.). Difficult to measure savings but savings can be modeled. Demonstration projects advocated. Impacts to wildlife Mixed. Tamarisk Induced Changes in Channel Structure and Associated Habitats Figure 1 Water Savings You do the ET Math 1.Cottonwoods and willows 2.Upland shrubs and grasses 3.Measure water savings -- difficult 4.Model water savings (e.g. GSFLOW) 5.Demonstration Projects Colorado River near CO/UT border Canyon de Chelly, AZ CWCB Tamarisk Mapping for Colorado 2006 Close-up of flowers Courtesy of Dr. Phil Westra, CSU Other Impacts Wildfires Rio Grande in Albuquerque 4/2002 Purgatoire River east of Trinidad, CO Sedimentation Water value $/ac-ft Always senior, even in extreme drought Value of water lost by Tamarisk ?? Almost always senior, except in a drought Water Rights Available for Purchase Normal water year Usually called, except in wet years Always called, except in extremely wet years Water rights Seniority Water Market Value, Seniority, & Availability Question: What is the value of water Preserved in the groundwater & surface water systems ? Climate Change INVASIVES ?? Courtesy of Fred Nibling, US Bureau of Reclamation or Natives?? Near Garden City, Kansas