Until the 1930s, flows of the Colorado River maintained approximately 781,060 hectares of wetlands in its delta. These wetlands provided important feeding and nesting grounds for resident and migratory birds as well as spawning and protection habitat for many fish and other invertebrate species. However, the Delta's wetlands started to disappear as water was used for agricultural and urban uses in the United States and Mexico. The 1944 United States-Mexico water treaty, which allocates 1.8 million m��/year to Mexico, did not define a minimum flow to maintain the Delta's ecosystems. The resulting degraded Delta lead to the perception in the 1980s that the Delta was a dead ecosystem. This study investigates whether this "dead Delta" perception is valid. Its central hypothesis is that regenerated vegetation in riparian and flood plain zones is associated with surplus river flows during the 1990s. A vegetation analysis, using satellite imagery and field methods, shows that native trees have regenerated during the last 20 years, and now account for 23% of vegetation in a 100 km, non-perennial, stretch of river below the United States-Mexico border. A spatial trend analysis using multi-temporal data on percent vegetation cover indicates that there are 6,320 hectares that show a significant increasing trend (p-value<0.05) in vegetation cover, with the Delta's riparian zone having at least 18% of its area showing this trend. The study estimates that once in four years February to April flow of 300 million m�� (at 80-120 m��/s) is sufficient to germinate and establish new cohorts of native trees, and highlights the need for smaller but more periodic flows in order to maintain wetland areas. It is concluded that there is clear evidence of the resilience of the Delta's ecosystems and that the "dead Delta" perception is no longer valid. There exist critical habitat in the Delta that needs to be protected, while there also exist short and long term opportunities to ecologically enhance and expand current habitat. Hydrological and ecological studies are needed to estimate specific water requirements for these areas in order to efficiently target them for immediate and long term conservation actions. / Graduation date: 2003

Thesis (Ph. D. - Geosciences)--University of Arizona, 1987. / Includes bibliographical references (leaves 321-348).

Thesis (M.S. - Geosciences)--University of Arizona. / Includes bibliographical references.

Thesis (Ph.D.)--University of Rhode Island, 2008. / Includes bibliographical references (leaves 230-244).

Ecosystem services and goods are non-market values that are increasingly being accounted through contingent valuation methods and more specifically by studying people’s willingness-to-pay for them. Large ecosystem restoration is an area that benefits from economic valuation because placing a monetary value proves that restoration efforts are justified to preserve resources for future generations, wanted by a community, and even a profitable investment of public funds. However, what determines that a community supports and understands restoration efforts is linked to their social, economic, cultural, and geographic reality. In this study I adopted the idea of willingness-to-pay to examine people’s attitudes towards river flow restoration efforts in the Colorado River Delta. The Colorado River Delta is a resilient ecosystem that has endured severe river flow depravation for more than 70 years now; yet, this ecosystem still provides many environmental services and goods and its restoration is well justified for that. This research mainly reveals that the Colorado River Delta is still an undervalued ecosystem despite its resiliency and the many regional benefits it still provides. This study has two research questions. Fist, I determined what factors influence Mexicali’s willingness-to-pay. Second, I compared willingness-to-pay attitudes between the cities of Mexicali and San Luis Rio Colorado (SLRC); two neighboring Mexican cities of different size and economic structure but of similar social, ecologic and geographical conditions. The instrument to collect field data was a survey that posed a realistic river flow restoration scenario at a range of prices from 10 to 90 pesos in order to test people’s willingness-to-pay; a total of 564 surveys were delivered face to face in Mexicali. Subsequently, I compared Mexicali survey results with a previous SLRC survey. Descriptive statistics, non-parametric analysis, and qualitative analysis were the main instruments to arrive to my conclusions. Within Mexicali, I found that parenthood and the perception of received benefits from the river were the most significant factors that determined people’s willingness-to-pay. Migration was also a salient socio-demographic factor that probably has an influence on people’s attitudes towards river flow restoration. When making comparisons between cities I found that SLRC is more willing to pay than Mexicali, which confirmed my hypothesis that environmental awareness influences willingness-to-pay in each city given that SLRC is a true river city while Mexicali is 64 km away from the river. Pricing was also influential in both cities. People’s exposure to the river varied from one city to the other –SLRC people have more interactions with the river than people from Mexicali do, thus matching again the difference in willingness-to-pay attitudes of each city. Although income, education, frequency of visits, and awareness of dry river conditions were expected to have a clear connection to willingness-to-pay within Mexicali, I found only a marginal statistical relationship that was very close to be significant. This was due to the fact that I analyzed the dependency of those variables for all prices and not at a specific price range where the actual average willingness-to-pay resides. Finding that average and then analyzing the relationships again should clarify this issue. What motivates people to pay was related to resource conservation and the recognition of the river’s ecological importance. What motivates people to not pay relates to negative attitudes such as incredulity and lack of trust in Mexican institutions. My main recommendations are to raise local environmental awareness of river issues with environmental education, to address local negative attitudes towards river restoration, and to explore the analysis of these data with other approaches such as socio-psychological models.

Ecosystem services and goods are non-market values that are increasingly being accounted through contingent valuation methods and more specifically by studying people’s willingness-to-pay for them. Large ecosystem restoration is an area that benefits from economic valuation because placing a monetary value proves that restoration efforts are justified to preserve resources for future generations, wanted by a community, and even a profitable investment of public funds. However, what determines that a community supports and understands restoration efforts is linked to their social, economic, cultural, and geographic reality. In this study I adopted the idea of willingness-to-pay to examine people’s attitudes towards river flow restoration efforts in the Colorado River Delta. The Colorado River Delta is a resilient ecosystem that has endured severe river flow depravation for more than 70 years now; yet, this ecosystem still provides many environmental services and goods and its restoration is well justified for that. This research mainly reveals that the Colorado River Delta is still an undervalued ecosystem despite its resiliency and the many regional benefits it still provides. This study has two research questions. Fist, I determined what factors influence Mexicali’s willingness-to-pay. Second, I compared willingness-to-pay attitudes between the cities of Mexicali and San Luis Rio Colorado (SLRC); two neighboring Mexican cities of different size and economic structure but of similar social, ecologic and geographical conditions. The instrument to collect field data was a survey that posed a realistic river flow restoration scenario at a range of prices from 10 to 90 pesos in order to test people’s willingness-to-pay; a total of 564 surveys were delivered face to face in Mexicali. Subsequently, I compared Mexicali survey results with a previous SLRC survey. Descriptive statistics, non-parametric analysis, and qualitative analysis were the main instruments to arrive to my conclusions. Within Mexicali, I found that parenthood and the perception of received benefits from the river were the most significant factors that determined people’s willingness-to-pay. Migration was also a salient socio-demographic factor that probably has an influence on people’s attitudes towards river flow restoration. When making comparisons between cities I found that SLRC is more willing to pay than Mexicali, which confirmed my hypothesis that environmental awareness influences willingness-to-pay in each city given that SLRC is a true river city while Mexicali is 64 km away from the river. Pricing was also influential in both cities. People’s exposure to the river varied from one city to the other –SLRC people have more interactions with the river than people from Mexicali do, thus matching again the difference in willingness-to-pay attitudes of each city. Although income, education, frequency of visits, and awareness of dry river conditions were expected to have a clear connection to willingness-to-pay within Mexicali, I found only a marginal statistical relationship that was very close to be significant. This was due to the fact that I analyzed the dependency of those variables for all prices and not at a specific price range where the actual average willingness-to-pay resides. Finding that average and then analyzing the relationships again should clarify this issue. What motivates people to pay was related to resource conservation and the recognition of the river’s ecological importance. What motivates people to not pay relates to negative attitudes such as incredulity and lack of trust in Mexican institutions. My main recommendations are to raise local environmental awareness of river issues with environmental education, to address local negative attitudes towards river restoration, and to explore the analysis of these data with other approaches such as socio-psychological models.

Thesis (M.S.)--University of Waterloo. / Includes bibliographical references.

In arid lands, wetland loss is the result not only of the scarcity of water itself, but of the management of water to maximize off-stream uses. Declaring a wetland as a protected natural area is not enough when its water supply is not protected as well. In a fully-diverted, over-allocated, drought-prone Colorado River ecosystem, its delta has no instream flows allocated. Water use efficiency (WUE) is touted as the panacea for water shortages and lack of instream flows. I evaluated the relationships between water use in the Mexicali Irrigation District and the water supply for the Colorado River delta wetlands. The survey applied to 521 farmers complemented the GIS analysis to create a spatial distribution of agronomic and socio-economic factors influencing farmers’ options to improve WUE in irrigation. Mexicali farmers apply 10,496 m³/ha/yr; 4% higher than the legal allotment. Still, 28% of the district’s soils are salt-affected (ECe > 8dS/m), 19% are sodic (ESP > 50%), and 39% of the salt load in irrigation water accumulates in the soils. Thus, Mexicali farmers apply more water than plants need in order to maintain the sustainability of their soils. From an agronomic perspective, increasing WUE is feasible in 80% of the valley. However, high costs and lack of technical knowledge limit farmers’ options to either continue using as much water as they do now or rent/sell their water rights to larger farming operations or urban developments. Mexicali’s agriculture provides 87 Mm³ of water to the delta marshes, and seepage from unlined canals and subsurface flows generated by irrigation contribute to sustain riparian areas. Agricultural “inefficiencies” become the main source of water for wetlands when flows are fully diverted. The Irrigation District 014 is an integral part of the delta ecosystem; this is a required change in the agriculture-wetland paradigm. The restoration of arid and over-allocated rivers requires the integration of irrigation practices and WUE with the allocation of water for instream flows. The restoration of wetlands of international watersheds like the Colorado River requires the bi-national collaboration beyond memorandums of understanding between the countries; treaties where environmental flows are actually allocated will better serve shared ecosystems.