4 from Half-Full to Half-Empty: the Hydraulic Mission and Water Overexploitation in the Lerma–Chapala Basin, Mexico

4 From Half-full to Half-empty: the Hydraulic Mission and Water Overexploitation in the Lerma–Chapala Basin, Mexico Philippus Wester,1* Eric Mollard,2** Paula Silva-Ochoa3*** and Sergio Vargas-Velázquez4**** 1Irrigation and Water Engineering Group, Center for Water and Climate, Wageningen University, Wageningen, The Netherlands; 2Centre IRD, Montpellier, France; 3CH2MHILL, Water Business Group, San Diego, California, USA; 4Barrio del Sumidero Lote 6 Mz 22, Fracc. Las Fincas, CP 62565 Jiutepec, Morelos, México; e-mails: *[email protected]; **[email protected]; ***[email protected]; ****[email protected] Introduction downstream lake into which the Lerma River flows, nearly fell dry, losing more than 80% of This chapter portrays the river basin trajectory its volume on both occasions. Between 2003 of the Lerma–Chapala basin in central Mexico. and 2008 above-average rainfall lessened the It analyses the relationship between basin surface water crisis, with Lake Chapala recov- closure and the hydraulic mission, defined as ering to above 80% of its storage capacity in the strong conviction that the state should September 2008, the highest level since 1979. develop hydraulic infrastructure to capture as While years of abundant rainfall can temporar- much water as possible for human uses (Wester, ily stop the overexploitation of surface water, 2008). In particular, it focuses on the role of the long-term consequences of water pollution the hydrocracy (hydraulic bureaucracy) in the and groundwater overexploitation are more creation of water overexploitation in the dramatic and difficult to reverse. Tackling these basin. three water crises requires addressing their The Lerma–Chapala basin is in serious trou- interlinkages and the social mechanisms and ble, with water use at unsustainable levels and institutional arrangements that govern water severe water pollution. Since the late 1970s, use. groundwater overexploitation has led to The Lerma–Chapala basin provides a strik- sustained declines in aquifer levels of 2 m/year ing example of the complexities of water on average, while surface water depletion has reforms in closed river basins, where consump- been close to, or has exceeded, annual river tive water use is close to, or even exceeds, the runoff in all but the wettest years. This was level of renewable water availability (Keller et made possible by the drawing down of water al., 1996; Seckler, 1996). It is a basin in which stored in lakes and reservoirs. Twice in the 20th many of the policy prescriptions emphasized in century (in 1955 and 2002), Lake Chapala, the international water debates, such as irrigation © CAB International 2009. River Basin Trajectories: Societies, Environments and Development (eds Molle and Wester) 75 76 P. Wester et al. management transfer (IMT) (Gorriz et al., basin crosses five states (Querétaro, covering 1995; Rap, 2006), integrated river basin 5% of the basin, Guanajuato (44%), Michoacán management (IRBM) (Mestre, 1997; Wester et (28%), México (10%) and Jalisco (13%)) and al., 2003) and increasing stakeholder partici- covers around 55,000 km2, nearly 3% of pation in water management have been Mexico’s land area. Although the average applied. Owing to the important economic and annual runoff in the basin of 5513 Mm3 social interests linked to water in the densely (DOF, 2003) is only 1% of Mexico’s total populated and economically important Lerma– runoff, the basin is the source of water for 15% Chapala basin, it has served as a water policy of Mexico’s population (11 million in the basin testing ground for successive Mexican govern- and 2 million each in neighbouring Guadalajara ments. Starting in the early 1990s, the federal and Mexico City). Located in central Mexico, government has enacted far-reaching water the basin is an important agricultural and indus- reforms (decentralization, participatory organi- trial area, containing around 13% of the area zations, a new water law in 1992), accompa- equipped for irrigation in the country and nied by substantial funding for water treatment generating 9% of Mexico’s gross national plants, support to water organizations, water- product (Wester et al., 2005). saving programmes and public-awareness Irrigated agriculture, covering some campaigns. However, these efforts have not 795,000 ha, is the main water user in the reversed environmental degradation in the basin. Eight irrigation districts (formerly state basin nor led to a reduction in water use, and managed) cover around 285,000 ha, while the three water crises remain dramatic today. some 16,000 farmer-managed or private irri- This chapter explores why this is so, primarily gation systems (termed ‘irrigation units’ in focusing on surface water. Mexico) cover 510,000 ha. Twenty-seven The next section introduces the basin and reservoirs provide 235,000 ha in the irrigation describes the process of basin closure. The districts with surface water, while around 1500 following three sections provide a broad over- smaller reservoirs serve 180,000 ha in the irri- view of the trajectory of the Lerma–Chapala gation units. An estimated 17,500 tube-wells basin, focusing on three periods (1500–1910, provide around 380,000 ha in the basin with 1911–1980 and 1981 to the present). For groundwater, of which 47,000 ha are located each period, an analysis of the history of water in irrigation districts (CNA/MW, 1999). The development and the concomitant transforma- area actually irrigated between 1980 and 2001 tions in terms of water control and manage- is a matter of debate, with estimates ranging ment are given. Conclusions are then drawn. from 628,000 ha (CNA/MW, 1999) to more than a million ha (INE, 2003) per year. Lake Chapala, with a length of 77 km and The Main Water Challenges in the a maximum width of 23 km, is Mexico’s larg- Lerma–Chapala Basin est natural lake. At maximum capacity the lake stores 8125 Mm3 and covers an area of 1154 Physical setting of the Lerma–Chapala basin km2 (Guzmán, 2003:110). When full, the average depth of the lake is 7.2 m, making it one The Lerma–Chapala basin is named after the of the world’s largest shallow lakes. The shal- Lerma River and the lake into which this river low depth of the lake results in the loss of a drains, Lake Chapala (see Fig. 4.1). When full, large percentage of its storage to evaporation Lake Chapala discharges into the Santiago each year, with net evaporation of around 600 River, which flows in a north-westerly direc- Mm3 per year. Lake Chapala is highly valued tion, to meet the Pacific after some 520 km. by the inhabitants of Jalisco state, where the Since the early 1980s, very little water has lake is situated, as well as by some 30,000 flowed naturally from Lake Chapala to the foreigners (mostly American retirees) living on Santiago River, due to dropping lake levels, its shores, and is a prime tourist destination. In and the Lerma–Chapala basin has, in effect, addition, it provides Guadalajara, Mexico’s become a hydrologically closed basin. Lying second largest city, with 65% of its water between Mexico City and Guadalajara, the supply. The Lerma–Chapala Basin, Mexico 77 Fig. 4.1. States and rivers in the Lerma–Chapala basin. Water overexploitation and Basin Closure on Water Reforms and Water Transfers discusses how the lake fared after 2002. Since the early 1980s, surface water and Starting in 1945, water storage in the lake groundwater in the basin have been overex- declined sharply, from an average of 6429 ploited. Although average rainfall from 1990 Mm3 between 1935 and 1945 to 954 Mm3 in to 2001 (679 mm) was only 6% below the July 1955, due to a prolonged drought historical average (722 mm) (IMTA, 2002a), combined with significant abstractions (750 the amount of water depleted in the basin Mm3 per year on average) from the lake for exceeded annual renewable water during this hydroelectricity generation and irrigation (de P. period, with no allocations for environmental Sandoval, 1994). During this period, around flows. This was made possible by lowering the 214,000 ha were irrigated in the basin, mainly interannual stock of water stored in the basin’s with surface water, and the constructed storage lakes, reservoirs and aquifers. Groundwater capacity in the basin was 1628 Mm3. However, was overexploited, with declines in static aqui- because of good rains towards the end of the fer levels of 1–5 m per year due to an esti- 1950s, the lake recuperated, and storage aver- mated annual groundwater deficit of 1336 aged 7094 Mm3 from 1959 to 1979. Mm3 (IMTA, 2002a), while the consumptive In 1980, a second period of decline set in. use of surface water exceeded supply in all but By this time, constructed storage capacity in the wettest years, nearly leading to the demise the basin had increased to 4499 Mm3 and the of Lake Chapala. Figure 4.2 presents the fluc- average irrigated area had grown to around tuations in Lake Chapala’s volume from 1934 680,000 ha, with a significant increase in to 2002, while Table 4.1 relates these fluctua- groundwater irrigation. Although abstractions tions to developments in the basin. The section from the lake for hydropower generation had 78 P. Wester et al. Fig. 4.2. Monthly Lake Chapala storage volumes and average inflows from 1934 to 2002. Table 4.1. Overview of key water indicators in the Lerma–Chapala basin. Original Dry Wet Normal Latest Period (1934–1944) (1945–1957) (1958–1978) (1979–1988) (1989–2001) Rainfall (mm/year)a 683 626 764 705 679 Inflow to Lake Chapala 2,485 1,085 2,127 429 677 (Mm3/year)b Inhabitants (thousands of 2,500 3,000 4,500 8,700 11,000 people)c (1940) (1950) (1970) (1990) (2000) Irrigated area (ha)d 155,000 214,000 508,000 675,000 689,000 Sources: ade P.

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