Let's match each modification to its effect on the ecosystem:
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Many desert regions in the West were transformed into lush urban areas and farmlands.
- This modification can be associated with the construction of large highways because urban development often follows the establishment of transportation infrastructure, leading to the transformation of desert landscapes into urban areas and agriculture.
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Water bodies in the Owens Valley and its surrounding areas began to dry up.
- This effect is directly linked to the construction of the Los Angeles aqueduct as it diverted water from Owens Valley to supply the growing demands of Los Angeles, leading to the drying up of local water bodies.
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Runoff containing disease-carrying organisms contaminated soil and caused water pollution.
- This statement can pertain to construction of large highways as well, where increased runoff from impervious surfaces (like highways and urban areas) can lead to contamination of soil and water bodies.
While there could be some overlap, the most direct matches based on the context provided would be:
- Many desert regions in the West were transformed into lush urban areas and farmlands. → Construction of large highways
- Water bodies in the Owens Valley and its surrounding areas began to dry up. → Construction of the Los Angeles aqueduct
- Runoff containing disease-carrying organisms contaminated soil and caused water pollution. → Construction of large highways (as highway construction can lead to increased runoff and pollution).