Biological Control of Giant Reed (Arundo donax): Economic Aspects

return to water of $273 per acre foot using market prices, and $259 per acre-foot using
normalized prices (Table 1).

Table 1. Per Acre Irrigated Crop Water Use Estimates and Returns per acre-foot: High-Value
and Low-Value Composite Acre, Lower Rio Grande Valley, 2008.

As illustrated in Table 1, the high-marginal value irrigated crops use approximately 1.40
acre-feet of water per composite acre, while the low-marginal value irrigated crops use
approximately 0.54 acre-feet of water per composite acre. The water use per acre for high-
versus low-value crops ultimately impacts the number of acres converted from dryland crops to
irrigated crops, with the addition of the water saved from the control of giant reed upstream.
Total Value of Water Saved

Based on 2009 dollars, the total value to the Rio Grande Valley of the water saved in
2009 using the low marginal-value irrigated crop composite acre is more than $173 thousand,
compared to $4.5 million for 2024 and $10.0 million in 2058, using market prices. Inflated at
2.043% and discounted at a rate of 6.125%, the net present value for 50 years (2009-2058) is
$100.4 million for the low-marginal value crops. Results for the high marginal-value crops were
similarly obtained, producing a total value of $249.1 thousand for 2009, $6.4 million for 2024,
and $15.7 million for 2058. When the sum total for 50 years (2009-2058) is inflated at 2.043%
and discounted at 6.125%, a net present value of $144.0 million is obtained. These results are
presented in Table 2.

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