Section 6 Supplement 1

Projected Irrigation Water Needs and Economic Feasibility of Meeting Projected Irrigation Water Needs

South Central Texas Region

Introduction

Texas Water Development Board (TWDB) Rules, Section 357.7(5)(A) specify that Regional Water Management Plans "…shall meet all needs for the water use categories of municipal, manufacturing, irrigation, steam-electric power generation, mining, and livestock watering except: (A) plans may identify those needs for which no water management strategy is feasible. Full evaluation of water management strategies must be presented and reasons given for why no water management strategies are feasible; or (B)…”[1] The purposes of this report are to present: (1) estimates of projected irrigation water needs of the South Central Texas Region (Region L), and (2) information about the economic feasibility of meeting the projected irrigation water needs.

Irrigation Water Needs

The TWDB's estimates of irrigation water use in the 21-county South Central Texas Region was 669,440 acft/yr in 1990, with projected irrigation water demands in 2030 of 563,513 acft/yr, and in 2050 of 516,244 acft/yr.[2] A comparison of projected irrigation demands with available irrigation supplies for each of the counties of the region shows that 14 counties do not have an irrigation water need, with 7 counties showing an irrigation water need (Table A). The total of the projected irrigation needs for these 7 counties, with adjustments for water conservation in 2030 are 289,743 acft/yr, and in 2050 are 251,550 acft/yr (Table A).[3] Estimated additional irrigation conservation is 28,903 acft/yr (Table A and Demand Reduction [L-10] Water Management Strategy).[4]

Economic Feasibility of Meeting Projected Irrigation
Water Needs of South Central Texas Region

The concept or expression of economic feasibility to be used in this analysis is based upon estimated income per acre-foot of water used in irrigation that remains after all other irrigation production expenses have been met (e.g., net return to water at the irrigation farm, on the surface of the land, at the point from which the water is distributed to the crops being irrigated). For example, in the South Central Texas Region for the case of irrigation using groundwater, this is net return per acre-foot of water at the land surface where the irrigation well is located. In the case of irrigation using surface water, the net income data needed are for the land surface location on the irrigation farm where water is or would be diverted from delivery canals or pipelines to be distributed to the crops being irrigated.

The reason for the form of net income to irrigation water expressed above is that information is available in the form of Crop Enterprise Budgets of the "costs and returns" from irrigation of individual crops in the South Central Texas Region.[5] These Crop Enterprise Budgets were developed using representative crop yields, production practices, and irrigation applications of the region. These budges take into account the gross income, the quantity of water applied per acre, and all of the costs of production, including pumping costs to lift water from the aquifer to the surface of the land, costs to move the water from the well and distribute it to the crops, hired labor, seed, fertilizer, fungicides, insecticides, pesticide application, harvesting, transportation, insurance, fuel, lubrication, interest on capital, machinery depreciation and maintenance, administration, and a charge for land use. Thus, by deleting from the Crop Enterprise Budgets, the cost of pumping water (pump fuel and maintenance, amortized well drilling, pump, and motor costs) one can see the net returns from the water used for irrigation, as of the location from which it is distributed to the crops.

Net income computations have been made for crops that are irrigated in the South Central Texas Region, including: corn, cotton, grain sorghum, guar, peanuts, sesame, wheat, beets, cantaloupes, carrots, cucumbers, cabbage, lettuce, onions, and spinach (Table B). For example, in the case of corn for food, the yield is 115 bushels per acre and gross income is $373.75 per acre (Table B). The quantity of water used per acre is 1.42 acft (17 inches) (Table B cont). Variable costs per acre are $234.20 and fixed costs are $112.98, for a total cost of $347.18 per acre (Table B). Net income to pay for water from the production of corn for food is $26.57 per acre, and $18.71 per acft of water used for irrigation (Table B cont). That is to say, that for 1997 price and cost conditions, the most that an irrigation farmer of the South Central Texas Region could afford to pay for water delivered to his present well locations for use in producing corn for food is $18.71 per acft.

The estimated net returns to water for other irrigated crops of the region are shown in Table B and range from a loss of $75.80 for lettuce to a positive net return of $782.80 for onions.

Although costs have not been computed for water management strategies that would deliver water to the locations of irrigation water needs in the South Central Texas Region, costs were calculated for water management strategies that are indicative of strategies which would provide meaningful quantities of water that could be considered to meet irrigation needs. These include (1) raw water at new reservoirs, (2) Edwards Recharge—raw water in the aquifer, and (3) Carrizo Aquifer water pumped and delivered to the major municipal demand center. These costs of raw water, which is judged to be suitable for irrigation of crops grown in the region, range from $390 per acft to $764 per acft (Table B, Page 2, Box in Lower Right Corner and Figure 1). When compared to net returns to water, as described above, of all the crops produced in the region only one crop—onions—could afford any of this water (Table B cont). In addition, the costs of raw water shown in Table B cont are only a portion of the total costs to develop and convey this water from reservoirs and/or the Carrizo Aquifer to the irrigation farms of the South Central Texas Region. For example, the costs shown in Table B cont do not include conveyance costs to the farms from the reservoirs and Carrizo wells. Thus, it is clear that it is not economically feasible to meet the projected irrigation needs of the South Central Texas Region, since the net income to pay for water is less than the costs of water at the sources without including the conveyance costs from the sources to the farms (Table B cont).

Third party impacts of water shortages for all water user groups, including irrigated agriculture, were computed by TWDB for the SCTRWPG (Tables 4-24 through 4-28). The SCTRWPG has recognized the importance of both direct and third party impacts of irrigation water shortages, and has recommended an irrigation technology center, expanded water data and research programs, and major emphasis be placed upon in-depth socio-economic analyses of water shortages in the next water planning cycle (see Section 6).

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[1] Regional Water Planning Areas and Special Water Resources, Adopted Rules for: Regional Water Planning Grants, Regional Water Planning Guidelines, State Water Planning Guidelines, and Initial Coordinating Body Representatives, Texas Water Development Board, Austin, Texas, March 11, 1998.

[2] South Central Texas Region Water Management Plan, Task 1 and Task 2, Interim Report, SCTRWPG, San Antonio, Texas, August 1999.

[3] South Central Texas Region Water Management Plan, Water Supplies and Water Needs by Water User Group, Task 3 and Task 4, Interim Report, SCTRWPG, San Antonio, Texas, February 2000.

[4] Water conservation in addition to that included in the irrigation water demand projections.

[5] "Texas Crop Enterprise Budgets," Southwest Texas District, Texas Agricultural Extension Service, B-1241 (C10), Texas A&M University System, College Station, Texas, 1997.