UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D .C ., 20460 

### MAR 2 6 2015

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES
MEMORANDUM SUBJECT :

FROM:

THRU:

TO : 

### Estimates of Crop Irrigation for Endothall Regis tratio n (DP# 426243)

Derek Berwald, Economist Economic Analysis Branch Biological and Economic Analysis Division (7503P) · Timothy Kiely, Chief 

# Q

# l~ Economic Analysis Branch 

## \J ) lM. Biological and E conomic Analysis Division ( 3P)

Garland Waleko, Chemical Review Manager Risk Management and Implementation Branch 2 Pesticide Re-evaluation Division (7508P)

Product Review Panel:


### . March, 11,2015

1Summary As part of a dietary risk assessment for Registration Review of endothall, OPP's Health Effects Division is evaluating potential risks from exposure to endothall from irrigat ion water. This memo provides estimates for the percentage of crops that may be exposed to endotha ll that EPA is reasonably certain will not be exceeded. For crops that may be exposed to endothall by irrigation water, the maximum percent that could be exposed is the share of production of that crop from irr igated land. This document provide s est imates ofthe percent of various <.:•)mmouities that cou ld be exposed to endothall v ia ir rigation water. The commodities in this memo were chosen by the Health Effects Division. These estimates of the percentage ofthe commodities that may be exposed to endothall in irrigation water in this document are unlikely to be exceeded. In addition to the commodities in this memo, endothall can be applied directly to potatoes and cotto n , but they are not discuss ed here. EPA used two methods t o est imate percent crop irrigated , which were combined to make the final est imates shown in Table 1. The preferred method , used where data on irrigated production are ava ilable , is an estimate of the share of total production that is irrigated. Esti mates from this method are pro v ided for barley , com, dry edible beans, oats, peanuts , rice , sorghum , soybeans, sugarbeets, sugarcane , and wheat, shown in Table 2. Where data on irrigated production are not availab le, EPA estimated the percent crop irrigated by determining the percentage of United States pro duction of a crop that is grown in 17 western states where endothall may be used, s hown in Table 3. The 17 western states are Arizona, Californi a, Colorado , Idaho , Kansas, Montana, Nebraska, Nevada, New Mexico , North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington , and Wyoming. These states are the states where large scale water projects predominate , and where other chemicals are used in canals for weed control. These ty pes of irrigati o n projects are relatively rare in other patts of the country. Use ofthese estimates in the exposure assessment i s conservative, because it is the equivalent of assum ing l 00% of irrigated crops are irrigated with water from endothall-treated canals

. In fact, even in areas with surface water deliv ery systems, all irrigation canals may not be treated with endot hall, and even if they are, may only be treated periodica ll y . Eve n in the heavily irrigated areas of the West , some crops, such as dryland grains, are not irrigated. Some irrigated production is irrigated directly from wells, rather than from water transported in surface canals. The final column of Table 1 shows BEAD 's estimates of the maximum share of crops that may be treated with endothall, using the estimates from Table 2 based on irrigation data when availab le

. or using the state production estimates from T able 3 when necessary.

2Table 1. Estimated Percent Crop Treated with Endothall for Dietary Risk Assessment Estimated Share of Percent Crop Share of Production Treated for Irrigated in the Dietary Risk Production West 1 Assessmen t Apple n/a 78% 78% Fresh market n/a 84% 84% Processing n/a 49% 49% Juice n/a 22% 22% Canned n/a 55% 55% Barley for grain 40% 40% Corn for grain 21% 21% Dry Beans 35% 35% Grape n/a 97% 97% Fresh market n/a 99% 99% Processing n/a 96% 96% Green Peas n/a 42% 42% Oats for grain 8% 8% Peanut for nuts 34% 34% Rice 100% 100% Sorghum for grain 19% 19% Soybean for beans 12% 12% Strawberry n/a 92% 92% Fresh market n/a 90% 90% Processing n/a 100% 100% Sugarbeetforsugar 37% 37% Sugarcane for sugar 54% 54% Watermelon n/a 38% 38% Wheat for grain 13% 13% Source: USDA 2015a, 2015b, 2015c, 2014, EPA calculations. ! Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, and Wyoming. Estimates are only provided for ce rtain crops.



### 3Background Endothall is an herbicide registered for control of plants in water bodies. Normal methods for es t imating th e percent crop treate d for a pestic ide are inappropriate in this case, because t h e pesticide is not directly ap p li ed to the crop. Pote nt ia l exposure occurs via irri gation water , excep t for potatoes and cotton, where the chemical can be applied directl y to the crop. Most of the water that goes through a canal to irrigate crops w ill not be treated. Instead, e ndo thall is periodically injected into irrigati on water to keep weed populations down. Becau se the w ater in the canal is rapidly turned over, after severa l hours mo st if not all of the endothall will no longer be in the canal systems. Furthermore, much production can receive water that is not delivered from surface water cana l s.
Method for Estim ating Percent Commodity Treated For so me crops , the estimates in thi s memo are ba sed on yield and acreage data fo r irrigated and non - irTiga t ed crops from the 20 1 2 Census of Agriculture (U SDA 2014). The estimates provided w ill be an upper bound on the percentage of crop s that may have been irri gated with water from ca nals that were treated with endothall, because some of the irrigated c rops are not grown in areas where endothall is u sed nor irrigated with su rf ace water. Other crops that are importa nt to the dietary risk assessme nt do not have data on irrigated and non-irrigated production available

. For these crops, this memo provides estimates of the amount o f the crop grown in 17 western states where endothall use is expected. These are states where s ubstantial amounts of water are transported through o pen canai systems to be used for irrigation. It is these sy stems where weed control is important and endot hall exposure is more likely. Other states do not have large scale irrigation projects that transport water through surface canals.
Estimates from the 2012 Census of Agriculture For select crops, the 2012 Census of Agriculture (USDA 20 14) provides estimates of the acres and y ield f rom farms with irrigation, farms without irrigation, and farms where some of the crop is ir rigated. T his information is us e d to estimate maximum share of production that could have bee n ex posed to irrigation water. Using this information we pro vide estim ates of the share of production irrigated for those crops where the data are avai lable. These crops are barley, com , dry edible beans , oats, peanuts for nut s, rice , sorghum, soybeans, sugarbeets , sugarcane, and wheat. Table 2 shows the estimated percent of the commodity that has been irrigated for the food crops f or w hich data are availab le. To estimate the production from the irri gated acres , the first step is to esti mate the crop p roduction fro m irri gated land. U si ng the data in Table 2 , the irrigated yield is m ul tip lied by the irrigate d acreage, w hich is the acreage from farms where the entire crop is irrig ated plus the irrigated acreage from partially irrigated farms. To get an estimate of the share o f the crop irrigated , this is divided by an estimate oftotal production. To estimate total

4production from the informati on in Table 2, the yield is multiplied by the acreage for each type of farm, and these are added together. Taking wheat as an examp le, estimated production from irrigated fam1land is (2,064,900 acres + 1,303,265 acres) x 81.8 bushel s/acre= 275,5 15 ,897 bushels, which is the numerator for our percentage calcula tion. T otal estimated production is 2,064 ,900 acres x 81.8 bushels/acre+ (1 ,3 03 ,265 acres + 3,549,686 acres) x 43.0 bushels per acre+ 42,122,375 acres x 42.9 bushels per ac re = 2, 184 , 635,601 bushels. Dividing estimates for production from irrigated land by the estimate of total production yields an estimate of the share of production that has been irrigated, in this case 13%. The estimates for all the food crops with available data in the census are in the last column of Table 2. Note that the data available in the Census of Agriculture only provide s overall yield for farms where only part of the crop is irrigated, although it does provide total production and irrigated and dryland acreage data. For this analysis , B EAD assumed the yield from the irrigated acreage on partially irrigated farms to be equal to the average yield per acre from irrigated farms. In addition the implied yields for the non-irrigated portion of partly irrigated farms are lower than non-irrigated farms

. with the exception of peanuts and sugarbeets. This is further evidence that this method tends to provide conservative estimates. The se es t imates are based on only one year of data , but they are similar to estimates from 2012, based on 2007 data (EPA 20 12 )

. However, it is unlikely that the amount of acreage irrigated will change a large amount from one year t o the next, because irrigation equipment is an expensive cap ital investment. I n so me cases, weather cond itions may cause water availability to change, which may cause growers to change irrigation decisions.

ote that these are estimates of the amount of the crop irrigated, not the amount of the crop that may have endothall residues. Not all ofthe crop that is irrigated will be g rown in areas where endotha ll is likely to be used , and even in the We st, where e ndothall use for irrigation is expected, not all systems will necessarily be using endothall. Therefore, B EAD i s reasonably certain the share of crops that are actually exposed to endothall will no t exceed the estimates of irrigated acreage in Tabl e 2.

5-able 2

. Share of Crop Production Irriga ted



## - -· Entire crop i rrigated Part of crop i rrigat ed None o f c rop i r rigated EPA Ave r age Est imated

Yield Acres Acres not Average Averag e S h a re of Per Yield Yield Per Pro du c tion :rop F arms Acres Acre Farms irrigated i rr igated Per Acre Farms Acres Acre Irr i gated• lar l ey for grain (bushels) 3,892 692,023 100.7 765 159,670 211,532 58.1 14,010 2,220,680 55.8 40% :orn for grain (bushels) 20,040 6,202,712 171.1 21,211 6,616,357 6,947,141 129.4 307,279 67,646,835 111.1 21% )ry edible beans, excluding Iimas (cwt) 2,758 429,218 22.8 226 44,288 50,983 18.5 3,912 1,118,308 17.8 34% )ats for grain (bushels) 905 51,076 87.1 356 8,056 15,311 66.2 33 ,777 1,004,255 5 9.4 8% >eanuts for nuts (polllnds) 1,239 304,922 4,362.0 1,262 216, 75 1 265,710 4,347.7 4,060 834,248 3,875

. 1 34% \ice (cwt) 5,591 2,693,759 74.3 

## - - - - - - 100% ;o rghum for grain (bu sh e l s) 1,848 377,68 1 80.7 1,617 248,725 499,499 56.3 1 6 ,5 72 4,016,194 47.7 19% ;oyb ea ns for bean s (bu sh e l s) 8,124 2,978,353 49.4 16,246 4,1 79,061 4,691, 518 41.0 278, 593 64,255,848 37 .6 12% ;ugarbe et s for suga r (tons) 1,436 394,5 8 8 32.8 50 7 ,2 09 24,771 28.2 2,427 822,913 26 .2 37% ;ugarcane for sugar (ton s) 195 N/A 3 5 .7 21 N/A N/A 35.1 4 50 401,816 34.7 54%b Nheat for grain, a ll ( b ushels) 8,520 2,064,900 81.8 6,766 1,303,26 5 3,549,686 43.0 132,346 42,122,375 42.9 13% ;ource: USDA 2014 and EPA Calculations Assumes irrigated acres on farms where only part of the crop is irrig ated obtain t h e same yield as acres on farms where the enti re crop is irrigated Some data on acreage for suga rcane were not released by USDA, as shown i n the table. However, using the total production of sugarcane for sugar repo rted in USDA 2015X (30,500 housand tons) and subtract ing off the non - irr i gated production in this tab l e (401,816 acres x 34.7 thousand tons = 13,943 t h o us an d tons) l eaves yields tota l product io n f r om irr i gated and >artially irri gated farms of 16,577 tons , or 54% of total production.

6Crop Estimates for Other Dietary Crops of Concern End othall residue s o n some crops for which irri gatio n data are not available are of pa rticular concern to EPA based on residue trial s and dietary hab its. Thes e crops are peas , watermelon, strawbe rries, apples , and grapes . For these crops BEAD provides estimates of the proportion of the crop that is grown in the 17 western states (Arizo na, California, Colorado, Idaho, Kansas, Mo ntana, N ebraska , Nevada, New Mexico , North Dakota, Oklahoma, Oregon , South Dakota, Texas , Uta h, Washington, and Wyoming), which are the states that are potential users of endothall in irri gation water (Table 3). According to the Farm and Ranch Irrigation Su rve y (USDA 2004 ) , almost 70% of the irrigated acreage in

. the United States i s in the 17 western states, and about 87 % of the irrigation water appli ed to crops is in thes e western sta tes, which co rrespond to the states se rved by Bur eau of Reclamation water projects. In the West larg e scale water delivery systems are important to agriculture ; these are the systems that may use endothall fo r irrigation. Agriculture in the East, where it is less arid , does not require large sca le water trans fe rs , a lthough end othall may be used for drainage systems and water bodies. The share of the crop grown in the 17 western s tate s can be used as a crude measure of the share of the crop that may come in contact with endothall. T hese estimates are the best that can be made with the available data, and they likel y overestim ate the crop that wi ll enco unter endothall treated water becau se not all production in the western states will be irrigated wi th water from canal s th a t have b een treated with endothall. Not a ll irrigation sys tems use endothall , so me crop p rod uction is irrigated w ith wells that do not require weed control , and some crops such as wheat and oats may be farmed without irrigation , even in the arid West
. As an example of the degree to which this method can overestimate potential exposure to endothall , recall that the data on irri gated production showed that an estimated 13 % of whea t is irrigated. Using the share of production in the 17 western states indic ates that up to 78% (not shown in Table 3) of wheat could have potentially been exposed to endothall. T hi s is an example where a majority o f production i s in th e W est, but relatively little wheat is irrigated

. Whe re available, estimates of the crop grown in the 17 western states are provided for different e nd-uses ofthe particular crop. This information can be useful for dietary risk es timates , which are based on consumpt io n of specific food products. The estimate s of the amount grown in the 17 western states are p ro v ided in Tab le 3. 

### Peas Only two western states are important producers of g reen peas f or pro cess ing , whi ch can appear in baby foods

. In 2012, abo u t 128,000 tons were produced in Washington State, and about 41 ,000 tons in Oregon. Pr od uctio n in these two states was about 42% of US pro duct ion of ab out 407.000 tons (USDA 20 15a).

7Wat erm e lon Four western states produce enough watermelon to show up in the USDA data, Arizona, California , Oklahoma, and Texas. California and Texas produced about 6,800 , 000 cwt. and 5,400 ,000 cwt
. in 2012, respectively

. Arizona produced abaout 1,200,000 cwt., and Oklahoma on ly produced about 348,000 cwt
. Together, the almost 13,700 ,000 cwt. ofwatermelon repre s ented about 38% ofUS production of about 36,200,000 cwt. in 20 1 2 (USDA 2015a)

. Str a wb e rries Cali fornia is the major strawberry producing state in the United States. In 2012, Californi a produced abo ut 2 7 , 600 , 000 cwt. of strawb erries, and Oregon anoth e r 213,000 cwt., and Was hin gton about 103,000 cwt. Together, the three states pro duc e about 92% of the total US strawberr ies. Abou t 90% of the fresh market strawberries come f r om the western states of Californ ia, Was hi ngton and Oregon, and almost all the processing s trawberrie s come from the sam e thre e states, acco unting fo r almost all strawberries used fo r processing (U SDA 20 15b )

. App le Availab le data o n apple production covers the production for the western states of Arizona, Ca li fornia , Idaho, Oregon , Utah , and Washington , with Washington being by far the largest producer. Combi ned these states accounted for about 78% oftotal US ap ple production in 20 12 , with over 72 % of the total coming from Washington alone (USDA 20 1 5b). The west has a much larger share o f fresh apple production (84%) than it does wi th apples used fo r processing; less than half o f proc e ssing apples come from the western states. Grapes California was the larges t producer of grapes in 2012, acco untin g for a lmost 9 1% of total .production. T he 17 western states combined accounted for abo ut 97% of total production. Looking a t the end u ses of th ese grapes, the picture i s s imilar. About 99% of fres h grapes were f rom the western states in 2012 , and about 96% of the processed g rape s (USDA 20 15b)

.



### 8Table 3

. Share of Production of Specific Crops in the 17 Western States, 2012 Weste rn States Western Crop US Production Production States Share Green Peas (Tons) 407,250 1 69,040 42% Waterme l on ( 1 ,000 cwt.) 36,153 13 , 726 38% Strawberries ( 1 ,000 cwt

. ) 30,520 27 , 962 92% Fresh Market 24,552 21,995 90% Processing 5,968 5 , 967 1 00% Apple (Million Pounds) 8,927 6,961 78% Fresh Market 6,595 5,539 84% Processing 2,332 1 , 152

. 49% Juice 749 164 22% Canned 1 , 112 610 55% Grapes (Tons) 7,524,443 7,287,450 97% Fresh Ma r ket 962,983 957,150 99% Processing 6 , 56 1 ,460 6,330,300 96% Source: USDA 2015a, 2015b, 2015c, EPA Calculations The 17 Western states a r e Arizona, California, Colorado, Idaho, Kansas, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma , Oregon, S

o uth Dakota, Texas, Utah, Washington, and Wyoming.



### 9References

EPA 2012

. Berwald, Derek and Bill Phillips II. Updated Estimates of Percent Commodity Exposed to Endothall via Irrigation (DP# 369862, 369863). Nove mb er 19 , 2012. USDA 2004. US Department of Agriculture, National Agricultural Statistics Service, The Census ofAgriculture, Farm and Ranch Irrigation Survey (2003) Volume 3, Special Studies Part 1 . November 2004. Available here : http: //www.agcensus.usda. gov /Publications/2002/FRIS!index.asp USDA 20 15a. US Department of Agriculture, National Agricultural Statistics Service, Vegetables 2014 Summary. January 2015

. Available here: http: // usda.mannlib .cornell.edu/usd alcurrentNegeSumrn!Vege Summ-01-29-2015 .pdf USDA 2015b

. US Department of Agriculture , National Agricultural Statistics Service, Noncit rus Fruits and N uts 2014 Preliminary Summary. January 2015

. Available here: http: // usda.mannlib.cornell.edu/usdalc urrent/No ncFrui Nu/NoncFruiNu

- 01

- 23

- 2015

.pdf USDA 20 15c. US Depart ment of Agriculture, National Agricultural Statistics Serv ice, Crop Production 20 14 Summary

. January 2015. Available here : http:/ /usda.mannlib.cornell.edu/usda/curre nt /CropProdSu/CropProdSu-0 1-12- 20 15_revisio n. pdf USDA 2014

. US Department ofAgricu lture, 2012 Census of Agriculture: United S tates Summary and Sta te Data Vo lume: 1, Geographic Area Series, Part 51. May 2014, Tab le 36. Available here: http:/ /www . agcensus .usda

.gov/Publications/2012/Full

_ Report/Volume

_ l , _ C hapter

_ l

_ U S/usvl.pdf

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