Scientific Investigations Report 2007–5102
U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5102
The Granger Drain and DR2 basins are located in south central Washington State. The study area is bounded on the south by the Yakima River and Snipes Mountain and on the north by the Rattlesnake Hills (fig. 1). Granger Drain basin includes about 62 mi2, and the DR2 basin, nested within the Granger Drain basin, has a drainage area of 2.1 mi2 (fig. 1). Because the region lies in the rain shadow east of the Cascade Mountains, it receives about 7 in. of precipitation per year (Western Regional Climate Center, 2005). The city of Granger, a community of about 2,500 people, is in the southwest part of the basin. Agriculture is the primary economic activity in these basins. The area was selected for this study because environmental conditions and agricultural practices are similar to other parts of the lower Yakima River basin.
The defining physical and cultural features in Granger Drain basin include two major highways, numerous rural agricultural roads, a railroad, the city of Granger, one minor and two major canals, and dozens of irrigation distribution laterals and agricultural drains. Interstate 82 runs east-west through Granger Drain basin and effectively divides it, resulting in a steep, narrow strip south of the interstate which includes Snipes Mountain and a vastly larger northern area, which constitutes most of the Granger Drain basin. Parallel to and north of the interstate highway is a lightly-traveled spur to the main railroad and the Yakima Valley Highway (an important local east-west county road), and Granger Drain, an agricultural drain providing the only surface-water outlet from the basin. Paved and unpaved rural roads are located mostly on section and quarter section lines and run north-south and east-west through the basin. The small community of Outlook is located in the southeast corner. The city of Sunnyside is about 2 mi east of the basin and the city of Zillah is just outside the western boundary.
Two large canals cross the Granger Drain basin from west to east: the Roza Canal to the north and the Sunnyside Canal to the south. Water delivered to farms in the Granger Drain basin eventually drains to Granger Drain by surface and groundwater flow, which enters the Yakima River downstream of the city of Granger.
The Granger Drain basin is bounded on the north by the Rattlesnake Hills and the south by Snipes Mountain (fig. 2). The eastern and western divides are marked by well defined ridges in the uplands and poorly defined, low rises in the valley bottom. Excepting the north-facing slope of Snipes Mountain, most of the Granger Drain basin slopes to the south. The entire basin slopes gently to the southwest. Land surface elevation ranges from 740 ft in the valley bottom to 3,020 ft along the divide in the Rattlesnake Hills. Maximum elevation along Snipes Mountain is 1,300 ft. The Granger Drain basin is characterized by generally flat, agricultural land. In the cultivated portion of Granger Drain basin, the median land slope is 3.1 percent with an interquartile range of 1.8 percent to 5.7 percent.
Elevations in the DR2 basin range from 745 ft along DR2 drain in the south to 850 ft along the Sunnyside Canal in the north. Median land slope is 2.3 percent with an interquartile range of 1.1 to 4.5 percent. The upper part of the DR2 basin is dissected by north-northeast trending ridges. Up-slope, to the north-northeast, the ridges grade into the smooth alluvial apron in the central part of the basin. Down-slope, to the south-southwest, the ridges taper to a rounded point that gently slopes down to the valley bottom. The ridges are of modest relief, averaging 10–20 ft above the adjacent low lands.
Regionally, the Granger Drain basin lies in the Yakima fold belt near the western margin of the Columbia Plateau physiographic province. In this area, Miocene-aged basalts of the Columbia River Basalt Group have been folded into east-west trending synclinal basins and anticlinal ridges. Thick deposits of alluvium, fluvial deposits, debris flows, and loess have accumulated along the margin of and between the rising ridges. These deposits are largely unconsolidated; however, beds of moderately to highly indurated material are exposed throughout the area. For brevity, further references to these deposits in this text will describe them simply as “unconsolidated” to contrast them with the underlying basalt rock.
Geology of the Granger Drain basin is interpreted from 1:100,000 scale geologic maps produced by the Washington State Department of Natural Resources (Schuster, 1994). The Granger Drain basin is in a structural basin bounded on the north by the Rattlesnake Hills and on the south by Snipes Mountain (fig. 3). Basalts of the Saddle Mountains Basalt Formation outcrop on both of these ridges and are believed to underlie the unconsolidated surficial deposits in the basin. The maximum thickness of the unconsolidated sediments is uncertain, but is known to exceed 300 ft based on well logs. Interpolation from nearby surficial outcrops and wells indicates a likely depth of approximately 650 ft. The unconsolidated sediments fall into four broad groups. The oldest are assigned to the Ellensburg Formation, which in this area are Miocene-age lahars and sands and gravels deposited by the ancestral Columbia River, Yakima River, and tributaries. Overlying these are Pleistocene to Quaternary-aged alluvial fan deposits shed from the rising ridges and large areas of loess. These deposits are spatially heterogeneous and discontinuous. Blanketing the entire basin at an elevation below approximately 1,000 ft is a sequence of alternating fine sand and silt deposited by the Late Pleistocene Missoula Floods (Bretz, 1930; Waitt, 1984). A thin veneer of Quaternary-aged loess overlies the Missoula Flood silts in isolated areas.
Geology of the DR2 basin was determined from nearby outcrops, cores collected from wells drilled for this study, and well logs from existing wells. As in the Granger Drain basin, the Ellensburg Formation underlies the entire DR2 basin. When encountered in wells constructed for this study, the Ellensburg formation is notably coarser than overlying material, consisting of medium to coarse sand interbedded with thinner layers of silt and gravel. Overlying the Ellensburg Formation is the Pleistocene to Quaternary-aged alluvial fan and loess material previously described, which occurs as 15 to 30 ft of geographically heterogeneous clay- to gravel-sized material. The upper 10–30 ft are the Late Pleistocene Flood Silts. Approximately 25 to 35 flood sequences are present in the study area. Sequences are between 10 and 25 in. thick and typically contain a 0.25- to 5-in. thick basal deposit of silty sand capped by 8–20 in. of clayey silt to very fine sand. Observations of nearby exposures indicate the flood deposits in the study area likely are dissected by vertical to sub-vertical planar clastic dikes.
Identification of soil types in the Granger Drain and DR2 basins (fig. 4) were based on field mapping data contained within the Soil Survey Geographic (SSURGO) database. SSURGO is the most detailed level of soil mapping done by the Natural Resources Conservation Service (NRCS) (U.S. Department of Agriculture, 2005). The soils found within the basin were formed in alluvium, eolian sand, lake sediment, loess, and residuum derived from basalt and sandstone. Most of the soils are well drained. The soils are sandy to clayey in texture and are very shallow (surface to 10 in.) to very deep (surface to 60 in.). In irrigated areas, the soils are nearly level to strongly sloping and moderately steep to steep in the non‑irrigated areas.
In the Granger Drain basin, 29 generalized soil series are present (fig. 4). Many of these generalized series are composed of 2–4 slope-defined phases (table 1). Of the 29 soil series, 2 represent over 50 percent of the basin. The remaining 27 soil series individually account for no more than 6.89 percent of the basin. The most abundant soil type is the Warden silt loam series with 5 slope-defined phases ranging from 0 to 30 percent slopes. The most dominant Warden phase is the 2 to 5 percent slope phase, which accounts for 22 percent of the basin. In total, the Warden silt loam series accounts for 41 percent of the Granger Drain basin.
In the DR2 basin, 87 percent of the basin is composed of the Warden series. The Warden silt loams are very deep, well drained soils on terraces. Warden soils were formed in lacustrine sediment and have a mantle of loess. Typically, the surface layer is a brown silt loam about 5 in. thick and the subsoil is a pale brown silt loam about 14 in. thick. The substratum extends to a depth of 60 in. or more and is a light gray to pale brown stratified silt loam, loam, and very fine sandy loam. In some areas the surface layer is fine sandy loam. Permeability of the Warden series is moderate and available water capacity is high. Runoff for the Warden series is slow and the water erosion hazard is slight. The Warden series generally is used for irrigated field and orchard crops and generally has very few limitations in terms of crops and irrigation methods below 8 percent slopes. In irrigated areas with slopes greater than 8 percent, runoff and erosion can be a problem. A plowpan can develop in this soil, but can be broken by chiseling or subsoiling when the soil is dry.
The Esquatzel silt loam accounts for 8 percent of the DR2 basin and has two slope-defined phases: 0–2 percent and 2–5 percent. The Esquatzel silt loam is a very deep, well drained soil usually located on flood plains and is dissected by intermittent and perennial streams. Typically, the surface layer is a brown silt loam about 17 in. thick. The surface layer can be a fine sandy loam, stratified with thin lenses of sandy loam or very gravelly loamy sand to a depth of 36 in. or more. The surface layer is underlain by a more pale brown silt loam to a depth of 60 in. Permeability of this soil is moderate and available water capacity is high. Runoff potential for the Esquatzel series is low.
The Outlook silt loam accounts for 5 percent of the DR2 basin and is a very deep, artificially drained soil usually located on flood plains. The Outlook silt loam has a slope of 0 to 3 percent. Typically, the surface layer is a very dark brown, very dark grayish brown and dark grayish brown silt loam about 8 in. thick and has a yellowish brown or dark yellowish brown mottling. It is strongly alkaline. The subsoil is a grayish brown, mottled silt loam about 10 in. thick. The substratum to a depth of 60 in. or more is dark brown silt loam. The subsoil and substratum are moderately alkaline. Permeability of this soil is moderate and available water capacity is high. Runoff generally ponds and the hazard of water erosion is slight. This soil generally needs to be drained to be agriculturally productive.
Land use—Major land use activities in the Granger Drain and DR2 basins include irrigated agriculture, dairies, grazing on non-irrigated land, and limited urbanization (fig. 5). Based on field mapping conducted by U.S. Geological Survey (USGS) in 2003 and 2004 (table 2), the major crops within the Granger Drain basin consisted of alfalfa and other hays, asparagus, corn, hops, mint, pasture, juice grapes, wine grapes, and apple, pear, and cherry orchards. The DR2 basin contains a less diverse mixture of crops with most agricultural land dedicated to the production of corn, juice grapes, and pasture. Numerous dairies varying in size from a few hundred dairy cows to more than a thousand dairy cows operate within the Granger Drain and DR2 basins (Washington State Department of Ecology, 2005). The dairy industry substantially influences the crops grown in the basin as dairies require enormous amounts of corn and alfalfa for feed.
Crop maps were obtained for the 1992 growing season and some significant shifts in cropping patterns were noted in comparing the 1992 to the 2003-2004 data sets. In the Granger Drain basin, the largest change in crop type was a 24 percent increase in grapes and orchards. The increase in grape and orchard acreage was largely at the expense of asparagus, hops, and mint, which decreased 21 percent over the same period. Although it cannot be discerned from the 1992 data, large amounts of wine grapes and cherries also were planted in the decade between crop maps. In the DR2 basin, notable decreases in acreages of asparagus, hops and mint (26 percent) occurred between 1992 and 2003, although corn increased by 17 percent. Between 2003 and 2004, changes in crop type were much smaller. Both asparagus and squash decreased by 3.8 and 2.2 percent, respectively, while corn increased by 7.7 percent. The dairy and beef industries expanded rapidly in the past decade, resulting in an 83 percent increase in the number of dairy animals in the watershed from 1989 to 2000 (20,000 to 36,500) (Bohn, 2001). Most animals are maintained in confined lots or small pastures and do not range freely.
Chemical use—Agricultural chemical use within the Granger Drain and DR2 basins is difficult to determine because the state of Washington has no public record of how much agricultural chemicals are used on specific fields. Estimates of agricultural chemical applications were derived from county-level data compiled by the National Agricultural Statistics Service (NASS) Agricultural Chemical Use Database for the state of Washington (National Agricultural Statistics Service, 2005). After compiling chemical use for each crop type found within the Granger Drain basin, private and university agricultural extension crop consultants in the Yakima River basin reviewed and updated the chemical list and application rates. The data were reviewed one last time by crop and pesticide-use scientists at the Washington State Department of Agriculture. The list of potential pesticides and application rates in the DR2 basin is provided in table 3. It should be noted that this table contains a list of potentially used compounds and likely application rates. Given the limits of the data and this method, there is no way to know whether any particular field was treated or even if the pesticide was applied in the DR2 basin. Confidence can be gained in aggregated, basin-wide application estimates for a given chemical if (1) the crop is common in the basin, (2) the crop is grown by multiple farmers, and (3) the NASS-reported percentage of crop treated is high, for example, terbacil is applied to 70 percent of the mint in Yakima County. An additional degree of confidence was obtained if the chemical has been detected in recent water-quality data from Granger Drain and (or) DR2 basins. With varying degrees of confidence, the most abundantly applied fungicides in the DR2 basin in 2004 were sulfur, fenarimol, triflumizole, and myclobutanil; the most abundantly applied herbicides were EPTC, glyphosate, acetochlor, and metolachlor (all of which are commonly used on corn); and the most abundantly applied insecticides were petroleum distillates, disulfoton, chlorpyrifos and carbaryl.
As was the case with pesticide application information, detailed information about fertilizer applications in Granger Drain and DR2 basins does not exist. University extension publications (Washington State University, 1999) provide the best estimate of application rates for nitrogen, phosphorus, potassium, sulfur, and various micronutrients. Estimates are typically expressed as a range due to variations in natural soil fertility. In this part of the Yakima Valley, however, liquid and solid manure from local dairy operations is commonly used as a primary or supplemental source of nitrogen and phosphorus, particularly on fields planted in corn and the various types of grass hay used for cow feed, for example, matua, triticale, and sudan grass. Lagoon liquid, fresh solid, and composted solid manures vary widely in the ratios of nitrogen to phosphorus and in the forms of nitrogen. When used, manure is typically supplemented with a commercial fertilizer to achieve the desired nitrogen – phosphorus – potassium ratio, as well as any desired micronutrients.
USGS studies in the late 1980s demonstrated that Granger Drain was a source of nutrients and pesticides to the Yakima River (Rinella and others, 1999). Additional work in the late 1990s characterized the intra-annual variability of agricultural contaminants in Granger Drain and noted substantial decreases in suspended sediment and dichlorodiphenyltrichloroethane (DDT) and DDT metabolites compared to samples collected a decade earlier (Ebbert and Embrey, 2002; Ebbert and others, 2003; Fuhrer and others, 2004). Numerous agricultural chemicals and transformation products were identified in water samples collected from Granger Drain and DR2 basins in 1999 and 2000 (Ebbert and Embrey, 2002; Ebbert and others, 2003). During the 1999 and 2000 sampling, concentrations of total phosphorus ranged from 0.15 to 1.1 mg/L, with highest concentrations occurring during the irrigation season and typically associated with high concentrations of suspended sediment. Concentrations of dissolved nitrate ranged between 2 and 4 mg/L during the irrigation season and increased to about 6 mg/L after the irrigation season. Insecticides and herbicides and breakdown products detected in Granger Drain and DR2 basins, in order of detection frequency included: atrazine (100 percent), carbaryl (100 percent), deethylatrazine (100 percent), p,p’-DDE (96 percent), trifluralin (88 percent), simazine (83 percent), azinphos-methyl (79 percent), acetochlor (54 percent), terbacil (54 percent), malathion (38 percent), diazinon (25 percent), tebuthiuron (8 percent), cyanazine (4 percent), dieldrin (4 percent), and metolachlor (4 percent) (Ebbert and Embrey, 2002; Ebbert and others, 2003).
Population in the Granger Drain basin is concentrated in the southern and southwestern areas with approximately 68 people per square kilometer (fig. 6). The DR2 basin has a population density ranging from 11 to approximately 40 people per square kilometer (fig. 6). The southeastern part of the basin has a population density of approximately 40 people per square kilometer, and the remaining central and northern parts of the basins contain less than 30 people per square kilometer. In the town of Granger, the only urbanized area in the Granger Drain basin, population increased by nearly 500 people in the past decade and reached 2,500 people in 2000 (fig. 7). The rest of the population resides in rural areas.
The climate of the Granger Drain basin is characterized by hot, dry summers and cold winters with limited snow and rain. The nearest long-term weather station is located 10.75 mi east of the city of Granger at the Sunnyside airport. This site is part of the Western Regional Climate Center network of weather stations that are funded and administered by the United States National Oceanic and Atmospheric Administration (NOAA). Data for this station is available online at http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?wasunn (accessed December 7, 2005) (fig. 8). For the period of record, 1948-2004, the average minimum temperature was 39.4°F and the average maximum temperature was 65.5°F (fig. 8). The warmest months are July and August with average monthly high temperatures of 89.7 and 88.5°F, respectively, and average monthly lows of 55.8 and 54.2°F, respectively. The coldest months are December and January with average monthly high temperatures of 40.6 and 39.6°F, respectively, and average monthly lows of 25.9 and 23.9°F, respectively. Mean temperatures for most months during 2004 were slightly higher than temperatures during the past 56 years.
For 1948–2004, the average annual precipitation was 7.27 in. ( fig. 9A ). More than 50 percent of precipitation occurs between November and March ( fig. 9B ). Snowfall is common in December and January and averaged 9.85 in. per year over the period of record. July and August usually are the driest months, and the area typically receives less than 0.25 in. of rain per month during those months. It is not unusual for several weeks to pass in the summer without a trace of precipitation. The driest year during the 56-year period was in 1999 when a scant 1.33 in. of precipitation fell at the Sunnyside weather station. The wettest year was in 1995 when 12.92 in. of precipitation were recorded. In 2004, June and August were unusually wet and received nearly 1.5 in. each month. January, February, and October were slightly wetter than normal, while November was atypically dry. Total precipitation for 2004 was 8.7 in., nearly 1.5 in. greater than normal.
Prior to agricultural development in 1893, Granger Drain basin was covered with “sagebrush and smaller desert shrubs” like other low-lying areas of the lower Yakima River Valley (Waring, 1913). Historical documents provide no indication of flowing or standing water in the Granger area. Mapped ephemeral streams in the Granger Drain basin terminate near what is now the Roza canal. Referencing soil maps published in 1901, Waring (1913) reported that “alkali was present in objectionable amounts at the surface in only a few places.” Depth to water near Sunnyside in the 1890s exceeded 40 ft. With the construction of Sunnyside Canal from 1890 to 1907 and the resultant expanding agricultural development, there was a rapid rise in the water table by 1906. This, compounded by an underdeveloped drain system, had rendered large tracts of land in the lower elevations of Granger Drain basin unsuitable for agriculture by turning the area into seasonal wetlands or concentrating alkali in the soils (United States Reclamation Service, 1912). To prevent further loss of agricultural land and in an attempt to return damaged areas to production, the Bureau of Reclamation constructed Granger Drain and connected, deepened, and widened major tributary drains, including DR2. Further agricultural development was made possible by the construction of Roza Canal from 1941 to 1950. The modern surface-water and shallow ground-water systems are entirely a result of irrigated agriculture.
Canals and delivery laterals operated by the Roza Irrigation District (RID) and Sunnyside Valley Irrigation District (SVID) as part of the Bureau of Reclamation Yakima Project serve irrigated land in the Granger Drain and DR2 basins (fig. 10). In a typical year, irrigation water is available to the farmers around March 15 and becomes unavailable around October 15. Unusually drier or wetter weather may affect the start and end dates of the irrigation season. Jointly, the Roza and Sunnyside Canals convey between 2,000 and 2,500 ft3/s during the height of the irrigation season. An estimated 20 to 25 percent of this water is delivered to farmers in Granger Drain basin. On average, each farmer takes delivery of 3–4 acre feet per acre of cultivated land per growing season. A network estimated at 13.8 mi of surface drains and 26.9 mi of subsurface drains conveys used irrigation water and end-of-system “spill” resulting from normal irrigation water delivery operations to Granger Drain and back to the Yakima River (Morace and others, 1999; Bohn, 2001).
The main stem of Granger Drain runs parallel to Interstate 82 and Yakima Valley Highway. It begins one-quarter mile west of the community of Outlook and extends westward to the city of Granger. In Granger, the drain turns southwest, passes through the town, and discharges into the Yakima River. Five significant drains enter Granger Drain from the north. Among these is the DR2 drain that joins Granger Drain approximately halfway between the communities of Granger and Outlook. Granger Drain and the lower reaches of these five tributary drains intercept the water table and, as a result, flow year-round.
Discharge data for the Granger Drain is collected at a stream gaging station located near the western city limits of Granger. For the period of record (2000–03), total annual discharge from Granger Drain ranged from 9,310 to 14,700 ft3, with a mean of 12,300 ft3 (fig. 11). Flow in Granger Drain is higher during the summer irrigation season and lower during the winter non-irrigation season (fig. 12). During the irrigation season, monthly average flows in the Granger Drain ranged between 34 and 52 ft3/s. Streamflows during the non-irrigation season dropped to monthly average flows between 18.2 and 20.7 ft3/s. Daily mean streamflow exceeded 64 ft3/s only 5 percent of the time and was greater than 16 ft3/s at least 95 percent of the time (table 4).
Discharge data for the DR2 Drain were collected from a gaging station located about 400 feet upstream from the confluence with Granger Drain. Daily mean flows within the DR2 Drain ranged between 2.6 to 10 ft3/s with a mean of 5 ft3/s (fig. 12 ). As in the Granger Drain, flows within the DR2 Drain were higher during the summer irrigation and lower during the winter non-irrigation season. Monthly average flows during the irrigation season ranged from 4.3 to 7.6 ft3/s, while non-irrigation season flows ranged between 2.7 and 4 ft3/s. Daily mean streamflow exceeded 8 ft3/s only 5 percent of the time and was greater than 2.7 ft3/s at least 95 percent of the time (table 4 ).r>
The ground-water system in the Granger Drain basin consists of a surficial unconfined to semi-confined aquifer composed of the unconsolidated surficial deposits described in the Geology and Stratigraphy section of this report. This aquifer is bounded on the bottom, north, and south by basalts of the Columbia River Basalt Group. Basalt aquifers underlying the surficial aquifer are believed to be isolated from the surficial aquifer and stream systems. A dramatic drop in head between deep wells in surficial deposits and the basalt reinforce this conceptual model. The remaining discussion focuses on the surficial aquifer.
Recharge to the surficial aquifer is largely the result of applied irrigation water, with a much smaller amount resulting from winter precipitation (Vaccaro and Olsen 2007), Ground-water movement is generally from the Rattlesnake Hills in the north toward the Yakima River in the south based on water levels observed in wells within and adjacent to the basin (fig. 13). Flow to the Yakima River is blocked by Snipes Mountain. Deep water in the surficial aquifer probably circumvents the obstruction to the east near Sunnyside and to the west near Granger based on local geology (fig. 14).
Since the onset of irrigation in the 1890s, the water table in the Granger Drain basin has risen and in the lower elevations is within inches of the land surface. The magnitude of the rise remains uncertain, but is likely at least 40 ft based on water levels recorded near Sunnyside during the early period of development (Waring, 1913). An extensive artificial drainage network developed to control the water table and prevent alkali accumulation and water logged soils. The configuration of the water table is now strongly controlled by the elevations of tile drains and the streambed elevations along Granger Drain and major tributaries.
Within the DR2 subbasin, excess irrigation water that is not taken up by evapotranspiration infiltrates downward through a 5- to 25-ft thick unsaturated zone in the northern part of the DR2 subbasin. Once the water reaches the water table it moves laterally from north to south in a direction roughly parallel to the surface-water-drainage network. Upward vertical hydraulic gradients in the lower parts of the DR2 subbasin provide ground-water seepage that supply the DR2 and Granger Drains with base flow. The presence of Snipes Mountain to the south probably forces deeper ground-water moving from north to south to upwell near Granger Drain.
Superimposed on the north-south oriented system just described is a series of short, local, east-west trending flow systems. These originate along the crests and flanks of the north-south trending ridges that dissect the northern part of the DR2 basin. Ground water moves obliquely to the south down the sides of these ridges until it encounters the regional water table or an agricultural drain.
In the Granger Drain basin, local climate, including extremes, has relatively little effect on the hydrology and agricultural activities in the area. The greatest effect on the local hydrology and farming community comes from the accumulation of snow pack in the Cascade Mountains. Extended deficiencies of snow pack result in water shortages and crop failures in the Granger Drain basin. A significant drought in 1977 prompted many farmers to reevaluate the types of crops being grown and the methods being used for irrigation (Fuhrer and others, 2004). More recently, 1992–94, 2001, and 2004 were notable for significant shortages of irrigation water.
U.S. Department of the Interior | U.S. Geological Survey
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