EAGSA Managing groundwater sustainably for generations to come. Chapter 3. Basin Setting
1 3. Basin Setting
2 3.1 Hydrogeological Conceptual Model
3 A hydrogeological conceptual model (HCM) is a description of the physical system within a basin, 4 including (but not limited to) topography, geology and structure, three-dimensional geometry of water- 5 bearing units (aquifers) and aquitards, land and water use, hydrology, and groundwater quality. The HCM 6 provides a framework for understanding the interrelationships among these components, and their 7 influence on occurrence and movement of groundwater. The HCM can be used to develop numerical 8 modeling tools and water budgets, and to help inform decision making with respect to selection of 9 sustainable management criteria, monitoring networks, and potential management actions. An HCM 10 should be periodically reviewed and revised as new data become available. The following sections 11 describe the HCM of the Enterprise Subbasin.
12 The Enterprise Subbasin (5-006.04) is one of five groundwater subbasins within the RAGB of Northern 13 California (Figure 2-1). The roughly north/south-oriented subbasin is approximately 15 miles long and 14 8 miles wide. The Sacramento River forms the western/southwestern boundary of the subbasin; whereas, 15 Cow Creek forms the eastern boundary, and the Klamath Mountains form the northern boundary 16 (DWR, 2004).
17 3.1.1 Topography
18 Figure 3-1 presents the topography of the Enterprise Subbasin. The data presented on Figure 3-1 19 represent topographic data from a number of sources that were compiled into a single surface. These 20 data sources include the following: 21 • USGS 1/3-arcsecond (approximately 30-foot) digital elevation model data (USGS, 2019b) 22 • Light detection and ranging (Lidar) data collected as part of a Federal Emergency Management 23 Agency study of the Cow Creek drainage area; 2-foot resolution (USGS, 2018) 24 • High-resolution (3-foot) Lidar data collected as part of a collaborative effort between COR and Shasta 25 County (COR, 2019b)
26 Ground surface elevations across the Enterprise Subbasin vary by approximately 450 feet as the foothills 27 of the Klamath Mountains in the north descend to the trough of the Sacramento Valley in the south. The 28 maximum ground surface elevation in the Enterprise Subbasin, 825 feet above North American Vertical 29 Datum of 1988 (NAVD88), is in the foothills of the Klamath Mountains. Where these foothills have been 30 deeply incised by Stillwater Creek and Cow Creek, there is local relief in excess of 100 feet at high 31 grades. Farther south, surficial features transition from sandstone and mudstone deposits to alluvial 32 plains, terrace and channel deposits, and river-flood deposits. Topographic relief generally decreases 33 toward the Sacramento Valley, with a minimum ground surface elevation of approximately 372 feet 34 NAVD88 in the southernmost portion of the Enterprise Subbasin.
35 3.1.2 Climate
36 3.1.2.1 Precipitation
37 Figure 3-2 presents an isohyetal map of 1981–2010 mean annual precipitation for the Enterprise 38 Subbasin (PRISM Climate Group, 2012), showing that precipitation varies along a primarily north-south 39 trend in the Enterprise Subbasin. Based on these 30-year averages from Parameter-elevation 40 Regressions on Independent Slopes Model (PRISM) datasets, the foothills of the Klamath Mountains on 41 the northern periphery of the subbasin receive a mean annual precipitation of 51 inches, and the valley 42 floor on the southern periphery receives 30 inches per year (Figure 3-2). Mean annual precipitation is 43 greater outside the Enterprise Subbasin in the mountains to the north, west, and east. The Redding area
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44 receives about 84 percent of its precipitation in the autumn (35 percent) and winter (49 percent), with only 45 about 16 percent falling in the spring (14 percent) and summer (2 percent) (UCC, 2019a; Station 46 USR0000CREA).
47 Figure 3-3 presents a chart of water year type based on the Sacramento Valley Water Index (an 48 accounting of the volume and timing of unimpaired runoff at specific stream gauges in the Sacramento, 49 Feather, Yuba, and American Rivers) (DWR, 2020a). The water year index is computed as follows:
50 Sacramento Valley Water Year Index = 0.4 * Current April-July Runoff Forecast (in million-acre feet 51 [MAF]) + 0.3 * Current October-March Runoff in (MAF) + 0.3 * Previous Water Year’s Index
52 The computed water year index is used to classify the water year as one of the following: 53 Year Type Water Year Index 54 Wet Equal to or greater than 9.2 55 Above Normal Greater than 7.8, and less than 9.2 56 Below Normal Greater than 6.5, and equal to or less than 7.8 57 Dry Greater than 5.4, and equal to or less than 6.5 58 Critical Equal to or less than 5.4
59 The Redding area (included in the Sacramento Valley Water Year Index) had several notable wet years in 60 the early 1980s and in the late 1990s, interspersed by several critical water years in the late 1980s and 61 early 1990s. Prior to 1986, wet years were more frequent, and critical years were scarce. In the decades 62 since 1986, precipitation has become more inconsistent, with periods of drought interrupted by one or a 63 few very wet years. Furthermore, a recent increase in atmospheric river events is bringing more intense 64 storms to California, with total annual precipitation falling in fewer total storms (Swain et al., 2018).
65 3.1.2.2 Temperature
66 Within the Enterprise Subbasin, summers are hot and arid, and winters are cool and typically wet. Based 67 on data from weather stations at Shasta Dam and Whiskeytown Reservoir, the average annual high 68 temperature is approximately 73 degrees Fahrenheit (°F), ranging from a low of 53°F in January to a high 69 of 96°F in July. The average annual low temperature is approximately 51°F, ranging from a low of 38° in 70 January to a high of 66° in July (UCC, 2019b, 2019c; Stations USC00048135 and USC00049621).
71 3.1.2.3 Evapotranspiration
72 Reference evapotranspiration (ETo) in the Enterprise Subbasin has been calculated based on data 73 collected at California Irrigation Management Information System (CIMIS) Station 224 at Shasta College 74 between January 2013 and October 2019. The average annual ETo measured over the period of record is 75 55 inches per year, or 4.6 feet per year. The ETo values calculated from the CIMIS data indicate the 76 amount of water that could be transpired from a reference crop, such as grass or alfalfa if supplied by 77 irrigation. To calculate a specific crop evapotranspiration (ET) rate, the ETo is multiplied by a crop 78 coefficient that adjusts the water consumption for each specific crop relative to the water consumption of 79 the reference crop.
80 According to the State of California Reference Evapotranspiration Map developed by CIMIS, the 81 Enterprise Subbasin is located within Zone 14, with an annual average ETo of 57 inches, or 4.8 feet 82 (CIMIS, 2012). This regional average annual ETo is comparable to the ETo measured at CIMIS 83 Station 214.
84 3.1.3 Hydrology
85 Many streams cross the Enterprise Subbasin, generally flowing down from the foothills of the Klamath 86 and Cascade Mountains in the north, west, and east to confluences with the Sacramento River. The 87 Sacramento River is the largest and most significant hydrological feature in the subbasin (Figure 3-4).
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88 Data referenced in this section were sourced from USGS and the Sacramento River Watershed Program 89 (SRWP, 2020).
90 The Sacramento River is the largest river and watershed system in California, carrying 31 percent of the 91 state’s total surface-water runoff. Around 6,500 square miles of the 27,000-square-mile Sacramento River 92 watershed drain into the Enterprise Subbasin. Sourced from volcanic plateaus around 40 miles north of 93 the Enterprise Subbasin, its headwaters comprise the Upper Sacramento, McCloud, and Pit Rivers. After 94 being released from Shasta Dam, the Sacramento River flows south, making up the 95 western/southwestern boundary of the Enterprise Subbasin. The Sacramento River is gauged at Keswick 96 Reservoir, where the flow is controlled by releases from Shasta and Keswick Dams. Based on data from 97 this gauge (USGS #11370500, see Figure 2-11, USGS, 2019a) extending back to 1938, the annual 98 average flow in the Sacramento River at this location is approximately 10,000 cubic feet per second (cfs), 99 with peaks as high as 50,000 to 70,000 cfs in wet years and lows around 5,000 cfs during drought 100 periods.
101 Water from the Trinity River is imported to the Sacramento River watershed through diversions from 102 Lewiston Lake in Trinity County. Water from Lewiston Lake is conveyed via the Clear Creek Tunnel to the 103 Carr Powerhouse on Whiskeytown Lake in Shasta County. Several purveyors in Shasta County, including 104 COR, divert water from Whiskeytown Lake through contracts with Reclamation.
105 The eastern boundary of the Enterprise Subbasin coincides with Cow Creek. Cow Creek and the northern 106 fork of Little Cow Creek flow west out of the foothills of the Cascade Mountains, a 425-square-mile 107 watershed, and then south along the eastern edge of the Sacramento Valley. Cow Creek reaches a 108 confluence with the Sacramento River south of the Enterprise Subbasin, near the city of Anderson. Cow 109 Creek streamflow is monitored by USGS near the town of Millville with a record extending back to 1949 110 (USGS #11374000, see Figure 2-11, USGS, 2019a). Average annual flow in Cow Creek at this stream 111 gauge has been around 700 cfs, increasing to around 2,000 cfs during the wet months and decreasing to 112 less than 100 cfs during the summer months. However, Cow Creek is known to produce peak flood flows 113 upwards of 20,000 cfs during heavy storms, comprising up to 21 percent of the peak discharge for the 114 Sacramento River between Shasta Dam and Red Bluff.
115 Stillwater Creek flows southward along the north-south axis of the Enterprise Subbasin. It is a rainfall- 116 driven stream with a high degree of seasonal variability and rapid response to storm events. Its 117 watershed covers approximately 120 square miles and includes most of the area of the Enterprise 118 Subbasin. There are no gauges in Stillwater Creek, but 10-year peak flow has been estimated at 119 7,000 cfs (SRWP, 2020).
120 3.1.4 Regional Geologic Setting
121 The RAGB consists of 510 square miles in the northern Central Valley of California. It is bounded by the 122 foothills of the Cascade Range in the East, the Klamath Mountains in the north and northwest, the Coast 123 Ranges in the west, and the Red Bluff Arch in the south (Pierce, 1983). The Red Bluff Arch, a subsurface 124 structural feature, defines the boundary between the RAGB and the Sacramento Groundwater Basin to 125 the south. The area of the RAGB is an interior dissected plain, consisting of a sediment-filled, southward- 126 plunging, symmetrical trough, crossed by the valleys of the Sacramento River and of Churn Creek, Clear 127 Creek, Cottonwood Creek, and Stillwater Creek.
128 Tertiary deposition of material sourced from the Coast and Cascade Ranges created the principal 129 freshwater-bearing formations in the basin: the Tuscan and Tehama Formations. These formations are up 130 to 2,000 feet thick near the confluence of the Sacramento River and Cottonwood Creek and are 131 interbedded throughout the RAGB, with the Tuscan more prominent to the east and the Tehama more 132 prominent to the west. The Tuscan Formation is generally more permeable and productive than the 133 Tehama Formation (DWR, 2003).
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134 3.1.5 Local Geologic Setting
135 3.1.5.1 Surface Soils
136 Figure 3-5 presents the distribution of surface soils within the Enterprise Subbasin. Soils are derived from 137 the weathering of underlying geological units and are influenced by lithology as well as climate, biological 138 factors (vegetation, biota, human influences), topography, and hydrologic conditions. The United States 139 Department of Agriculture’s NRCS developed a hierarchical classification system consisting of 140 Order, Suborder, Great Group, Subgroup, Family, and Series. This classification system (or taxonomy) is 141 based on quantitative soil properties such as depth, moisture, temperature, texture, structure, cation 142 exchange capacity, base saturation, clay mineralogy, organic matter content, and salt content. The soil 143 distribution presented on Figure 3-5 categorizes surface soils based on taxonomic order. As shown on 144 Figure 3-5, 5 of the 12 NRCS taxonomic orders are present in the Enterprise Subbasin, as follows: 145 • Alfisols are present across approximately 80 percent of the subbasin. Alfisols are naturally fertile 146 soils, high in aluminum and iron, have clay rich horizons, and form in semi-arid to humid regions with 147 at least several months of vegetation grown throughout the year (sufficient moisture and warmth). 148 • Entisols are make up approximately 9 percent of the Enterprise Subbasin, primarily present adjacent 149 to surface streams and within stream floodplains. Entisols are young soils with no profile development 150 (that is, they have not been significantly altered from the parent material). 151 • Mollisols are present over approximately 4 percent of the Enterprise Subbasin, primarily in the 152 dissected highlands in the eastern portion of the subbasin and along Cow Creek. Mollisols are dark- 153 colored naturally fertile (high base nutrient content) soils with a deep, high organic content horizon, 154 typically derived from decaying root material. 155 • Inceptisols are present over approximately 3 percent of the Enterprise Subbasin, primarily along the 156 Cow Creek floodplain. Inceptisols are generally young soils, with limited soil profile development 157 (more developed than entisols). 158 • Ultisols are present over approximately 2 percent of the Enterprise Subbasin within stream channels. 159 Ultisols are highly weathered, acidic, clay-rich mineral soils with little base nutrients.
160 Regions of the subbasin classified as “other” on Figure 3-5 are primarily areas that have been mapped 161 as water.
162 3.1.5.2 Geologic Units
163 Figure 3-6a,b presents a geologic map of the RAGB, derived from the Digital Geologic Map of The 164 Redding 1° X 2° Degree Quadrangle, Shasta, Tehama, Humboldt, And Trinity Counties, California 165 (USGS, 2012). North-south and east-west trending cross sections are presented on Figures 3-7 and 3-8, 166 respectively. Geologic cross sections were developed based on available lithologic information with the 167 primary objective of displaying the water-bearing units within the subbasin. Because the level of detail 168 and consistency of historical lithologic logging varied greatly, units are presented on the cross section as 169 dominated by either finer- or coarser-grained materials. Lack of detailed lithologic information precludes 170 differentiating major geologic units in section view. Major geologic units underlying the Enterprise 171 Subbasin include (from oldest to youngest) the following:
172 Basement Complex (Various Units on Figure 3-6a,b)
173 The pre-Tertiary igneous and metamorphic basement complex is the oldest geologic unit underling the 174 Central Valley. The formations that make up the basement complex formed throughout the Devonian and 175 terminated during the Cretaceous with the inception of the Chico Formation. The basement complex 176 crops out along the steep slopes surrounding the RAGB, forming a nearly impermeable boundary for 177 groundwater. The basement complex is considered non-water bearing, yet scarce water is stored in joints 178 and fractures, permitting small well yields.
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179 Chico Formation (Kc on Figure 3-6a,b)
180 Unconformably overlying the basement complex is the Cretaceous Chico Formation. The Chico 181 Formation was deposited in a marine and shore zone environment, consisting of a variety of sedimentary 182 rocks—conglomerate, siltstone, sandstone, and shale. Although this formation is generally impermeable, 183 some beds yield small amounts of saline water. In certain places, this water may be under artesian 184 pressures, especially where shale beds are extensive. The thickness of the Chico Formation ranges from 185 zero feet in the northern RAGB to 6,000 feet to the south, forming the base of the southerly tilt of the 186 Central Valley. Because the Chico Formation contains connate water, the top of the Chico Formation 187 defines the base of fresh water in the RAGB.
188 Nomlaki Tuff (Ttn on Figure 3-6a,b)
189 The basal member of both the Tuscan and Tehama Formations is the Pliocene-age Nomlaki Tuff. 190 The Nomlaki Tuff unconformably overlies the Chico Formation and thickens to the east. The Nomlaki Tuff 191 is primarily of volcanic origin and consists of pumice fragments in a matrix of volcanic glass and minerals. 192 It is poorly consolidated and has been described by Pierce (1983) as one massive bed.
193 Tehama Formation (Tte on Figure 3-6a,b)
194 The Pliocene-age Tehama Formation consists of fluviatile silt, sand, gravel, and clay originating in the 195 Klamath Mountains and Coast Ranges. Sourced from the west, the Tehama Formation is most prominent 196 in the western portion of the RAGB and is interbedded with the Tuscan Formation in the central portion of 197 the RAGB. This unit crops out in the northern, northeastern, and eastern portion of the Enterprise 198 Subbasin, near Bella Vista, dipping and thickening to the south. The thickness of the Tehama Formation 199 is variable, from around 300 feet at the southwestern extent of the Enterprise Subbasin to around 200 1,000 feet at the confluence of Cow Creek and the Sacramento River (DWR, 2004). Permeability is 201 generally moderate to high with yields of 100 to 1,000 gallons per minute (gpm), making the Tehama 202 Formation one of the principle water-bearing formations in the RAGB (Pierce, 1983).
203 Tuscan Formation (Tt on Figure 3-6a,b)
204 The Pliocene-age Tuscan Formation consists of volcanic breccia, tuff-breccia, volcanic sandstone and 205 conglomerate, coarse- to fine-grained tuff, and tuffaceous silt and clay predominately derived from 206 andesitic and basaltic sources. The Tuscan Formation crops out east and south of the Enterprise 207 Subbasin, near Red Bluff; and much of the formation lies east of the Sacramento Valley under a volcanic 208 plateau of the Cascade Range. The Tuscan Formation dips to the southwest and thins from east to west. 209 The maximum thickness of the Tuscan Formation is 1,600 feet in the Cascade Range, thinning to about 210 1,000 feet near Chico, and farther to around 300 feet where it interfingers with the Tehama Formation in 211 the central portion of the RAGB (Pierce, 1983). Fresh water is found throughout the Tuscan Formation, 212 with a thick and impervious basalt flow separating it from the underlying and saline Chico Formation. It 213 contains moderately permeable beds at a range of depths, with lenticular clay beds resulting in locally 214 confined conditions. Yields are similar to that of the Tehama Formation—100 to 1,000 gpm (Pierce, 215 1983).
216 Red Bluff Formation (Qrb on Figure 3-6a,b)
217 Unconformably overlying the Tehama and Tuscan Formation is the Pleistocene-age Red Bluff Formation. 218 It is composed of coarse gravels and boulders in a matrix of reddish sand, silt, and clay. This formation is 219 discontinuous, with thicknesses ranging from 1 foot to 100 feet. The Red Bluff Formation typically lies 220 above the zone of saturation, but there are areas of perched water. Permeability generally ranges from 221 poor to moderate, and yields are small to moderate and sufficient for domestic wells (Pierce, 1983).
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222 Riverbank Formation (Qr on Figure 3-6a,b)
223 The Pleistocene-age Riverbank Formation is present as alluvial fan and terrace deposits along streams in 224 the RAGB. The unit consists of weathered reddish gravel, sand, and silt (USGS, 2012). The Riverbank 225 Formation reaches thicknesses of up to 50 feet in the Enterprise Subbasin (DWR, 2004).
226 Modesto Formation (Qm on Figure 3-6a,b)
227 The Pleistocene-age alluvial deposits of the Modesto Formation are primarily present along the 228 Sacramento River, Cottonwood Creek, and tributary floodplains in the RAGB. The unit consists of tan and 229 light-gray gravely sand, silt, and clay, except where derived from volcanic rocks of the Tuscan Formation, 230 where it is distinctly red and black with minor brown clasts (USGS, 2012). The Modesto Formation 231 reaches thicknesses of up to 50 feet in the Enterprise Subbasin (DWR, 2004).
232 Terrace Deposits (Qt on Figure 3-6a,b)
233 Composed of poorly consolidated silt, sand, and gravels, Holocene and Pleistocene-age terrace deposits 234 are found alongside the Sacramento River and its tributaries, specifically Cow and Cottonwood Creeks. 235 Thickness ranges from 1 to around 50 feet, and permeability is moderate to high (Pierce, 1983 and 236 DWR, 2004).
237 Alluvium and Overbank Deposits (Qa, Qao, Qo on Figure 3-6a,b)
238 Alluvium is found in channels and floodplains along the Sacramento River and its tributaries, and has 239 been described by Pierce (1983) as unconsolidated, interbedded, gravel, sand, silt, and clay. Permeability 240 is generally moderate but may be quite high in regions dominated by gravels. Some wells in the alluvium 241 have produced as much as 2,000 gpm, but many others produce only enough for domestic use.
242 3.1.5.3 Geologic Structures
243 Red Bluff Arch
244 A series of northeastward-trending anticlines and synclines located north of Red Bluff, the Red Bluff Arch 245 distinguishes the RAGB from the Sacramento Groundwater Basin. Data are insufficient to determine the 246 groundwater and surface-water relationship in the vicinity of the Red Bluff Arch; however, the effect of the 247 arch is hypothesized to force groundwater toward the surface to induce gaining streams (Pierce, 1983).
248 3.1.6 Local Hydrogeology
249 3.1.6.1 Lateral Basin Boundary
250 The RAGB is bounded by the foothills of the Cascade Range to the east, the Klamath Mountains to the 251 north and northwest, the Coast Range to the west, and the Red Bluff Arch to the south (Pierce, 1983). 252 Unlike the RAGB, the Enterprise Subbasin is not bounded by structural features, but rather by hydrologic 253 features. The Enterprise Subbasin is bounded by Little Cow Creek and Cow Creek to the east, and by the 254 Sacramento River to both the west and south. Because the lateral subbasin boundaries are defined by 255 surface streams, there is likely hydraulic communication between adjacent subbasins. That is, there may 256 be groundwater underflow into Enterprise Subbasin from adjacent subbasins and from the Enterprise 257 Subbasin into adjacent subbasins.
258 3.1.6.2 Definable Bottom of Basin
259 The base of fresh water defines the bottom of the basin. In the RAGB, this is the top of the Chico 260 Formation (Figure 3-9). Although water-bearing formations exist below this depth, the saline nature of the 261 groundwater and the depth to formation prevent the Chico Formation from being a viable aquifer. The top
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262 of the Chico Formation in the Enterprise Subbasin ranges from a depth of less than 100 feet in the north 263 to a depth of greater than 1,000 feet in the south (DWR, 1968).
264 3.1.6.3 Principle Aquifers and Aquitards
265 Major water supplies in the Enterprise Subbasin, and in the greater RAGB, are stored in surface 266 reservoirs; and as a result, the communities in the region are less dependent on groundwater. This may 267 contribute to the fact that groundwater elevations in the RAGB do not show evidence of continuous 268 decline (as will be discussed further in subsequent sections). Depths to groundwater are shallowest near 269 the Sacramento River and Cow Creek, and are generally within a few feet of land surface. In the more 270 central portions of Enterprise Subbasin, depths to groundwater range between 100 to 150 feet and 271 approach depths of nearly 200 feet in a few streams water bodies. Alluvial deposits have moderate to 272 high permeabilities in the subbasin, but deposits are not significant sources for groundwater use in the 273 subbasin because of the limited lateral and vertical extents. The Red Bluff Formation is generally present 274 above the regional water table; however, local perched zones may yield small quantities of water to 275 domestic wells (DWR, 1968, Pierce, 1983). The principle water-bearing formations in the Enterprise 276 Subbasin, the Tuscan and Tehama Formations, together function as one large, leaky unconfined aquifer 277 with increasing degrees of confinement with depth. Groundwater use of the principle aquifer is for urban, 278 industrial, and agricultural purposes, and is described in greater detail in Chapter 2. Due to the reliability 279 of surface-water storage and the readily available groundwater supply within the Tuscan and Tehama 280 aquifers, few resources have been dedicated to describing other aquifers within the RAGB. As shown on 281 Figures 3-7 and 3-8, although laterally discontinuous fine-grained lenses/beds are present within the 282 subbasin, there is no regional aquitard.
283 3.1.6.4 Aquifer Properties
284 Aquifer systems function as a combination of subsurface reservoirs for storage of groundwater and 285 conduits for the transmission of groundwater. The following sections describe the aquifer system 286 properties in the Enterprise Subbasin. The magnitude and distribution of hydrogeologic properties of the 287 principal aquifers in the subbasin have not been well characterized or documented. The scarcity of 288 available quantitative estimates of the aquifer properties of the subbasin’s principal aquifers results in 289 uncertainties that will be further refined during implementation of this GSP. This will be accomplished 290 through evaluation of hydraulic data collected during development of the new monitoring well and through 291 calibration of the numerical model being developed as part of this GSP.
292 Transmissivity and Hydraulic Conductivity
293 There are two general terms that are used to describe the capacity of an aquifer to transmit water, 294 hydraulic conductivity and transmissivity. Hydraulic conductivity is defined as the coefficient of 295 proportionality describing the rate at which a fluid can move through a permeable medium and is 296 dependent on the fluid density and fluid viscosity and the intrinsic permeability. Transmissivity is defined 297 as the capacity of an aquifer to transmit groundwater through a unit width of the aquifer under a unit 298 hydraulic gradient. Transmissivity is equal to the product of the hydraulic conductivity (which is reported in 299 units of feet per day [ft/day]) and saturated thickness, and is generally reported in units of gallons per day 300 per foot or square feet per day (ft2/day).
301 A number of the well completion logs filed with DWR include information that can be used to estimate the 302 specific capacity of the associated well, which can then be used to approximate the transmissivity (DWR, 303 2020b). In general, estimated transmissivity values are lower in the northern portion of the Enterprise 304 Subbasin and increase to the south, where the thickness of unconsolidated deposits increases. Estimated 305 transmissivities based on reported specific capacity values on well logs by well type are as follows for the 306 Enterprise Subbasin: 307 • Domestic Wells (100 logs): 2 to 4,000 ft2/day with a geometric mean of 210 ft2/day 308 • Public Wells (4 logs): 120 to 13,750 ft2/day with a geometric mean of 1,600 ft2/day 309 • Industrial and Irrigation Wells (7 logs): 150 to 25,000 ft2/day with a geometric mean of 1,000 ft2/day 310 • Monitoring and Test Wells (6 logs): 35 to 1,600 ft2/day with a geometric mean of 210 ft2/day
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311 Hydraulic conductivity was estimated from specific capacity data by dividing the estimated transmissivity 312 by the well screen length, where available. Estimated hydraulic conductivity values for the Enterprise 313 Subbasin are as follows: 314 • Domestic Wells (66 logs): 0.2 to 350 ft/day with a geometric mean of 9.5 ft/day 315 • Public Wells (3 logs): 8 to 230 ft/day with a geometric mean of 45 ft/day 316 • Industrial and Irrigation Wells (4 logs): 1.5 to 40 ft/day with a geometric mean of 9 ft/day 317 • Monitoring and Test Wells (6 logs): 0.2 to 160 ft/day with a geometric mean of 7 ft/day
318 Excluding lower yield wells (those with reported pumping rates less than 50 gpm) and relatively shallow 319 wells (those with depths less than 150 feet below ground surface [bgs]), transmissivity ranges from 100 to 320 25,000 ft2/day (hydraulic conductivity of 1.5 to 230 ft/day) with a geometric mean of 650 ft2/day (hydraulic 321 conductivity of 10 ft/day).
322 In addition to estimating transmissivity based on specific capacity measurements, aquifer properties have 323 been estimated through the process of numerical model calibration, which is a process of adjusting model 324 inputs (such as transmissivity) to achieve a reasonable match to field observations of interest. The most 325 recent version of the Redding Basin Finite Element Model (REDFEM) included transmissivity estimates of 326 less than 1,000 ft2/day (hydraulic conductivity of 5 ft/day) in the northern portion of the subbasin to more 327 than 200,000 ft2/day (hydraulic conductivity of 300 ft/day) in the southern portion of the subbasin 328 (CH2M HILL, 2011). These values represent the estimated transmissivity for the entire thickness of 329 unconsolidated materials overlying the Chico Formation (see Figure 3-9) as opposed to aquifer thickness 330 associated with a well screen (as is the case for specific capacity estimates). Estimates of transmissivity 331 and hydraulic conductivity will be further refined in the numerical groundwater flow model being 332 developed to support this GSP.
333 Storativity
334 Storativity (or storage coefficient) is the volume of water released from (or taken into) storage in the 335 aquifer system per unit area per unit change in head (i.e., groundwater elevation). In general, unconfined 336 aquifer systems have relatively higher storativity values (typically known as specific yield), whereas 337 confined aquifer systems have lower storativity values. Point estimates of aquifer storage from hydraulic 338 testing within the Enterprise Subbasin are currently unavailable. Values incorporated into REDFEM 339 include a specific yield of 10 percent of the shallow aquifer and a specific storage of the deeper aquifer 340 layers of 2×10-6 per foot. Storativity values are computed by multiplying the specific storage value by the 341 aquifer thickness. The assumed resulting storativity values for the deeper model layers in REDFEM range 342 from 1×10-4 to 4×10-3 (CH2M HILL, 2011). Similar to transmissivity, storage properties will be further 343 refined in the numerical groundwater flow model that is being developed as part of this GSP.
344 3.1.6.5 Natural Recharge Areas
345 Recharge to the primary aquifer units (i.e., Tuscan and Tehama Formations) in the Enterprise Subbasin 346 and the shallower, overlying water-bearing units occurs through a combination of the following 347 (DWR, 1968; Pierce, 1983): 348 • Groundwater recharge from precipitation 349 • Groundwater recharge from applied water 350 • Groundwater recharge from streams and irrigation canals 351 • Subsurface inflow from adjacent subbasins
352 Recharge to aquifer systems is influenced by a number of parameters including (but not limited to) the 353 following: surface soil infiltration capacity, land use/vegetative cover, topography, lithology, and the 354 frequency, intensity, duration, and volume of precipitation. Figure 3-10 presents the distribution of the Soil 355 Agricultural Groundwater Banking Index (SAGBI) for the Enterprise Subbasin. The SAGBI was developed 356 by the University of California–Davis as part of a study of the potential to bank groundwater, while 357 maintaining healthy crops as a drought management strategy (O’Geen et al., 2015). The SAGBI data
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358 presented on Figure 3-10 are based on the following factors: infiltration capacity of soils, the duration that 359 the root zone would be anticipated to remain saturated, topography, potential for leaching of high-salinity 360 soils to degrade groundwater quality, and the susceptibility of soils to compact and erode. As shown on 361 Figure 3-10, the SAGBI indicates that much of the eastern (between Stillwater and Cow Creeks) and 362 northern portions of the subbasin overlie areas with a poor potential for groundwater recharge while 363 locations within and along stream channels represent areas of good to excellent potential for groundwater 364 recharge. This distribution provides good guidance on where natural recharge to the groundwater system 365 likely occurs. Quantitative estimates of natural and anthropogenic recharge are discussed further in 366 Chapter 4, Water Budgets.
367 3.1.6.6 Natural Discharge Areas
368 Natural groundwater discharge areas within the Enterprise Subbasin include groundwater discharge to 369 surface-water bodies (streams, ponds, wetlands), subsurface outflow to adjacent subbasins, and shallow 370 groundwater ET by phreatophytes. Although groundwater discharge to streams has not been mapped, 371 previous numerical modeling efforts indicate that the Sacramento River and at least the lower portions of 372 primary tributaries are gaining streams. REDFEM output indicate that the Sacramento River gains 373 approximately 700,000 acre-feet per year (on average) from groundwater as it flows through the RAGB. 374 Updated estimates of the location and magnitude of natural groundwater discharge are discussed further 375 in Chapter 4, Water Budgets.
376 Figure 3-11 presents the distribution of potential groundwater-dependent ecosystems (GDEs) within the 377 Enterprise Subbasin contained in the DWR Natural Communities (NC) dataset (DWR, 2020c). The NC 378 dataset is the product of a collaborative effort between DWR, California Department of Fish and Wildlife, 379 and The Nature Conservancy. These agencies compiled and screened information from 48 datasets 380 (such as the National Hydrography Dataset, National Wetlands Inventory, Vegetation Classification and 381 Mapping Program, and Classification and Assessment with Landsat Of Visible Ecological Groupings) to 382 produce the NC dataset. As defined in the NC dataset, the two classifications of GDEs are (1) wetland 383 features commonly associated with the surface expression of groundwater under natural, unmodified 384 conditions (NC wetland) and (2) vegetation types commonly associated with the sub-surface presence of 385 groundwater (NC vegetation or phreatophytes). Within the Enterprise Subbasin, NC wetlands typically 386 occur within and immediately adjacent to stream channels, whereas NC vegetation areas are typically 387 present in floodplain areas associated with streams. However, there has been no independent verification 388 that the locations shown on this map constitute actual GDEs; therefore, Figure 3-11 shows only potential 389 GDEs. Additional field reconnaissance may be necessary to further inform the potential existence of 390 these GDEs.
391 3.2 Groundwater Conditions
392 This section describes current and historical groundwater conditions in the Enterprise Subbasin. Unless 393 otherwise specified, current conditions will refer to conditions occurring after January 1, 2015, and 394 historical conditions will refer to those occurring prior to January 1, 2015. The groundwater conditions 395 described in the following sections present the current and historical variability of groundwater levels and 396 groundwater quality.
397 3.2.1 Groundwater Elevations
398 The assessment of groundwater elevation conditions in the Enterprise Subbasin is largely based on data 399 collected by the DWR from November 7, 1955 to March 18, 2019. The groundwater-level monitoring 400 network in the Enterprise Subbasin comprises 28 groundwater wells gauged by DWR, Shasta County, or 401 USGS (DWR; 2019a; DWR, 2019b; USGS, 2019a). Groundwater wells in the monitoring network have 402 various uses including residential, irrigation, industrial, stock watering, and observation, as well as three 403 wells with unknown groundwater use. The location and type of monitoring program are shown on 404 Figure 2-9 and listed in Table 3-1. All but 1 of the 28 groundwater wells comprising the groundwater-level 405 monitoring network are located in the southern two-thirds of the Enterprise Subbasin.
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406 Groundwater elevation data have been routinely collected by DWR at 20 wells to better understand 407 seasonal changes and to monitor longer-term trends in groundwater levels. Groundwater wells monitored 408 by DWR have generally been accessed monthly to semiannually. Shasta County has monitored one 409 groundwater well in the Enterprise Subbasin under the CASGEM program since 2014. Between October 410 2017 and April 2019, USGS began monitoring 7 groundwater wells in the Enterprise Subbasin. A 411 summary of the historical groundwater-level monitoring activities conducted within the Enterprise 412 Subbasin since 1955 is described below: 413 • Between 1955 and 1990, DWR gauged up to 12 groundwater wells monthly to biannually 414 • Between 1990 and 2016, DWR gauged up to of 16 groundwater wells bimonthly to annually 415 • Between 2017 and 2018, DWR gauged up to 10 groundwater wells triannually 416 • Between 2014 and 2019, Shasta County gauged 1 well semiannually to annually 417 • Between January 2017 and March 2019, USGS gauged 7 groundwater wells once
418 The amount of available groundwater-level data for a given well varies from 1 measurement at the USGS- 419 monitored wells to over 300 data points at a DWR-monitored location. The period of record for wells 420 included in the DWR dataset ranges from 4 years at well Columbia, to nearly 63 years of groundwater- 421 level monitoring at 31N04W27P001M, with an average period of record of nearly 36 years.
422 Due to the various regional and local influences on groundwater elevations, characterization of subbasin 423 groundwater elevation conditions was completed using three methodologies: groundwater elevation 424 contour maps, hydrographs, and vertical hydraulic gradients, as follows: 425 • Groundwater elevation contour maps show the geographic distribution of groundwater elevations at a 426 specific time. Contours and posted groundwater elevations represent the elevation of the 427 groundwater in units of feet NAVD88. 428 • Hydrographs show variations in groundwater elevations at an individual well over time. A review of 429 hydrographs can provide insight to both seasonal and longer-term temporal trends in groundwater 430 elevations. 431 • Vertical hydraulic gradients provide information on the potential for vertical groundwater flow at a 432 given location.
433 A summary of current and historical groundwater elevations and evaluations of vertical and horizontal 434 flow directions are included herein.
435 3.2.1.1 Groundwater Elevation Contours and Horizontal Groundwater Gradients
436 Because the Enterprise Subbasin comprises a portion of the larger RAGB and groundwater flow is not 437 affected by jurisdictional boundaries (such as subbasin boundaries), a regional review of groundwater- 438 level data is important for understanding groundwater flow on a basin-wide scale. Consistent with GSP 439 requirements, groundwater-level data for two recent timeframes, March 19 through April 3, 2018 (spring) 440 and October 16 through October 26, 2018 (fall), were used to create groundwater elevation contour maps 441 for the RAGB. Groundwater levels from wells within the Enterprise Subbasin were measured between 442 March 19 and March 22, 2018 (spring) and October 16 and October 17, 2018 (fall). These groundwater 443 measurements represent the most recent groundwater-level data as of the time of this evaluation.
444 The first step in the process of groundwater elevation contouring was to identify wells representative of 445 groundwater conditions across the RAGB (that is, completed at consistent depths within the primary 446 aquifer units). With some exceptions, wells included in the contouring were generally completed between 447 depths of 50 and 150 feet bgs. A limited number of wells completed deeper (between 150 to 770 feet bgs) 448 were considered outlier data and were not included in the contouring.
449 As mentioned in Section 2.2.1.3, Sacramento River and Cow Creek serve as western and southwestern, 450 and eastern boundaries for the Enterprise Subbasin, respectively. These surface-water bodies are 451 gaining streams, or streams in which the stream stage is at a lower elevation than the underlying water
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452 table. Thus, groundwater moves from the aquifer into the stream channel. A gaining stream is 453 hydraulically connected to the water table; and as a result, surface-water elevations in perennial streams 454 that are coupled with the underlying aquifer must be considered when generating water table surface 455 contours. Because the Sacramento River is perennial and coupled with the groundwater system, the river 456 surface elevation was included in groundwater contouring. The river gauge below Keswick Reservoir 457 (11370500) and the river gauge at Bend Bridge in Red Bluff (11377100) served as upper and lower 458 extents for consideration of Sacramento River stages in groundwater elevation contouring (USGS, 459 2019a). The topographic data (discussed in Section 3.1.1) were used to help inform Sacramento River 460 stage between Keswick Reservoir and Bend Bridge. The average surface-water elevations between 461 March 19 through April 3, 2018 (spring) and October 16 through October 26, 2018 (fall) at the Keswick 462 Reservoir and Bend Bridge river gauges were computed. The average surface-water elevations at the 463 two river gauges during the dates above were compared to the surface-water elevations in the digital 464 elevation model near these two locations. The average spring surface-water elevation was more similar to 465 the topographic elevation measured in the digital elevation model, and the topographic elevations along 466 the Sacramento River were extracted from the digital elevation model to represent spring 2018 surface- 467 water elevations. The fall 2018 Sacramento River surface-water elevations were interpolated from the 468 previously extracted elevations from the digital elevation model and the difference between the spring 469 2018 and fall 2018 surface-water elevations at the river gauges. Because there is a lack of measured 470 groundwater-level data in the northern portion of Enterprise Subbasin, groundwater elevation output from 471 REDFEM (CH2M HILL, 2011) were used to augment the dataset used in the contouring in the northern 472 portion of the Enterprise Subbasin. Groundwater elevation contours for the Enterprise Subbasin for spring 473 and fall 2018 are shown on Figures 3-12 and 3-13, respectively.
474 During spring and fall 2018, groundwater flow in the Enterprise Subbasin was generally south-southeast 475 toward the confluence of Cow Creek and the Sacramento River. Groundwater flow directions and 476 variations in groundwater elevation generally mimic a muted version of ground surface topography. 477 Horizontal hydraulic gradients are estimated to be steeper in the northern and central portions of the 478 Enterprise Subbasin where transmissivity estimates are lower, and flatter in the southeastern portion of 479 the subbasin, near the Cow Creek and Sacramento River confluence, where transmissivity estimates are 480 higher. The steepest horizontal hydraulic gradient is near 31N03W06H001M, with both a spring and fall 481 2018 hydraulic gradient of approximately 0.004 foot per foot (ft/ft). The shallower horizontal gradients in 482 the southeast near 30N03W06K001M are approximately 0.001 ft/ft in spring 2018 and 0.0007 ft/ft in fall 483 2018. Measured spring 2018 groundwater elevations considered in the contouring ranged from a high of 484 463.34 feet NAVD88 at 31N03W06H001M in the central portion of the subbasin to a low of 390.07 feet 485 NAVD88 at 30N03W06K001M farthest south. Measured fall 2018 groundwater elevations considered in 486 the contouring ranged from a high of 459.14 feet NAVD88 at 32N04W33G001M farthest north to a low of 487 389.17 feet NAVD88 at 30N03W06K001M farthest south.
488 A comparison of Figures 3-12 and 3-13 shows that wells with groundwater levels measured in both spring 489 and fall 2018 generally exhibit a decrease in groundwater levels between spring and fall. Generally, most 490 groundwater recharge occurs from increased precipitation and less groundwater pumping in winter and 491 spring. Conversely, groundwater recharge decreases during summer and fall when there is less 492 precipitation and more groundwater pumping. Seven of the ten wells with measurements in both spring 493 and fall demonstrated declining groundwater levels, ranging from 0.9 foot at wells 30N03W06K001M and 494 31N04W29R003M to a maximum decrease of 14 feet observed at Columbia. Groundwater levels in wells 495 31N04W29R004M, 31N04W29R005M, and 31N04W29R006M have slightly increasing groundwater 496 levels between spring and fall 2018 (up to 4 feet). These wells are part of a quadruple well cluster near 497 the Sacramento River.
498 3.2.1.2 Hydrographs
499 As mentioned above, the Enterprise Subbasin groundwater monitoring network consists of USGS- and 500 DWR-monitored groundwater wells. Each of the seven USGS-monitored groundwater wells has only one 501 groundwater-level measurement, whereas the datasets associated with the DWR-monitored groundwater 502 wells are more robust, with an average of approximately 105 datapoints per groundwater well. With the
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503 USGS and DWR datasets combined, temporal groundwater-level data for the Enterprise Subbasin date 504 as far back as November 7, 1955, with some locations continuing to be updated annually.
505 Temporal trends in groundwater elevations can be assessed with hydrographs that plot changes in 506 groundwater elevations over time. Figure 3-14 depicts locations and hydrographs of representative wells 507 in the Enterprise Subbasin. The points on the plots represent groundwater elevation measurements, 508 whereas the color-coded bars on the hydrographs represent the Sacramento Valley Water Year Index 509 (as discussed in Section 3.1.2.1). Representative wells were chosen based on their distribution across 510 the subbasin, and the timeframe and continuity of their monitoring record. A complete set of hydrographs 511 is included in Appendix C.
512 Historical groundwater-level records for the Enterprise Subbasin indicate groundwater levels have been 513 relatively consistent, generally without long-term trends of increasing or decreasing groundwater levels 514 (30N03W06K001M, Figure 3-14). However, groundwater levels at locations 32N04W33G001M, 515 31N04W09D001M, and 31N04W09C001M depict increasing water levels from the 1970s to current in the 516 central portion of the Enterprise Subbasin. At groundwater well 32N04W33G001M, groundwater levels 517 increased by approximately 40 feet, from approximately 500 feet elevation in the early 1980s to 518 approximately 540 feet elevation in 2010. Groundwater levels at 31N04W09C001M and 31N04W09D001M 519 were plotted together because of their proximity to each other, the similar total depths, and the succeeding 520 periods of record. Similar to groundwater levels at 32N04W33G001M, groundwater levels at 521 31N04W09C001M and 31N04W09D001M increased by nearly 50 feet, from approximately 405 feet 522 elevation in the late 1970s to approximately 455 feet in the early 2010s.
523 Although there have been relatively few long-term changes in groundwater levels, there are seasonal 524 variations in groundwater levels that are evident in hydrographs. Figure 3-14 shows that groundwater 525 levels in many wells can fluctuate between 0 and 10 feet within a year. Groundwater levels increase 526 during the rainy season only to decrease during the dry season. As discussed in Section 3.1.2.1, 527 precipitation has been variable in the RAGB, with multi-year droughts (critical and dry water years) 528 occurring between 1976 and 1977, 1987 to 1992, 2007 to 2009, and 2013 to 2015, and wet years 529 occurring between 1970 to 1975, 1982 to 1984, and 1995 to 2000.
530 Groundwater levels in most of the wells shown on Figure 3-14 depict some influence from droughts and 531 wet periods. Despite the general increasing trend, groundwater levels in the centrally located groundwater 532 wells 31N04W09C001M and 31N04W09D001M and the northernmost groundwater well 533 32N04W33G001M are responsive to sustained wet and dry periods. Sustained droughts between 1987 to 534 1992 and 2013 to 2015 had a large impact on groundwater levels in the vicinity of these wells, with 535 groundwater levels decreasing by approximately 10 to 20 feet during droughts. Conversely, even brief 536 wet periods have resulted in increasing groundwater levels at these locations.
537 Wet and dry climatic periods are less pronounced in the groundwater-level records of the remaining wells 538 in the Enterprise Subbasin.
539 3.2.1.3 Vertical Hydraulic Gradients
540 The potential for groundwater to move vertically within an aquifer system is evaluated by comparing 541 groundwater elevations in wells screened at different depths. Because groundwater elevations change 542 spatially, the potential for vertical movement is computed between wells of differing depths that are in 543 proximity to each other (that is, a well cluster or a multiple completion well). For the purposes of this 544 analysis, the vertical hydraulic gradient is computed as the groundwater elevation at the shallower well 545 minus the groundwater elevation at the deeper well divided by the vertical distance between the well 546 screen midpoints. Based on this calculation method, a positive vertical hydraulic gradient represents the 547 potential for downward groundwater flow, and a negative vertical hydraulic gradient represents the 548 potential for upward groundwater flow. The larger the value of the vertical hydraulic gradient (either 549 positive or negative), the stronger the potential for upward or downward groundwater flow.
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550 Because of their proximity to each other (they are part of a quadruple well cluster or within 40 feet of each 551 other), the groundwater wells 31N04W29R003M, 31N04W29R004M, 31N04W29R005M, and 552 31N04W29R006M were used for evaluating vertical hydraulic gradients in spring and fall 2018. The 553 groundwater well pair represented by 31N04W29R005M and -R004M is the shallowest; Well R005M 554 screened at 330.6 to 320.6 feet NAVD88, and 31N04W29R004M screened at 275.6 to 235.6 feet 555 NAVD88. The groundwater well pair represented by wells 31N04W29R003M and 31N04W29R006M is 556 the deepest with Well R003M screened from 200.6 to 119.6 feet NAVD88 and Well R006M screened 557 from 199.6 to 119.6 feet NAVD88. Hydrographs of these four wells show that historical vertical hydraulic 558 gradients have been downward, with smaller downward gradients within the shallower well pair and much 559 larger downward gradients within the deeper well pair. Vertical hydraulic gradients calculated from 560 groundwater well data are summarized in Table 3-2. Figure 3-15 illustrates groundwater-level 561 hydrographs associated with the quadruple well cluster. Vertical hydraulic gradients are downward, 562 ranging between 0.02 ft/ft to 0.21 ft/ft. Downward vertical gradients generally increased between spring 563 and fall 2018, likely due to deeper agricultural pumping.
564 3.2.2 Interconnected Surface Water and Groundwater
565 Surface water that is in hydraulic communication with the groundwater flow systems is referred to as 566 interconnected surface water. If the groundwater elevation beneath a stream is higher than the stream 567 stage (i.e., surface-water elevation), the stream is considered to be a gaining stream, because it gains 568 water from the underlying groundwater. If the groundwater elevation is lower than the stream stage, the 569 stream is considered to be a losing stream, because it loses water to the underlying groundwater. If the 570 groundwater elevation is below the streambed elevation, the stream and groundwater are considered to 571 be disconnected (or decoupled).
572 As previously discussed, the RAGB is bounded on the east by the Cascade Range, on the north and 573 northwest by the Klamath Mountains, and on the west by the Coast Range. Following rain and snowmelt 574 events, the resulting discharge to surface-water channels and infiltration to the aquifer system produces 575 flow within the multiple tributaries to the perennial Sacramento River and recharges the aquifer within the 576 RAGB. The shallow groundwater and perennial nature of surface-water flow in the RAGB suggest there is 577 potential for interconnected surface waters to be present. To identify areas where interconnected surface 578 waters may be present, an analysis was performed based on reviewing depth to groundwater data. The 579 underlying assumption of this analysis is that the shallower the depth to groundwater, the more likely that 580 area is in hydraulic connection to surface water.
581 To document this relationship, the groundwater elevation contours for spring of 2018 were compared to 582 ground surface elevations presented in Section 3.1.1 to estimate the depth to groundwater across 583 Enterprise Subbasin. Spring 2018 was selected because it represents a period of seasonal high 584 groundwater levels that would be anticipated to result in greater connection between groundwater and 585 surface-water features in the Enterprise Subbasin. Figure 3-16 presents the results of that analysis and 586 shows that groundwater in Enterprise Subbasin is generally greater than 20 feet bgs in most of the 587 subbasin.
588 Most areas of interconnected surface water are located along the Sacramento River and Cow Creek, 589 where surface water flows perennially. An additional area of potentially interconnected surface water is 590 located along portions of upper and lower reaches of Stillwater Creek and its tributaries and Churn Creek.
591 This analysis of locations of interconnected surface water is based on available data but contains 592 significant uncertainty. Additional data are needed to reduce uncertainty and refine the map of 593 interconnected surface waters. The main source of these data will be the numerical model being 594 developed as part of this GSP.
595 3.2.3 Groundwater Storage
596 To be included in a future draft of this chapter.
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597 3.2.4 Seawater Intrusion
598 The RAGB is not vulnerable to seawater intrusion, given its distance from the Pacific Ocean.
599 3.2.5 Groundwater Quality
600 This section presents a summary of current groundwater quality conditions. The EAGSA does not have 601 regulatory authority over groundwater quality and is not charged with improving groundwater quality in 602 Enterprise Subbasin under SGMA. Although there may be localized areas of impairment, the overall 603 quality of groundwater in the Enterprise Subbasin is good and suitable for the designated beneficial uses 604 of the subbasin. Under SGMA, projects and actions implemented by a GSA are not required to improve 605 groundwater quality; however, the management actions and projects recommended under SGMA must 606 not further degrade groundwater quality, as compared with baseline (i.e., January 2015) conditions.
607 The SWRCB monitors and regulates activities and discharges that can contribute to constituents that are 608 released to groundwater over large areas. The SWRCB’s GAMA program compiles groundwater quality 609 data from a variety of sources and makes these data available to the public for download by county 610 (SWRCB, 2019a). Groundwater quality monitoring programs incorporated into the dataset include the 611 following: 612 • Data from a GAMA domestic well sampling program 613 • USGS GAMA program 614 • Lawrence Livermore National Laboratory GAMA program 615 • Data from the Department of Pesticides Regulation groundwater sampling program 616 • Data from groundwater sampling programs conducted by DWR 617 • Data from the California Department of Public Health’s sampling of public water supply wells 618 • Data from sampling of environmental monitoring wells at regulated sites
619 The Shasta County dataset was downloaded, and a compiled dataset of publicly available groundwater 620 quality results from Enterprise Subbasin were used for establishing baseline groundwater quality in the 621 subbasin. Groundwater quality data were then compared to an applicable regulatory standard including 622 the following: 623 • Primary MCLs established by either the U.S. Environmental Protection Agency (EPA) or the 624 California EPA (Cal/EPA), whichever was more strict 625 • Secondary maximum contaminant levels (SMCLs) established by either EPA or Cal/EPA, whichever 626 was more strict 627 • Federal Action Level established by EPA 628 • Cancer or non-cancer Health Based Screening Level established by USGS 629 • Chronic non-cancer Human Health Benchmark for Pesticides established by EPA 630 • Federal Health Advisory Level established by EPA 631 • Reference Dose as a drinking water level 632 • National Academy of Science Health Advisory Level 633 • California Cancer Potency Factor 634 • California Proposition 65 Safe Harbor Levels as a drinking water level 635 • SWRCB notification levels
636 The following analyses used analytical data collected between 2000 and 2019 to compare to state or 637 federal groundwater limits. Detected concentrations of constituents based on groundwater analytical data 638 were compared to the associated regulatory limit to evaluate whether the concentration was higher (an
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639 exceedance) or lower (a non-exceedance) than the limit. Most tested constituents were either nondetect 640 or detected at concentrations below regulatory limits. Constituents with low detection frequencies do not 641 represent pervasive groundwater quality issues throughout Enterprise Subbasin; therefore, these 642 constituents will not be considered further in this GSP.
643 Figures 3-18 and 3-19 present the distribution of sampled locations and locations of exceedances for 644 each constituent that exceeded the applicable regulatory limit at 10 percent or more of the sampled 645 locations. The locations are symbolized as either non-exceedance (indicating that the constituent has not 646 exceeded the applicable limit in any of the samples at a given well) or symbolized by the number of 647 exceedances over time at a given location. Groundwater quality data included in the analysis of recent 648 subbasin groundwater quality are presented in Appendix D.
649 In the Enterprise Subbasin, the following water quality constituents were identified to have exceedances 650 in 10 percent or more of tested groundwater wells: iron, manganese, lead, arsenic, aluminum, benzene, 651 gasoline, tert-butyl alcohol (TBA), and methyl-tert-butyl ether (MTBE). Naturally occurring water quality 652 constituents include the metals iron, manganese, lead, arsenic, and aluminum; whereas groundwater 653 quality constituents related to human activity include the fuel-related compounds, such as benzene and 654 gasoline and the non-hydrocarbon solvents TBA and MTBE. Table 3-3 summarizes the analytical results 655 for each of the above water quality constituents. Although available data show localized areas of potential 656 groundwater impairments, the overall quality of groundwater in the Enterprise Subbasin is good and 657 suitable for the designated beneficial uses of the subbasin.
658 3.2.5.1 Point-Source Contamination
659 Point-source contamination data collection activities take place in the Enterprise Subbasin in response to 660 known or potential sources of groundwater contamination. These sources include leaking underground 661 storage tank (LUST) sites and a sewage settling pond.
662 SWRCB and DTSC have the responsibility for cleanup and monitoring of point-source pollutants. Both 663 entities make all related materials available to the public through two public portals: GeoTracker managed 664 by SWRCB (SWRCB, 2019b) and EnviroStor managed by DTSC (DTSC, 2019). Figure 3-20 presents a 665 map with locations of active remediation sites within the Enterprise Subbasin, and Table 3-4 summarizes 666 the active remediation sites.
667 The SWRCB’s GeoTracker database identifies three open LUST remediation sites with potential or actual 668 groundwater contamination within Enterprise Subbasin. DTSC’s EnviroStor database identifies the same 669 three open LUST remediation sites but includes one additional remediation site that may be open with 670 potential or actual groundwater contamination within Enterprise Subbasin. The EnviroStor database 671 redirects the user to the GeoTracker database for more information; however, attempts to locate this site 672 have been unsuccessful as the GeoTracker database does not contain an entry for this remediation site. 673 Resolution of the status of the fourth potentially open remediation site remains a data gap that will be 674 filled via additional communication with DTSC and/or SWRCB.
675 As indicated in Table 3-4, point-source contaminants include gasoline, sewage sludge, and solvents or 676 non-petroleum hydrocarbons. Although these constituents are of concern, only fuel-related compounds 677 and metals were detected in more than 10 percent of sampled wells within the Enterprise Subbasin to 678 warrant inclusion in the GSP monitoring program.
679 3.2.5.2 Connate Water
680 In addition to the above potential constituents of concern, there exists a potential source of saline water 681 intrusion from the Chico Formation. The Chico Formation, which underlies the primary aquifer units of the 682 RAGB, contains saline water under artesian pressure (Pierce, 1983). The Chico Formation is composed 683 of marine deposits of sandstone, conglomerates, and shale, most of which are considered impermeable 684 with a few exceptions. Pumping at depths near the top of the Chico Formation may induce upward
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685 migration of the connate water into the primary aquifer units. Currently, migration of connate water into 686 the primary aquifer is not an issue.
687 3.2.6 Land Subsidence
688 Land subsidence was recently measured across the Sacramento Valley by DWR, and results were 689 published in the report 2017 GPS Survey of the Sacramento Valley Subsidence Network (DWR, 2018). 690 The DWR document provides no indication of inelastic subsidence to have occurred in the entire RAGB. 691 As such, land subsidence from groundwater extraction in the Enterprise Subbasin is not considered a 692 current issue of concern.
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Table 3-1. Enterprise Subbasin Groundwater Monitoring Network Ground Surface Elevation Reference Point Elevation Total Well Depth Top of Well Screen Bottom of Well Screen Location ID Easting Northing Well Type Monitoring Agency (ft NAVD88) (feet NAVD88) (feet bgs) (feet bgs) (feet bgs)
30N03W06J001M 6495383.401 2059689.186 Irrigation Well California DWR 405.87 406.57 128 -- --
30N03W06K001M 6494035.689 2059865.925 Residential Well California DWR 412.57 413.07 66 -- --
30N04W02E001M 6480263.49 2060382.618 -- U.S. Geological Survey 475 -- 120 -- --
30N04W03Q001M 6478024.495 2059050.431 Residential Well California DWR 475.88 477.58 140 -- --
31N03W06H001M 6495194.984 2092445.357 Residential Well California DWR 523.14 523.64 96 -- --
31N03W07R002M 6494954.583 2084219.027 -- U.S. Geological Survey 456.628 -- 360 -- --
31N03W18B001M 6493918.04 2082861.892 Stockwatering California DWR 460.23 460.63 210 -- --
31N03W29N001M 6495629.42 2068358.543 Unknown California DWR 418.99 419.59 130 -- --
31N04W07D001M 6459364.886 2088187.852 -- U.S. Geological Survey 476 -- 64 -- --
31N04W09C001M 6471050.589 2087708.813 Residential Well California DWR 537.64 538.84 215 188 215
31N04W09D001M 6471014.643 2088874.31 Residential Well California DWR 546.64 545.64 160 -- --
31N04W11P001M 6481586.967 2084562.911 -- U.S. Geological Survey 496 -- 178 -- --
31N04W12B001M 6488433.775 2088815.676 Residential Well California DWR 597.24 597.64 180 -- --
31N04W15K001M 6477587.337 2080190.11 Irrigation Well California DWR 517.63 518.63 352 120 350
31N04W16H001M 6474352.322 2082195.613 Unknown California DWR 514.64 515.64 140 -- --
31N04W16M001M 6470315.769 2080316.118 Residential Well California DWR 524.63 525.63 140 -- --
31N04W25Q001M 6487781.792 2068498.013 Irrigation Well California DWR 491.59 494.59 770 220 770
31N04W27P001M 6476693.034 2068089.369 Irrigation Well California DWR 494.59 494.59 300 90 296
31N04W27R001M 6478187.957 2067968.831 -- U.S. Geological Survey 492 -- 395 -- --
31N04W29R002M 6468990.251 2067935.307 Residential Well California DWR 444.6 445.7 40 -- --
31N04W29R003M 6467601.519 2068341.346 Industrial Well California DWR 444.6 445.9 325 244 325
31N04W29R004M 6467601.379 2068304.918 Observation Well California DWR 444.6 445.6 210 169 209
31N04W29R005M 6467601.379 2068304.918 Observation Well California DWR 444.6 445.5 126 114 124
31N04W29R006M 6467601.238 2068268.49 Unknown California DWR 444.6 445.8 325 245 325
32N04W26K001M 6482614.995 2101640.693 -- U.S. Geological Survey 633 -- 128 -- --
32N04W33G001M 6472631.92 2098084.886 Residential Well California DWR 632.64 633.64 208 188 208
33N04W34G001M 6476924.372 2128678.187 -- U.S. Geological Survey 691 -- 247 -- --
Columbia 6476433.763 2097269.833 Observation Well California DWR 622 624 270 222 270
Notes: -- = information not available bgs = below ground surface DWR = Department of Water Resources NAVD88 = North American Vertical Datum of 1988 The horizontal datum for well coordinates is North American Datum 1983, State Plane California Zone I in feet. 693
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Table 3-2. Enterprise Subbasin Vertical Head Differences during Spring and Fall 2018 Distance Measured Groundwater Measured Groundwater Difference in Screen Elevation of Screen Elevation of Calculated Vertical Location ID of Location ID of Between Wells Elevation in Shallow Well Elevation in Deep Well Groundwater Elevation Measurement Date of Shallow Well Deep Well Hydraulic Gradient Shallow Well Deep Well (feet) (feet NAVD88) (feet NAVD88) (feet) Groundwater Levels (feet NAVD88) (feet NAVD88) (foot/foot)
31N04W29R005M 31N04W29R004M 0 415.5 412.1 3.4 3/22/2018 330.6-320.6 275.6-235.6 0.05
31N04W29R005M 31N04W29R003M 36.7 415.5 395.9 19.6 3/22/2018 330.6-320.6 200.6-119.6 0.12
31N04W29R005M 31N04W29R006M 36.1 415.5 406.4 9.1 3/22/2018 330.6-320.6 199.6-119.6 0.05
31N04W29R004M 31N04W29R003M 36.7 412.1 395.9 16.2 3/22/2018 275.6-235.6 200.6-119.6 0.17
31N04W29R004M 31N04W29R006M 36.1 412.1 406.4 5.7 3/22/2018 275.6-235.6 199.6-119.6 0.06
31N04W29R005M 31N04W29R004M 0 417.6 416.2 1.4 10/17/2018 330.6-320.6 275.6-235.6 0.02
31N04W29R005M 31N04W29R003M 36.7 417.6 395.9 21.7 10/17/2018 330.6-320.6 200.6-119.6 0.13
31N04W29R005M 31N04W29R006M 36.1 417.6 407.6 10 10/17/2018 330.6-320.6 199.6-119.6 0.06
31N04W29R004M 31N04W29R003M 36.7 416.2 395.9 20.3 10/17/2018 275.6-235.6 200.6-119.6 0.21
31N04W29R004M 31N04W29R006M 36.1 416.2 407.6 8.6 10/17/2018 275.6-235.6 199.6-119.6 0.09
Notes: Positive vertical hydraulic gradient indicates downward flow. NAVD88 = North American Vertical Datum of 1988
694
GES0905191027RDD 3-19 EAGSA Managing groundwater sustainably for generations to come. Chapter 3. Basin Setting
Table 3-3. Summary of Enterprise Subbasin Analytical Chemistry for Potential Analytes of Concern, 2000–2010 Regulatory Limit Number of Number of Number of Analyte Limit Type (µg/L) Wells Sampled Samples Collected Wells with Exceedances
Aluminum CA MCL 1,000 77 210 8
Arsenic CA MCL 10 82 370 12
Iron EPA SMCL 300 114 359 41
Lead U.S. Federal Action Level 15 76 159 8
Manganese U.S. Health Advisory Level 50 102 479 38
Benzene CA MCL 1 198 2,399 54
Gasoline U.S. Health Advisory Level 5 49 158 34
Methyl-Tert-Butyl Ether CA MCL 13 197 2,462 75
Tert-Butyl Alcohol Federal Notification Level 12 171 2,267 48
Notes: µg/L = micrograms per liter CA MCL = California Maximum Contaminant Limit EPA SMCL = Environmental Protection Agency Secondary Maximum Contaminant Limit 695
GES0905191027RDD 3-21 EAGSA Chapter 3. Basin Setting Managing groundwater sustainably for generations to come.
Table 3-4. Enterprise Subbasin Active Remediation Sites Site Name Site Type Status Constituents of Concern Address City
76 SS# 2611241 LUST Open - Remediation Other Solvent or Non-petroleum Hydrocarbon 5101 Churn Creek Road Redding
Churn Creek Chevron LUST Open - Remediation Gasoline 4746 Churn Creek Road Redding
Tay Van Car Wash LUST Open - Remediation Gasoline 1803 Hilltop Drive Redding
Sewage Settling Pond Under Evaluation Unknown Sludge - Sewage 4001 Victor Avenue Redding
Note: LUST = leaking underground storage tank
696
3-22 GES0905191027RDD r e iv R o t n e
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a r k c MODOC e SISKIYOU a e COUNTY r COUNTY S SHASTA r C ate HUMBOLDT COUNTY illw COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
s
a SUBBASIN LASSEN E k COUNTY Cree TRINITY Cow COUNTY Little
«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a SACRAMENTO RIVER m
e n RIVER/STREAM t ¤£299 o Rock Creek INTERSTATE/HIGHWAY R
i v COUNTY BOUNDARY LINE e
r ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN GROUND SURFACE ELEVATION (feet NAVD88) (! 772 to 819.21
722 to 772
672 to 722
622 to 672 «¬44 (! 572 to 622 Cow Creek 522 to 572
472 to 522
422 to 472 ¨¦§5 372.48 to 422
372.48 Creek Ch Olney u r n C reek NOTES:
DATA SOURCE: SURFACE DATA REPRESENTS TOPOGRAPIC DATA FROM MULTIPLE SOURCES THAT WERE COMPILED INTO A SINGLE SURFACE (USGS, 2018; USGS, 2019b; AND COR, 2019) Creek Clear
S NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988 t i l l w Sacra a SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, m te e r INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, n C t re GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, o e k R METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP i v e CONTRIBUTORS, AND THE GIS USER COMMUNITY r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
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«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a SACRAMENTO RIVER m
e n RIVER/STREAM t ¤£299 o Rock Creek INTERSTATE/HIGHWAY R
i v COUNTY BOUNDARY LINE e
r ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN MEAN ANNUAL PRECIPITATION (inches) (! 31.25 to 34
34 to 36
36 to 38
38 to 40 «¬44 (! 40 to 42 Cow Creek 42 to 44
44 to 46
46 to 48.63 ¨¦§5
Creek Ch Olney u r n C reek NOTES:
DATA SOURCE: PRISM CLIMATE GROUP, OREGON STATE UNIVERSITY, HTTP://PRISM.OREGONSTATE.EDU. ACCESSED MARCH 2020 (PRISM CLIMATE GROUP, 2012) Creek Clear S SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, t i l l INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, w Sacra a GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, m te e r METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP n C t re o e k R i v e r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
S
a c
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i H v S Enterprise Subbasin Groundwater Sustainability Plan
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15
10
5 SACRAMENTO VALLEY WATER YEARINDEX
0 1951 1959 1963 1967 1982 1974 1978 1954 1962 1966 1981 1958 1973 1977 1961 1969 1953 1957 1972 1976 1964 1968 1952 1956 1971 1979 1998 2002 1986 1994 2009 2013 2017 1997 2001 1989 1993 2008 2012 2016 1996 2004 1984 1988 1992 2019 1999 2003 2007 2011 1983 1987 1991 2018 2006 2014 1955 1970 1950 1965 1980 1960 1975 1990 2005 1985 2020 2000 2015 1995 2010
WATER YEAR LEGEND WET YEAR ABOVE NORMAL YEAR BELOW NORMAL YEAR NOTE: FIGURE 3-3 DRY YEAR HTTP://CDEC.WATER.CA.GOV/REPORTAPP/JAVAREPORTS? WATER YEAR TYPE CRITICAL YEAR NAME=WSIHIST Enterprise Subbasin Groundwater Sustainability Plan
D:\ReddingCACityof\EAGSA\Figures\Grapher\EGSP\FIG03-03_WY_SacValley.grf k MODOC e SISKIYOU e COUNTY r COUNTY SHASTA r C ate HUMBOLDT COUNTY illw COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
s
a SUBBASIN LASSEN E k COUNTY Cree TRINITY Cow COUNTY Little
«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek (! CITY
MAJOR HYDROLOGIC FEATURE
RIVER/STREAM ¤£299 Rock Creek INTERSTATE/HIGHWAY COUNTY BOUNDARY LINE
ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN Sacramento River
(!
«¬44 (! Cow Creek
¨¦§5
Creek Ch Olney u r n C reek NOTES:
SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, Creek Clear METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP
S CONTRIBUTORS, AND THE GIS USER COMMUNITY t i l l w a te r C re e k
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
FIGURE 3-4 A COUNTY ST MAJOR HYDROLOGIC FEATURES HA Enterprise Subbasin Groundwater Sustainability Plan S
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«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a SACR AMENTORIVER m
e n R IVER /STR EAM t ¤£299 o Rock Creek INTER STATE/HIGHWAY R
i v COUNTYBOUNDAR LINE Y e
r ENTER PRGR ISE OUNDWATERSUBSASINPLAN AR (5-006.04, EA)
R EDDINGAR EAGR OUNDWATERBASIN ENTERPRISE SUBBASIN SURFACE SOIL (! ALFISOLS
ENTISOLS
INCEPTISOLS
MOLLISOLS «¬44 (! ULTISOLS Cow Creek OTHER
¨¦§5
NOTES: Creek Ch Olney u r n DATASOUR SUR CE: FACESOILSAR BASED E ON TAXONOMIC OR DER , Cr eek DEVELOPEDBYTHE UNITED STATES DEPAR TMENTOF AGR ICULTUR E’S(USDA) NATIONAL RESOUR CESCONSER VATION SER VICE(USDA,2019)
e SER VICELAYER CR EDITS:SOUR CES:ESRHER GAR I, E, MIN, ar Cre k Cle INTER MAP,INCR EMENTCORP GEBCO, P., USGS, FAO,NPS,NR CAN, S
t GEOBASE,KADASTERIGN, ORNL, DNANCESUR VEY,ESR JAPAN, I i l l w ESRMETI, CHINA (HONG I KONG), SWISSTOPO, ©OPENSTREETMAP Sacra a m te CONTR IBUTORAND S, THE GISUSER COMMUNITY e r n C t re o e k R i v e r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
S
a c
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i H v S e Enterprise Subbasin Groundwater Sustainability Plan
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a Mbd Mbd Qls Qls r Dbr Dbr Dcg Pm c unlab Pbh SISKIYOU MODOC Dcg Mbd Pd k Dcg a Dcg Ppr e COUNTY COUNTY S Mbd e Trp Tt SHASTA Dbr Qls r Dcg Qrb r C Trp HUMBOLDT COUNTY Dcg md ate unlab Dbr llw COUNTY Dcg (! ti ENTERPRISE unlab k S or Pbh Qa F GROUNDWATER
t unlab s
Dcg a SUBBASIN LASSEN Dmm Qcb E Qrb unlab Kc COUNTY TRINITY Ch Qrb Qa Kc ek Kc Dbr Dbr Dbr urn Dk Qrb Cre COUNTY C Cow Dbr r le e itt Dbr Dbr e Qrb 299 L unlab Dbr k Qr «¬ Dcg Qr Kc Dbr unlab Qrb Qrb unlab Kc unlab unlab Qrb unlab Tt unlab Dbr unlab Qrb unlab unlab unlab TEHAMA Dcg Qa Kc COUNTY PLUMAS unlab unlab unlab unlab unlab Qrb BUTTE COUNTY unlab unlab Dcg unlab Qrb Kc Tva COUNTY Tte (! unlab unlab Qr Qa Qr Qr Dbr unlab Tva Qr LEGEND Dbr Dbr Dbr Spring Creek Dcg unlab Qrb Aunlab unlab Qrb S unlab Qr (! CITY Qrb Qrb Qr Tva Tva unlab a Qrb unlab Kc c Qrb Qr unlab r unlab Qr Kc a LOCATION OF CROSS SECTION m Qrb Qr Qr e unlab Rock C n FAULT LINE ree t Tt unlab k o unlab Qr 299 Tte Qr Dbr ¤£ Dmm Qrb Qrb unlab FAULT LINE (CONCEALED) Qr Tt Dcg R Qrb unlab Tva i Tte v Tte unlab SACRAMENTO RIVER e Qrb unlab unlab Tt r unlab unlab RIVER/STREAM unlab unlab Dbr t Tte unlab Qm unlab Qr Tt Tt INTERSTATE/HIGHWAY Dcg unlab Qrb Qr unlab Tmc Tt Tmc COUNTY BOUNDARY LINE Qrb unlab Tte Tt unlab (! unlab Kc unlab unlab unlab ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA) unlab Qr Qao Tte Tt unlab unlab unlab unlab unlab unlab Qls REDDING AREA GROUNDWATER BASIN Dbr unlab Tt Qm Qm Qrb Tte Qa unlab Tt Qa Tmc Tmc unlab Tte Tte unlab Tmc unlab Tte Qrb unlab unlab Ttm Kc Dbr unlab unlab unlab Tte «¬44 Tmc unlab unlab Qr unlab unlab Tmc unlab Qr(! Qvu Qa 5 Qrb Qa Qr unlab unlab unlab ¨¦§ Qrb unlab Qls unlab unlab unlab Qrb Qr unlab unlab unlab unlab unlab Qrb Qrb unlab Qrb Kc Dbr unlab unlab unlab unlab Tt Dmm unlab Qr unlab Qls k Qr Qr Tte unlab unlab e unlab unlab Qm e unlab unlab r Qr unlab wC Qm Qa unlab C o re unlab Qr r unlab C ek NOTES: unlab Qm e Kc t unlab unlab unlab a unlab
Kqd Tte Tte w l
Dbr Qm l GEOLOGY DERIVED FROM THE DIGITAL GEOLOGIC MAP OF THE Dbr unlab unlab i unlab Qao t Tt
Dbr Qr S Qbs REDDING 1° X 2° DEGREE QUADRANGLE, SHASTA, TEHAMA, Dbr Olney Creek unlab unlab t unlab Tt HUMBOLDT, AND TRINITY COUNTIES, CALIFORNIA (USGS, 2012). unlab Tt Qbs unlab unlab Qr FIGURE 3-6b PRESENTS EXPLANATION OF MAP UNITS. Dcg Dbr Dbr Qr B unlab unlab B' Qr Dbr Tte SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, unlab unlab unlab unlab Kqd unlab Tte unlab unlab Qr unlab Kqd unlab Qr INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, unlab unlab unlab Qrb unlab Tte unlab Tte Qr GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, Ks unlab unlab Qr unlab e METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP ar Cre k unlab Kqd Cle Qa unlab CONTRIBUTORS, AND THE GIS USER COMMUNITY unlab Qo Qr Qrb t Kqd unlab unlab unlab unlab A' Qm Qrb Qo unlab Qo Tte Kqd Sacra Qr t m e Qr Qr n Qo t unlab Qr Tt Qr o Qbs Qa R i v e Qr r Qm Qa Qm Qr Qbs unlab Qr Qr Qrb Qrb unlab Tt Qo Qo Qbs Qa Qr t 273 Qr «¬ Qo Qr Qr Qa Qrb unlab Qr Tte Qr Qm Qr Qrb Tt Miles Qm (! 0 2 4 q Qrb e Qm Qm unlab And rson Creek Ash Qr Creek unlab Qrb A Qm n ders Qr on C Tte o Tte t Qcb Qr to n S wo Ks Qr o a Qrb d c Qr r C a a m na FIGURE 3-6a l e Qrb Qab unlab n Qrb t COUNT Qeb o A Y ENTERPRISE SUBBASIN GEOLOGY Qrb Qr T R S Qrb A Enterprise Subbasin Groundwater Sustainability Plan i v H Qrb Qr unlab e S Qrb Ttc
r Qm Qrb t Qrb Qr Qr Qra Qcb D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-06A_GEOLOGY.MXD 6/8/2020 3:25:37 PM FELHADID FIGURE 3-6a MAP UNIT EXPLANATION SURFICIAL DEPOSITS t Ma n-m a d e m a te ria ls (Holoce ne ) Qa Alluvium a nd colluvium (Holoce ne ) Qo Ove rba nk d e pos its (Holoce ne ) Qao Alluvia l a nd ove rba nk d e pos its , und ivid e d (Holoce ne ) Qls La nd s lid e d e pos its (Holoce ne ) Qm Mod e s to form a tion of Da vis a nd Ha ll (1959) (Ple is toce ne ) Qr Rive rba nk Form a tion (Ple is toce ne ) Qrb Re d Bluff form a tion of Dille r (1894) (Ple is toce ne ) Qvu Volca nic rocks of the Millville qua d ra ngle (Ple is toce ne ) VOLCANIC ROCKS Qbs Ba s a lt of Shingle tow n Rid ge (Ple is toce ne ) Qeb Olivine ba s a lt of Ea gle Ca nyon (Ple is toce ne ) Qab And e s ite of Broke off Mounta in (Ple is toce ne ) Qra Rockla nd a s h be d of Sa rna -Wojcicki a nd othe rs (1982) Qcb Ba s a lt of Cole m a n Fore ba y (PIe is toce ne ) Tva And e s itic bre ccia (Plioce ne ) Kqd Sha s ta Ba lly Ba tholith (Low e r Cre ta ce ous ) PLUTONIC ROCKS Tte Te ha m a Form a tion (Plioce ne ) Tt Tus ca n Form a tion, und ivid e d (Plioce ne ) Ttc La ha rs w ith m inor inte rbe d d e d volca nic conglom e ra te a nd s a nd s tone SEDIMENTARY ROCKS Tmc Montgom e ry Cre e k Form a tion (Eoce ne ) Kc Chico Form a tion (Uppe r Cre ta ce ous ) Ks Se d im e nta ry Rocks (Low e r Cre ta ce ous ) Trp Pit Form a tion (Pe rm ia n(?) or Tria s s ic)) Pbh Bully Hill Rhyolite (Pe rm ia n(?)–Mid d le Tria s s ic(?)) Pd De kka s And e s ite (Pe rm ia n) Pm McCloud Lim e s tone (Pe nns ylva nia n(?) a nd Pe rm ia n) EASTERN KLAMATH TERRANE Ppr Pit Rive r s tock (Pe rm ia n) md Ma fic rocks (Pe rm ia n(?)) Mbd Bra gd on Form a tion (Mis s is s ippia n) Dk Ke nne tt Form a tion (De vonia n) Dmm Mule Mounta in s tock (De vonia n) Dbr Ba la kla la Rhyolite (De vonia n(?)) Dcg Cople y Gre e ns tone (De vonia n(?))
NOTES:
GEOLOGY DERIVED FROM THE DIGITAL GEOLOGIC MAP OF THE REDDING 1° X 2° DEGREE Q UADRANGLE, SHASTA, TEHAMA, HUMBOLDT, AND TRINITY COUNTIES, CALIFORNIA (USGS, 2012). FIGURE 3-6b MAP UNIT (Ttm ) LABELED ON THE MAP IS OF UNKNOWN IDENTITY AND AGE; OTHER AREAS (unla b) ARE OF UNKNOWN IDENTITY AND AGE. BOTH ARE UNFILLED ON THIS LIST OF MAP UNITS MAP. Enterprise Subbasin Groundwater Sustainability Plan
D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-06B_MAPUNITEXPLANATION.MXD 5/12/2020 8:30:06 AM FELHADID NORTH SOUTH A A' 800 800
700 700 Highway 299 at East Fork Stillwater Creek Highway 44 Intersection with B-B' Section
600 WCR1965-001100 600 31N04W03M 32N04W34L01 WCR2007-008837 32N04W27D01 31N04W09 31N04W16 31N04W22 31N04W22P1 31N04W22H 31N04W22P2 31N04W27P1 31N04W27 500 31N04W34 500
400 ? 400
300 300
200 200 Elevation (feet NAVD88) 100 100
0 0
-100 -100
-200 -200
?
-300 -300
0 000,5 000,01 000,51 000,02 000,52 000,03 000,53 000,04 000,54 000,05 Distance (feet)
GROUND SURFACE ELEVATION (feet NAVD88) SCALE EXAGGERATION – 20:1 (H:V) TOP OF CHICO FORMATION (DASHED WHERE UNCERTAIN) SOIL AND LITHOLOGY GROUNDWATER ELEVATION (feet NAVD88) SCREEN INTERVAL SAND GRAVEL CLAY BASALT FINE-GRAINED UNITS NOTES: CLAYEY SAND CLAYEY GRAVEL SANDY CLAY HARD PAN COARSE-GRAINED UNITS LOCATION OF CROSS SECTION SHOWN ON FIGURE 3-6. GRAVELLEY SAND SANDY GRAVEL GRAVELLEY CLAY SHALE GROUNDWATER ELEVATION IS ESTIMATED FROM GROUNDWATER LEVELS MEASURED BETWEEN OCTOBER 16 AND OCTOBER 26, 2018 SILTY SAND SILTY GRAVEL SILT UNDIFFERENTIATED ROCK (DWR, 2019b) (SEE FIGURE 3-13). FIGURE 3-7 TOP OF CASING ELEVATION OF SOME WELLS DIFFER FROM THE SANDSTONE TUFF SILTSTONE UNDIFFERENTIATED SOIL ELEVATION OF THE PROFILE BECAUSE THOSE WELLS ARE NOT GEOLOGIC CROSS SECTION A-A' COLLINEAR WITH THE SECTION LINE. Enterprise Subbasin Groundwater Sustainability Plan
NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988. D:\REDDINGCACITYOF\GINT\EAGSA_SECTIONS.GPJ; 800 800
700 700 WEST B Intersection with A-A' Section Airport Road 600 600 WCR1992-013953 31N03W19M 31N04W22H 31N04W22P1 31N04W23 31N04W22P2 31N04W26 31N04W21
500 31N04W23E01 500 31N04W20J01 WCR2018-003336 Cow Creek 31N03W20
400 400
300 300
200 200 Elevation (feet NAVD88) 100 100
0 0
-100 -100
-200 ? -200 ?
-300 -300
0 000,5 000,01 000,51 000,02 000,52 000,03 000,53 Distance (feet)
GROUND SURFACE ELEVATION (feet NAVD88) SCALE EXAGGERATION – 14:1 (H:V) TOP OF CHICO FORMATION (DASHED WHERE UNCERTAIN) SOIL AND LITHOLOGY GROUNDWATER ELEVATION (feet NAVD88) SCREEN INTERVAL SAND GRAVEL CLAY BASALT FINE-GRAINED UNITS NOTES: CLAYEY SAND CLAYEY GRAVEL SANDY CLAY HARD PAN COARSE-GRAINED UNITS LOCATION OF CROSS SECTION SHOWN ON FIGURE 3-6. GRAVELLEY SAND SANDY GRAVEL GRAVELLEY CLAY SHALE GROUNDWATER ELEVATION IS ESTIMATED FROM GROUNDWATER LEVELS MEASURED BETWEEN OCTOBER 16 AND OCTOBER 26, 2018 SILTY SAND SILTY GRAVEL SILT UNDIFFERENTIATED ROCK (DWR, 2019b) (SEE FIGURE 3-13). FIGURE 3-8 TOP OF CASING ELEVATION OF SOME WELLS DIFFER FROM THE SANDSTONE TUFF SILTSTONE UNDIFFERENTIATED SOIL ELEVATION OF THE PROFILE BECAUSE THOSE WELLS ARE NOT GEOLOGIC CROSS SECTION B-B' COLLINEAR WITH THE SECTION LINE. Enterprise Subbasin Groundwater Sustainability Plan
NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988. D:\REDDINGCACITYOF\GINT\EAGSA_SECTIONS.GPJ; r e iv R o t n e
m
a
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c SISKIYOU MODOC k a e COUNTY COUNTY S e r SHASTA r C HUMBOLDT COUNTY ate lw COUNTY (! til ENTERPRISE k S or F GROUNDWATER
C t
s
h a SUBBASIN LASSEN u E r COUNTY n k TRINITY Cr Cree eek Cow COUNTY Little
«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a DEPTH TO CHICO FORMATION (feet BGS) m
e n SACRAMENTO RIVER t ¤£299 o Rock Creek RIVER/STREAM R
i v INTERSTATE/HIGHWAY e
r COUNTY BOUNDARY LINE
ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN (!
100
«¬44 (! Cow Creek 500
¨¦§5
NOTE: Olney Creek DATA SOURCE: DIGITIZED FROM DWR, 1968 200 BGS = BELOW GROUND SURFACE 300 700 400 SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP CONTRIBUTORS, AND THE GIS USER COMMUNITY Sacra Cle eek m S ar Cr t e il n lw 600 t o a te R r i v C e r r e e k
«¬273
700
800 Miles (! 900 0 2 4 q derso An n Creek As h Creek A 1000 n ders on C o t to n S wo o a d 1500 c r C a an m 2000 a FIGURE 3-9 l e n OUN t C TY o A ST DEPTH TO THE TOP OF THE CHICO FORMATION R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
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a r k c MODOC e SISKIYOU a e COUNTY r COUNTY S SHASTA r C ate HUMBOLDT COUNTY illw COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
s
a SUBBASIN LASSEN E k COUNTY Cree TRINITY Cow COUNTY Little
«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a SACRAMENTO RIVER m
e n RIVER/STREAM t ¤£299 o Rock Creek INTERSTATE/HIGHWAY R
i v COUNTY BOUNDARY LINE e
r ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN SAGBI RATING (RATING CLASS) (! 85 to 100 (EXCELLENT)
69 to 85 (GOOD)
49 to 69 (MODERATELY GOOD)
29 to 49 (MODERATELY POOR) «¬44 (! 15 to 29 (POOR) Cow Creek 0 to 15 (VERY POOR)
¨¦§5
NOTES: Creek Ch Olney u r n DATA SOURCE: SOIL AGRICULTURAL GROUNDWATER BANKING INDEX Cr eek (SAGBI) (O'GEEN ET AL., 2015)
SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, e GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, ar Cre k Cle METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP S
t CONTRIBUTORS, AND THE GIS USER COMMUNITY i l l w Sacra a m te e r n C t re o e k R i v e r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
S
a c r FIGURE 3-10 a m SOIL AGRICULTURAL GROUNDWATER e n OUN t C TY o A ST BANKING INDEX MAP R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
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a r k c MODOC e SISKIYOU a e COUNTY r COUNTY S SHASTA r C ate HUMBOLDT COUNTY illw COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
s
a SUBBASIN LASSEN E k COUNTY Cree TRINITY Cow COUNTY Little
«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a SACRAMENTO RIVER m
e n RIVER/STREAM t ¤£299 o Rock Creek INTERSTATE/HIGHWAY R
i v COUNTY BOUNDARY LINE e
r ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN NATURAL COMMUNITIES COMMONLY ASSOCIATED (! WITH GROUNDWATER VEGETATION NATURAL COMMUNITIES COMMONLY ASSOCIATED WITH GROUNDWATER WETLANDS
«¬44 (! Cow Creek
NOTES: 5 ¨¦§ DATA SOURCE: HTTPS://GIS.WATER.CA.GOV/APP/NCDATASETVIEWER/#. ACCESSED MARCH 2020 (DWR, 2020c)
Creek Ch Olney u r n SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, C INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, ree k GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP CONTRIBUTORS, AND THE GIS USER COMMUNITY
Creek Clear
S
t i l l w Sacra a m te e r n C t re o e k R i v e r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
S
a c r FIGURE 3-11 a m POTENTIAL GROUNDWATER-DEPENDENT e n OUN t C TY o A ST ECOSYSTEMS R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
e
r D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-11_POTGWECOSYSTEM.MXD 6/8/2020 3:29:34 PM FELHADID r e iv R o t n e
m
a
r
c SISKIYOU MODOC k a e COUNTY COUNTY S e r SHASTA r C HUMBOLDT COUNTY ate lw COUNTY (! til 750 ENTERPRISE k S or F GROUNDWATER
t
s a SUBBASIN LASSEN
675 E 700 reek COUNTY C Cow C TRINITY hurn 675 ittle COUNTY C L r e 650 e k «¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY 625 (! COUNTY
pring Cr LEGEND S eek ´ S ! GROUNDWATER ELEVATION LOCATION a
c r MEASURED GROUNDWATER ELEVATION (feet NAVD88) a 600 m 463.34 (GRAY TEXT INDICATES ELEVATION NOT USED e n IN CONTOURING) t 299 o ¤£ R 600 (! oc k Creek 575 CITY R
i v 550 SPRING 2018 GROUNDWATER ELEVATION CONTOUR (feet NAVD88) e
r SACRAMENTO RIVER 525 32N04W33G001M RIVER/STREAM 534.44 !´ 500 INTERSTATE/HIGHWAY (! !´ Columbia 473.00 COUNTY BOUNDARY LINE 475 ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA) 31N03W06H001M 463.34 !´ REDDING AREA GROUNDWATER BASIN
«¬44 450 (! owC C re e k 31N04W15K001M 412.63 §5 425 NOTES: ¨¦ ´ ! GROUNDWATER LEVELS WERE MEASURED BETWEEN MARCH 19 AND APRIL 3, 2018 (DWR, 2019b). reek 31N04W29R003M Olney C S t 408.40 i WELLS SCREENED IN SHALLOW GROUNDWATER, POINT LOCATIONS l l w 31N04W29R004M a ALONG SACRAMENTO RIVER WITH INTERPOLATED SURFACE WATER t e ELEVATIONS, AND RIVER GAGES BELOW KESWICK RESERVOIR 412.10 r C (11370500) AND AT BEND BRIDGE IN RED BLUFF (11377100) WERE r 31N04W29R005M e e 31N04W25Q001M USED IN CONTOURING SHALLOW GROUNDWATER. REDFEM MODEL 415.50 k OUTPUTS WERE USED TO SUPPLEMENT AREAS WITHOUT CURRENT 31N04W29R006M 406.09 Creek GROUNDWATER ELEVATION DATA (CH2M HILL, 2011 AND USGS, 2019a). Clear !´ 406.40 !´ !´ 31N04W27P001M NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988 Sacr 407.79 am 400 SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, e n INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, t o GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, R i 30N03W06K001M v METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP e ´ r 390.07 ! CONTRIBUTORS, AND THE GIS USER COMMUNITY
«¬273 375
Miles (! 0 2 4 q e And rson Creek Ash Creek A n ders on C o t to n S wo o a d c r FIGURE 3-12 C a a m na SPRING 2018 GROUNDWATER l e n OUN t C TY o A ST ELEVATION CONTOURS R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
e
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a
r
c SISKIYOU MODOC k a e COUNTY COUNTY S e r SHASTA r C HUMBOLDT COUNTY ate lw COUNTY (! til 750 ENTERPRISE k S or F GROUNDWATER
t
s a SUBBASIN LASSEN
675 E 700 reek COUNTY C Cow C TRINITY hurn 675 ittle COUNTY C L r e 650 e k «¬299 625 TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
pring Cr LEGEND S eek ´ S ! GROUNDWATER ELEVATION LOCATION a
c r 600 MEASURED GROUNDWATER ELEVATION (feet NAVD88) a m 463.34 (GRAY TEXT INDICATES ELEVATION NOT USED e n IN CONTOURING) t 299 o ¤£ R 600 (! oc k Creek 575 CITY R
i v FALL 2018 GROUNDWATER ELEVATION CONTOUR (feet NAVD88) e 550 r SACRAMENTO RIVER 32N04W33G001M 525 523.44 RIVER/STREAM !´ 500 INTERSTATE/HIGHWAY (! !´ Columbia 459.00 COUNTY BOUNDARY LINE 475 ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA) 31N03W06H001M 459.14 !´ REDDING AREA GROUNDWATER BASIN
«¬44 450 (! owC C re e k 31N04W15K001M 410.33 §5 425 NOTES: ¨¦ ´ ! GROUNDWATER LEVELS WERE MEASURED BETWEEN OCTOBER 16 AND OCTOBER 26, 2018 (DWR, 2019b) reek 31N04W29R003M Olney C S t 407.50 i WELLS SCREENED IN SHALLOW GROUNDWATER, POINT LOCATIONS l l w 31N04W29R004M a ALONG SACRAMENTO RIVER WITH INTERPOLATED SURFACE WATER t e ELEVATIONS, AND RIVER GAGES BELOW KESWICK RESERVOIR 416.20 r C (11370500) AND AT BEND BRIDGE IN RED BLUFF (11377100) WERE r 31N04W29R005M e e USED IN CONTOURING SHALLOW GROUNDWATER. REDFEM MODEL 417.60 k OUTPUTS WERE USED TO SUPPLEMENT AREAS WITHOUT CURRENT 31N04W29R006M Creek GROUNDWATER ELEVATION DATA (CH2M HILL, 2011 AND USGS, 2019a) Clear !´ 407.60 !´ 31N04W27P001M NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988 Sacr 401.19 am SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, e n 400 INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, t o GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, R i 30N03W06K001M v METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP e ´ r 389.17 ! CONTRIBUTORS, AND THE GIS USER COMMUNITY
«¬273 375
Miles (! 0 2 4 q e And rson Creek Ash Creek A n ders on C o t to n S wo o a d c r FIGURE 3-13 C a a m na FALL 2018 GROUNDWATER l e n OUN t C TY o A ST ELEVATION CONTOURS R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
e
r D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-13_GWELEVFALL2018.MXD 6/11/2020 3:37:23 PM FELHADID m
a r k MODOC c e SISKIYOU a e COUNTY r COUNTY S C SHASTA ter COUNTY wa HUMBOLDT ill COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
s
a SUBBASIN 560 LASSEN E k COUNTY Cree TRINITY Cow COUNTY Little k ee 520 Cr g n 299 i «¬
r p
S 480 TEHAMA COUNTY PLUMAS BUTTE COUNTY 440 (! COUNTY
MAP LEGEND Groundwater Elevation(feet NAVD88) 400 ´! S GROUNDWATER ELEVATION LOCATION
a
c r (! CITY a
m 1995 2005 2000 2010 2015 1975 1985 1970 1980 1990 560 e SACRAMENTO RIVER n
t ¤£299 o Rock Creek RIVER/STREAM
R 520
i v INTERSTATE/HIGHWAY e r COUNTY BOUNDARY LINE 480 ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN ´! 32N04W33G001M 440 (!
560 GRAPH LEGEND Groundwater Elevation(feet NAVD88) 400 GROUNDWATER ELEVATION (feet NAVD88) 31N03W06H001M ´! SACRAMENTO VALLEY HYDROLOGIC REGION 520 UNIMPAIRED RUNOFF (5 MILLION ACRE-FEET) 1995 2005 1975 1985 2000 2010 2015 1970 1980 1990 31N04W09D001M «¬44 eek WET YEAR ´! (! Cr ! w 480 ´ o C ABOVE NORMAL YEAR 31N04W09C001M 560 BELOW NORMAL YEAR
440 520 DRY YEAR ¦¨§5 CRITICAL YEAR
Groundwater Elevation(feet NAVD88) 31N04W15K001M ´! 400 31N04W09D001M 31N04W09C001M 480 O ln Ch NOTES: ey u C r 1995 2005 1975 1985 2000 2010 2015 n 1970 1980 1990 re ek C 440 DATA SOURCES: DWR, 2019b reek NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988 Groundwater Elevation(feet NAVD88) 400 SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, Creek INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, Clear 1995 2005
1975 1985 2000 2010 2015 GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, S 1970 1980 1990
t i METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP l l w CONTRIBUTORS, AND THE GIS USER COMMUNITY Sacra a m te e r 560 n C t re o e R k i v e 520 r 30N03W06K001M ´!
480
«¬273 440
A nd ers Groundwater Elevation (feet NAVD88) 400 on C Miles ot ton (! 0 2 4 wood q C 1995 2005 2000 2010 2015 1975 1985 er 1970 1980 1990 a And son Creek n al
A sh Cree k
S
a c
r a m FIGURE 3-14 e n COUNT t A Y SELECT HYDROGRAPHS o ST
R A H Enterprise Subbasin Groundwater Sustainability Plan i
v S
e
r D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-14_SELECTHYDROGRAPHS.MXD 6/8/2020 3:48:12 PM FELHADID 425
420
415
410
405
400
395 GROUNDWATER ELEVATION (feet NAVD88) ELEVATION GROUNDWATER
390
385 2008 2005 2002 2006 2003 2008 2005 2002 2006 2003 2017 2014 2011 2018 2015 2012 2009 2017 2014 2011 2018 2015 2012 2009 2001 2004 2007 2010 2013 2016
WATER YEAR LEGEND 31N04W29R003M (200.6 to 119.6) WET YEAR ABOVE NORMAL YEAR 31N04W29R004M (275.6 to 235.6) BELOW NORMAL YEAR 31N04W29R005M (330.6 to 320.6) DRY YEAR 31N04W29R006M (199.6 to 119.6) CRITICAL YEAR NOTES: FIGURE 3-15 (200.6 to 119.6) = WELL SCREEN ELEVATION (feet NAVD88) ENTERPRISE SUBBASIN WELL DATA SOURCES: DWR, 2019a and 2020a CLUSTER HYDROGRAPHS Enterprise Subbasin Groundwater Sustainability Plan NAVD88 = NORTH AMERICAN VERTICAL DATUM OF 1988
D:\ReddingCACityof\EAGSA\Figures\Grapher\EGSP\FIG03-15_ClusterHydrographs.grf r e iv R o t n e
m
a r k c MODOC e SISKIYOU a e COUNTY r COUNTY S SHASTA r C ate HUMBOLDT COUNTY illw COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
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«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S (! CITY a
c
r a SACRAMENTO RIVER m
e n RIVER/STREAM t ¤£299 o Rock Creek INTERSTATE/HIGHWAY R
i v COUNTY BOUNDARY LINE e
r ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA)
REDDING AREA GROUNDWATER BASIN GROUNDWATER LEVELS WITHIN 20 FEET OF (! GROUND SURFACE (feet BGS) ABOVE GROUND SURFACE TO 5 FEET 5 to 10
10 to 15 ¬«44 (! 15 to 20 Cow Creek
¨¦§5 NOTES: BGS = BELOW GROUND SURFACE
Creek Ch SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, Olney u r n INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, C GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, ree k METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP CONTRIBUTORS, AND THE GIS USER COMMUNITY
Creek Clear
S
t i l l w Sacra a m te e r n C t re o e k R i v e r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
S
a c r FIGURE 3-16 a m GROUNDWATER WITHIN 20 FEET OF e n OUN t C TY o A ST LAND SURFACE R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
e
r D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-16_GW_LANDSURFACE.MXD 6/8/2020 3:55:11 PM FELHADID Figure 3-17 -PENDING- r r e e iv iv R R o o t t SHASTAn COUNTY SHASTAn COUNTY e e
m m
a a
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c c SISKIYOU a a COUNTY S S COUNTY SHASTA (! (! HUMBOLDT COUNTY C C COUNTY h (! h ENTERPRISE ur ek ur ek n C Cre n C Cre GROUNDWATER r ow r ow e e C e e C e ttl e ttl SUBBASIN LASSEN k Li k Li 299 299 COUNTY «¬ «¬ TRINITY COUNTY (! (! ¨¦§5 (! ¨¦§5 Spring Creek (! Spring Creek S S
a a
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r r a a
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t t o o COUNTY PLUMAS AAA(! AAAAA(! COUNTY R A(! R BUTTE i i v A v e A e COUNTY r r (! LEGEND (! (! (! SAMPLING LOCATION (NO EXCEEDANCES) (!(!A (! (! AAAA(! (! A SAMPLING LOCATION (1 to 5 EXCEEDANCES) !(A!(!(!A(!(! (!A(! AAA((!AA(! (! (! AAAAAAA A ¬44 C ¬44 C ! (! « (! (! (!A(!(! o (! « (! o ( (! (! A w Creek w Creek A SAMPLING LOCATION (> 5 EXCEEDANCES) (! (!(! A(! A A(! A(! (! (!(!A (!(! (! (!(! (! (! (! (! (! (! CITY (! ! (! (! ( AAA(! (! A SACRAMENTO RIVER Olney Creek A (!(! (! Olney Creek RIVER/STREAM (! (! (!(! (! (! INTERSTATE/HIGHWAY
An (! An COUNTY BOUNDARY LINE de (!! (!(! de rs (!( S rs S o o k n (! t k n t e (! (!(! il e il ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA) Clear Cre C lw Clear Cre C lw o a o a t (! (! te t te to (! r to r REDDING AREA GROUNDWATER BASIN n (!(! C n C wo (!! (! ! (! (! wo o (! ((! r o r d (! e d e C ! !( e C e a ( ( k a k n n a a l l BENZENE «¬273 GASOLINE «¬273
r r e e iv iv R (! R (! o o t t SHASTAn COUNTY SHASTAn COUNTY e e
m m
a a
r r NOTES:
c c
a a
S S (! (! DATA USED TO ASSESS AREAS OF AFFECTED GROUNDWATER ARE C C FROM 2000 THROUGH 2019 (SWRCB, 2019a). h h (! ur ek ur ek n C Cre n C Cre r Cow r Cow BENZENE CA EPA MAXIMUM CONTAMINANT LEVEL = 1 µg/L e le e le e itt e itt k 299 L k 299 L «¬ «¬ GASOLINE US FEDERAL HEALTH ADVISORY LEVEL = 5 µg/L
(! (! TERT-BUTYL ALCOHOL FEDERAL NOTIFICATION LEVEL = 12 µg/L ¨¦§5 (! ¨¦§5 (! Spring Creek (! Spring Creek A(! METHYL-TERT-BUTYL ETHER (MTBE) CA EPA MAXIMUM S S
a a
c c r r CONTAMINANT LEVEL = 13 µg/L a a
m m
e e
n n
t t o o µg/L = MICROGRAMS PER LITER AAAA(! AAAA R A(! R A(! i A i A v A v A e e A r r SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, (! INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, (! (! METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP AAA(!(! (!(!AA CONTRIBUTORS, AND THE GIS USER COMMUNITY (!A(!(!!( (!(!A(!(!(! A(!A(! (! AA(!AAA (! A ¬44 C AAA ¬44 C (! « (! (!A(!(! o ! (! « (! (! (!(!(! o (! (! A w Creek ( (! (! A w Creek A(! (!(! A(! (!(! (! A A(! (!(! (! (!(!A (! (! (! (! (! (! (! (!A (! (! (! (! (! (! (! ! (! ! (! (! ( (! (! ( A(! (! A(! (! Cree A (! (! Cree A (!(! (! Olney k Olney k Miles (! (! (! 0 3.5 7 q (!(! (! (!(! (!
An An (! de (!! (! de (!! (! rs (!( S rs (!( S o o k n t k n t e (! (!(! il e (! (!(! il Clear Cre C lw Clear Cre C lw o a o a t (! te t (! (! te to (! r to (! r n (!(! C n (!(! C wo (! wo (! (! (! (! (! (! r (! (! (! r o A e o (! e d (! d (! FIGURE3-18 C ! (! e C ! (! e a ( k a ( k n n GROUNDWATERSAMPLING LOCATIONS – a a l l ORGANICS 273 273 TERT-BUTYLALCOHOL «¬ MTBE «¬ Enterprise Subbasin Groundwater Sustainability Plan (! (! D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-18_ORGANICSGW.MXD 6/10/2020 12:36:27 PM FELHADID r e r r v e e i v v R i i R R o t o o t t n SHASTACOUNTY n SHASTACOUNTY n SHASTACOUNTY e e e
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S S S (! (! (! C C C h (! h (! h (! u k u u rn Cree rn reek rn reek Cr w C C C C e Co r ow r ow e e C e C e tl e le e le k it tt tt L k Li k Li «¬299 «¬299 «¬299 5 (! 5 (! 5 (! ¨¦§ (! ¨¦§ (! ¨¦§ (! (! (! (! (! (! S S S a a a c c c r a r r a a m m m e (! (! e ! e ! n ( ( ! n n t ( !! ! t (( t ( o o o ! R (! ( R (! R (! i v i i v v e e e r r r (! (! (! (! (! (!
(! (! (! (! (! (! (! (! AAAAA(!(! (! (!(! ! ! AAAAA !( ((! ! (! ((! (! A (! (!(!AAAA( (! (! (!AAAAA(!AAAAAA A (! ¬44 C 44 A 44 ! (! « (! (! (! o (! «¬ (! Co (! «¬ (! (! Co ( (! (! w Creek (! (! A (! w Cr (! A (! w Cr (!(! (!(! eek eek (! (!(! (! (! AA(!(! A (! (! (! (! (! (! A(! (!! (!(! (!(! (! (!(! (! (!(! ( (! (!(! (!(! (!(! (! (!(! (! (! (!(! (! (!(! (! A(! (! (! (! ! ! (! (! (! ( ( (! AA (! (! (! (! (! (! (! (! (! A(! (! re (! (! A A Olney C ek (!(! (! Olney Creek (!A(!(! A Olney Creek (!(!(! (! (! (! (! A (! (! (! (! (! (! (! (! A A nd (! (! A (! A (! e (!(! nde !(! (! nde !(! (! r (!(! S (! (! s r (!(! S r (!(! (! S o s s n t o t o t (! (!(! il n i n i C lw C (! (!(! ll C (! (!(! ll o w w a o a o a t (! (! te t t t t t r (! (! e (! (! e o (! to r to r n (!(! (! C n (!! n (!! wo (! ! (! (! w ((! (! (! C ! w A( (! (! C ! (! ( ! r o (!(! (! ! ( o (!(! (! (! ! ( o ( e o (! (! ((!r o (! (! ((!r d (! (! e e C (! e d (! (! e d (! (! e a (! C ! (! C ! (! k a ( k a ( k n n n a a a l l l ALUMINUM «¬273 ARSENIC «¬273 IRON «¬273
r r e e iv iv R (! R (! (! o o t t n SHASTACOUNTY n SHASTACOUNTY e e NOTES: LEGEND m m
a a
r r
c c a a (! SAMPLING LOCATION (NO EXEEDANCES) S S DATA USED TO ASSESS AREAS OF AFFECTED (! (! GROUNDWATER ARE FROM 2000 THROUGH 2019 (SWRCB, A SAMPLING LOCATION (1 to 5 EXCEEDANCES) C C h (! h (! 2019a). ur ek ur ek n C Cre n C Cre r ow r ow SAMPLING LOCATION (> 5 EXCEEDANCES) e e C e e C ALUMINUM CA EPA MCL = 1,000 µg/L A e ttl e ttl k Li k Li ARSENIC CA EPA MCL = 10 µg/L (! CITY ¬299 ¬299 « « SACRAMENTO RIVER 5 (! 5 (! IRON SECONDARY MCL = 300 µg/L ¨¦§ (! ¨¦§ (! (! (! (! (! RIVER/STREAM S S LEAD US FEDERAL ACTION LEVEL= 15 µg/L a a
c c
r r a a m (! m (! INTERSTATE/HIGHWAY e (! e (! n ! n MANGANESE US HEALTH ADVISORY LEVEL = 50 µg/L t ( t (! o o (! COUNTY BOUNDARY LINE R AAA (! R (! i i v v µg/L = MICROGRAMS PER LITER e e r r ENTERPRISE GROUNDWATER SUBSASIN (! (! (! (! SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, (5-006.04, PLAN AREA) GARMIN, INTERMAP, INCREMENT P CORP., GEBCO, USGS, REDDING AREA GROUNDWATER BASIN (! (! (! (! FAO, NPS, NRCAN, GEOBASE, IGN, KADASTER NL, (! AAAAA(!(! (! ORDNANCE SURVEY, ESRI JAPAN, METI, ESRI CHINA (!(! (! (!(! (! (HONG KONG), SWISSTOPO, © OPENSTREETMAP (!(!(! (! (!AA(!AAA (! (! A CONTRIBUTORS, AND THE GIS USER COMMUNITY ¬44 C ¬44A C ! (! « (! (! (! o ! (! « (! o ( (! (! w Creek ( A A w Creek (!(! (! (!(! A A(! !(! (! ! (!A(! (! (! ( (!(! (! (!(! A ( (! (!(! (! (!(! (! (! (!(! (! (!(! (! A(! ! ! (! (! A ((!( (! (!(! (! (! (! AA (! (! (!A (! A (! Cree (!(!(!A (! Cree A (!(! Olney k Olney k A A Miles (! A (! 0 3.5 7 q (! (! (! AA (! (! An (! (! An (! (! de ! (!(! de ! (!(! rs (A S rs ((! (! S o o n t n t (! (! il (! (!(! il C lw C lw o a o a t (! (! te t (! (! te to (! r to (! r n (!(! (! C n (!(! (! C wo (!! (! (! (! wo (!! ! ! (! (! o (! (! (!(!r o (! ( ((! (!(!r d (! (! e d (! (! e FIGURE3-19 C ! (! e C ! (! e a ( k a ( k n n GROUNDWATERSAMPLING LOCATIONS – a a l l INORGANICS 273 273 LEAD «¬ MANGANESE «¬ Enterprise Subbasin Groundwater Sustainability Plan (! (! D:\REDDINGCACITYOF\EAGSA\FIGURES\ARCMAP\MAPFILES\EGSP\3.0\FIG03-19_INORGANICSGW.MXD 6/11/2020 3:39:23 PM FELHADID r e iv R o t n e
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a r k c MODOC e SISKIYOU a e COUNTY r COUNTY S SHASTA r C ate HUMBOLDT COUNTY illw COUNTY (! St ENTERPRISE rk Fo t GROUNDWATER
s
a SUBBASIN LASSEN E k COUNTY Cree TRINITY Cow COUNTY Little
«¬299
TEHAMA COUNTY PLUMAS BUTTE COUNTY (! COUNTY
LEGEND Spring Creek S ACTIVE REMEDIATION SITE
a c CALIFORNIA STATE DEPARTMENT OF r a ") m TOXIC SUBSTANCES CONTROL
e
n t ") STATE WATER RESOURCES CONTROL BOARD ¤£299 o Rock Creek (! CITY R
i v e SACRAMENTO RIVER r RIVER/STREAM
INTERSTATE/HIGHWAY
(! COUNTY BOUNDARY LINE ") TAY VAN CAR WASH ENTERPRISE GROUNDWATER SUBSASIN (5-006.04, PLAN AREA) REDDING AREA GROUNDWATER BASIN
¬«44 (! Cow Creek
SEWAGE SETTLING POND ") 5 NOTES: ¨¦§ CHURN CREEK CHEVRON ") DATA SOURCES: DTSC, 2019 AND SWRCB, 2019b ") 76 SS# 2611241
Creek Ch SERVICE LAYER CREDITS: SOURCES: ESRI, HERE, GARMIN, Olney u r n INTERMAP, INCREMENT P CORP., GEBCO, USGS, FAO, NPS, NRCAN, C GEOBASE, IGN, KADASTER NL, ORDNANCE SURVEY, ESRI JAPAN, ree k METI, ESRI CHINA (HONG KONG), SWISSTOPO, © OPENSTREETMAP CONTRIBUTORS, AND THE GIS USER COMMUNITY
Creek Clear
S
t i l l w Sacra a m te e r n C t re o e k R i v e r
«¬273
A n ders o n C Miles ot ton 0 2 4 wo (! q od C a ers And on Creek A n al sh Creek
S
a c
r a m FIGURE 3-20 e n OUN t C TY o A ST ACTIVE REMEDIATION SITES R A Enterprise Subbasin Groundwater Sustainability Plan i H v S
e
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