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USGS Surface-Water Daily Statistics for the Nation

The statistics generated from this site are based on approved daily-mean data and may not match those published by the USGS in official publications. The user is responsible for assessment and use of statistics from this site. For more details on why the statistics may not match, click here.

USGS 08150700 Llano Rv nr Mason, TX


Mason County, Texas
Hydrologic Unit Code 12090204
Latitude  30°39'38", Longitude  99°06'32" NAD27
Drainage area 3,247  square miles
Contributing drainage area 3,242  square miles
Gage datum 1,225.60 feet above NAVD88
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00060, Discharge, cubic feet per second,
Day of
month		 Mean of daily mean values for each day for water year of record in, ft3/s   (Calculation Period 1967-10-01 -> 2024-09-30)

Calculation period restricted by USGS staff due to special conditions at/near site
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1 440 179 193 184 202 401 220 231 210 210 271 198
2 233 206 186 181 372 331 231 296 350 167 248 195
3 214 234 184 184 636 306 232 738 196 154 892 193
4 205 356 193 184 332 535 216 189 193 240 1,760 192
5 198 295 199 183 291 341 291 152 179 471 356 192
6 193 243 210 193 238 253 240 180 165 299 377 192
7 189 215 255 212 208 283 177 177 159 234 281 191
8 186 204 217 215 239 237 154 156 1,430 770 261 193
9 186 197 211 204 302 291 148 132 491 618 245 193
10 185 192 202 216 343 255 143 131 189 418 232 191
11 182 193 219 214 734 257 190 133 166 215 219 190
12 181 191 233 193 351 397 717 408 165 263 210 189
13 180 188 232 186 245 268 179 312 173 1,850 207 188
14 178 185 211 179 289 245 148 273 158 1,210 203 188
15 179 183 199 370 288 212 140 205 158 343 567 190
16 180 202 221 728 348 261 225 171 171 2,810 690 188
17 180 188 202 387 252 613 220 316 291 555 1,130 184
18 180 190 197 355 283 377 168 254 670 290 370 182
19 178 190 194 322 236 219 156 169 253 491 279 183
20 176 181 241 245 245 194 153 147 204 540 251 219
21 175 183 268 277 308 178 140 152 249 300 236 285
22 174 186 248 232 281 197 150 145 488 238 226 247
23 172 207 212 235 215 169 142 162 291 283 223 225
24 171 215 197 208 321 174 173 355 199 868 217 211
25 171 293 190 193 523 187 191 243 192 364 219 201
26 178 226 197 181 663 165 280 206 217 392 223 203
27 185 203 346 215 393 230 175 176 325 390 221 201
28 184 194 267 237 307 199 161 287 217 266 211 193
29 207 216 220 211 348 208 143 820 187 338 205 190
30 192   206 194 341 320 134 819 322 386 201 189
31 184   194   297   195 388   296   1,260