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USGS 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 -> 2025-09-30)

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
1 433 178 191 179 197 396 217 233 207 207 267 196
2 230 203 184 177 375 327 227 297 345 165 245 192
3 211 231 182 180 621 302 229 729 196 152 877 191
4 202 350 190 179 372 527 212 191 194 237 1,730 190
5 195 291 197 178 323 336 286 153 181 464 351 190
6 190 240 207 189 243 249 236 180 166 295 371 190
7 187 212 251 206 208 279 175 178 159 231 277 189
8 184 201 214 209 236 233 152 157 1,410 757 258 191
9 184 195 208 199 296 286 146 132 484 608 242 191
10 183 190 200 211 334 251 141 132 188 411 229 188
11 180 191 216 208 710 254 187 133 165 212 216 188
12 179 189 230 188 341 391 704 403 164 260 207 187
13 178 186 228 181 239 266 177 308 171 1,820 204 185
14 176 183 208 175 281 243 146 270 157 1,190 201 186
15 177 181 196 359 280 210 138 203 157 338 558 187
16 178 200 218 703 337 257 221 170 170 2,760 679 186
17 178 185 199 375 245 603 217 312 288 545 1,110 182
18 178 188 194 344 275 372 166 251 658 286 365 180
19 176 187 191 312 233 216 154 167 250 483 275 180
20 174 179 237 238 242 193 150 146 201 531 247 216
21 173 181 264 269 304 177 138 151 246 296 233 281
22 172 183 245 226 277 195 148 144 480 235 224 244
23 170 204 209 229 212 168 538 161 287 279 220 222
24 169 213 194 203 316 173 554 350 197 852 214 208
25 169 289 188 188 514 185 243 240 190 359 216 199
26 176 223 194 177 651 163 300 203 214 386 221 200
27 183 200 336 209 387 227 189 175 320 384 218 198
28 182 192 260 230 302 196 171 284 214 262 209 191
29 205 216 214 206 342 205 151 806 185 332 203 188
30 190   201 189 335 315 141 805 317 380 198 186
31 183   189   295   199 382   291   1,230