2004-07-01_REVISION - M1987064

• Permit No: M1987064
• IBM Index Class Name: Revision
• Doc Date: 7/1/2004
• Doc Name: Hydro-Logic Report and Proof of Publication
• From: Frank Anesi
• To: DMG
• Type & Sequence: AM1
• Media Type: D
• Archive: No

CONTENTS
Abstract ......
huroduction
Description of Study Arca ....................................._........__..................._..................._........................ ............._................. 3
Geology and Gcomor)tlrology ..................................................................................................... ................................ 3
Climatc ........................................................................................................................................ ................................ 3
liydrology ................................................................................................................................... ................................ 3
Resource Uscs ....................................................................................................................................... ................................ 3
Historical Uses ............................................................................................................................ ................................ 3
Reclamation of Historical Use Area ........................................................................._...... ................................ S
Future Use Area .......................................................................................................................... ................................ 5
Seasonal River Crossing ................................................................................................... ................................ 5
Reclamation oC Future Use Arca ....................................................................................... ................................ 8
Effects of Flow Regime on Ore Animas River Channel and the Future Use Area ................................ ........_...................... 8
Floods .......................................................................................................................................... ................................ 8
Modeling the 100-Year Flood ........................................................................................... ................................ 8
Environmental Effects of the Future Use Area ..................................................................................... ................................ 12
Water Quantity .............................................................................. .............................................................................. 12
Water Qualily ................................................................................ .............................................................................. 18
Erosion .......................................................................................... .............................................................................. 18
Summary ................................................................................................. ......................................._......................_........ _... 20
References cited ...................................................................................... .............................................................................. 20
List of Figures
Pigurc L Location of the study area in [he northern Animas River vallcy ...............__......................_............................................ ._......2
2. Strcamflow discharges for the Animas River at Durango, Colorado: (A) Annual peak [lows,
(b) Daily-mean strcamflows for 1992-99, and (C) Maximum, minimum, and mean-daily strcam0ow
water years 1897 to 2003 ................................................................................................................................................ .........4
3. Aerial photograph mosaic of the Sandco Reach of [he Animas River, approximate extent of
the future use area after completion of the work, and locations of channel cross sections..._........._ ........................... _ ........6
4. Photograph of the Sandco Reach of the Animas River, future use area, and location of the
seasonal road crossing ..................................................................................................................................................... ......... 7
5. Computations- o(culvert capacity (Total Flow, Qt) to the culvert tops at the road crossing,
Sandco reach of the Animas River, cross section SC-I 1 ................................................................................................ .........9
6. Computations of the maximum culvert capacity (Total Flow, Qt) for overflow of the road crossing,
Sandco reach of ttre Animas River, cross section SC-I I ................................................................................................ ......... 10
7. (A) Excerpt from the surficial geologic map of the Hemrosa quadrangle (Blair and others, 2002) showing
oxbows in the Animas River valley, and (B) Photograph of an oxbow lake in [Ite Animas River
valley (Blair and others. 2002) ......................................................................................................................................... ........ I
8. Water-surface elevations for different flow regimes, Sandco Reach of the Animas River ........................_...................._ ......... 13
9. Water-surface elevations for the 100-year flood in the Sandco reach of [he Animas River
modeled using HEC-RAS (cross sections SC-I through SC-6) ........................._........................................................... ........ 14
10. Water-surface elevations (or the 100-year flood in [hc Sandco reach of the Animas River
modeled using HEC-RAS (cross sections SC-7 lhrouglr SC-12) .................................................................................... ........ IS
1 !. Water-surface elevations for the I00-year flood in the Sandco reach of the Animas River
modeled using HEC-RAS (cross sections SC-13 through SC-16) .................................................................................. ........ 16
12. Evaporation depletions from the future use lake area by year of operation.
Exposed lake area will be 44 acres at completion of the project ..................................................................................... ........ 17
13. Hjulstrom diagram showing the average velocity required for erosion of different particle sizes .............._......_.............. ........ 2!
List of Tables
"fable 1. Flood flows and frequencies for the Sandco Reach of the Animas River ............................:.......................... ....... 3
2. Ranges of (lows in the Animas River a[ Durango Cor winter months .............................................................. ....... 8
3. Water-quality analyses from historic use operations during installation of Ore temporary road crossing ....... ....._ 19
4. Water quality standards for metals in Colorado ............................................................................................... ....... 19
Appendix 1. Output tables from F{EC RAS for steady Ilow conditions in the Sandco Reach of the Animas River, I00-year
(7 ood .................................................................................................................................................................. 2 2
CONTENTS