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Home My WebLink AboutCS-Prosser Dam Rd-Interflow_Memo\� InterFlow Hydrology, Inc. Hydrog,6gy and ftv Resources fonwhmj MEMORANDUM To: Mr. Michael Holley, TDPUD Mr. Steven Poncelet, TDPUD Mr. Brian Wright, TDPUD Date: May 8, 2014 Regarding: Prosser Dam Road Domestic Well Water Level Monitoring From: Jack Childress, PG, Senior Hydrogeologist Dwight L. Smith, PG, CHg, Principal Hydrogeologist Interflow Hydrology has reviewed water level measurement data collected by the TDPUD from domestic wells in the Prosser Dam Road monitoring network. As a public service, the TDPUD began measurement of water levels in domestic wells in 2008, and the monitoring network has grown to include 29 actively monitored wells in 2014. The water level data has been compiled to determine average annual water level at each well, and the associated elevation of the water table. This data was then contoured to create a topographic representation of the water table elevation. The water table elevation contours are used to better understand the groundwater flow system, including flow directions and year to year changes. The annual average changes in water level elevation have also been compiled and contoured. This provides a means to review long-term trends and water level changes, including identification of where the greatest changes have occurred. Results of data compilation and contouring are shown in the figures accompanying this memorandum. Figure 1 illustrates how annual changes in water level correspond consistently with climate (precipitation) conditions for the year. The Polaris Fault crosses the western side of the monitoring area as illustrated in Figures 2 and 3. Average annual water table elevation contours are illustrated in Figures 4 through 9, and Figure 10 is a 3D depiction of the Year 2013 water levels. The following key observations are derived from the water level contouring work. 1. The Polaris Fault and its associated splay is significantly affecting local groundwater flow. 2. There is a 30 to 40 foot average drop in water table elevation on the west side of the Polaris Fault indicating the fault is locally behaving as a barrier to groundwater flow. 3. Annual water level changes throughout the Prosser Dam area show significant response and correlation to annual climate conditions. Interflow Hydrology, Inc. P.O. Box 1482, Truckee, CA 96160 (530) 582-1622 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 2 of 12 4. There is no indication of a long-term declining or rising trend in water levels other than what is associated with climate response. 5. However, there is a noticeable difference in the annual magnitude of water level change on the west side versus east side of the Polaris Fault. Annual water level responses are approximately 2-fold in magnitude on the west side of the fault as compared with the east side. 6. Given both the noticeable barrier effect of the Polaris Fault and the difference in magnitude of water level response to water -year conditions, it is likely that the domestic wells on the west side of the fault are in a compartmentalized aquifer condition which is not only more sensitive to annual climate conditions, but will also be more sensitive to local pumping. Interflow Hydrology, Inc. P.O. Box 1482, Truckee, CA 96160 (530) 582-1622 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 3 of 12 180% a°10 160% m 140% 120% a, 100% 80% 60% 40% U a 20% 0% 5780 E 5770 Annual Water -Year Precipitation 2007 2008 2009 2010 2011 2012 2013 2014 ■ Boca Precipitation Station Average Annual Water Table Elevation - Prosser Dam Road Network :° 5760 c 5750 0 5740 °1 5730 w v 5720 5710 a; 5700 2007 2008 2009 2010 2011 2012 2013 2014 tWest of Polaris Fault tEast of Polaris Fault Annual Average Change in Water Level from Previous Year 20 - 15 - U 10 - i 5 - 0 0 v v -5 2010 2011 J i a; -10 M �: -15 c -20 — < Q ■ East of Polaris Fault ■ West of Polaris Fault Figure 1— Comparison of Water -Year Precipitation and Annual Water Table Elevations and Changes Interflow Hydrology, Inc. P.O. Box 1482, Truckee, CA 96160 (530) 582-1622 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 4 of 12 Figure 2 - Polaris Fault Mapping for the Segment between Prosser Creek Reservoir and the Truckee River (Hunter, et al, 2011) — Study Area Added Interflow Hydrology, Inc. P.O. Box 1482, Truckee, CA 96160 (530) 582-1622 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 5 of 12 h �" .. lJf: � • �� rr .......... .................... Study Area }.fir I 44 } �f' f I {b { -axis .� Q41a QTah 58mt4M: Qpc of right-iatet.@J.... ....... ..................................r '. offset Stud Area..-` `. `L T-axis Qpc y - . 43 m + 5 In ``, T r V, ' of left -lateral r offsets Qdio 0 200 400 600 800 m QTp. rti Figure 3 - Polaris Fault Mapping for the Prosser Dam Road Area (Hunter, et al, 2011) — Study Area Added Interflow Hydrology, Inc. P.O. Box 1482, Truckee, CA 96160 (530) 582-1622 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 6 of 12 2261000 7081000 Interflow Hydrology, Inc. North S-'>s0 Obi \ s G d� � d ,L 7082000 7083000 7084000 7085000 7086000 State Plane Easting (Feet) Figure 4 — Contours of Average Annual Groundwater Elevations in 2008 I 7087000 5780 5775 5770 5765 5760 5755 5750 5745 5740 5735 5730 5725 5720 5715 5710 5705 5700 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 7 of 12 2265000 2264000 LL 0 z m 2263000 2262000 2261000 7081000 Interflow Hydrology, Inc. b d L a� a0 v- 57 5 (D4 _{ y 0 57 0 4 B� o I `sue 00 O/ 0 T 11,41 .y - 7082000 7083000 7084000 7085000 7086000 State Plane Easting (Feet) Figure 5 — Contours of Average Annual Groundwater Elevations in 2009 North 7087000 5780 5775 5770 5765 5760 5755 5750 5745 5740 5735 5730 5725 5720 5715 5710 5705 5700 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 8 of 12 2265000 2264000 LL 2263000 2262000 2261000 Interflow Hydrology, Inc. O a' �I North 5760 - 5725 /� - O O S?SS (• " -' 5745 5765 ° 5155 —5740 5735 o CV { s Q 5730 5725 5720 ^% 5715 5710 5705 5700 O s 7081000 d� ll 7082000 7083000 7084000 7085000 7086000 7087000 State Plane Easting (Feet) Figure 6— Contours of Average Annual Groundwater Elevations in 2010 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 9 of 12 a North n7 d 2265000 CO ;? 0 5780 5775 5765 � 5770 v 2264000 5770 0 5765 _ _ 5765 .�4 ti 5760 r o h t7y �- �Q 5755 o t m ¢ Cr^ 5750 5745 2263000 7s - 5740 5735 i 5730 OD - - - - 5725 o ON ` 5720 2262000 �� 5715 5710 0� 5705 5700 Dx 4„tp 2261000 <O / 7081000 7082000 7083000 7084000 7085000 7086000 7087000 State Plane Easting (Feet) Figure 7 — Contours of Average Annual Groundwater Elevations in 2011 Interflow Hydrology, Inc. TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 10 of 12 L1 fA r r 0 z m m a 2263000 m W 2262000 2261000 7081000 Interflow Hydrology, Inc. r L + co co a (575)51 5760 O s1 h o O� 4� s North CamC_, - 5-T 55 0 o 5765 cS� 00 O � S>6S \ \ 7082000 7083000 7084000 7085000 7086000 7087000 State Plane Easting (Feet) Figure 8 — Contours of Average Annual Groundwater Elevations in 2012 5780 5775 5770 5765 6760 5755 5750 5745 5740 5735 5730 5725 5720 5715 5710 5705 5700 TDPUD - Prosser Dam Groundwater Monitoring May 8, 2014 Page 11 of 12 70 North 2265000- < 2264000- c,,5760 74� D Cn W j <0 z a)O 5745, Q) 2263000A N Ile. U% 0 (90 2262000- 01- 2261000�'G �/ - ........... 7081000 7082000 7083000 7084000 7085000 7086000 7087000 State Plane Easting (Feet) Figure 9 - Contours of Average Annual Groundwater Elevations in 2013 Interflow Hydrology, Inc. 5775 5770 5765 5760 5755 5750 5745 5740 5735 5730 5725 5720 5715 5710 5705 5700 TDPUD — Prosser Dam Groundwater Monitoring May 8, 2014 Page 12 of 12 5775 5770 5765 5760 5755 5750 5745 5740 5735 5730 5725 5720 5715 5710 5705 5700 m CO Figure 10 — 31) View of Average Annual Groundwater Elevations in 2013 Interflow Hydrology, Inc. es�� 5