During August 2003 an intense 40-minute monsoon-type storm event occurred at OMYA’s White Knob Quarry in Lucerne Valley CA (Figure 1), resulting in a debris flow that flowed from a combined natural/man-made talus slope through the Ruby Springs area of OMYA’s Western Drainage.  The California Department of Fish and Game claimed that approximately 1.8 miles of the drainage were damaged via scouring of vegetation and native soils.  A 2005 DCI initial field investigation determined that only the uppermost 1.2 miles of the drainage had been scoured, whereas the remaining lower portion of the drainage below a confluence with a “twin” drainage to the west received only a relatively watery discharge.

Using the (Chezy-Manning equation) estimated water fraction peak flow discharge rate of approximately 1,120 ft³/s with the Rational Method, approximately 5.5 inches of precipitation were estimated to have occurred during the storm event.  The storm event appears to have been comparable to a 100-Year/6-Hour statistical storm event (1986 San Bernardino County Hydrology Manual) and the following 2004 NOAA Atlas 14 statistical storm events: 1,000-Year/6-Hour, 500-Year/6-Hour, 50-Year/12-Hour, 10-Year/24-Hour, 5-Year/48-Hour, 2-Year/7-Day, and 1-Year/20-Day, indicating a highly unusual storm intensity.

Via the use of 52 trenches distributed throughout 19 drainage reaches (Figure 2), ~341 yd³ of native soils had been eroded by the debris flow within the steeper upper reaches, and ~6,512 yd³ of debris flow materials (eroded native soils, talus slope clasts) had been deposited throughout the upper reaches (from the toe of the talus slope down to the confluence reach), with the majority being deposited within the uppermost reach (~4,362 yd³) and the confluence reach (~519 yd³) (Figure 3). 

In accordance with a 2008 DCI technical work plan, baseline and interim cross-channel topographic data were collected at 49 of the trench locations to estimate annual rates/volumes of erosion/sedimentation of native soils and debris flow materials (“matrix”), along with post-storm event precipitation data and Ruby Springs discharge rate/surface flow distances, for the 2008-2009, 2009-2010, 2011-2012, 2012-2013, 2013-2014, 2014-2015, 2015-2016, and 2016-2017 rain years (Reporting Periods).  To date, native soil annual erosion/sedimentation rates have ranged between -10 mm/yr (erosion) and +18 mm/yr (sedimentation), whereas matrix annual erosion/sedimentation rates have ranged between -16 mm/yr (erosion) and +32 mm/yr (sedimentation). Western Drainage and nearby CIMIS station precipitation data indicate what appears to be a temporary change in the local rain microclimate precipitation pattern during the 2012-2013 and 2013-2014 Reporting Periods, and Western Drainage precipitation data as snow (%) indicate what appears to be also a temporary change in the local snow microclimate precipitation pattern during the 2013-2014 and 2014-2015 Reporting Periods, independent of OMYA site activities.

Ruby Springs discharge rates collected by DCI since 2007 indicate a virtually immediate response to the 2009-2010 Reporting Period change from drought to wet conditions and an approximate two-year delayed response to the 2011-2012 Reporting Period change from wet to drought conditions (Figure 4).  Furthermore, a series of seasonal short-duration cycles of Ruby Springs discharge rates has been superimposed onto an underlying long-duration cycle of Ruby Springs discharge rates.  The short-duration cycles appear to represent relatively immediate responses to storm event precipitation occurring near to Ruby Springs.  However, the long-duration cycle appears to represent the delayed response to storm event precipitation occurring within the upper portion of the Western Drainage watershed, farther away from Ruby Springs, as a function of the cyclical cumulative effects of multi-year drought conditions, followed by multi-year wet precipitation conditions, and then followed by the current multi-year drought conditions.

A non-numerical conceptual groundwater model (Figure 5) was developed to explain the simple cause (precipitation) and effect (spring discharge rates) hydrogeological scenario within the Western Drainage. Precipitation occurs as rain and/or snow, typically during November to April, with monsoonal rains during the summer.  Most precipitation appears to percolate directly in the fractured bedrock complex that underlies the Western Drainage as "new" groundwater, with the remainder being either evaporated (rain) or sublmimated (snow).  Groundwater flows downward through the fractured bedrock aquifer toward Lucerne Valley, via classic "rangefront" recharge of the Lucerne Valley aquifer system.  Subparallel NW/SE-trending reverse faults that cross the confluence area intercept fracture flow groundwater, forcing groundwater upward to the ground surface, creating Ruby Spring and the nearby down-channel "Unnamed" Spring.

Finally, a series of annual photos were taken by DCI during 2005-2009, at the same locations and perspectives as those taken by CDFG during its 2003 post-storm event investigation.  Photo locations included the talus slope, reaches above/below the springs area, Ruby Springs, and the "Unnamed" Spring.  All locations, especially those of Ruby Springs and the "Unnamed" Spring, demostrated robust vegetation rebound by 2008, approximately five years after the scouring that resulted from the August 2003 storm event.  Figures 6 and 7 show vegetation rebound within the Ruby Springs and "Unnamed" Spring areas, respectively.  The upper photo of each figure was taken by CDFG during August 2003 and the lower photo of each figure was taken by DCI during September 2008.

NOTE: Figures are from latest report (2016-2017 Reporting Period) submitted to BLM via OMYA.

Associated documents produced by DCI on this project:

Site Hydrogeologic Opinion, Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (30 January 2006)

Site Historical Aspects, Ruby Springs and “Unnamed Spring”, OMYA White Knob Quarry, Lucerne Valley, California (22 December 2006)

Site Hydrogeologic Opinion, Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California – 2006 Update (4 April 2007)

Sediment Volume Estimation, Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (7 December 2007)

Site Hydrogeologic Opinion – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California – 2007 Update (18 December 2007)

Sedimentation and Erosion Monitoring Technical Work Plan – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (31 May 2008)

Boulder Interstitial/Step-Pool Sediment Storage – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (30 September 2008)

Erosion Volume Estimation – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (23 October 2008)

Site Hydrogeologic Opinion – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California – 2008 Update (24 October 2008)

Response to 2003 and 2005 CDFG Documents – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California – 2008 Update (21 November 2008)

Sedimentation and Erosion Monitoring, 2008-2009 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (20 August 2009)

Statistical Storm Event Estimation, August 2003 Storm Event – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (30 September 2009)

Site Hydrogeologic Opinion – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California – 2009 Update (17 December 2009)

Revised Statistical Storm Event Estimation, August 2003 Storm Event – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (22 July 2010)

Sedimentation and Erosion Monitoring, 2009-2010 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (23 July 2010)

Talus Slope Impact on Ruby Springs – Western Drainage, OMYA White Knob Quarry, Lucerne Valley, California (15 September 2011)

Sedimentation and Erosion Monitoring, 2011-2012 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (13 September 2013)

Sedimentation and Erosion Monitoring, 2012-2013 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (14 September 2013)

Sedimentation and Erosion Monitoring, 2013-2014 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (9 February 2015)

Sedimentation and Erosion Monitoring, 2014-2015 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (17 January 2016)

Sedimentation and Erosion Monitoring, 2015-2016 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (22 August 2016)  

Sedimentation and Erosion Monitoring, 2016-2017 Reporting Period – Ruby Springs Area, OMYA White Knob Quarry, Lucerne Valley, California (14 August 2017)