Mono Lake Water Year Analysis

Los Angeles Department of Water and Power, California Public Records Act Request 26-348, hosted through NextRequest. ↩︎

Los Angeles Department of Water and Power, official website. ↩︎

Los Angeles Department of Water and Power, Urban Water Management Plan. ↩︎

Los Angeles Department of Water and Power, Mono Basin Annual Operations Plan release. ↩︎

Local source workbook: 2026 - CPRA26-348 Mono Basin.xlsx. ↩︎

Local cleaned daily comma-separated values file used by this page: mono-lake-daily.csv. ↩︎

Local cleaned daily JavaScript Object Notation file with the same daily table: mono-lake-daily.json. ↩︎

Local Mono Lake elevation-storage model used for storage interpolation: mono-lake-elevation-storage-model.json. ↩︎

Source: cleaned daily CSV from the LADWP CPRA R26-348 Mono Basin workbook, station 5115. Storage values are interpolated from the Mono Basin Research smoothed Pelagos bathymetry curve. The dashed reference line marks the 6,392 ft management level established by State Water Resources Control Board Decision 1631 in 1994. ↩︎

Working definition: each water year is shown as a vertical guide with points for lake storage change, computed lake inflow, and the Mono Basin total runoff index. Storage change is derived from boundary lake elevations and the Mono Basin Research storage curve, and may be negative. The hover readout reports the difference between basin runoff and computed lake inflow. ↩︎

Working definition: water-year storage change converts Mono Lake elevations nearest to October 1 and September 30 into storage using the Mono Basin Research smoothed Pelagos bathymetry curve, then subtracts starting storage from ending storage. Boundary elevations must be within 14 days of the water-year boundary. ↩︎

Source: cleaned daily CSV from LADWP CPRA R26-348 Mono Basin workbook, station 5045. This plots measured Grant Lake elevation in feet. ↩︎

Working definition: Lee Vining Creek component charts compare the above-intake creek record (5008), the below-intake creek record (5009), and the Lee Vining Conduit below-intake record (5012). Daily values are plotted in cubic feet per second. Water-year totals convert daily cfs to acre-feet and omit incomplete water years for each individual series. ↩︎

Working definition: Rush Creek / Grant Lake component charts compare Rush Creek at dam site (5013), Grant Lake outflow (5044), Grant Lake spill (5078), and Mono Gate Return Ditch (5007). This is an operational comparison, not a final accounting sum. ↩︎

Working definition: this allocation treats Mono Gate Return Ditch (5007) as water returned toward Rush Creek / Mono Lake, Grant Lake spill (5078) as uncontrolled spill toward the lake system, and the positive difference between Grant Lake outflow (5044) and Mono Gate Return Ditch (5007) as Grant outflow not returned through the ditch. That third bucket is a likely export/routing signal, not final legal export accounting. ↩︎

Working definition: this chart plots Grant Lake spill (5078) as reported in the LADWP workbook. Daily values are plotted in cubic feet per second. Water-year totals convert daily cfs to acre-feet using 1 cfs-day = 1.98347 acre-feet and omit incomplete water years. ↩︎

Working definition: Parker Creek component charts compare the above-conduit record (5017) with the below-conduit record (5003). Daily values are plotted in cubic feet per second. Water-year totals convert daily cfs to acre-feet and omit incomplete water years for each individual series. ↩︎

Working definition: Walker Creek component charts compare the above-conduit record (5016) with the below-conduit record (5002). Daily values are plotted in cubic feet per second. Water-year totals convert daily cfs to acre-feet and omit incomplete water years for each individual series. ↩︎

Working definition: the basin total runoff index sums Lee Vining Creek above intake (5008), Walker Creek above conduit (5016), Parker Creek above conduit (5017), and Rush Creek at dam site (5013) where all four daily records are present. Daily values are plotted in cubic feet per second. Water-year totals convert daily cfs to acre-feet using 1 cfs-day = 1.98347 acre-feet and omit incomplete water years. ↩︎

Working definition: the lake inflow index sums Lee Vining Creek below intake (5009), Walker Creek below conduit (5002), Parker Creek below conduit (5003), Grant Lake spill (5078), and Mono Gate Return Ditch / Rush Creek ditch flow (5007) where all five daily records are present. This is an index of measured water remaining in or released toward the lake after the diversion infrastructure represented in the LADWP workbook, not yet a final natural-flow or complete lake water-budget estimate. ↩︎

Working definition: paired annual bars compare the same basin total runoff index and measured lake inflow index used above. The comparison is intended to show the scale of water measured before infrastructure relative to water measured as remaining in or released toward the lake. ↩︎

Working definition: this chart subtracts the measured lake inflow index from the basin total runoff index. The result is a broad routing/diversion/storage/accounting difference, not a final export figure. It can include water exported from the basin, water temporarily stored in Grant Lake, changes in routing, measurement mismatch, and other operational accounting effects. ↩︎

Working definition: annual stacked bars sum positive daily differences for Lee Vining (5008 - 5009), Parker (5017 - 5003), Walker (5016 - 5002), and Rush Creek / Grant Lake (5013 - 5078 - 5007). The cumulative chart begins with WY1995, the first complete water year after D-1631 was adopted in September 1994. This is a working diversion/routing index, not final legal export accounting. ↩︎

Working definition: this chart plots West Portal flow (5190) as reported in the LADWP workbook. Daily values are plotted in cubic feet per second. Water-year totals convert daily cfs to acre-feet using 1 cfs-day = 1.98347 acre-feet and omit incomplete water years. Treat this as a measured/estimated West Portal series, not yet as final export accounting. ↩︎