This is the working draft for a Mono Lake water-year analysis.
The goal is to understand the Mono Basin record methodically before turning it into charts or argument. Start with the plain-language questions, define each data series, verify what each station measures, then decide what deserves to be plotted.
Daily Elevation (Full Record)1
Annual Storage Change2
Storage Change vs. Basin Runoff3
Grant Lake Elevation4
Lee Vining Creek5
Rush Creek / Grant Lake6
Grant Lake Outflow Allocation7
Grant Lake Spillway8
Parker Creek9
Walker Creek10
Basin Total Runoff (Before Infrastructure)11
Lake Inflows (After Infrastructure)12
Basin Runoff vs. Lake Inflows13
Basin Runoff Minus Lake Inflows14
Creek Diversion Difference15
West Portal Flow16
First Questions
- What is the present condition of Mono Lake?
- What has the lake level done by water year?
- How much water is entering the Mono Basin system?
- How much water is being released toward Mono Lake?
- How much water is being exported away from the basin?
- Which records represent measured hydrology, and which are operational choices?
- Which comparisons are meaningful, and which are tempting but misleading?
Source Inventory
- LADWP CPRA R26-348 Mono Basin workbook.
- Local cleaned daily CSV: mono-lake-daily.csv.
- Local cleaned daily JSON: mono-lake-daily.json (large; keep for local/reference use rather than browser charts).
- Local chart-ready elevation dataset: mono-lake-elevation-daily.json (small legacy chart extract; current chart uses the daily CSV).
- Local derived water-year dataset: mono-lake-water-year.json.
- Working reference shelf: Mono Lake References.
- Working quote shelf: Mono Lake Quotes.
- Exploratory chart sandbox: Mono Lake Water Year Analysis - Exploratory Draft.
Terms to Define
Mono Lake Elevation
- Station:
5115. - Clean key:
mono_lake_elevation_5115. - Unit: feet.
- Question: Is this the best daily record for lake elevation, and how does it compare with any State Water Board or USGS elevation references?
Tributary Flow
- Lee Vining Creek above intake:
5008. - Lee Vining Creek below intake:
5009. - Walker Creek above conduit:
5016. - Walker Creek below conduit:
5002. - Parker Creek above conduit:
5017. - Parker Creek below conduit:
5003. - Rush Creek at dam site:
5013. - Question: Which of these represent supply before diversion, and which represent water left in the stream below diversion points?
Grant Lake
- Grant Lake outflow:
5044. - Grant Lake spill:
5078. - Grant Lake elevation:
5045. - Working definition: Grant Lake outflow plus spill is useful for Grant operations, but lake inflow should use spill plus the return ditch / Rush Creek ditch flow rather than treating all Grant outflow as direct lake inflow.
- Question: How should Grant outflow be separated from measured water actually routed toward Mono Lake?
West Portal
- West Portal flow:
5190. - Working definition: This appears to represent water leaving the Mono Basin conveyance system through the West Portal / export path, but the exact station description needs to be verified before treating it as a clean export series.
- Question: Is this the best measured proxy for Mono Basin exports?
Mono Gate Return Ditch
- Station:
5007. - Question: What is being returned, from where, and to which channel?
Candidate Accounting Frames
- Daily flow in cubic feet per second.
- Daily flow converted to acre-feet per day.
- Cumulative water-year volume.
- Runoff-season volume.
- Calendar-year volume.
- Water exported versus water released toward Mono Lake.
- Lake elevation change by water year.
Chart Ideas, Later
Do not start with all of these. Pick one question, verify the definitions, and build only the chart needed to answer it.
- Mono Lake elevation through time.
- Water-year lake elevation change.
- Tributary supply above diversion points.
- Below-diversion streamflow compared with above-diversion streamflow.
- Grant Lake release and spill, separated.
- West Portal flow as possible export volume.
- Lake elevation against export volume.
Open Checks
- Verify LADWP station names and meanings from the workbook tabs or metadata.
- Confirm whether West Portal flow is the right export signal.
- Confirm whether Grant Lake outflow plus spill should be summed or shown separately.
- Compare LADWP lake elevation against an independent public source.
- Identify the legal or operational rule that explains current export limits and required lake levels.
- 1
Source: cleaned daily CSV from LADWP CPRA R26-348 Mono Basin workbook, station
5115. The dashed reference line marks the 6,392 ft management level established by State Water Resources Control Board Decision 1631 in 1994. ↩︎ - 2
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. ↩︎
- 3
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. ↩︎
- 4
Source: cleaned daily CSV from LADWP CPRA R26-348 Mono Basin workbook, station
5045. This plots measured Grant Lake elevation in feet. ↩︎ - 5
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. ↩︎ - 6
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. ↩︎ - 7
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. ↩︎ - 8
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. ↩︎ - 9
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. ↩︎ - 10
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. ↩︎ - 11
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. ↩︎ - 12
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. ↩︎ - 13
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. ↩︎
- 14
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. ↩︎
- 15
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. ↩︎ - 16
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. ↩︎