Skip to main content

Comment: Plan for Water Hydrology and Demand Model - Dianna Suarez

From: Dianna Suarez  
Sent: Monday, January 9, 2023 3:08 PM
To: Jennifer Hanson  
Subject: Comment for Plan for Water Hydrology and Demand Model

Dear Jennifer Hanson, 

Thank you for the opportunity to comment on the next Plan for Water Workshop.  I looked with interest at your Demand Model sources and Assumptions Matrix.  While reviewing the first 3 rows, I noted that "Same platform as historical simulation" is cited as "future projections sources and assumptions". My first attachment is a spreadsheet showing actual use (sales) from 2010-2018 and "historical simulation" projections for 2015-2040, from past water management plans.  According to your 2020 Urban Water Management Plan the actual "duty" water was 139,519 acre feet while ordered raw water was 120,145 acre feet.  According to the projection from past history, the 2020 "Agricultural Irrigation" was nearly 175,000 acre feet.  This historical simulation is off by nearly 50%.  And the total use projection was off by 1/3.  This kind of inaccuracy is unacceptable.  During a later hydrologic study, the contractors explained that these projections were "one point in time" that did not project a realistic future but with subsequent frequent corrections would produce a curve that would be more accurate.  I sincerely hope you do not use the bad data from the past.


Department of Water Resources



INVESTIGATION from April of 1964

Starting on page 73 is the history of Nevada Irrigation District and a volume of helpful information on all aspects relevant to the Plan for Water.  It turns out that this document is more accurate in its predictions of population in 2020 (table 12) than NID's recent attempts.  This information may provide soils, slope, and hydrologic data on a timeline giving continuity and understanding to the landscape and its connection to the rest of the surrounding area.

Land Use is another key component that is subject to great variability.  According to your Matrix, "Future projected land use areas will be developed based on historical trends in land use, with spatial land use changes informed by zoning and general plan GIS data. The effects of alternate future land use scenarios on demand will be evaluated through sensitivity analyses to identify "bookend" results. Land use areas, trends, and sensitivity analysis results will be checked against other available tabular land use information and will be verified with NID and city/county staff."

It is possible that some raw water users may be less than accurate in their reporting and ground-truthing is essential to insure accuracy.  Also wildfire, drought, and flooding in extreme climate change scenarios greatly increase the potential future uncertainty of land use.  I support the use of bookend results.

I applaud your use of current models and methodologies congruent with neighboring agencies, and statewide standards.  It looks like a good effort and far better than in the past.  I would like to warn that just because some people want more water, does not mean that they are entitled to it.  Additionally, it may not even be cost effective to feed the Tar Ditch when so many of your customers out there pay only $12/ miners inch of water.


In conclusion, I congratulate you on the use of DWR Integrated Water Flow Model and inputs that record measurable factors like standard crop requirements, soil moisture, and methodology instead of human greed.  Please keep in mind that the vast majority of people living in our area depend on wells and groundwater, (which NID likes to pretend do not exist). I hope some day your model will include groundwater and the interests of the rest of us.  Best wishes and good luck with the analysis. 

Dianna Suarez



Join our mailing list