C06__Attachment_1_-_Enclosure_1_Final_Determination_Report_2022_0001.pdf

- BUREAU OF -

RECLAMATION

Final Determination Report

OCAP Annual Determination 2022 Irrigation Season

Interior Region 10 · California-Great Basin

U.S. Department of the Interior September 2023

Enclosure 1

Mission Statements The Department of the Interior (DOI) conserves and manages the Nation’s natural resources and cultural heritage for the benefit and enjoyment of the American people, provides scientific and other information about natural resources and natural hazards to address societal challenges and create opportunities for the American people, and honors the Nation’s trust responsibilities or special commitments to American Indians, Alaska Natives, and affiliated island communities to help them prosper.

The mission of the Bureau of Reclamation is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American public.

Final Determination Report

OCAP Annual Determination 2022 Irrigation Season

Interior Region 10 · California-Great Basin prepared by

U.S. Department of the Interior Bureau of Reclamation Interior Region 10 · California-Great Basin Lahontan Basin Area Office

Contents Page

Contents ............................................................................................................iii Acronyms and Abbreviations ................................................................................ iv

1 Introduction

1.1 Annual Determination Process

1.2 Irrigation Season Overview

1.3 Report Overview

1.4 Changes from 2021 Final Annual Determination and Additional

Information 2 Input Data

2.1 Multispectral Satellite Imagery

2.2 District Agricultural Fields Geodatabase

2.3 District Delivery Report

2.3.1 Serial Numbers

2.3.2 Subdivisions

2.3.3 State of Nevada Division of Water Resources Farm Units

2.4 Other Data Sources

3 Irrigation Status Determination Methodology

3.1 Irrigation Status Determination

3.1.1 Initial Irrigation Status Identification

3.1.2 Manual Review of Irrigation Status

4 Preliminary Acreage Summarization, Calculation of Incentive Credit/Disincentive Debit and Lahontan Storage Targets

4.1 Calculation Procedures and Results

Step 1. Calculate Acreage and MHE for Project Lands Step 2. Calculate Incentive Credit/Disincentive Debit Step 3. Calculate CDT and Lahontan Reservoir Storage Targets

4.2 Final Irrigation Status Determination

5 References 6 Appendices iii

Acronyms and Abbreviations ac acres ac-ft acre-feet ac-ft/ac acre-feet of water per acre of land

Annual Reclamation generated geospatial dataset for processing Determination field irrigation status Dataset

CDT Carson Division Total Diversion Requirement

CLP Carson Lake and Pasture

District Truckee-Carson Irrigation District

District Report District allocation and delivery record report

DWR State of Nevada Division of Water Resources

Fields Geodatabase District agricultural fields geodatabase

GIS Geographic Information System

KAF thousand acre-feet

LSOCM end-of-month storage objectives for Lahontan Reservoir

MHE maximum headgate entitlement

NDVI Normalized Difference Vegetation Index

NRCS Natural Resources Conservation Service

NRS Nevada Revised Statute

NWIS National Water Information Service

OCAP Operating Criteria and Procedures for the Newlands Project

Project Newlands Project

Reclamation U.S. Bureau of Reclamation

TSM/J end-of-month May/June Lahontan Reservoir target storage

USGS U.S. Geological Survey iv

WY water year v

1 Introduction

1.1 Annual Determination Process

The U.S. Bureau of Reclamation (Reclamation) is responsible for the administration of the Operating Criteria and Procedures (OCAP) for the Newlands Project (Project), Nevada. Section

418.8 of OCAP directs Reclamation and the Truckee-Carson Irrigation District (District) to identify and report annually “the number of acres of eligible land irrigated in the Project” as well as “possible irrigation of ineligible land” and “eligible land that was not irrigated” each year. Sections 418.36 and

418.37 of OCAP specify procedures for calculating Incentive Credit or Disincentive Debit based on operational efficiency, and Section 418.22 of OCAP provides for adjustment of Lahontan Reservoir storage targets each year. These annual determinations are made through a series of analyses and calculations. Reclamation makes a preliminary determination by analyzing Geographic Information System (GIS) data, District allocation and delivery records (District Report), and U.S. Geological Survey (USGS) and Reclamation gage records. The preliminary determination is sent out for stakeholder review. After the review period, Reclamation responds to all comments and produces a final determination.

1.2 Irrigation Season Overview

Lahontan Basin snowpack for the 2022 season started below average and reservoir storage was further depleted from the previous year. The water year started with snowpack well below normal until a series of December storms contributed to a snow water equivalent (SWE) in the Carson River Basin of 200% of the 1991-2020 median by January 1st, according to Natural Resources Conservation Service (NRCS) estimates. A lack of meaningful mid-winter storms led to little change in SWE until melt off began in mid-March, by which time SWE was only near 70% of the median.

The observed April through July runoff volume at the Carson River at Fort Churchill gage was 60.3 thousand ac-ft (KAF) and only 46% of the NRCS 30-year median (1991-2020).

The Truckee and Carson Divisions of the Project started the 2022 irrigation season with a 70% yearly water allocation with water orders beginning on March 15th and April 6th, respectively. The allocation was updated to 85% for both divisions in June and on September 8th the Truckee Division allocation was increased to 100%. Water deliveries ended for the irrigation season on October 31st.

1.3 Report Overview

This report summarizes the calculations and describes the procedures that result in the determination. A brief description of the data and sources used in the report are detailed in Section

2. The annual determination process includes two general components: determining the irrigation status of fields (Section 3) and performing the calculations (Section 4). The calculations are further divided into three steps: calculating acreage and maximum headgate entitlement (MHE) (Section 4, Step 1), calculating Incentive Credit or Disincentive Debit (Section 4, Step 2), and calculating adjustments to Lahontan storage targets (Section 4, Step 3).

The report includes appendices A – C that list the lands determined to be water-righted and irrigated (WR/I), non-water-righted but irrigated (NWR/I), and water-righted but not irrigated (WR/NI), respectively.

1.4 Changes from 2021 Final Annual Determination and

Additional Information

During the 2020 irrigation season Reclamation began working with the Fallon Paiute-Shoshone Tribe (Fallon Tribe) to establish GIS field polygons within the tribal reservation boundary for inclusion in the District agricultural fields geodatabase (Fields Geodatabase) (Section 2.2). These polygons were approved by the Fallon Tribe in 2022 and integrated into the 2022 annual determination process. The MHE and irrigated acreage calculations for the Fallon Tribe are detailed in Step 1.3.2.

2 Input Data The sets of input data and data sources used in the annual determination calculations are described below.

2.1 Multispectral Satellite Imagery

Satellite imagery and remote sensing data form the basis for determining irrigation status of agricultural lands in the Project area. Planet Labs satellite imagery was acquired for the 2022 irrigation season. Planet Labs images are obtained from the Planetscope and SkySat satellite constellations, which collect 3-meter resolution 4-band imagery and 0.5-meter resolution panchromatic imagery, respectively. The 4-band imagery was processed to develop monthly Normalized Difference Vegetation Index (NDVI) images which were used as a proxy to determine field irrigation history. A single high-resolution 0.5-meter panchromatic image was collected during the peak growing season and used for manual analysis.

Image acquisition target dates are chosen to encompass the irrigation season and to accommodate crop growth characteristics, crop rotation, and field modifications. Typically, one image acquisition per month during the growing season is recommended to provide a reasonable temporal cross-section of irrigation practices. For the 2022 irrigation season, a total of 9 multispectral images were acquired on the following dates: March 23rd/24th, April 1st, May 19th, June 6th, July 29th, August 22nd, September 23rd/28th, and October 17th, from Planetscope and from June 26th to July 1st from SkySat.

2.2 District Agricultural Fields Geodatabase

The District maintains a geospatial polygon dataset representing irrigated or potentially irrigated field extents within the District boundary. Each polygon within the Fields Geodatabase represents a field and its associated attributes, including serial number (defined in Section 2.3.1), duty, water right status, field size, and water allocation. The District and Reclamation annually review and refine the field perimeters and their associated attributes. The District's data is delivered to Reclamation at the end of each irrigation season for use in combination with the multispectral satellite imagery to determine field irrigation status as part of the annual determination.

2.3 District Delivery Report

The District Report is a Microsoft Access database containing data tables that list the volume of water allocated and delivered to District serial numbers. The allocation is an estimate of the acres likely to be irrigated in the coming irrigation season based on District data. The allocated acres are then multiplied by each field’s duty to determine the allocated volume. Each month during irrigation season, the District provided reports of allocations and deliveries to Reclamation. Reclamation reviewed these reports and provided comments to the District. The District then made corrections to the allocation and delivery records as necessary. After completion of the irrigation season, the District provided Reclamation with a set of water allocation and delivery records for the entire irrigation season. Reclamation reviewed this year-end dataset before using it for annual determination calculations.

2.3.1 Serial Numbers

A serial number is a District accounting identifier that is comprised of one or more adjoining fields in the Project, under identical ownership. The District Report identifies the serial number total water-righted acres, total allocated acres at 100% allocation, and total allocated acres at the annual allocation percentage (85% for the Carson Division and 100% for the Truckee Division in 2022) of Project lands.

2.3.2 Subdivisions

A watering subdivision is a group of “Water Users or Authorized Irrigators in a neighborhood who irrigate from an original takeout” (Truckee-Carson Irrigation District, 2021). The District's policy is to deliver water for all serial numbers through the original takeout, when possible, even when a property has been subdivided into multiple serial numbers. A Subdivision Coordinator is responsible for the ordering and delivery of water to individual water users within each Subdivision.

2.3.3 State of Nevada Division of Water Resources Farm Units

A State of Nevada Division of Water Resources (DWR) approved Farm Unit is comprised of tracts of land with water rights that are considered appurtenant to an entire farm rather than to individually identifiable land within the farm (NRS 533.040(4)). A water rights transfer permit is required by the DWR to designate a Farm Unit. In the District Report, the entire Farm Unit is water-righted, but the acres of water rights may be less than the acreage of the Farm Unit. The water user must file a map with the District and the State Engineer to designate where the water rights will be used within the Farm Unit. The District does not allocate water to the Farm Unit until the designation map is filed.

The water user must inform the District of any changes to designated fields anticipated to be irrigated. Farm Units eliminate the need for annual temporary transfers between serial numbers that encompass the Farm Unit. The District is still required to report water deliveries by headgate and serial number as directed by OCAP.

2.4 Other Data Sources

Reclamation used gage data, estimated diversions to the Fernley pipelines and other direct takeouts on the Truckee Canal, and the 2022 District anticipated acreage data in the annual determination calculations. Gage data used included USGS gage data, Reclamation Truckee Canal lateral gage data, and Rock Dam Ditch gage data. The other data sources are described in further detail in Sections 3 and 4 below.

3 Irrigation Status Determination Methodology

The first step to determine acreage, storage targets, and incentive credit was determining the water right and irrigation status of Project fields. Satellite imagery and the Fields Geodatabase were used after the conclusion of the irrigation season to determine water rights and irrigation status.

Definitions of water rights and irrigation status determinations are shown in Table 1 and Table 2, and categories are shown in Table 3.

Table 1. Water rights status definitions.

Water Rights Status Description

WR The field has a water right. DWR Farm Unit fields that are designated for irrigation are also labeled as “WR.”

NWR The field does not have a water right.

ND The field is within a Farm Unit, but the field has not been designated to receive water.

NWRT The field is non-water-righted by temporary transfer. NRS § 533.345 describes the conditions under which the State Engineer may approve an application for a temporary transfer of the place of diversion, manner of use, or place of use of water already appropriated. When the State Engineer grants a temporary change in place of use that removes water from a parcel, the District designates the field as “NWRT.”

WRT The field is water righted by temporary transfer.

Table 2. Irrigation status definitions.

Irrigation Status Description

I Greater than 90% of the field appears irrigated.

NI Less than approximately 10% of the entire field appears irrigated.

Partially Irrigated

Where more than 10% and less than 90% of a field appears irrigated, the field is determined to be partially irrigated. The polygon is split, and the Irrigated and Non- Irrigated acreages are calculated and attributed as described above.

Table 3. Categories of water rights and irrigation status determinations for the annual determination.

Determination Status Description WR/I Water-righted, Irrigated WR/NI Water-righted, Not Irrigated WRT/I Water-righted by temporary transfer ON, Irrigated WRT/NI Water-righted by temporary transfer ON, Not Irrigated ND/I Not Designated under a DWR Farm Unit Map, Irrigated ND/NI Not Designated under a DWR Farm Unit Map, Not Irrigated NWR/I Non-Water-Righted, Irrigated NWR/NI Non-Water-Righted, Not Irrigated NWRT/I Non-Water-Righted by temporary transfer OFF, Irrigated NWRT/NI Non-Water-Righted by temporary transfer OFF, Not Irrigated

3.1 Irrigation Status Determination

3.1.1 Initial Irrigation Status Identification

Reclamation generated a geospatial dataset (Annual Determination Dataset) for processing the irrigation status of field polygons provided by the District. Initial irrigation status identifications were made through an automated computerized process. The initial automated process was based on generating mean NDVI values for each field polygon using the near-infrared values from each image acquisition and ArcGIS software (ESRI, 2022). Reclamation then established an NDVI threshold value indicating probable irrigated status for each imagery set. When the calculated NDVI value was above the established threshold, the polygon was determined to be “irrigated” (denoted as I within the Annual Determination Dataset). A field determined as irrigated in a single image maintained that status regardless of NDVI values in prior or subsequent images. Field polygons that did not meet threshold values in any month were determined to be “not irrigated” (denoted as NI within the Annual Determination Dataset). Field polygons for which the NDVI analysis could not make a determination were flagged for manual review.

3.1.2 Manual Review of Irrigation Status

Reclamation further refined the automated irrigation status determination through manual review of the geospatial analysis results. OCAP Section 418.28 requires quantification of deliveries to non-water-righted lands. The manual review provided more accurate determinations for non-water-righted fields that appeared irrigated, partially irrigated fields, and fields for which the NDVI analysis could not make a determination.

The Annual Determination Dataset was queried to identify polygons as NWR/I, NWRT/I, WR/NI, or undetermined. Reclamation staff then manually reviewed these fields to verify the automated status determination. Each field was examined using field boundaries, multispectral imagery, the District Report, and aerial photography. As part of this process, Reclamation identified partially irrigated fields through visual examination of each of the imagery sets. If less than 90% but greater than 10% of a field polygon appeared irrigated, the field was attributed as Partially Irrigated, field polygons were split into irrigated and non-irrigated polygons, and the irrigated acreage was updated for each field. Water diverted to serve non-water-righted lands is included in the calculation of Project efficiency calculations (Step 1.4).

Stakeholders review Reclamation’s initial irrigation status determinations during the comment period for the preliminary determination report and letter each year. Any change to status determinations resulting from the preliminary determination stakeholder review process are changed in the Annual Determination Dataset to create the final determination.

Step 1.1.

4 Final Acreage Summarization, Calculation of Incentive Credit/Disincentive Debit and Lahontan Storage Targets

Reclamation completed data analysis and calculations to generate both irrigated and non-irrigated acreage, as well as the water volume demand for the Project. Reclamation also completed the calculation process for determining new Incentive Credit or Disincentive Debit. The final step was to adjust Lahontan Reservoir storage targets for water year (WY) 2024.

4.1 Calculation Procedures and Results

The primary input data for the calculations were the District Report and the Annual Determination Dataset. The following calculations were completed within a Microsoft Access database and Excel spreadsheet.

The calculations occurred in three steps: (1) Calculation of acreage and MHE for WR/I lands, NWR/I lands, and WR/NI lands; (2) Calculation of Incentive Credit/Disincentive Debit; and (3) Calculation of Carson Division total diversion requirement (CDT) and determination of the Lahontan Reservoir Storage Targets. The results are summarized below.

Step 1. Calculate Acreage and MHE for Project Lands Section 418.8 of OCAP directs Reclamation and the District to identify and report annually “the number of acres of eligible [valid water right and an allocation of Newlands Project water from the District] land irrigated in the Project” as well as “possible irrigation of ineligible land” and “eligible land that was not irrigated” each year. In general, acreage was calculated using the field polygons in the Annual Determination Dataset (e.g., as described in Step 1.3.1). Exceptions were made for the Truckee Division stockwater lines (Step 1.3.1.1), Fallon Indian Reservation Wetlands (Step 1.3.3), Stillwater National Wildlife Refuge (Step 1.3.4), and Carson Lake and Pasture (CLP) (Step 1.3.5) because water may be applied unevenly (e.g., stored in ponds or spread across large areas) for environmental consumptive use rather than agricultural production.

Reclamation calculated MHE for Project lands. MHE represents the maximum volume of water that could be applied to water righted-irrigated fields. MHE was calculated as the product of the water-righted irrigated acreage and the allowable duty for each serial number (Step 1.3.1). An exception was made for the Truckee Division stockwater lines, the Fallon Indian Reservation Wetlands, Stillwater National Wildlife Refuge, and CLP for reasons indicated above. The steps used to calculate acreage and MHE are described below.

Consolidate Irrigated Acreage on Each Serial Number A database query summed acreage for all irrigated fields in each serial number, regardless of duty.

Step 1.2.

Step 1.3.

Calculate Allowable Duty for Each Serial Number The allowable duty (allowable application rate or weighted average duty) is the maximum rate (ac-ft per acre; ac-ft/ac) at which water may be applied to a field over the course of an irrigation season.

Serial numbers may contain fields with a variety of duties: bench (4.5 ac-ft/ac), bottom (3.5 ac-ft/ac), wetlands or other (2.99 ac-ft/ac), and pasture (1.5 ac-ft/ac). For each serial number, a database query of the District Report summed the product of allocated acres for each possible duty times the duty value (ac-ft/ac). The resulting volume was then divided by the total allocated acres for each serial number (calculated in Step 1.1) to obtain a weighted average allowable duty.

Calculate Acreage and MHE for WR/I Lands The irrigated acreage and MHE for water righted lands were calculated as described in Step 1.3.1 through Step 1.3.5 below. Totaling the acreage and MHE values from Step 1.3.1 through Step 1.3.5 gave the total irrigated acreage and MHE for the Project. From the District Report, the total allocated acres (eligible acres reported at the end of the irrigation season), allocated volume at 100%, allocated volume at the annual allocation (85% for the Carson Division and 100% for the Truckee Division in 2022), and the total volume delivered were extracted and summarized for each Project area. The results of the calculations for water-righted and irrigated acreage appear in Table 4, and the lands determined to be WR/I are listed by serial number in Appendix A.

Step 1.3.1

Table 4. Summary of Irrigated Acreage in the Carson and Truckee Divisions of the Newlands Project for the 2022 Irrigation Season.

Water- Righted Irrigated

Acres (ac)

Non- Water- Righted Irrigated

Acres (ac)

Allocated Acres7

(ac)

MHE

(ac-ft)

Allocated Volume at 100%8

(ac-ft)

Pct. Year Allocation

(CD-85%)

(TD-100%)

(ac-ft)

Total Delivered9

(ac-ft)

Carson Division1 41,285 646 42,494 149,573 152,573 129,709 120,747 Truckee Division2 1,513 23 1,875 6,772 8,316 8,216 7,126 Fallon Indian Reservation3 2,276 n/a 2,537 7,966 8,878 8,056 7,851 Fallon Indian Reservation wetlands4 469 n/a 468 1,401 1,400 1,400 1,401 Stillwater National Wildlife Refuge 5 7,296 n/a 8,622 21,742 25,720 21,862 21,742 Carson Lake and Pasture6 2,151 n/a 2,406 6,432 7,195 6,115 6,432 Total10 54,990 669 58,402 193,886 204,082 175,358 165,299 1 Irrigated lands in all Carson Division serial numbers except 712-x, 970, 970-C, and 975 (Percent Year Allocation for 2022 was 85%). Irrigated acres and MHE were calculated as described in Step 1.3.1.

2 Irrigated lands and stockwater line deliveries (Step 1.3.1.1) for all Truckee Division serial numbers (Percent Year

Allocation for 2022 was 100%). Irrigated acres and MHE were calculated as described in Step 1.3.1. and Step 1.3.1.1.

3 Irrigated lands in all 712-x District serial numbers except 712-37 (Fallon Indian Reservation wetlands). Irrigated acres and

MHE were calculated as described in Step 1.3.2.

4 District serial number 712-37. Irrigated acres and MHE were estimated as described in Step 1.3.3.

5 District serial numbers 970 and 970-C. Irrigated acres and MHE were estimated as described in Step 1.3.4.

6 District serial number 975. Irrigated acres and MHE were estimated as described in Step 1.3.5.

7 Acres eligible for delivery of Project water as reported by the District at the end of the irrigation season. The 'allocated acres' figure for the Fallon Tribe does not represent acres 'eligible for delivery,' the Fallon Tribe's water rights or the quantity of Newlands Project water to which the Fallon Tribe irrigators and wetlands are entitled to receive, but instead represent estimates of the acres likely to be irrigated in the coming irrigation season based on District data.

8 The allocation at 100% from the District Report does not accurately reflect the annual use cap of 10,692.85 ac-ft for the Fallon Indian Reservation.

9 The headgate deductions include excess water applied to water-righted lands and water applied to non-water-righted lands. Headgate deductions totaled 3,509 ac-ft (Step 2.2), resulting in valid deliveries of 161,790 ac-ft (Step 2.4). The total diversion was 258,655 ac-ft (Step 2.9).

10 Totals for Irrigated Acres, MHE, and Total Delivered columns include stockwater line deliveries (Step 1.3.1.1), which are not included in Appendix A.

All serial numbers except 712-x, 970, 970-C, and 975 (Fallon Indian Reservation/Wetlands, Stillwater National Wildlife Refuge, Carson Lake and Pasture) Irrigated Acreage: A query summed acres found to be irrigated in the aerial imagery analysis (see Section 3.1) for each serial number, except 712-x, 970, 970-C, and 975. Query results summarized the total irrigated acreage by division (Truckee or Carson).

MHE: Maximum headgate entitlement is derived by multiplying the irrigated acreage by the allowable water duty. A set of queries summed the product of allowable duty and irrigated acres for each serial number to calculate MHE. Results summarized the total entitlement in ac-ft by division (Truckee or Carson).

https://10,692.85

Step 1.3.2

Step 1.3.3

Step 1.3.4

Step 1.3.1.1.

Fernley Stockwater Pipeline Delivery Volume The consumptive use of water for stockwater pipelines (see Step 2.9.2.3) limits accurate calculation of acreage and MHE using field polygons. Therefore, irrigated acreage and MHE for stockwater pipelines were estimated as described below instead of being calculated using the field polygons.

These estimated values were included in the Truckee Division values in Table 4.

Irrigated Acreage: Stockwater pipeline delivery volume totals were reported by the District to Reclamation at the end of the irrigation season. Then the total delivered volume was divided by the Truckee Division standard duty of 4.50 ac-ft/ac. to calculate estimated irrigated acreage.

MHE: The total stockwater pipeline delivery volume was used as the estimated MHE.

Fallon Indian Reservation (Serial Numbers 712-x, except 712-37) Approved field polygons and associated water right status were implemented into the Fields Geodatabase for the Fallon Tribe in 2022. Therefore, irrigated acreage and MHE were calculated using the same process as for the Truckee and Carson Divisions (Step 1.3.1) for the annual determination.

Irrigated Acreage: A query summed acres found to be irrigated in the aerial imagery analysis (see Section 3.1) for each 712-x serial number, except 712-37. Results summarized the total irrigated acreage.

MHE: Maximum headgate entitlement is derived by multiplying the irrigated acreage by the allowable water duty. On the Reservation, the water duty for all non-wetland serial numbers is 3.5 ac-ft/ac. A set of queries summed the product of allowable duty and irrigated acres for each serial number to calculate MHE. Results summarized the total entitlement in ac-ft.

Fallon Indian Reservation Wetlands (Serial Number 712-37) The consumptive use of water for the Fallon Indian Reservation wetlands limits accurate calculation of acreage and MHE using field polygons due to the uneven distribution of water on the land.

Therefore, irrigated acreage and MHE were estimated as described below instead of being calculated using the field polygons.

Irrigated Acreage: A query extracted the water volume delivered to the Fallon Indian Reservation wetlands from the District Report. Then the total delivered volume was divided by the Fallon Indian Reservation wetlands average duty of 2.99 ac-ft/ac. to calculate estimated irrigated acreage.

MHE: A query extracted the total delivered volume from the District Report and used this value as the estimated MHE.

Stillwater National Wildlife Refuge (Serial Numbers 970 and 970-C) The consumptive use of water for Stillwater National Wildlife Refuge limits accurate calculation of acreage and MHE using field polygons due to the uneven distribution of water on the land.

Therefore, irrigated acreage and MHE were estimated as described below instead of being calculated using the field polygons.

Step 1.3.5

Step 1.4.

Step 1.5.

Irrigated Acreage: A query extracted the water volume delivered to the Stillwater National Wildlife Refuge from the District Report. Then the total delivered volume was divided by the Stillwater National Wildlife Refuge weighted duty of 2.98 ac-ft/ac to calculate estimated irrigated acreage. The weighted duty for the Stillwater National Wildlife Refuge includes lands with duties of both 1.50 ac-ft/ac and 2.99 ac-ft/ac.

MHE: A query extracted the total delivered volume from the District Report and used this value as the estimated MHE.

Carson Lake and Pasture (Serial Number 975) The consumptive use of water for CLP limits accurate calculation of acreage and MHE using field polygons due to the uneven distribution of water on the land. Therefore, irrigated acreage and MHE were estimated as described below instead of being calculated using the field polygons.

Irrigated Acreage: A query extracted the water volume delivered to CLP from the District Report.

Then the total delivered volume was divided by the CLP average duty of 2.99 ac-ft/ac to calculate estimated irrigated acreage.

MHE: A query extracted the total delivered volume from the District Report and used this value as the estimated MHE.

Calculate Acreage and Applied Volume for NWR/I Lands The total irrigated acreage and applied volume for non-water righted lands were determined using a similar methodology as the calculations for water righted lands.

Irrigated Acreage: A set of database queries summed the acreage determined to be NWR/I for each serial number.

Volume: A set of database queries summed the product of the NWR/I acreage and the estimated duty for each serial number determined in Step 1.2.

The lands determined to be NWR/I appear in Table 4 and the lands determined to be NWR/I are listed by serial number in Appendix B.

Calculate Acreage and MHE for WR/NI Lands The total non-irrigated acreage and MHE for water-righted lands were determined using similar methodology as the calculations for water-righted lands.

Acreage: A set of database queries summed the non-irrigated acres for each serial number.

MHE: A set of database queries multiplied the allowable duty by the non-irrigated acres for each serial number and then summed to obtain a total.

The lands determined to be WR/NI are listed by serial number in Appendix C.

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Step 2.1.

Step 2.2.

Step 2.2.1

Step 2. Calculate Incentive Credit/Disincentive Debit OCAP Section 418.12 describes the calculation of Incentive Credit and Disincentive Debit for Project efficiency. An Incentive Credit or Disincentive Debit is calculated based on the difference between expected and actual diversions to the Project. The actual diversion is calculated from measured river and canal flows and reservoir releases. The expected diversion depends on valid deliveries and expected efficiency (calculated from irrigated acreage in the Project and the percentage of MHE delivered). Valid deliveries (Figure 1) are deliveries applied to eligible land with a valid water right and an allocation of Newlands Project water from the District. Invalid deliveries (headgate deductions in Figure 1) are deliveries applied to non-water-righted land or applications in excess of the allowable duty.

A llo w ab le D ut y

Valid Deliveries: Water applied to water-righted lands

Acreage of non-water-righted lands

Headgate Deductions: Water applied in excess of allowable duty Headgate Deductions:

Water applied to non-water-righted lands

Acreage of water-righted lands

Figure 1. Diagram of valid deliveries and headgate deductions.

The available delivery data for the 2022 irrigation season was used to carry out the calculations. The calculations were performed in a spreadsheet (as described below) using the results from Step 1, values obtained from additional queries of the Annual Determination Dataset and District Report, from OCAP, and from other sources as described below.

Input Total Water Righted Irrigated Acres The first input to the calculation is the total WR/I acres, which is used in Step 2.7 to calculate the expected efficiency. The total WR/I acres from Step 1 (Table 4) were input into the spreadsheet.

Calculate Headgate Deductions Headgate deductions were used to calculate valid deliveries in Step 2.4. These deductions include water applied to non-water-righted lands and water applied in excess of allowable duties, as shown in Figure 1. The calculations are described below and summarized in Box 1.

Calculate Water applied to water-righted lands in excess of allowable duties A set of queries summed the acreage for serial numbers, calculated the applied duty, and compared the applied duty to the allowable duty to calculate any excess application rate. For water applied in excess of allowable duty, only application rates more than 10% above the allowable duty were considered to allow for measurement error. A reasonable accuracy for the measurement of volumes of water delivered to a farm property is plus or minus 10% (Styles, 2012). Therefore, application rates of less than 110% of the allowable application rate were not included in excess deliveries.

However, the entire volume above the allowable duty was considered excess delivery (e.g., an application rate of 125% would result in a 25% excess delivery). A query summed excess volumes for serial numbers to obtain the total excess volume for the Project.

Total water applied to non-water-righted lands The spreadsheet used the results from Step 1.4 for non-water-righted lands.

Total headgate deductions The spreadsheet estimated the excess water applied to water-righted lands, and water applied to non-water-righted lands to obtain the total headgate deductions (Box 1).

Box 1. Calculation of total headgate deductions.

Water applied to non-water-righted lands

Water applied to water-righted lands in excess of allowable duties

2,486 1,023 ac-ft ac-ft

Total headgate deductions = 3,509 ac-ft

Calculate Total Water Delivered to Farm Headgates The total water delivered is used to calculate valid deliveries in Step 2.4. The volume of water delivered to each group of serial numbers in Step 1.3 was totaled in the spreadsheet to obtain the total water delivered to the Project (Table 4).

Calculate Valid Deliveries The volume of valid deliveries is the difference between the total water volume delivered (Step 2.3) and the total headgate deductions (Step 2.2.3). The spreadsheet subtracted headgate deductions from total water deliveries (Box 2) to obtain the valid deliveries.

Box 2. Calculation of valid deliveries.

Total water delivered to farm headgates

Head gate deductions

165,299 3,509 ac-ft ac-ft

Valid deliveries = 161,790 ac-ft

Input Project MHE Project MHE is used to determine the percentage of MHE delivered (Step 2.6) for use in the expected efficiency calculation (Step 2.7). The Project MHE from Step 1 (Table 4) was used as an input to the spreadsheet (Box 3).

Box 3. Project MHE.

Maximum head gate entitlement (MHE) = 193,886 ac-ft

Step 2.2.2

Step 2.2.3

Step 2.3.

Step 2.4.

Step 2.5.

Step 2.6. Calculate the Percentage of MHE Delivered The percentage of MHE delivered is used to determine expected efficiency in Step 2.7. The spreadsheet divided valid deliveries by Project MHE (Box 4).

Box 4. Calculation of percent of MHE delivered.

Valid deliveries = 161,790 ac-ft

MHE = ÷ 193,886 ac-ft % MHE delivered = 83.4%

Determine Expected Efficiency The OCAP Expected Project Distribution System Efficiency table in OCAP Section 418.13(4) determines efficiency from irrigated acreage and percent of MHE delivered. The spreadsheet looks up the expected efficiency using the values from Step 2.1 and Step 2.6 (Box 5).

Box 5. Expected efficiency.

Irrigated acres = 54,990 ac

% MHE delivered = 83.4% Expected efficiency (from OCAP Section 418.13) = 63.3%

Step 2.7.

Step 2.8.

Step 2.9.

Step 2.9.1

Step 2.9.2

Calculate Expected Diversion The expected diversion is calculated by dividing valid deliveries by expected efficiency (Box 6).

Box 6. Expected diversion.

Valid deliveries = 161,790 ac-ft

Expected efficiency = ÷ 63.3% Expected diversion = 255,592 ac-ft

Calculate Actual Total Project Diversion The actual total diversion to the Project was calculated as described in Section 418.15(b) of OCAP.

Required input data included USGS flow data measured at the Truckee Canal near Wadsworth, Truckee Canal near Hazen, Carson River below Lahontan Dam, and Carson River at Tarzyn, along with flows measured by Reclamation in the Rock Dam Ditch, estimated losses in the Truckee Canal and any flood operation or precautionary releases from Lahontan Reservoir. The steps in the calculation are described below.

Assemble USGS Data USGS gage data was downloaded from the USGS National Water Information System website

(NWIS).

Estimate Truckee Canal Losses To estimate losses in the Truckee Canal, Reclamation subtracted all metered and unmetered (estimated) deliveries along the Truckee Canal from the difference between the flow measured by the USGS gages in the Truckee Canal near Wadsworth and the Truckee Canal near Hazen. The loss calculations are summarized in Table 5 below.

Step 2.9.2.1. Truckee Canal Lateral Gages Truckee Canal deliveries are gaged by Reclamation at each of the TC-1 through TC-13 laterals. The raw 15-minute data is collected on field data loggers linked to satellite telemetry. It is processed monthly by Reclamation staff to correct for instrumentation drift and to fill missing or erroneous data. The processed data is sent to stakeholders each month and compiled into annual records.

Before using these data for the annual determination, Reclamation staff performs a final review of the data and makes corrections as appropriate using District Reports from relevant periods, scaled by a calculated historical delivery efficiency for each Truckee Canal lateral.

Step 2.9.2.2. Truckee Canal Direct Takeouts and Unmetered Laterals Direct takeouts draw water directly from the Truckee Canal. There are 11 permitted direct takeouts from the Truckee Canal, as reported by the District. Three direct takeouts are measured with metering devices by the District and Reclamation (TC-T9, TC-T13, and TC-T15), and the remaining eight are unmetered. Deliveries to unmetered takeouts are quantified with ditch rider point measurements and records. For the total diversion calculation in 2022, Reclamation identified deliveries to four unmetered direct takeouts using District delivery records. The other four unmetered takeouts did not have deliveries recorded in District records. All deliveries through direct takeouts were compiled into monthly volume records. Direct takeouts are short, piped systems and are assumed to be 100% efficient.

Unmetered laterals are laterals or takeouts that are directly upstream of a Truckee Canal Lateral gage.

Deliveries to these laterals and takeouts are diverted before they pass through a measurement device.

There are three unmetered laterals along the Truckee Canal: TC2-t1, TC4-t1, and TC5a. Deliveries to unmetered laterals are quantified with ditch rider point measurements and summarized in the District Report. Reclamation has submitted a purchase request for gage equipment on the TC4-t1 and TC5a laterals. Gage installation is anticipated to be completed during the 2023 irrigation season.

Step 2.9.2.3. Fernley Stockwater Lines Stockwater pipelines made deliveries directly from the Truckee Canal near Fernley to both stock and irrigable land during the irrigation season. These turnouts connect to the Truckee Canal at turnout structures. The District reported pipeline flows to Reclamation for the entire irrigation season. The reported readings sum the flow through each turnout structure. These sums were then divided evenly among each month of the season.

Step 2.9.3

Table 5. Estimated 2022 Truckee Canal losses for the actual diversion calculation.

Mar Apr May Jun Jul Aug Sep Oct Nov Total

Additions Truckee Canal Nr Wadsworth (ac-ft) 15,285 27,451 29,232 15,763 7,766 8,473 8,622 13,208 3,957 129,757

Subtractions

Truckee Canal Nr Hazen (ac-ft) 14,122 25,839 24,545 12,194 3,438 5,158 5,685 11,181 4,436 106,598

Truckee Canal Lateral Gages1

(ac-ft) 0 359 1,220 1,247 1,372 1,252 1,155 1,118 0 7,723

Truckee Canal Direct Takeouts and Unmetered Laterals2 (ac-ft)

0 82 116 112 286 149 175 83 10 1,013

Fernley Stockwater Lines3 (ac-ft) 4 8 8 8 8 8 8 8 4 64

Estimated Truckee Canal Loss4 (ac-ft)

1,159 1,163 3,343 2,202 2,662 1,906 1,599 818 -493 14,359

1 Truckee Canal deliveries gaged by Reclamation at the TC-1 through TC-13. Records were corrected for missing data using the District Report.

2 Truckee Canal Direct Takeout and unmetered lateral diversions estimated using District Report and Reclamation gage records.

3 Fernley Stockwater diversions as reported by the District and prorated monthly.

4 Estimated Truckee Canal Loss is negative for November. This is a result of temporary storage in

Truckee Canal flowing through the Hazen gage after diversions from the Truckee River ceased in early November.

Calculate Actual Newlands Project Diversion The actual Newlands Project diversion was calculated as the sum of flows measured at the Truckee Canal near Wadsworth, the Carson River below Lahontan Dam, and the Rock Dam Ditch minus flows measured at the Truckee Canal near Hazen, the Carson River at Tarzyn, estimated Truckee Canal losses, and precautionary releases (including flood operations). The results are summarized in Table 6 below.

Step 2.10.

Step 2.11.

Table 6. Actual Newlands Project Diversion Calculation for 2022.

Mar Apr May Jun Jul Aug Sep Oct Nov Total

Additions Truckee Canal Nr Wadsworth (ac-ft) 15,285 27,451 29,232 15,763 7,766 8,473 8,622 13,208 3,957 129,757

Carson River Blw Lahontan (ac-ft) 6,954 28,196 40,282 38,938 47,689 41,883 30,089 14,677 58 248,766

Rock Dam Ditch (ac-ft) 4 290 331 447 439 387 298 193 0 2,389

Subtractions

Truckee Canal Nr Hazen (ac-ft) 14,122 25,839 24,545 12,194 3,438 5,158 5,685 11,181 4,436 106,598

Carson River at Tarzyn1 (ac-ft) 587 651 62 0 0 0 0 0 0 1,300

Estimated Canal Loss2,3 (ac-ft) 1,159 1,163 3,343 2,202 2,662 1,906 1,599 818 -493 14,359

Precautionary Drawdown4 (ac-ft) 0 0 0 0 0 0 0 0 0 0

Total Diversion (ac-ft) 6,375 28,284 41,895 40,752 49,794 43,679 31,725 16,079 72 258,655

1 According to OCAP 418.25, flow past the Tarzyn gage in excess of 1,300 ac-ft is not considered a delivery.

2 Estimated Canal Loss = Wadsworth gage flow - Hazen gage flow - diversions from the Truckee Canal (in ac-ft), as shown in Table 5.

3 Total Diversion is negative for November. This was a result of temporary storage in Truckee Canal flowing through the Hazen gage after diversions from the Truckee River ceased in early November.

4 Precautionary drawdown did not occur during the 2022 season.

Calculate Actual Efficiency The spreadsheet divided the valid deliveries by the actual diversion to calculate the actual efficiency (Box 7).

Box 7. Actual efficiency calculation.

Valid deliveries = 161,790 ac-ft

Actual diversion = ÷ 258,655 ac-ft Actual efficiency1 = 62.6%

1Rounded for the report.

Calculate Diversion Difference The spreadsheet calculated the difference between expected and actual diversion (Box 8).

Box 8. Diversion difference.

Expected diversion = 255,592 ac-ft

Actual diversion = - 258,655 ac-ft Diversion difference = -3,063 ac-ft

Calculate Incentive Credit/Disincentive Debit The diversion difference calculated in Step 2.11 results in an Incentive Credit if positive, and a Disincentive Debit if negative. An Incentive Credit is determined by multiplying the diversion difference by 2/3 and rounding to the nearest 100 ac-ft. If the diversion difference is negative, then the entire volume, rounded to the nearest 100 ac-ft, is applied as a Disincentive Debit (Box 9).

Box 9. Incentive Credit/Disincentive Debit.

Amount debited =

Step 2.12.

Step 3.1.

3,063 ac-ft Disincentive Debit (Rounded) = 3,100 ac-ft

This debit amount will be added to the actual Lahontan Reservoir storage for the purposes of determining allowable monthly diversions and other operating decisions, beginning in WY 2024 and continuing until the debit is repaid. The debit can be repaid by crediting incentive water earned by the District or through a voluntary headgate shortage or natural drought in following years as described in OCAP Section 418.37.

Step 3. Calculate CDT and Lahontan Reservoir Storage Targets Lahontan Reservoir storage targets are adjusted to accommodate changes in Carson Division water demand. Per OCAP 418.22(a)(1), only water demand reported for full water years (100% supply) will be considered for adjustments to the storage targets. Because the 2022 allocation was less than 100% (85%), the values from 2020, the last 100% year, were used. The calculations of CDT and storage targets are described below.

Calculate Carson Division Acreage, MHE, and Average Duty for 2022.

These calculations, seen in Box 10 below, followed the same procedures as Step 1.3, except only included lands in the Carson Division. Box 10. 2022 Carson Division acreage, MHE, and average duty.

Irrigated Acres MHE (ac-ft)

Lands Except for Fallon Reservation, Wetlands, Stillwater National Wildlife Refuge, and CLP 41,285 149,573

Fallon Indian Reservation 2,276 7,966 Fallon Indian Reservation Wetlands 469 1,401 Stillwater National Wildlife Refuge 7,296 21,742

Carson Lake and Pasture + 2,151 + 6,432 Total 53,477 187,114

Total MHE 187,114 Total Acres ÷ 53,477

Weighted Average Duty = 3.50 ac-ft/ac

Step 3.2.

Step 3.2.1

Step 3.2.2

Calculate Carson Division Total Diversion Requirement The CDT was calculated from the Carson Division anticipated acres, the historical Project headgate delivery rate, the Carson Division weighted average duty, and the Project target efficiency and is rounded to the nearest 100 ac-ft. The formula for calculating CDT is:

𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝐶𝐶𝐷𝐷𝐷𝐷𝐷𝐷𝐶𝐶𝐷𝐷𝐶𝐶𝐶𝐶

𝐻𝐻𝐷𝐷𝐶𝐶𝐴𝐴𝐶𝐶𝐶𝐶𝐷𝐷𝐴𝐴𝐶𝐶𝐸𝐸 𝑃𝑃𝐶𝐶𝐶𝐶𝑃𝑃𝐸𝐸𝐴𝐴𝐴𝐴 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝐶𝐶𝐷𝐷𝐷𝐷𝐷𝐷𝐶𝐶𝐷𝐷𝐶𝐶𝐶𝐶 𝑊𝑊𝐸𝐸𝐷𝐷𝐸𝐸ℎ𝐴𝐴𝐸𝐸𝐿𝐿𝐸𝐸𝐸𝐸𝐷𝐷𝐸𝐸𝐷𝐷𝐸𝐸𝐸𝐸𝐸𝐸 𝐿𝐿𝐶𝐶𝐶𝐶𝐿𝐿

� � × �𝐻𝐻𝐸𝐸𝐶𝐶𝐿𝐿𝐸𝐸𝐶𝐶𝐴𝐴𝐸𝐸 𝐶𝐶𝐸𝐸𝐸𝐸𝐷𝐷𝐷𝐷𝐸𝐸𝐶𝐶𝐷𝐷 � × � 𝐴𝐴𝐷𝐷𝐸𝐸𝐶𝐶𝐶𝐶𝐸𝐸𝐸𝐸 𝐶𝐶𝐷𝐷𝐴𝐴𝐷𝐷 𝐷𝐷𝐶𝐶 𝐿𝐿𝐶𝐶𝐶𝐶𝐴𝐴 �𝐴𝐴𝐶𝐶𝐴𝐴𝐷𝐷𝐴𝐴𝐷𝐷𝐴𝐴𝐶𝐶𝐴𝐴𝐸𝐸𝐿𝐿 𝑅𝑅𝐶𝐶𝐴𝐴𝐸𝐸 𝐹𝐹𝐷𝐷𝐸𝐸𝐸𝐸 𝐴𝐴𝐸𝐸𝐸𝐸𝐶𝐶𝐴𝐴𝐶𝐶𝐴𝐴𝐷𝐷𝐶𝐶𝐶𝐶 𝑌𝑌𝐸𝐸𝐶𝐶𝐶𝐶𝐴𝐴𝐶𝐶 𝐸𝐸𝐸𝐸 𝐼𝐼𝐶𝐶𝐶𝐶𝐷𝐷𝐸𝐸𝐶𝐶𝐴𝐴𝐸𝐸𝐿𝐿 𝐶𝐶𝐶𝐶𝐶𝐶 =

𝑃𝑃𝐶𝐶𝐶𝐶𝑃𝑃𝐸𝐸𝐴𝐴𝐴𝐴 𝐶𝐶𝐶𝐶𝐶𝐶𝐸𝐸𝐸𝐸𝐴𝐴 𝐸𝐸𝐸𝐸𝐸𝐸𝐷𝐷𝐴𝐴𝐷𝐷𝐸𝐸𝐶𝐶𝐴𝐴𝐷𝐷 𝐶𝐶𝐴𝐴 𝐻𝐻𝐷𝐷𝐶𝐶𝐴𝐴𝐶𝐶𝐶𝐶𝐷𝐷𝐴𝐴𝐶𝐶𝐸𝐸 𝑈𝑈𝐶𝐶𝐶𝐶𝐸𝐸𝐸𝐸 𝑅𝑅𝐶𝐶𝐴𝐴𝐸𝐸

2023 Carson Division Acres Anticipated to be Irrigated The first component of the CDT calculation is the eligible acres anticipated to be irrigated in the Carson Division. This value is an average of the District's anticipated acreage for 2023 and the actual irrigated acres for the most recent 100% year (2020). Section 418.9 of OCAP directs the District to submit its annual report on eligible acres anticipated to be irrigated by March 1st and to notify Reclamation of any changes in lands anticipated to be irrigated during the irrigation season. These data were reviewed by Reclamation and used for the CDT calculation. Table 7 summarizes the District's 2023 anticipated irrigated acreage, and Box 11 shows the calculation of eligible acres to be irrigated for the Carson Division.

Table 7. Summary of 2023 eligible acres anticipated to be irrigated excerpted from the District's anticipated acreage table August update.

Anticipated Acreage (ac)

Land Classification 1.5 ac-ft/ac duty

2.99 ac-ft/ac duty

3.5 ac-ft/ac duty

4.5 ac-ft/ac duty Totals

Truckee Division

Carson Division

Temporary Transfers - Truckee Division

Temporary Transfers - Carson Division

0.00

2,891.73

0.00

0.00

0.00

11,616.04

0.00

58.49

0.10

31,070.98

0.00

585.26

1,261.54

9,620.32

0.00

144.14

1,261.64

55,199.07

0.00

787.89

Total - Truckee Division Total - Carson Division

0.00 2,891.73

0.00 11,674.53

0.10 31,656.24

1,261.54 9,764.46

1,261.64 55,986.96

Total 2,891.73 11,674.53 31,656.34 11,026.00 57,248.60

Box 11. Calculation of eligible acres to be irrigated for the Carson Division.

2023 District anticipated acreage for Carson Division 55,987 ac (2023 anticipated)

Actual irrigated acres for Carson Division in most recent 100% year 55,335 ac (2020 actual) Avg = Land anticipated to be irrigated for Carson Division = 55,661 ac

Carson Division Weighted Average Duty The second component is the “weighted average duty” for the Carson Division in the most recent 100% year (2020). This value was calculated as the Carson Division MHE divided by the actual irrigated acreage (Box 12).

Step 3.2.3

Step 3.2.4

Box 12. 2020 Carson Division irrigated acres, MHE, and weighted average duty.

MHE 191,705 ac-ft Acres ÷ 55,335 ac

Carson Division Weighted Average Duty1 = 3.46 ac-ft/ac 1Rounded for report.

Historical Project Headgate Delivery Rate The historical Project headgate delivery rate was calculated as the average percent MHE delivered from past annual determinations (Table 8). The average historical MHE was calculated from 100% allocation years without precautionary drawdown or data concerns.

Table 8. Historical Project Headgate Delivery Rates (% MHE Delivered).

Year Allocation Valid

Deliveries MHE

% MHE

Delivered Notes

2002 100% 188,995 203,300 93.0%

2003 100% 195,590 209,191 93.5%

2004 100% 194,994 199,169 97.9%

2005 100% 189,503 199,322 95.1%

2006 100% -- -- -- Not used due to precautionary drawdown

2007 100% 189,340 198,473 95.4%

2008 80% -- -- -- Not calculated due to data concerns

2009 100% -- -- -- Not calculated due to data concerns

2010 100% -- -- -- Not calculated due to data concerns

2011 100% -- -- -- Not calculated due to data concerns

2012 90% 177,223 202,163 87.7%

2013 75% 134,189 191,626 70.0%

2014 45% 89,793 160,661 55.9%

2015 21% 34,249 132,665 25.8%

2016 75% 145,446 181,758 80.0%

2017 100% -- -- -- Not used due to…