Methodology

Primary sources

All data on this site is drawn from official documents: the Johnson County Sheriff's Office monthly control sheets, Iowa Department of Inspections, Appeals and Licensing jail inspection reports, Johnson County Board of Supervisors meeting minutes and agenda packets (accessed via the County's Granicus archive), Johnson County budget documents (FY24–FY27), and consultant reports obtained from the County's website or via open-records requests.

The Sheriff's Office publishes annual jail statistics in two formats: "Weekly Jail Statistics Summary" PDFs (FY15–FY20, with daily detail) and "Control Sheet" PDFs (FY21–present, with monthly summary). All ADP figures on this site are computed from these primary documents.

Column-swap warning (FY15 and FY16 source PDFs)

The "INMATES IN J.C. JAIL" and "HOUSED ELSEWHERE" column labels in the top summary table of the FY14FY15 and FY15FY16 Weekly Statistics Summary PDFs are reversed relative to the daily-detail tables that follow. Values used on this site are from the daily-detail legend, which is canonical. This is documented in the source manifest.

What "ADP" means on this site

"In-house ADP" means the average number of people held physically present at 511 S. Capitol Street, Iowa City (the Johnson County Jail) per day, computed from the 6 a.m. location report or equivalent. "Total in-custody ADP" means in-house plus out-of-county housed prisoners plus electronic monitor participants, as reported in the Sheriff's control sheets.

The CSSI fact sheet figure of "86 ADP" is consistent with the calendar year 2024 ADP, calculated from FY2024 and FY2025 control sheets. The fact sheet itself does not specify how the number is calculated.

ADP data — March 2026 update

In July 2026 the March 2026 Sheriff's control sheet was added to the dataset, extending ADP records through March 2026. The 12-month window (April 2025–March 2026) shows a mean total in-custody ADP of approximately 89.6 and a peak of approximately 97.03 in July 2025. Analysis of what this means for the capacity argument is on the Overview page.

Open-records requests

Documents obtained via open-records requests are identified as such in source citations and tracked on the Records page. Originals are available for download where noted.

Inflation adjustment

Bond amounts in the history section are adjusted to 2026 dollars using the Turner Construction Cost Index (CCI), which is the industry-standard index for construction cost escalation and is the index cited in Shive-Hattery's own cost estimates.

Bond amortization — term and rate assumptions

All debt-service figures on this site use a 10-year level-payment (PMT) amortization term. This matches the term stated publicly for the first time at the June 10, 2026 Board of Supervisors work session, when Chair Jon Green confirmed that Finance Director Dana Aschenbrenner's $107/$100K tax figure is based on a 10-year repayment schedule. All prior Shive-Hattery reports and board presentations either used a 20-year assumption or stated no term at all.

The interest rate is estimated at 4.5%, based on current Iowa general-obligation bond market conditions (4.25–4.75% range for 2026–2027 issuance). No Shive-Hattery document states an assumed rate. A 10-year bond typically prices modestly below a 20-year bond, so 4.5% may be slightly conservative; sensitivity rows at 4.0% and 5.0% are shown on the Cost Analysis page.

The county's published tax figure ($107 per $100,000 of taxable value per year) can be independently cross-checked: FY27 debt-service taxable valuation of $11,810,397,592 (FY27 Tax Calculation Worksheet, April 20, 2026) × $1.07/$1,000 levy ≈ $12.64M/yr raised — consistent with $96M at approximately 4.5%–5.5% over 10 years.

Claims registers — extraction and basis

Payment figures on this site tied to the jail project were extracted from the weekly claims registers attached as item C.1.a to Board of Supervisors formal-meeting packets on the County's Granicus archive: "Supplier Invoice Payments" lists in the Workday era (October 9, 2025–present) and "Account Distribution" registers in the Innoprise era (January 2, 2025–September 18, 2025). Every register reconciles to the totals printed in its packet.

The basis is the payment/register date (cash), not accrual. These figures will differ slightly from the County's accrual actuals, and the site labels payment-basis figures as such wherever both bases exist. No claims registers were published for September 25 and October 2, 2025, during the Innoprise-to-Workday ERP cutover; the October 9, 2025 register is a catch-up batch. The February 5, 2026 register was published as image-only pages and was recovered by OCR; it reconciles exactly to its printed totals ($1,508,192.43 supplier invoices / $1,644.46 previously-approved / $811.20 expense reports).

Corrections log

Update log

Additions and status changes that did not correct an error in previously published material.