# Pima County Subdivision Assurances, Encroachment Insurance and Floodplain Rules

URL: https://mycontractorsinsurancequote.com/arizona/metros/tucson/pima-county
Updated: 2026-10-29 · Reviewed by the Principal, Gleason Insurance Brokers, LLC
Publisher: My Contractors Insurance Quote, a website of Gleason Insurance Brokers, LLC

In unincorporated Pima County, subdivision improvements are secured with a third-party trust or a financial security (a letter of credit, cash or a certificate of deposit) in the amount the County approves from a sealed engineer's estimate, and the County's assurance page does not list a performance bond. The County's trust agreement gives the subdivider four years to complete the improvements, and an encroachment license, which is separate from an ordinary right-of-way use permit, calls for a $2,000,000 commercial general liability policy naming the County as additional insured. Incorporated cities and towns, including Tucson, Marana, Oro Valley, Sahuarita and South Tucson, set their own rules.

## Key Decision Points
- Pima County's subdivision assurance page lists a third-party trust or a letter of credit, cash or certificate of deposit, and it does not list a performance bond.
- The security is posted in the amount the County approves after its Site Review Unit reviews a sealed engineer's cost estimate and completion date.
- Partial releases generally require at least 10 lots, or 50 percent of the lots in a subdivision of fewer than 20 lots.
- The County's third-party trust agreement sets a four-year completion deadline and lets the County withhold building and zoning permits on default.
- An encroachment license requires a $2,000,000 CGL policy, primary and noncontributory, with a waiver of subrogation and the County as additional insured.
- Floodplain use permits can take several weeks, and riparian mitigation plans carry five years of monitoring.

## Unincorporated Pima County and the Cities Inside It

This page covers land outside any incorporated city or town in Pima County. Pima Association of Governments counted 371,835 residents in unincorporated Pima County in 2022, a little more than a third of the county's 1,072,298 people. Plats inside the City of Tucson, Marana, Oro Valley, Sahuarita or South Tucson go through those jurisdictions, which set their own assurance, right-of-way and insurance terms.

The County's assurance rules rest on A.R.S. § 11-821 and Pima County Zoning Code Chapter 18.69, as its trust agreement states. The details below come from the County's forms and permit pages rather than the code text, so confirm the current Chapter 18.69 provisions with Pima County Development Services before relying on any figure.

How the City of Tucson's assurance forms compare is explained under [Tucson-area bond and insurance rules](https://mycontractorsinsurancequote.com/arizona/metros/tucson).

## Assurance Forms: Trust or Financial Security, No Bond Listed

Pima County's Subdivision Assurance Process page says acceptable assurances are a third-party trust agreement or a financial security, citing A.R.S. § 32-2183, subsections F.4 and F.2. The financial security options it names are a letter of credit, cash or a certificate of deposit. A performance bond is not on the list. The page describes the assurance as securing improvements the developer builds before any subdivision lot is sold.

The amount is not a fixed percentage. The developer submits a cost estimate sealed by a professional engineer, along with a completion date. The County's Site Review Unit reviews it, which the page says takes 10 working days. The security is then posted in the amount approved.

For a developer used to bonding improvements in other jurisdictions, this changes the credit plan. A letter of credit typically uses bank capacity that might otherwise support construction loans, cash or a certificate of deposit ties up liquidity directly, and a third-party trust holds the lots until the County releases them. Ask the County whether any other form is acceptable before assuming a surety bond line can carry a Pima County plat.

How assurance choices differ across Arizona agencies is explained under [Arizona subdivision assurance bonds](https://mycontractorsinsurancequote.com/construction-surety-bonds/subdivision-improvement-bonds/arizona).

### Illustrative scenario: A Trust, a Wash and a Riparian Mitigation Plan

Desert Wash Homes (fictional) plans a 64-lot subdivision in unincorporated Pima County. Its engineer's sealed estimate for streets, drainage and utilities is $5.2 million, and its surety has offered a bond line. Because the County's assurance page lists a third-party trust or a letter of credit, cash or certificate of deposit, the developer chooses a third-party trust so its bank line stays available for the construction loan. A wash on the east boundary carries a base flood discharge above 100 cubic feet per second, so the site needs a Floodplain Use Permit, and the grading plan disturbs more than 1/3 acre of regulated riparian habitat, which calls for a mitigation plan with five years of monitoring. The site contract assigns plant replacement and annual photo reports to a landscape contractor, and the developer plans release requests in groups of at least 10 lots. The details are hypothetical, and a real program depends on the agency, the surety or carriers and the firm's own risk.

## Partial Releases and Release Timing

The County releases assurances in groups. A partial release must cover at least 10 lots, or 50 percent of the lots for a subdivision with fewer than 20 lots, and smaller releases are considered only for exceptional circumstances. The trust agreement adds that partial releases are granted only when the improvements serving the released lots are complete and usable separately from the rest of the subdivision.

Release inspections take place 10 working days after the request, an engineer's completion certification is required and only the Pima County Assurance Release Form is accepted. The title company records the release within 30 days. A recreation in-lieu fee is due before more than 75 percent of the lots are released.

Each of those steps affects how long a letter of credit or trust stays open. Building release timing into the construction schedule, and having the engineer's certification ready when the last improvement for a lot group is finished, helps keep the security from staying in place longer than the project needs.

## The Third-Party Trust Agreement: Four Years and Default Remedies

The County's Assurance Agreement for Construction of Subdivision Improvements (Third Party Trust) is a Word form with no printed revision date; its file was last modified on October 8, 2026. It requires the subdivider to complete the improvements not more than four years after the date of the agreement. The trustee may not convey lots without a County Release of Assurance, and the County may accept substitute assurances in a form and amount acceptable to it.

If the subdivider defaults, the form lets the County re-plat the land to its pre-plat configuration, require plat revisions and withhold building permits under Title 15 and permits under Title 18. The County does not take on maintenance until the improvements are complete, dedicated and accepted by the Board of Supervisors. An older version used for time extensions, dated 2018, adds that an extension may require an updated traffic impact study and a new or updated drainage report to current standards.

The form contains no insurance clause and no warranty clause. Pima County warranty periods and warranty security were not verified for this page, so confirm warranty terms with the County before pricing maintenance obligations or a site contractor's maintenance bond.

How maintenance obligations are typically secured is explained under [maintenance and warranty bond terms](https://mycontractorsinsurancequote.com/construction-surety-bonds/maintenance-warranty-bonds).

## Right-of-Way Use Permits and Encroachment Licenses

Work in County right-of-way, such as trenching, curb or pavement removal, paving, landscaping or flood control work in drainageways, needs a Right-of-Way Use Permit from the Pima County Department of Transportation. The permit page asks for a cost estimate for non-utility work, reviews it against the County's permit procedures and the PAG Standard Specifications and Details (2015 edition), adds cultural resources review for projects over 500 linear feet and lists about five business days for review. The application asks for the contractor's ROC number, its Arizona Registrar of Contractors license, along with an itemized cost breakdown and the work duration.

Bond, deposit and insurance requirements for an ordinary right-of-way use permit were not verified for this page. The readable permit page and application do not list them, and the County's fee schedule is a scanned image. Confirm any permit bond, deposit or certificate requirement with the County before bidding.

An encroachment license is a different instrument, and the County's procedure says encroachments are allowed only under extreme and unusual conditions. Under that procedure (file dated 2022), the licensee obtains a $2,000,000 commercial general liability policy that is primary and noncontributory, includes a waiver of subrogation in favor of the County and names the County as additional insured, and returns the certificate with the notarized license agreement. The filing fee is $2,900 and non-refundable, Board approval can take up to 90 days, and a right-of-way use permit and, where applicable, a floodplain use permit are still required.

How permit bonds and certificates for street work typically fit together is explained under [Arizona encroachment and right-of-way permit bonds](https://mycontractorsinsurancequote.com/construction-surety-bonds/encroachment-permit-bonds/arizona).

## Floodplain Use Permits and Riparian Mitigation

The Pima County Regional Flood Control District requires a Floodplain Use Permit before construction in regulatory floodplains, which include areas along any wash with a base flood discharge of 100 cubic feet per second or more, as well as erosion hazard areas and mapped riparian habitat in unincorporated Pima County. The District's application guide says these permits may take several weeks because of hydrologic review.

When a project disturbs more than 1/3 acre (14,520 square feet) of regulated riparian habitat, the District's Riparian Habitat Mitigation Plan checklist for single-lot development, revised 8/12/2024, requires a mitigation plan under Ordinance 2010-FC5, sections 16.30.040 and 16.30.050. Avoidance must be justified, and the checklist states that preserving views, cost of construction and similar factors are not sufficient justification. Planting is monitored for five years with annual photo reports, and success means 80 percent of the plants are living and growing without supplemental irrigation at the end of that period.

The checklist does not state a bond or financial assurance for mitigation, but five years of monitoring is a long tail for a site contract. Decide in writing who owns plant replacement and reporting after the grading contractor leaves, and check how the site contractor's liability and pollution policies treat sediment or erosion claims in and near washes.

Sediment, erosion and runoff exposures are explained under [pollution coverage for site development](https://mycontractorsinsurancequote.com/contractors-pollution-liability-insurance/site-development).

## Multi-Species Conservation Plan Certificate of Coverage

Pima County and the Regional Flood Control District hold a Section 10 permit from the U.S. Fish and Wildlife Service under the County's Multi-Species Conservation Plan. The County's page lists 44 permit-covered species and about 36,000 acres of ground disturbance under the permit, about 31,000 acres of it for private development. Developers can seek coverage through the County's Certificate of Coverage Program and use County-banked mitigation land.

The Certificate of Coverage is a permitting tool, not an insurance product. It can shape schedule and mitigation cost on sites with covered species, and those costs belong in the development budget and in the builders risk soft-cost discussion where delay is a concern. Confirm eligibility and terms with the County's Office of Sustainability and Conservation.

Bond capacity and program structure for developers are explained in [Arizona developer surety and insurance planning](https://mycontractorsinsurancequote.com/arizona/audiences/developers).

## Before You Ask for a Quote

### What to Gather
- Sealed engineer's cost estimate and completion date for the subdivision improvements
- Choice of assurance: third-party trust, letter of credit, cash or certificate of deposit
- Lot grouping plan for partial releases of at least 10 lots
- Right-of-Way Use Permit application with the contractor's ROC number and itemized costs
- Encroachment license certificate showing $2,000,000 CGL, primary and noncontributory wording, waiver of subrogation and the County as additional insured
- Floodplain Use Permit and any riparian mitigation plan with its monitoring schedule

### What to Ask the Insurer or Surety
- Will the County accept any assurance besides a trust, letter of credit, cash or certificate of deposit?
- What warranty period and warranty security does the County require for these improvements?
- Does our ordinary right-of-way use permit carry a bond, deposit or insurance requirement?
- Can our liability carrier issue primary and noncontributory wording and a waiver of subrogation for the County?
- Who owns riparian mitigation monitoring and plant replacement after grading ends?
- Is the site eligible for a Certificate of Coverage under the Multi-Species Conservation Plan?

## Broker Notes

**Quick Answer:** Unincorporated Pima County secures subdivision improvements with a third-party trust or a letter of credit, cash or certificate of deposit sized from a sealed engineer's estimate, and its trust form sets a four-year completion deadline. Encroachment licenses require a $2,000,000 CGL policy naming the County.

**Common Mistake:** Lining up a surety bond for a Pima County plat because the City of Tucson accepts one, then learning the County's assurance page lists a trust, letter of credit, cash or certificate of deposit.

**Broker Perspective:** A broker compares the County's accepted assurance forms with the developer's bank and surety capacity, and checks that the encroachment license certificate carries the primary, noncontributory and waiver of subrogation wording the County lists.

**Coverage Impact:** Trusts and letters of credit are not insurance. The encroachment license CGL terms are a County requirement, and whether a carrier can meet them typically depends on carrier guidelines, programs and underwriting, subject to the terms of the policy issued.

## Questions Buyers Ask

### Does Pima County accept a performance bond for subdivision improvements?

The County's Subdivision Assurance Process page lists a third-party trust agreement or a financial security, meaning a letter of credit, cash or a certificate of deposit. It does not list a performance bond. Ask Pima County Development Services directly before planning around a surety bond for an unincorporated plat.

### How much subdivision security does Pima County require?

The page does not set a percentage. The developer submits a cost estimate sealed by a professional engineer, along with a completion date. The Site Review Unit reviews it in about 10 working days, and the security is posted in the amount approved.

### When can Pima County release part of a subdivision assurance?

A partial release generally covers at least 10 lots, or 50 percent of the lots in a subdivision of fewer than 20 lots, once the improvements serving those lots are complete. An engineer's completion certification and the Pima County Assurance Release Form are required, and the title company records the release within 30 days.

### What insurance does a Pima County encroachment license require?

The County's encroachment license procedure calls for a $2,000,000 commercial general liability policy, primary and noncontributory, with a waiver of subrogation in favor of the County and the County named as additional insured. That applies to the encroachment license, not to an ordinary right-of-way use permit, whose bond and insurance terms should be confirmed with the County.

### When does a project need a Floodplain Use Permit in unincorporated Pima County?

The Regional Flood Control District requires one before construction in regulatory floodplains, including areas along washes with a base flood discharge of 100 cubic feet per second or more, erosion hazard areas and mapped riparian habitat. The District says these permits may take several weeks.

### What warranty does Pima County require on subdivision improvements?

That was not verified for this page. The County's trust agreement form has no warranty clause, and the assurance page does not state a warranty period or warranty security. Confirm warranty terms with Pima County before pricing maintenance obligations.

## Official Sources

1. [Subdivision Assurance Process](https://www.pima.gov/1035/Subdivision-Assurance-Process), Pima County Public Works, Building and Site Development. Acceptable assurances are a third-party trust agreement or a financial security (letter of credit, cash or certificate of deposit) citing A.R.S. § 32-2183 F.4 or F.2, no performance bond listed; improvements constructed before any lot is sold; sealed PE cost estimate and completion date reviewed by the Site Review Unit in 10 working days, security posted in the amount approved; partial release of at least 10 lots or 50% of lots for subdivisions under 20 lots, smaller only for exceptional circumstances; release inspections 10 working days after request, engineer's completion certification, only the Pima County Assurance Release Form, title company records release within 30 days; recreation in-lieu fee before more than 75% of lots are released. Verified 2026-10-26.
2. [Assurance Agreement for Construction of Subdivision Improvements (Third Party Trust), file modified 2026-10-08](https://content.civicplus.com/api/assets/1d4aa50b-ac90-42f7-a3da-93c1c5d3bd2b), Pima County Development Services. Required by A.R.S. § 11-821 and Pima County Zoning Code Chapter 18.69; completion not more than four years after the agreement date; no lot conveyance without a County Release of Assurance; partial release only when improvements are complete and usable separately; substitute assurances in a form and amount acceptable to the County; County maintenance only after completion, dedication and Board of Supervisors acceptance; default remedies of re-plat, plat revisions and withholding Title 15 and Title 18 permits; no insurance or warranty clause. Verified 2026-10-26.
3. [Assurance Agreement (Third Party Trust), time extension version, file dated 2018-12-06](https://content.civicplus.com/api/assets/6f50070a-77b6-41df-a80c-6e599853790e), Pima County Subdivision Coordinator. Same four-year completion and release structure; a time extension may require an updated traffic impact study and a new or updated drainage report to current standards. Verified 2026-10-26.
4. [Right-of-Way Use Permit](https://www.pima.gov/1065/Right-of-Way-Use-Permit), Pima County Department of Transportation. Permit required for work in County right-of-way (trenching, curb or pavement removal, paving, landscaping, flood control work in drainageways); cost estimate for non-utility work; review against County permit procedures and PAG Standard Specifications and Details (2015 edition); cultural resources review over 500 linear feet; about five business days review; no bond, deposit or insurance requirement on the readable page. Verified 2026-10-26.
5. [Right-of-Way Use Permit Application (file dated 2017-06-13)](https://content.civicplus.com/api/assets/a81ca014-02fa-4deb-82f9-856125c676e4), Pima County. Application asks for the contractor's ROC number, an itemized construction cost breakdown and work duration; no bond, deposit or insurance fields. Verified 2026-10-26.
6. [ROW Encroachment License Application Procedure (file modified 2022-01-18)](https://content.civicplus.com/api/assets/az-pimacounty/d26a0300-9a1b-4e56-86c9-234d79b264a7), Pima County Real Property Services. Encroachment license only: $2,000,000 CGL policy, primary and noncontributory, waiver of subrogation, Pima County as additional insured, certificate returned with notarized License Agreement; $2,900 non-refundable filing fee; Board approval up to 90 days; Right-of-Way Use Permit and, if applicable, Floodplain Use Permit still required; encroachments allowed only under extreme and unusual conditions. Verified 2026-10-26.
7. [Floodplain Use Permit (FPUP) Application Guide](https://pima.gov/1452/Floodplain-Use-Permit-FPUP-Application-G), Pima County Regional Flood Control District. Floodplain Use Permit required before construction in regulatory floodplains (washes with base flood discharge of 100 cfs or more), erosion hazard areas and mapped riparian habitat in unincorporated Pima County; permits may take several weeks. Verified 2026-10-26.
8. [Riparian Habitat Mitigation Plan Submittal Checklist, Single-Lot Development (Revised 8/12/2024)](https://content.civicplus.com/api/assets/az-pimacounty/e2ae35d1-62d7-4087-b978-1aa931a7222f), Pima County Regional Flood Control District. Mitigation plan required when more than 1/3 acre (14,520 sq ft) of regulated riparian habitat is disturbed (Ord. 2010-FC5, 16.30.040 and 16.30.050); avoidance must be justified, cost of construction is not sufficient justification; five-year monitoring with annual photo reports; success is 80% of plants living without supplemental irrigation at five years; no financial assurance stated. Verified 2026-10-26.
9. [Multi-Species Conservation Plan](https://www.pima.gov/635), Pima County Office of Sustainability and Conservation. Section 10 permit held by Pima County and the Regional Flood Control District with the U.S. Fish and Wildlife Service; 44 permit-covered species; about 36,000 acres of ground disturbance, about 31,000 for private development; Certificate of Coverage Program and County-banked mitigation land for developers. Verified 2026-10-26.
10. [RMAP Update: 2022 County and Subcounty Population Projections (October 18, 2023)](https://pagregion.com/wp-content/docs/pag/2023/10/PAG-TPC-2023-10-18-Item-5-RMAP-Update-Population-Projection.pdf), Pima Association of Governments, Transportation Planning Committee. 2022 population: Tucson 554,021; unincorporated Pima County 371,835; Marana 56,758; Oro Valley 48,906; Sahuarita 36,179; South Tucson 4,599; county total 1,072,298; county forecast 1.31 million in 2060. Verified 2026-10-26.

## Related Decisions

- [Tucson-area assurance and permit rules](https://mycontractorsinsurancequote.com/arizona/metros/tucson)
- [Arizona civil contractor bonds and insurance](https://mycontractorsinsurancequote.com/arizona/audiences/civil-infrastructure-contractors)
- [land developer insurance and bonds](https://mycontractorsinsurancequote.com/who-we-serve/developers-subdividers/land-developers)
- [soft costs and delay coverage](https://mycontractorsinsurancequote.com/builders-risk-insurance/soft-costs-and-delay)
- [grading contractor insurance](https://mycontractorsinsurancequote.com/who-we-serve/civil-underground-utilities/excavation-and-grading-contractors)

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