Pima County Is Laying Sewer for Houses That Don't Exist Yet
A 6,100-foot sewer extension is going in along the I-19 frontage road below Green Valley, and the trench decides what that corridor can build next.
Sewer capacity is the quiet gate on where southern Pima County can build, and the county is spending fourteen months of frontage-road closure to move that gate south.
A road below Green Valley closed in July and is not scheduled to reopen until the fall of 2027, and nothing is wrong with the road. Pima County shut the west frontage lane along Interstate 19 on July 13, with reopening set for September 22, 2027, so crews can work beside it: a trench, twenty feet deep in places, cut to lay sewer pipe through ground that public sewer service does not currently reach.
What Is Actually Going in the Ground
Phase I of the Canoa Road Sewer Extension installs 6,100 feet of new line, running from Canoa Road just south of the roundabout down to the Canoa Ranch rest area. Hunter Contracting is doing the work for the Pima County Regional Wastewater Reclamation Department. The closed segment runs from just below the Canoa Ranch traffic circle to Elephant Head Road, about a mile north of Amado, anchored at Exit 56; while it is shut, the east-side frontage road carries traffic in both directions.
- 6,100 ft
- New sewer line in Phase I, Canoa Road to the rest area
- 20 ft
- Depth of the trench in its deepest sections
- Sept. 22, 2027
- Scheduled reopening of the west I-19 frontage road
- 5
- Sub-regional county treatment plants, two of them in this corridor
Phase II Is the One to Watch
Phase I stops at the rest area. Phase II, still in design, continues south along the frontage road and crosses under I-19 at Elephant Head Road to tie into a 12-inch county line on the east side. Its purpose goes past capacity: carrying the Canoa Ranch line through to Arivaca Junction would let the county retire the Arivaca Junction lagoon and route that flow to the Green Valley plant instead. One fewer small treatment site, one larger service area, and a trunk line running the length of the corridor between them.
Why a Sewer Line Decides What Gets Built
Where a public line reaches, a parcel can be platted at the densities builders actually build. Where it does not, every house carries its own disposal system, and Arizona's subdivision rules put a floor under the lot: at least one acre where a lot must hold both its own water source and its own sewage disposal system, and otherwise enough room for the system plus 100 percent expansion sized to a four-bedroom house, with five feet of clearance to the property lines. A trunk line is what takes that floor away.
It also thins out the map. Pima County runs two metropolitan plants and five smaller sub-regional ones — Arivaca Junction, Avra Valley, Corona de Tucson, Green Valley and Mount Lemmon — and two of those five are the endpoints of this project. The system as a whole conveys more than 62 million gallons a day, with Tres Ríos alone treating roughly 30 million against a permitted 50 million. Against that, the Arivaca Junction lagoon is a small outpost, and closing it is one of the reasons the county gives for building this line at all.
What It Means If You Are Shopping the Corridor
For the next year, anything you tour on the west side of I-19 between Canoa Ranch Road and Elephant Head Road comes with a detour and a work zone attached. That is a real cost while it lasts and a temporary one. The durable part is what the pipe permits afterward. A trunk line does not rezone anything and does not commit a builder to anything — it removes the reason a piece of ground could not be built the way a builder wants to build it.
So the thing to track is not the trench. It is what shows up in Pima County development filings along that frontage in the year or two after the road reopens, because that is the window in which land that has been sitting quietly becomes land somebody can price.
Quick reference (September 3, 2026): Pima County's Regional Wastewater Reclamation Department closed the west I-19 frontage road from just south of the Canoa Ranch traffic circle to Elephant Head Road on July 13, 2026, with reopening scheduled for September 22, 2027. Phase I installs 6,100 feet of sewer line from Canoa Road, south of the roundabout, to the Canoa Ranch rest area; trenches reach 20 feet deep in places and Hunter Contracting is the contractor. Phase II remains in design and would continue south, cross under I-19 at Elephant Head Road, connect to a 12-inch county line on the east side, and allow the Arivaca Junction facility to be decommissioned. The east-side frontage road carries both directions of traffic during the closure. Construction schedules move — confirm current details before relying on any single figure.
The Pipe Goes In First
Infrastructure is the least glamorous leading indicator there is, and the hardest one to fake. An announcement costs nothing. Fourteen months of closed road, a twenty-foot trench and better than a mile of pipe is a public agency spending real money on the assumption that somebody will eventually need the capacity at the end of it. If you are watching this corridor, put the reopening date on your calendar and start reading the filings the week after — the ground behind that pipe will be priced by people who did.
Sources
KVOA News 4 Tucson — "Sewer line extension project to shut down I-19 frontage road in Green Valley" — kvoa.com/news/local/sewer-line-extension-project-to-shut-down-i-19-frontage-road-in-green-valley/article_237b03f5-11b9-4ec6-8107-4392e116c63a.html — published July 14, 2026, accessed September 3, 2026 (for the July 13, 2026 closure date; the September 22, 2027 scheduled reopening; the closure limits from just south of Canoa Ranch Road to Elephant Head Road; Hunter Contracting as contractor and the Pima County Regional Wastewater Reclamation Department as owner; the east-side frontage road carrying both directions; and the stated purpose of expanding wastewater capacity to support regional growth and eventually close the Arivaca Junction Water Reclamation Facility).
KGUN 9 — "Green Valley Traffic Alert: I-19 frontage road by Exit 56 closed until 2027" — kgun9.com/news/community-inspired-journalism/sahuarita-and-green-valley-news/green-valley-traffic-alert-i-19-frontage-road-by-exit-56-closed-until-2027-heres-what-drivers-need-to-know — accessed September 3, 2026 (for the Exit 56 location, the Canoa Sewer Line Extension project name, and the detour onto the east-side frontage road).
Green Valley News — "Q&A: Canoa Road Sewer Extension project" by Dan Shearer — gvnews.com/news/local/q-a-canoa-road-sewer-extension-project/article_4a872b42-b63f-4094-94d6-592c5321d6fa.html — published July 23, 2026 and updated September 1, 2026, accessed September 3, 2026 (for the 6,100 feet of Phase I line from Canoa Road south of the roundabout to the Canoa Ranch rest area; trench depths reaching 20 feet; Elephant Head Road being about a mile north of Amado; and Phase II remaining in design, continuing south on the frontage road and crossing under I-19 at Elephant Head Road to a 12-inch county line on the east side).
Pima County Regional Wastewater Reclamation Department — "Water Reclamation Facilities (WRF)" — pima.gov/1944/Water-Reclamation-Facilities-WRF — accessed September 3, 2026 (for the two metropolitan plants and the five sub-regional facilities — Arivaca Junction, Avra Valley, Corona de Tucson, Green Valley and Mount Lemmon; the system conveying more than 62 million gallons per day; and Tres Ríos treating approximately 30 million gallons per day against a permitted capacity of 50 million).
Arizona Administrative Code — Title 18, Chapter 5, Section R18-5-404, "Size of Lots" — law.cornell.edu/regulations/arizona/Ariz-Admin-Code-SS-R18-5-404 — accessed September 3, 2026 (for the one-acre minimum where both the water supply and the sewage disposal system must be developed on the same lot, and the requirement elsewhere that a lot accommodate the disposal system plus 100 percent expansion based on a four-bedroom house with a minimum of five feet to the property lines).
All details are current as of September 3, 2026; construction schedules, road closures, project phases and funding change, so readers should confirm current information before relying on any single figure. Nothing here is legal, tax or investment advice. This post is for informational purposes only and is not an offer to sell or a solicitation of an offer to purchase real estate. Kyle Berglund and Tierra Antigua Realty fully support and comply with the Fair Housing Act and the Equal Opportunity Act.
Topics
- High Growth Area
- Green Valley
- Canoa Ranch
- Sahuarita
- Amado
- Arivaca Junction
- I-19
- Infrastructure
- Pima County
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