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Water in Pima County
What the state and federal record says about water across Pima County. Each figure names the agency it came from.
Can I drill a well here?
Yes, an exempt well, with Active Management Area limits on much of the county
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Outside an Active Management Area
An exempt well (35 gallons a minute or less) is allowed for any use but irrigation, with no yearly cap. Domestic use includes growing plants on under two acres.
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Inside an Active Management Area
An exempt well is allowed, but use other than household and stock watering is capped at 10 acre-feet a year.
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Near a city water main, in an older AMA
No exempt well if any part of the land is within 100 feet of a designated city provider's water mains, unless ADWR grants an exemption. The 100 feet is a survey question.
- Active Management Areas here: Pinal AMA, Santa Cruz AMA, Tucson AMA.
- Every well needs a notice of intention to drill filed with ADWR and a licensed driller. On five acres or less the county health authority also signs off the site plan, and no well may sit within 100 feet of a septic system.
What has actually been permitted in Pima County
- 834exempt wells registered since 2015
- 1,770production wells of every kind since 2015
- 500feet, the typical exempt well depth
- 265feet down to water, typically
ADWR wells registry Decided by: ADWR, on the notice of intention to drill.
- 24,322 Wells on record across 9,277 square miles
- 400 ft Well depth middle value across 1,555 of 9,277 square miles
- 205 ft Depth to water middle value across 75 of 9,277 square miles
Point at any square mile to read what is on it. Hover the maps below to compare them.
Pima County by the square mile
Each figure below is one number for the whole county. The map places the same records on the ground, square mile by square mile.
Wells on record. Every well ADWR has a record of, exempt and non-exempt together.
- none on record (bare ground)
- up to 1
- 2
- 3 to 4
- 5 to 10
- 11 to 40
- over 40
9,277 surveyed sections, drawn 3 by 3 miles to a square. The shading is scaled against every county in Arizona, so a color means the same thing on any of these pages. The outline is the county boundary from the Census Bureau: ground inside the line and outside the shading is ground nobody has drilled, filed on or addressed. Aerial imagery is the USGS National Map.
Ground here is prime farmland, but only if it is irrigated
87% of sections carry soil the USDA classes as 'prime farmland if irrigated', against 7% in the median county. The qualifier is the whole sentence: the soil is excellent and the classification depends on water reaching it.
USDA SSURGO soil survey 1 of 10 counties
87% here 1st of 10 One bar per Arizona county from lowest to highest. Point at one to name it.
Most wells here have no record of what the drill went through
73% of wells on record have no drill log. The well exists on paper and nothing says what formation it hit, at what depth, or what the water was like. A neighbour's log is the cheapest evidence there is about your own ground, and here there usually is not one.
ADWR wells registry 3 of 15 counties
73% here 3rd of 15 One bar per Arizona county from lowest to highest. Point at one to name it.
Much of this county is inside an Active Management Area
50% of the county sits in Tucson AMA. Inside an AMA the state limits new groundwater pumping and a subdivision must prove a hundred-year assured water supply before it can sell lots. Outside one, almost none of that applies, and which side of the line a property falls on changes what can be built there.
ADWR Active Management Areas 4 of 9 counties
50% here 4th of 9 One bar per Arizona county from lowest to highest. Point at one to name it.
Wells here have to go a long way down
The typical well is 400 feet deep, across 24,322 wells on record. Drilling is priced by the foot and the casing with it, so depth is the first line of any estimate for putting water on raw land, and it is the number a seller is least likely to volunteer.
ADWR wells registry 4 of 15 counties
400 ft here 4th of 15 One bar per Arizona county from lowest to highest. Point at one to name it.
Water systems here are under enforcement
7% of the county is served by a system with a formal EPA or ADEQ enforcement action on record. An enforcement action is the step after a violation that was not fixed.
EPA Safe Drinking Water Information System 4 of 15 counties
7% here 4th of 15 One bar per Arizona county from lowest to highest. Point at one to name it.
Water rights here are still being decided in court
99% of the county falls inside a general stream adjudication that has run for decades and is not finished. Until it ends, who holds what is formally unsettled.
Arizona general stream adjudications 5 of 14 counties
99% here 5th of 14 One bar per Arizona county from lowest to highest. Point at one to name it.
FEMA has never determined the flood risk for most of this county
68% of the county is FEMA Zone D, which means undetermined hazard. Nobody has looked. That is a different thing from being studied and coming back outside the floodplain, and a lender or an insurer will treat the two differently.
FEMA National Flood Hazard Layer 5 of 15 counties
68% here 5th of 15 One bar per Arizona county from lowest to highest. Point at one to name it.
Parcels here are large
The typical parcel is 163 acres, against 42 ac in the median county. Size is the reason the water question is worth asking: a large parcel with no water is a large parcel you cannot do anything with.
County assessor parcel records 2 of 15 counties
163 ac here 2nd of 15 One bar per Arizona county from lowest to highest. Point at one to name it.
Much of this county is tribal land
44% of the county is tribal land, where water rights are federally reserved and settled separately from the state system.
Arizona general stream adjudications 3 of 13 counties
44% here 3rd of 13 One bar per Arizona county from lowest to highest. Point at one to name it.
The land here is sinking where the aquifer was drawn down
151 mapped subsidence features and no confirmed fissures yet. Subsidence is what precedes a fissure, and it is worth knowing about before it becomes one.
AZGS earth fissure and subsidence mapping 7 of 9 counties
151 here 7th of 9 One bar per Arizona county from lowest to highest. Point at one to name it.
Ground here has cracked open where the water was pumped out
22 confirmed earth fissures and 151 mapped subsidence features. Fissures open when an aquifer is drawn down and the land above settles unevenly. They swallow fences, roads and foundations, and no ordinary policy covers them.
22 here The bar is the whole county and the fill is this county's share.
The irrigation water here is already spoken for
3,175 grandfathered irrigation rights are recorded in this county. Inside an AMA, ground that was already being irrigated in 1980 kept the right to go on doing it and no new irrigation right can be created. New ground does not get water by asking for it.
3,175 here The bar is the whole county and the fill is this county's share.
The water table here has risen over twenty years
The median monitored well is 1.0 feet higher than it was twenty years ago, across 159 wells. That is unusual in Arizona and it is usually the result of a surface water supply arriving and pumping easing off rather than of rain.
1.0 ft here The bar is the whole county and the fill is this county's share.
This county is being platted into subdivisions
8,046 platted subdivisions are recorded here. Inside an AMA each one had to prove a hundred-year assured water supply before a lot could be sold; outside one, it did not, and the developer only had to disclose that fact.
8,046 here The bar is the whole county and the fill is this county's share.
For one parcel in Pima County
The figures above describe the whole county. The Land, Development and Rights reports answer for one parcel: what water conveys, whether a household well needs only a notice, and whether the county requires an adequate water supply to split it. Each answer gives the evidence within a mile and who decides.
Search an address in Pima County