Water

States with the Most Water 2026

Water Availability State Total (mm/month)

20K
40K
60K
80K
100K
State
Water Availability State Total 2019 (mm/month)↓
Water Availability 2019 (mm/month per mi²)
Oregon Flag
Oregon109.1K1.11
California Flag
California95K0.58
Washington Flag
Washington91.9K1.29
New York Flag
New York84K1.54
Pennsylvania Flag
Pennsylvania69.1K1.50
Wisconsin Flag
Wisconsin62.3K0.95
Mississippi Flag
Mississippi62.1K1.28
Alabama Flag
Alabama61.4K1.17
Missouri Flag
Missouri59.4K0.85
Michigan Flag
Michigan59.1K0.61
Kentucky Flag
Kentucky57.9K1.43
Louisiana Flag
Louisiana57.9K1.11
Arkansas Flag
Arkansas57.6K1.08
North Carolina Flag
North Carolina57.3K1.06
Maine Flag
Maine57.2K1.62
Tennessee Flag
Tennessee55.8K1.32
Iowa Flag
Iowa51.9K0.92
Georgia Flag
Georgia51.9K0.87
Ohio Flag
Ohio51.1K1.14
Indiana Flag
Indiana49.8K1.37
Minnesota Flag
Minnesota49.3K0.57
Idaho Flag
Idaho45.8K0.55
Montana Flag
Montana36.8K0.25
Illinois Flag
Illinois35.4K0.61
Virginia Flag
Virginia34.9K0.82
Florida Flag
Florida33.3K0.51
Texas Flag
Texas29.8K0.11
Colorado Flag
Colorado27.5K0.26
West Virginia Flag
West Virginia26.1K1.08
Oklahoma Flag
Oklahoma24.7K0.35
South Carolina Flag
South Carolina23.7K0.74
Wyoming Flag
Wyoming20K0.20
Kansas Flag
Kansas16.1K0.20
Utah Flag
Utah16K0.19
South Dakota Flag
South Dakota15.9K0.21
New Hampshire Flag
New Hampshire15.3K1.64
Vermont Flag
Vermont11.9K1.23
New Jersey Flag
New Jersey11.4K1.31
Nebraska Flag
Nebraska11.4K0.15
Nevada Flag
Nevada10.7K0.10
Massachusetts Flag
Massachusetts9.6K0.91
North Dakota Flag
North Dakota8.8K0.12
Connecticut Flag
Connecticut8.2K1.48
Maryland Flag
Maryland8.1K0.66
Arizona Flag
Arizona5K0.04
New Mexico Flag
New Mexico3.7K0.03
Rhode Island Flag
Rhode Island1.9K1.22
Delaware Flag
Delaware1.8K0.74
  • Integrated water availability is a measurement that begins with the total volume of water available, then considers factors such ecological needs, safety concerns, legal guidelines, and available water quality and accessibility to determine the quantity of legitimately usable water in a given area.
  • Integrated water availability is measured in millimeters (mm) of water available. One millimeter of water is equivalent to 1 liter of water per square meter of land (1L per m²)
  • Water area calculations in this table include only perennial water. All other water (intermittent, glacier, and marsh/swamp) is included in this table as part of land area calculations.
  • Inland water consists of any lake, reservoir, pond, or similar body of water that is recorded in the Census Bureau’s geospatial database. It also includes any river, creek, canal, stream, or similar feature that is recorded in that database as a two-dimensional feature (rather than as a single line).
  • The portions of the oceans and related large embayments (such as Chesapeake Bay and Puget Sound), the Gulf of Mexico, and the Caribbean Sea that belong to the United States and its territories are classified as coastal and territorial waters; the Great Lakes are treated as a separate water entity.
  • HUC stands for ‘Hydrological Unit Code’ which is a number that identifies a ‘Hydrological Unit’. Hydrological units represent the area of the landscape that drains to a portion of the stream network. More specifically, a hydrologic unit defines the areal extent of surface water drainage to an outlet point on a dendritic stream network or to multiple outlet points where the stream network is not dendritic. A hydrologic unit may represent all or part of the total drainage area to an outlet point so that multiple hydrologic units may be required to define the entire drainage area upstream of a given outlet. HUC12 denotes the smallest Hydrological Unit currently published by USGS, known as a ‘subwatershed’, being on average 40 square miles in size.
  • USGS defines water availability as how much water is physically accessible (water quantity) and whether that water is safe to use (water quality).
  • Water Availability per Square Mile is calculated by dividing the sum total of the water availability of all HUC12s fully within state boundaries by the total area of the state.

Sources

  1. Water Science School Home Page - USGS
  2. State Area Measurements and Internal Point Coordinates - United States Census Bureau
  3. State Water Facts - EPA
  4. Model: Public Supply Withdrawals Water-Use Model - USGS
  5. National Water Availability Assessment Data Companion - USGS
  6. Understanding Water Availability - USGS
  7. Hydrologic Units of the United States - USGS
  8. Integrated Water Availability Assessments - USGS