Idaho
Clean Watersheds Needs Survey 2008
The Clean Watersheds Needs
Survey (CWNS) is a comprehensive
assessment of needs1 to meet the water
quality and water-related public health
goals of the Clean Water Act (CWA).
States and the U.S. Environmental
Protection Agency (EPA) conduct the
CWNS every four years under CWA
Section 516 (b). Idaho documented
needs totaling $1.5 billion in 2008.
This is a 98 percent increase from the
$741 million in needs documented in
2004.
Documented Needs in Idaho
Needs (2008 Dollars, Millions)
Type of Need
2004
2008
Percent Change
Wastewater treatment
$336
$1,019
203%
Pipe repair and new pipes
$191
$349
83%
Recycled water distribution
<$0.5
<$0.5
0%
Combined sewer overflow correction
$0
$0
0%
Total Wastewater Treatment Needs
$527
$1,368
159%
Conveyance infrastructure
n/a
$1
n/a
Treatment systems
n/a
$2
n/a
Green infrastmcture
n/a
$2
n/a
General stormwater management
$38
$4
-89%
Total Stormwater Management Needsb
$38
$9
-76%
Agriculture (cropland) best management practices (BMPs)
$81
$30
-63%
Agriculture (animals) BMPs
$33
$37
12%
Silviculture (forestry) BMPs
$9
$2
-78%
Ground water protection: unknown source BMPs
nr
<$0.5
n/a
Marinas BMPs
<$0.5
<$0.5
35%
Resource extraction BMPs
$2
$1
-50%
Brownfields remediation
nr
nr
0%
Storage tank remediation
nr
nr
0%
Sanitary landfills BMPs
nr
nr
0%
HydromodiScalion (Water resource restoration and protection)
$51
$18
-65%
Other estuary management activities0
n/a
nr
n/a
Total Nonpoint Source Control NeedsM
$176
$88
-50%
Total Decentralized Wastewater Treatment Needsb'd
<$0.5
nra
-100%.
Total Needs
$741
$1,465
98%.
aNot reported; Actual needs may be higher, since documenting these needs is difficult; °In 2004, Other Estuary Management
Needs were reported under Separate State Estimates (SSEs); dNot included in Official Needs in the Report to Congress.
County Needs ($M)
None reported
< 5
5-25
>25
1 Documented needs in the CWNS include the unfunded capital costs of projects as of January 1, 2008 that address a water
quality or a water quality-related public health problem existing as of January 1, 2008, or expected to occur within the next 20
years; and meet the seven CWNS documentation criteria. All needs are in January 2008 dollars.

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Idaho
Clean Watersheds Needs Survey 2008
Wastewater Treatment Facilities
The enactment of the Clean Water Act (CWA) in 1972 resulted in dramatic improvements in the:
•	Number of wastewater treatment plants.
•	Percentage of the population served by wastewater treatment plants.
•	Quality of effluent treatment from wastewater treatment facilities.
In 2008, 72% of Idaho residents received centralized wastewater treatment services at the secondary,
advanced, or no discharge treatment level, compared to 16% in 1972.
Number of Centralized Treatment Facilities and Population Served
Number of Facilities
Population Served
%Total	%Total
Population	Population
Treatment Level
1972
2008
Projected"
1972
1972
2008
2008
Projected3
Less than Secondary
20
0
0
178,000
22
0
0
0
Secondary
11
98
87
108,000
13
530,059
35
543,194
Advanced
2
13
27
24,000
3
496,573
33
1,296,946
No Discharge
0
55
56
0
0
58,754
4
89,303
Total
33
166
170
310,000
38
1,085,386
72
1,929,443
a Number of facilities and population served if all needs documented in the CWNS 2008 are met.
Small Communities
In Idaho, small community wastewater
facilities serve 11% of the population
and comprise 19% of total wastewater
treatment and collection needs. EPA
small community support information is
available at:
www. epa. gov/owm/mab/smcomm
Reported Needs for Facilities in Small Communities
Facilities

1 Needs (2008 Dollars, Millions)
Population
2004
2008
2004
2008
0-999
20
18
$59
$51
1,000-3,499
24
22
$49
$160
3,500-10,000
10
6
$87
$50
Total
54
46
$194
$262
Visit www.epa.gov/cwns for more information including:
•	Detailed Reports to Congress
•	Other state fact sheets
•	Maps, charts, and data downloads for projects, facilities, watersheds, counties, congressional
districts, cities, states, and regions

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