The document summarizes Idaho's recycled water reuse program, which issues around 20 permits per year to 130 active projects reusing over 8 billion gallons of treated wastewater annually. It also highlights the evolution of a large potato processor's reuse system from unlined lagoons to advanced membrane treatment allowing some treated water to be reused internally. Finally, it notes the challenges of using land treatment and monitoring groundwater quality to evaluate reuse permit compliance.

1. Idaho Recycled Water
Reuse Program
June 2015

2. Reuse Program Summary
•1988 – Original rules for Land
Application of Wastewater issued
•Permit program is funded by
Federal Clean Water and State
General funds (approximately
50/50)
•No permit fees

3. Reuse Program Summary
• ~130 active reuse permits
•73% are municipal and 27% are
industrial permits
•Over 90% of the reuse permits are
agricultural irrigation systems
•Remainder are rapid infiltration

4. Reuse Program Summary
•Approaching 8 billion gallons of water
reuse per year
•The reuse water contains ~4 million
pounds of nitrogen and ~1 million
pounds of phosphorus

5. Reuse Program Sustainability
• 2011 revisions to the reuse rules allowed
DEQ to issue permits for up to 10 years
(versus 5 years previously)
• This allowed DEQ to “reward” facilities
with good compliance history longer-
term permits when permits expired
• This has made the permit program more
sustainable with the available staff
resources

6. Reuse Program Sustainability
• Over the past three years, DEQ has issued
59 permits or ~20 permits per year
• The average permit term is now up to 6.1
years and will continue to increase as
longer term permits are issued
• At an average permit term of 6.1 years,
DEQ has to issue 21 permits per year to
be sustainable (130 permits/6.1 year
permit term)

7. Simplot Caldwell (Potato Processing Facility)

8. Simplot Caldwell – Evolution of a
Successful Reuse Program
• Treatment in the early 1990’s were unlined
anaerobic lagoons located in close proximity
to the Boise River
• Current treatment system (started up in 2014)
advanced treatment processes membrane
bioreactor and filtration (activated sludge with
ultrafiltration membranes) and reverse
osmosis
• Nitrogen loading rates reduced from ~1,500
pounds per acre to agronomic rates

9. Simplot Caldwell – Evolution of
a Successful Reuse Program
•The high water quality from the new
wastewater treatment system allows
Simplot to return a portion of the
treated water for reuse in the potato
processing plant

10. Municipal Reuse Permits
• Municipal systems are split into classes based on
treatment and disinfection levels:
7%
22%
48%
10%
8%
Class E
Class D
Class C
Class B
Class A

11. What We Have Learned
Land treatment of recycled water is not an
exact science
• Multi-disciplinary – wastewater treatment,
hydrology, geology, agronomy, irrigation, soil
science, chemistry, biology, public (neighbor)
involvement, land use issues, etc.
• Most reuse systems are agriculturally based
activities and gathering and interpreting
environmental data takes time (years)

12. What We Have Learned
• Ground water quality can be difficult to
use as a measure of permit compliance
• For reuse systems in major agricultural
areas, it may be difficult to determine
impacts from the reuse system
• Site specific ground water conditions
may not show impacts for many years