Frequently Asked Questions



1. What is wastewater?
​Wastewater is used water from homes, businesses and industries. It includes water from washing machines, dishwashers, sinks, showers, toilets and industrial operations.

2. How is Nampa currently treating and disposing of its wastewater?
​Nampa’s wastewater is treated at the Nampa Wastewater Treatment Plant (WWTP). Nampa’s wastewater plant has the capacity to treat 18 million gallons of wastewater each day. It is one of the largest facilities in Idaho. The plant uses a variety of technologies and processes to treat the wastewater. After treatment, the water is discharged into Indian Creek.

3. Who regulates Nampa’s wastewater?
​The federal Clean Water Act requires Nampa to have a permit in order to discharge treated water into Indian Creek (or any water body of the United States). This permit is called a National Pollutant Discharge Elimination System (NPDES) permit. In Idaho, the NPDES permit is issued by the Environmental Protection Agency (EPA). The Idaho Department of Environmental Quality (DEQ) is the state agency that sets water quality standards for the state’s water bodies. EPA works closely with the Idaho DEQ during the permitting process.

4. Why is it necessary to upgrade Nampa’s wastewater treatment and disposal system?
​Nampa recently received a new NPDES permit that requires the City to meet more stringent limits for several constituents, including phosphorus and temperature. The Nampa WWTP will need extensive upgrades to meet these new requirements and maintain water quality in Indian Creek. In addition, some of Nampa’s wastewater facilities are at the end of their life cycle and need to be upgraded. The Nampa WWTP was constructed in the 1960s and the last major upgrades, prior to the current upgrades, were in the 1980s and 2000s. The Nampa WWTP will also need to be expanded in order meet the community needs as population growth continues.

5. How do EPA and DEQ decide what Nampa’s permit should require?
​The federal and state regulatory agencies (EPA and DEQ) work closely together during the permitting process. Nampa’s permit includes limits for constituents (such as nitrogen, phosphorus, cyanide, copper and mercury) that can be discharged into Indian Creek. These limits are based on state water quality standards that support the continued health of Indian Creek and the broader Lower Boise River watershed. State water quality standards are based on the “beneficial use” for each water body. DEQ sets the “beneficial use” standards for Indian Creek based on a public process. Through this public process, DEQ has determined that Indian Creek’s “beneficial use” is to sustain cold water aquatic life and secondary contact recreation (i.e., fishing).

6. Can Nampa work with the EPA to lower the requirements?
Nampa worked diligently with the EPA and DEQ to negotiate limits that were achievable and implemented over a realistic timeline. Throughout the process the City negotiated on a number of issues. Several positive changes resulted from this process:

​ • The City was allowed to meet the phosphorus regulations in two phases instead of all at once.
​ • Nampa was also granted a 15-year permit cycle for meeting temperature regulations instead of the originally proposed 10 years.
​• The permit also includes monthly limits for phosphorus, which are more manageable than weekly limits.


7. Why is phosphorus a problem?
​In recent years, elevated phosphorus levels have been identified in Indian Creek, the Lower Boise River, the Snake River and the Boise River. Phosphorus is a nutrient found in dishwasher detergent, human waste, fertilizer, industrial discharges and agricultural uses. Phosphorus is a nutrient taken up by algae and other aquatic organisms. Too much phosphorus can cause toxic algae blooms that use up oxygen in aquatic ecosystems, which can kill fish, negatively impact other aquatic life, and make our water unsafe for boating and swimming. Algae growth can also limit recreational use of the water, such as swimming or fishing.

8. Could we reduce some of the problems by asking people to conserve water or use phosphorus-free detergent?
​While water conservation is beneficial, it reduces overall flow sent to the WWTP but does not reduce the other constituents in wastewater as effectively, such as nitrogen and phosphorus. The City will still need to address phosphorus and nitrogen in its wastewater. Because of phosphorus bans in many larger markets, few detergents have high levels of phosphorus today.

9. Didn’t Nampa already upgrade its wastewater facilities to remove more phosphorus?
​Yes, the City is approaching completion of Phase I Upgrades at the Nampa WWTP. Phase I will be completed in 2019. It will allow the treatment plant to remove phosphorus to an intermediate level starting in 2020. Phase I includes building a new primary effluent pump station, a new aeration basin, retrofits to the existing aeration basins, a new anaerobic digester and a new solids handling facility. In 2009, City leaders began working with technical experts and community members to determine how best to meet the new regulatory requirements. Based on community feedback and negotiations with EPA, the City developed a phased schedule for meeting the new limits. This gave the City time to plan, fund, design and construct needed upgrades.

10. What are the exact phosphorus limits?
​ By 2020, the Nampa WWTP discharge limits for Indian Creek are:
​• 0.5 milligrams of phosphorus per liter (mg/L) in the summer (May through September)
​• 1.5 mg/L of phosphorus in the winter (October through April)

​ By 2026, the Nampa WWTP discharge limits for Indian Creek are:
​ • 0.1 mg/L phosphorus in the summer (May through September)
​• 0.35 mg/L phosphorus in the winter (October through April)

​When Nampa reaches the final limits in 2026, it will have reduced its phosphorus discharge by 98 percent.

11. Why is temperature a problem?
​ High temperatures in Indian Creek can make the creek unsafe for fish and other aquatic species. In the summer, the Nampa WWTP discharges water that is warmer than the temperature of Indian Creek, causing the temperature of the creek to rise. To meet the state’s water quality standards, Nampa is being required to reduce its temperature impacts on Indian Creek.

12. How will the current presidential administration affect what we do? Will the EPA requirements be relaxed?
​ Federal requirements for water quality and wastewater treatment are set by Congress through the 1972 Clean Water Act. Changes to the Clean Water Act would require a significant legal effort, public process, and ultimately a majority vote of Congress. There are no indications the Clean Water Act will be changed at this time. The City will continue to be proactively engaged with regulators and track current and future federal regulations and respond appropriately.


13. What is the schedule for these improvements?
• By 2019, the City will finish construction on the Phase I improvements, which began in 2013. • By 2020, the City must meet “interim” phosphorus limits.
​• By 2026, the City must meet final phosphorus limits. Design and construction will take approximately eight years to complete.
​• By 2031, the City must meet temperature requirements (Phase III).

14. What will happen if Nampa does not make additional upgrades after only completing Phase I?
​Nampa would face heavy fines for not complying with the Clean Water Act (up to $100,000 per day). Nampa could also be sued by a third party for discharging pollution into Indian Creek and the rest of the watershed. Finally, if no upgrades were made, Nampa’s WWTP would become more expensive to maintain as it aged and equipment failed. Emergency repairs would also become more frequent.

15. Will Nampa be dealing with even more “new” regulations in a few years?
​ The City is already looking ahead at possible regulations in 2040 and beyond. Future regulations for Nampa could include contaminants of emerging concern, sometimes referred to as CECs. These include pharmaceuticals and personal care products. Other states are already beginning to look at regulating these constituents. The City has accounted for this possibility in its facility plan and will continue to track the regulatory environment.

​16. Why is Nampa planning so far out?
​The upgrades are expensive and it is prudent to plan for them in advance. It can take up to 10 years to plan, fund, design and construct these improvements. Additionally, the Phase II and Phase III upgrades are closely linked. It is important for the City to consider the long-term impacts of their decisions by reviewing both phases at this time.


​17. What was the decision-making process for selecting an alternative for Phase II/III?
​The preferred alternative was developed over many months through technical analysis and input from the Nampa Wastewater Advisory Group (NWAG) and Industry Working Group (IWG). These groups have been an integral part of the City’s planning process. The decision-making process occurs in stages, beginning with assembling an expert team (technical consultants, City staff, community members, etc.), defining critical success factors (based on community input), brainstorming alternatives, and finally running an alternatives analysis to identify the lowest cost alternative that achieves level of service goals. The City began the Phase II Upgrades technical evaluation in June 2016 and held public meetings starting in January 2017. The public provided critical feedback and input into the facility plan development.

​In January and February 2018, Nampa residents had the opportunity to submit formal comments on the Nampa Wastewater Treatment Plant Facility Plan, which outlines the City’s long-range plan for the wastewater treatment and disposal system. The City Council adopted the Preferred Alternative and the Wastewater Facility Plan on Feb. 20th, 2018.

​18. What is the City planning to do for Phase II?
​The City’s course of action, or “Preferred Alternative,” includes a process of treating water to a very high level (Class A recycled water, as defined by Idaho DEQ) for irrigation and industries to re-use in some of their operations. The Preferred Alternative plan is to discharge Class A recycled water to the Phyllis Canal, an irrigation canal used for municipal and agricultural uses.

19. What is the advantage of re-using water?
​Re-using treated wastewater has several advantages. First, it is treated to strict recycled water quality standards that make it safe for a variety of public uses. Local industries can use Class A recycled water for uses such as dust suppression and cooling. Currently, many industrial customers use drinking water (potable water) for their operations. Recycled water can serve as an additional water supply that offsets the demands on the potable water supply. The Nampa WWTP would treat to Class A quality and provide it to industries; this can create a tool for economic development by attracting potential industries, and it benefits Nampa’s water supply resources.

​If the City discharges water to Indian Creek (instead of Class A recycled water to the irrigation canal), it must meet stringent requirements for water temperature. However, discharging to industry or irrigation systems does not involve temperature regulations. This allows the City to avoid building expensive cooling towers and chillers to reduce temperature.

20. Is Class A water safe?
​Yes. There are restrictions that apply to all types of recycled water. Class A water is the highest level of treatment for non-potable, recycled water. Class A water has the largest range of possible uses compared to lesser-quality classifications. Class A water has been treated to a level that is safe for vegetable gardens and public areas (such as parks and schoolyards). However, it is not treated to the level of drinking water.

21. Do the irrigation companies want to use treated wastewater?
​Pioneer Irrigation District has expressed interest in the additional water supply the City’s Class A recycled water program could potentially bring in to their system. The City and Pioneer Irrigation District have negotiated a long-term agreement that allows the City to discharge to the Phyllis Canal.

22. Will irrigation customers benefit from additional water in the system? Will there be any cost savings for customers?
​With the City discharging treated wastewater into the irrigation canal, the irrigation district and Nampa’s irrigation customers would potentially benefit from additional water in the canal.

23. What is “plan B” if the irrigation canal doesn’t work out?
​The City will always have a backup discharge approach. The City would maintain its NPDES permit that allows it to discharge to Indian Creek, if needed.

24. If we discharge to the irrigation canal, will we raise the water level of the canal? Is this a problem?
​The City would work closely with the irrigation company that controls the canal to manage the amount of water in the canal. It is not expected that the flow would impact the canal’s operation.

25. Since irrigation canals don’t run in the winter, how will Nampa dispose of wastewater in the winter?
​Wouldn’t this raise the temperature of Indian Creek? Temperature limits only apply to the City’s discharge during the summer (May-September). During the winter, when the irrigation canals are not running, the City would discharge treated wastewater into Indian Creek.

26. Does the City have any other options? What about building something like Boise’s Dixie Drain?
The City evaluated 42 options between 2009 and 2017. One of the alternatives was a “treat and offset” alternative similar to the Dixie Drain project. The cost of this alternative was roughly similar to other alternatives, but the City was unable to find suitable property to build this alternative. The property would need to be located along Indian Creek between the treatment plant and Caldwell. The City of Boise had more options for suitable property.


​27. What was the cost of Phase I? Has it been fully funded?
​The Phase I upgrades cost $38 million to plan, design and construct. The City paid for the Phase I upgrades with a $17 million loan from DEQ and a wastewater rate increase. Wastewater rates increased by an average of 27 percent.

28. What is the cost of Phase II and Phase III and are there cheaper alternatives? All of the alternatives explored involve similar costs. The chosen alternative is expected to cost $149.6 million in 2017 dollars.

29. You’ve stated it takes time to design and build the alternative. What are the expected real time costs?
​Phase II is expected to cost $189.9 million, including cash and debt, between now and 2026. Phase III is expected to cost another $22.5 million by its completion in 2031.

30. Are other cities in the Treasure Valley doing the same thing? How are they paying for it?
​Yes. Other cities in the Treasure Valley and around the U.S. are dealing with similar issues. Cities are using various treatment methods and funding options to reduce phosphorus and meet the requirements of their NPDES permits.

31. Is there any way to reduce the burden on low-income residents and seniors?
Affordability for Nampa’s citizens is a critical priority for the City. EPA defines affordability as a percentage of median household income. Rates are determined to be “affordable” if they are between 1 and 2 percent of the median household income. If Nampa’s upgrade is not affordable for residents, the City may have opportunities for extended loan repayment schedules, lower interest rates and/or loan principal forgiveness. The City is actively investigating these opportunities and working with Idaho DEQ to define funding options for the City.

​32. Could Nampa raise hookup fees to pay for the upgrade?
​Is there any other way to take the burden off people who have already paid into the system? Hookup fees are calculated based on the currently installed system, not future planned improvements. The cost of the capital infrastructure cannot be factored into the hookup fees charged to users until the project has been completed is in service. However, hookup fees can be increased and the revenue will offset further rate impacts.

33. Will industries pay for the Class A water? Why?
​The City has not determined the terms of the agreements with industrial customers for Class A recycled water. Therefore, the early rate calculations do not incorporate any potential revenue from the sale of recycled water to an industrial customer.

34. Does industry pay their fair share of the rate?
​A major component of the planning process is a cost-of-service study. This study is currently in process and will help the city ensure that rates are fairly distributed among customer classes. For example, industrial customers place a higher demand on the system than residential customers. The cost-of-service study determines the cost of treating wastewater from each customer class and assigned rates accordingly.

35. How long will it take to pay for the improvements? Will utility rates be lowered after they are paid off?
​The answer to this question will depend on how the community chooses to fund the improvements. • If the community chooses a cash-only approach, average customer rates would increase sharply (93 percent in fiscal year 2019 and then 12-35 percent annually through fiscal year 2025) and then decrease in fiscal year 2026 once project funding is complete. • If the community chooses to pursue bond funding, rates would increase more slowly (16.75% annually) in fiscal year 2019, which begins in October of 2018, and continue through fiscal year 2025.

36. Will rates drop in the future as Nampa grows?
Could additional users help offset the costs? The planning effort has accounted for expected growth within the City until 2040. The estimated rates already incorporate these growth projections.

37. How do Nampa’s utility rates compare to other cities’?
​ It is difficult to compare rates to other cities in an “apples to apples” approach, because each city is in a different position of meeting various regulatory requirements and population growth needs. Nampa’s existing wastewater utility rates are the lowest in the Treasure Valley.

38. How will the public be involved in the funding decision?
​ The City is generally unable to acquire debt without voter approval. The May 15 vote is a funding decision to the wastewater treatment facility plan. ​There are two options:

• “Yes” authorizes bond funding of up to $165 million and results in smooth increases of approx. 16.75% each year for seven years.

​• “No” indicates preference to fund project with cash and results in a sharp increase in rates of 93% in October of 2018, followed by annual increases ranging between 12-35% through 2025. Rates are expected to decrease by an estimated 47% in 2026.

​The bond requires a simple majority to pass (50% plus one vote). If the bond does not pass, the City will pay for the upgrades with cash through rate increases.

39. How will the bond be repaid?
​ A bond would be repaid through customers’ wastewater bills. City taxes will not be used to repay the bond.

40. Does a “no” vote on May 15 mean we won’t pay for this project?
​No. Voting “no” rejects bond funding, not the project. Voting “no” results in a sharp increase in rates of 93% in October of 2018, followed by 12-35% annual increases through 2025. Rates are expected to decrease by an estimated 47% in 2026.

41. Does the City have any other options for funding besides rates or a bond? What about federal grants?
​ The City is actively pursuing and will continue to pursue potential funding sources for these upgrades. This includes the DEQ State Revolving Fund loan program as well as other potential sources.

42. Does the City have a preference about funding?
​ The funding decision is the responsibility of the community. All proposed funding options are sufficient to complete the project. The City will support the decision of the community.

Do you have a question not covered in the above FAQ document?

Email or call (208) 565-5132.