Council Memo

Presentation on Water Model by Gary Woodard.


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Recommended Action: This item is for discussion only. No formal vote will be taken.


Item Summary


Presentation by Gary Woodard of Water Resource Consulting on a water model prepared for the City of Prescott.


Meeting History

May 28, 2019 1:00 PM Video City Council Study Session Meeting
draft Draft

Gary Woodard, Water Resources Consulting, provided a presentation to Council regarding the water budgets, forecasts, scenarios as an update to his February 2019 presentation. He reviewed the municipal water usage which peaked nationally 30 years ago, and the declines in demand across multiple providers throughout the state of Arizona. Prescott has a smaller, older, wealthier and more transient housing base than other communities and dog ownership is irrelevant. Prescott is also higher in elevation, cooler in temperature and generally wetter in climate, also swimming pools are more rare, there is no winter turf and there is more demand for non turf irrigation.

In 2019 7% lower potable water deliveries than in 2018. Large drop should continue this year because of wet and cool temperatures that we have experienced this winter.

Important to separate indoor from outdoor demand, that is more difficult here because

* Were inflows are good proxy

* Mid-winter demand is almost entirely indoor demand

* Indoor demand is relatively constant throughout the year

* Water demand and swerve inflow months cannot be alighted

* Many customers are septic

* Indoor/outdoor demand both peak in summer

* Many residences are unoccupied for more extended periods of time

Meter shutoff are recorded by month

* Average around 400 at any given time

* Lowest in the summer

* In February over 13% of homes are empty, in July that number drops to approximately 5%

* Seasonal residency is increasing slowly, by 20% over 15 years or 1% per year

Many challenges for data collection

* Yavapai County Assessor lost track of evaporative coolers

* Parcel sales data are unusable

*Many gaps in assessor data, including age and value

*Dates of construction are misleading - switching to date water service was established

* Disagreement between County and City on classification of lots

* Some data are by calendar year, some by fiscal year

* 14 categories of non-residential customers complicate the model

* No way to disaggregate non-residential customers that are on septic systems

* Estimating indoor demand is made difficult by I&I water impacting WWTPs, seasonal residents, and large numbers of non-sewered customers, including non-residential

In Prescott, people per household (PPH) is dropping, reduces demand by nearly .5% each year (fewer infants, smaller households, etc) which impacts rates. The biggest loss is the water that goes to the unsewered customers because all use consumptive.

Based on this information would not be beneficial to do indoor conservation for sewered customers because you are not going to get the most out of it. Most benefit would likely come from Reservoir Improvements.

Sewer vs septic - significantly smaller than area than its potable water (1 in 6 is septic), due to steep rocky terrain and the need for sewer lines to be sloped for gravity flow. 5% more for Single Family Residential (SFR) customers water use than same type of customers on sewer. Only 10% of wastewater will be recouped into aquifer. Owner vs renter occupancy also affects the use of outdoor water.

SFR year of construction also impacts water demand meaning that homes being built now are more economic than homes built in and pre-bubble time frame. Home value is usually a key determinant of water demand, indoor/outdoor water use steadily increase with increasing home value.

Non-residential customer are very diverse, total of 1334 non-residential customers. Indoor demand dominates among non-residential users with only 12% used outdoors. Hospitals use the most water by a great amount.

How to improve water budget?

* It is generally in balance, there is no urgency to do anything

* Promising areas include:

- Enhanced conservation of indoor demand for customers on septic

- Increase commercial water customer efficiencies of use

- Reduce leaks on customer side of the water meter

- Enhanced conservation, focusing on outdoor demand

- Enhanced rainwater and stormwater harvesting programs

*All of these items could be done incrementally over time as necessary

Water lost to Septic Systems

*Existing customers on septic

- Sewer some customers

- Focus on indoor conservation programs on customers on septic

- Encourage those on septic to develop gray water systems

- Require installation of high-efficiency fixtures and appliances at time of resale

*Potential new customers on septic

- Reduce new installations on septic

- Require installation of high-efficiency fixtures and appliances

- Require plumbing stub-outs for easy gray water harvesting

Legal Reuse of Gray Water

* Section 49-204 - use is legal, gives Council the option to ban, sewer customers within city limits could do it. The statue does not affect gray water options

Commercial & Institutional Conservation Options

*Water efficiency audits with particular attention to

-Water treatment systems (softeners, RO, etc.)

- Cooling towers and boilers

- Leaks

Leaks on customer side of water meter

*Studies of leaks on customer side of water meter suggest that

- The average SFR customer leaks 17 gallons per day, or over 500 gallons per month (as recorded by meter loggers)

- On average, another 5% of water passing through water meters goes unrecorded because of small leaks

*Automatic Meter Reading (AMR) offers the potential to identify customers with continuous water use

Outdoor conservation options

* Options include using new ADWR conservation funds to:

- Expand irrigation system audit program

- Significantly increase $0.25/sq ft turf removal rebate

- Offer rebates on easy-to-program irrigation controllers

- Offer SmartScape classes through Cooperative Extension

Rainwater harvesting observations

* Rebates are potentially very popular with elected officials and some customers

* These rebates can function like "reverse Robin Hood" subsidizing financially well-off customers

* Reduces outdoor demand, consumptive demand, peak demand, but in part because of other landscape changes

* Has ancillary environmental benefits

* Not very cost-effective compared to other measures

* Not clear what useful life of system is


1. Current water budget is currently balanced or in surplus depending on whether one focuses on wet water or paper water

* Four factors are driving declines in Prescott water demand

a. Changing demographics

b. Active conservation efforts

c. "Passive conservation" in existing homes

d. New homes tend to be highly water-efficient

*Forecasted increase efficiencies will at least equal increased water demand from growth

2. Uncertainties and risks remain

* Areas where policy changes and or expenditure of funds could improve budget in the future

a. Reducing flows to septic tanks

b. Offer water efficiency audits to large commercial

c. Reduce leaks on customers side of water meters

d. Enhancing outdoor conservation efforts

Mayor Mengarelli thanked Mr. Woodard for his presentation and the information. He said that he sees policy coming out of this data.

Councilman Blair asked if we should look at our golf course and attempt to determine areas where water use could be reduced in ancillary areas where it wouldn’t affect the golf.

City Manager Michael Lamar stated that he agreed that would be a good idea and Joe Baynes can look into it.

Mr. Woodard also commented that an irrigation auditor would be a good person to have look into this option as well.

Councilman Sischka stated that being able to get septic users sewered seems to not be a good option, but asked what other cities have done to reduce septic water flow and what the results of that were.

Mr. Woodard discussed Sierra Vista, where water was being pumped to provide water to homes, and determined that if water was coming from a particular area homes received a free high efficiency toilet. He also stated that it is possible to offer rebates specific to properties that are only on septic.

Councilman Goode noted that some older homes without efficient fixtures may not have the financial means to get them replaced and/or updated so implementing a program offering that would be beneficial.

Mr. Woodard commented that there are programs he has seen in other cities, where a fee is added to monthly water bill in order to pay the items off over a period of a few years to address this type of issue.

Mr. Lamar said that this would be a good idea and also commented that something like offering a shower head to all new homes on septic that come in and establish a water account.

Mayor Mengarelli stated that audits on some of the commercial use would make an impact as well.

Mayor Pro Tem Orr asked what Mr. Woodard’s recommendations would be for any possible gray water options.

Mr. Woodard stated that two things that make sense are to grab the water that is going into the washing machine, and shower or bathtub as well. However, he did stated that the payback period can be very long

Councilwoman Scholl said that a partnership with water users is a good idea, and that working with the school districts and other commercial businesses would be beneficial. She also commented on the new turf football field going in at the high school which will have an impact.

Mayor Mengarelli reiterated that we are on a great trajectory for water use and conservation, but we know that we are not done and will continue to do our part.

Mr. Woodard commented that at this time all of the pieces of the model are completed, but that the interface is still in progress and will take a few more days to complete.

Councilman Lamerson asked the City Manager about alternative alternative septic systems that are highly efficient and environmentally sensitive which would potentially be a good idea to look into by creating an opportunity for septic system customers and if staff could check into that as an option.

Mr. Lamar stated that this could be examined as an option and brought back to Council for discussion.

Leslie Hoy - Prescott Resident addressed Council regarding how exciting it is that this model is coming in as well as the Dishlip item. She stated that it is important to clarify the gray water policy because there is a lot of confusion in the community. Also, she was disturbed to hear that is growth approved in the non-sewered areas, and she agrees that there are alternate septic systems that would be beneficial. She asked if there will be an option to allow citizens to compare costs of various alternatives in water savings when the model is finished.

David Tunnell - Prescott Resident addressed Council regarding whether or not the model will be interactive when it is completed.

Peter Krupnick - Prescott Resident addressed Council stating that he likes the approach of looking at what the rest of the Country and state are doing. He also asked about the water balance in the reservoir is “low hanging fruit”.

Councilman Blair commented on the option of making new homes have two meters - one for indoor use and one for outdoor use - and if that may be possible and a potentially helpful conservation and use tracking option.

Mr. Woodard stated that AMR and updated infrastructure options with readers allow the city to capture more specific information provided and to read the meters from the building rather than having to go out to the property. He also stated that the concept of the model is to look at scenarios and variables and will be interactive. He also reiterated that the growth assumption and the 2030 date is that with the same amount of growth as we are currently experiencing the city of Prescott would still be using approximately the same amount of water per acre feet as we are using now without implementing any new policies prior to the 2030 date.

City Attorney Jon Paladini stated that a proposed policy will be coming back to Council over the summer, and it will address water usage outside of city limits and within city limits, specifically that septic customers would need to connect to sewer outside of city limits in order to have city water, but water will be provided to septic customers within city limits.

Mayor Megarelli stated that he looks forward to the policy coming forward that ties in this data and focuses on conservation where it makes the most sense.