Portland Water Bureau - City of Portland, Oregon
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Portland Water Bureau
Water Quality
2020 Seasonal Water Supply– Retrospective
Prepared: May 19, 2021, Portland Water Bureau
Summary
The 2020 Seasonal Supply year provided unique challenges in managing the drinking water system to
meet the needs of all customers. The 2020 seasonal supply was influenced by below average
precipitation in late winter and early spring followed by above average precipitation and snowfall in
March and April along with later than average snowmelt in the Bull Run Watershed. This resulted in
drawdown starting on July 11, 2020, the approximate average historical start of drawdown. System
demands during the 2020 seasonal supply season were also impacted by the COVID-19 pandemic,
resulting in reduced commercial demand. This along with moderate summer temperatures, saw lower
than average demands. The COVID-19 pandemic also impacted the annual groundwater maintenance
operation, delaying the operation until August and running for 10 hours a day to be able to keep staff
socially distant which extended the length of the run.
In late August and into September, large wildfires in Clackamas County along with severe fire conditions
in the Bull Run Watershed, resulted in a level 1 evacuation order (be ready) for Headworks. This resulted
in planning for a potential shut down of the Bull Run treatment facility and subsequent options for
meeting system demands.
Weather
The accumulation of snowpack during the snow season of 2019-20 was slow to start, with snow water
equivalent (SWE; the depth of liquid water if the snowpack were completely melted) values well below
average until mid-January. Intermittent weather systems maintained snow levels at near- or above-
average levels for the rest of the snow season. Notably, a large amount of snow accumulation happened
at all elevations toward the end of the season, bringing early April levels well above average. Snow cover
persisted far longer than average at low-elevations, slightly longer than average at mid-elevations, and
near-average at high-elevations. Snowmelt was complete throughout the watershed by the end of May.
Snowmelt was not a large contributor to summer supply from Bull Run in 2020 as is the case in most
years, since snowmelt is typically complete before reservoir drawdown begins. Figure 1 shows snow
water equivalent at the three snow monitoring sites in the watershed.
Precipitation during 2020 was, overall, close to average in the Bull Run watershed. Total rainfall for the
calendar year was 76.7 inches at Headworks, 96% of the 79.7 inches of annual average rainfall from
1899-2019. January started out with precipitation well above average followed by three months of drier
than average conditions. May and June were then substantially wetter than average followed by a rapid
transition to somewhat drier than average conditions that persisted the remainder of the year. Despite
the summer and fall being somewhat drier than average, temperatures were more moderate than in
many of the last several years. Consistent fall rains returned in late October. Figure 2 shows monthly
precipitation at Headworks for 2020.
Demand
Historic winter base demand peaked between 1979 and 1991 at an average of approximately 100
million gallons per day (MGD). Since then winter base demand (November-March) has declined, with
demand over the past 5 years approximately 18% lower at an average of about 82 MGD. In 2020,
average demand was 91 MGD (about 94% of the average for the previous five years). Figure 3 shows
demand from 2020 and the preceding five-year period. These demand numbers reflect the total amountof water supplied to serve Portland retail and wholesale customers and are not equivalent to the total amount of water that is metered and billed. A drop in base demand appeared to occur at the beginning of stay-at-home orders associated with COVID-19. Demands stayed below average through the summer season, but the magnitude of the impact of COVID-19 was difficult to discern when system demand was also responding to weather conditions. In the fall, the return to base demand levels was noticeably below previous levels. The average winter base demand of 2015-2019 was 82.9 MGD. Base demand in the 2019-20 winter through mid-March prior to stay-at-home orders was 79.2 MGD, already a decline from the past years. Base demand was 76.1 MGD on average in November-December 2020. Billing data showed a decrease in commercial water use concurrent with the timing of the pandemic. Base demand has improved somewhat in the early months of 2021. Bull Run Supply Drawdown of the Bull Run Reservoirs began on July 11th, which is approximately the historical average onset of drawdown. The reservoirs reached their minimum storage on October 9th, when 3.4 of 9.9 billion gallons (BG) of usable storage (34%) remained in the reservoirs. The reservoirs completed filling on November 14th. Figure 4 shows the 2020 drawdown of the Bull Run Reservoirs. Groundwater Use Each year, the Portland Water Bureau (PWB) operates the Columbia South Shore Well Field to exercise equipment and identify repair needs. The 2020 groundwater maintenance operation was originally planned for July, but due to the impacts of the COVID-19 pandemic, City of Portland staff were asked to take furloughs, most of which occurred in July 2020. As a result of the furloughs and resulting staff reductions, it was decided to delay the maintenance operation to August 4. In previous years, maintenance operations were performed for 24 hours a day for approximately 10 days. Running for 24 hours a day requires additional staff to be co-located at the GWPS where space confinements prevent appropriate social distancing. To ensure safe working conditions during the COVID pandemic in 2020,, groundwater was operated for only 10 hours a day Monday through Friday. This extended the maintenance run to 23 days. A total of 0.4 BG of groundwater were delivered to the distribution system with an approximate daily production of 54 MGD. During 2020, PW11 was out of service for routine 20-year maintenance. This work was completed in April 2021 and is now back in service. In March 2020, PW13 failed and has been offline while a new motor is being built. PW13 will be back in service in April of 2021. In September 2020, electrical testing of PW37 indicated that the motor/power cable is degrading and needed repair or replacement. While the well remains operable and in service, a new pump and motor will be installed in May or June of 2021, resulting in an approximately one-month outage. Groundwater Use Model The Groundwater Use Model was run in the spring of 2020 before drawdown began. The model does not incorporate weather forecasts and is therefore run only once each year. Subsequent application of the Groundwater Use Model involves comparison of the actual course of drawdown to the groundwater pumping curves generated by the model. Figure 5 shows the groundwater pumping curves that were developed, along with the actual reservoir volumes that were observed during the drawdown season. During drawdown, if the actual storage volume in the Bull Run Reservoirs drops below a groundwater pumping curve, then the pumping rate corresponding to that curve is recommended to augment supply. 2020 Seasonal Water Supply– Retrospective 2 May19, 2020
Instream Flows and Fish Habitat Management
The bureau managed water releases downstream of Bull Run Reservoir 2 to meet minimum flow
requirements and water temperature targets for the lower Bull Run River, which are required by the Bull
Run Water Supply Habitat Conservation Plan (HCP). This was the seventh year that PWB was using the
multi-level intakes on the Reservoir 2 north tower to meet downstream water temperature targets.
Per requirements under normal conditions as defined in the HCP, lower Bull Run flows stayed at or
above 120 cubic feet per second (cfs) January through mid-June then transitioned over time to summer
flow ranges of 20-40 cfs. Summer flow releases were actively managed each day to meet the water
temperature goal of keeping the 7-day average of the daily maximum water temperatures at the
warmest point on the Bull Run River, measured at Larson’s Bridge, below the temperature target, which
moves according to temperatures observed at the Little Sandy River. In October and November, lower
Bull Run River flows increased to reflect a percentage of tributary inflows per HCP requirements. Then in
December, minimum flows returned to 120 cfs. Neither critical spring nor fall conditions occurred in
2020. Each of these reduce the required minimum flow for portions of the spring and fall seasons,
respectively.
The bureau met downstream water temperature targets in the HCP for 2020 with the exception of a
period of time in the fall. Figure 6 shows the temperature of the Lower Bull Run River. Throughout the
management season, the bureau presented the 2020 water temperature information to the Oregon
Department of Environmental Quality, the National Marine Fisheries Service, and the Oregon
Department of Fish and Wildlife.
Cold-water Transfer
The bureau conducted a cold-water transfer in 2020 to move the bottom-most cold water from
Reservoir 1 downstream into Reservoir 2, where it would be available for release to town or
downstream. The transfer started on August 13th and continued through September 23rd releasing a
total of 5.2 BG of bottom water from Reservoir 1 via the Dam 1 needle valves (using the 895’ elevation
gates) into Reservoir 2. The temperature effect of these releases was most apparent in the upper and
middle elevations of Reservoir 2.
A capital improvement project to replace the needle valves with new fixed cone valves is currently in
construction. The new valves are expected to be operable by the end of June 2021.
Water Efficiency and Conservation
Water Efficiency programs and services continue to be one component of Portland’s approach to
meeting customer water use demands. Programing for the 2020 summer supply season was impacted
by the COVID pandemic as a result the bureau's water efficiency program did not carry out its typical
outreach or on-site water efficiency audits.
• Distributed water efficiency devices and information via online order form. These kits include
showerheads, aerators, and toilet leak tablets.
• Provided $50 rebates to replace old toilets with high-efficiency toilets for residential,
commercial, and multi-family customers.
• Provided rebates for improving the water efficiency of automatic irrigation systems.
• Published a Customer Newsletter with water conservation information that was included in all
bills that were sent out in the summer.
2020 Seasonal Water Supply– Retrospective 3
May19, 2020• The PWB is a member of the Regional Water Providers Consortium (RWPC), and an active
participant in the Conservation subcommittee. The bureau achieves public education and
communication goals through the RWPC’s regional conservation programming. Below is a
summary of key offerings completed in Summer 2020:
o The Consortium’s outdoor water conservation campaign ran from May - August 2020.
The campaign ran in English and Spanish and included ad buys and on-air interviews
with three television partners, five radio partners, and several digital advertising
platforms. The campaign’s messaging focused on tips to help use water wisely in
summer and included: giving your plants a deep soak a couple times a week rather than
watering daily, how to make sure your watering system is working efficiently, mow your
lawn less often and skip the fertilizer until fall, and the Weekly Watering Number.
o Summer outreach messaging was also distributed through the RWPC’s
website www.regionalh2o.org, social media (7+ messages per week on Facebook and
Twitter), and through the RWPC’s summer e-newsletter, which reached approximately
900 recipients per issue. In addition to televised programs, KUNP sent three Spanish-
language conservation e-newsletters which reached approximately 25,000 recipients.
o Provided the Weekly Watering Number (WWN) on www.regionalh2o.org and via a
weekly listserv that reached approximately 1,200 recipients from April-September. The
WWN is the amount of water in inches to apply to lawns and gardens based on local
weather conditions and evapotranspiration.
Conclusions
During the 2020 summer supply season, the PWB was able to meet all in-town and in-stream demands
using its baseline resources—Bull Run Reservoirs, streamflow, conservation, and groundwater. Several
key points from the supply planning season:
Groundwater
As mentioned above, the impacts of COVID-19 resulted in changes to the annual maintenance operation
by shortening the daily operation to 10 hours a day, and lengthening the duration of the run from 10
days to 23. Overall, this change was seen as a success by reducing the burden of staffing the
groundwater facility 24/7 and with no noticeable impacts to customers due to a fluctuating blend. It is
anticipated that this will be replicated in future years.
Demand
The impacts of the COVID-19 stay-at-home order resulted in an increase in residential demands (1-5%)
but with a greater decrease (20-25%) in commercial demands resulting in an overall reduction of retail
demand. While system demands were reduced compared to recent years it is unclear if these reductions
were strictly from COVID-19 impacts or the return to closer to average weather conditions than have
been seen in recent history.
Emergency Supply
The potential impact of regional forest fires, while not directly felt, highlighted the challenges of a
potential Bull Run shutdown near peak seasonal demands. The ability to meet this challenge relies on
the ability to offload wholesaler demands and utilize increased conservation resources. This challenge is
further complicated by the need to make a decision to fully shut-off the Bull Run and run the risk of
increased demands exceeding groundwater capacity plus emergency resources, or delivering untreated
Bull Run water to town, resulting in a system-wide boil water notice. The importance of communication
with wholesalers to identify and plan for offloads as well preparation of enhanced conservation
messaging are key to making these decisions. Through this process, it was also determined that due to
2020 Seasonal Water Supply– Retrospective 4
May19, 2020the high manganese levels at PW18, conservation (voluntary or mandatory) would be prioritized over its use as an emergency supply resource. In summary, the bi-weekly meetings of the Supply Planning Group were integral to the successful management of summer operations. The group balances multiple objectives in order to ensure a reliable high-quality water supply for all users while effectively managing costs. 2020 Seasonal Water Supply– Retrospective 5 May19, 2020
Figure 1. Snow water equivalent, in inches, at snow monitoring sites in Bull Run during
water year (WY) 2020
2020 Summer Water Supply Season – Retrospective 6
April 14, 2021Figure 2. Monthly precipitation at Headworks 2020 Summer Water Supply Season – Retrospective 7 April 14, 2021
Figure 3. Current demand compared to previous five years; 7-day moving averages 2020 Summer Water Supply Season – Retrospective 8 April 14, 2021
Figure 4. Bull Run Reservoirs drawdown and refill 2020 Summer Water Supply Season – Retrospective 9 April 14, 2021
Figure 5. Observed Bull Run Reservoirs storage and modeled groundwater pump rates 2020 Summer Water Supply Season – Retrospective 10 April 14, 2021
Figure 6. Water temperature of the Lower Bull Run River, summer 2020 2020 Summer Water Supply Season – Retrospective 11 April 14, 2021
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