HomeMy WebLinkAboutMemo - Mail Packet - 10/3/2023 - Memorandum From Jared Heath Re: 2023 Summer Water Quality Update – Upper Cache La Poudre Watershed
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700 Wood Street
PO Box 580
Fort Collins, CO 80522
970.221.6700
970.221.6619 – fax
970.224.6003 – TDD
utilities@fcgov.com
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M E M O R A N D U M
DATE: September 22, 2023
TO: Mayor Arndt and Councilmembers
FROM: Jared Heath, Senior Watershed Specialist
THROUGH: Kelly DiMartino, City Manager
Jason Graham, Director of Water Utilities
RE: 2023 Summer Water Quality Update – Upper Cache la Poudre Watershed
Bottom Line:
The Upper Cache la Poudre (CLP) Watershed Collaborative Water Quality Monitoring Program
is a partnership between the cities of Fort Collins, Greeley, Thornton, and Soldier Canyon Water
Treatment Authority. The goal of this shared monitoring effort is to assist the participants in
meeting current and future drinking water treatment goals by reporting current water quality
conditions and trends within the Upper CLP watershed. The attached water quality update
provides a summary of temperature, snowpack, streamflow, and water quality conditions
monitored in the Upper CLP watershed during the 2023 summer season.
Background:
The seasonal water quality updates are designed to inform the Upper CLP Watershed
Collaborative Monitoring Program partners, their customers, and other community stakeholders
about the condition of our source watershed and the quality of the raw CLP River drinking water
supply. This seasonal reporting effort began in 2015 to provide a succinct and timely summary
of current-year conditions in the Upper CLP Watershed. Seasonal updates are published for the
spring, summer, and fall seasons. In-depth water quality reporting is done through annual and
five-year technical reports. Water quality reports and seasonal updates are made publicly
available on the Fort Collins Utilities website, fcgov.com /source-water-monitoring.
Summer 2023 Highlights:
Summer water quality monitoring captures water quality conditions during peak snowmelt runoff
and the receding streamflow that follows through the summer monsoon season. Water quality
conditions vary with changes in elevation, hydrologic and weather conditions, and other potential
watershed impacts. The Upper CLP watershed experienced above-average air temperatures and
above-average precipitation over the summer 2023 season. The air temperature was 1.1 degrees
Fahrenheit warmer than average. Precipitation was measured at 122% of average over the
summer season and drought conditions were nonexistent across the Upper CLP watershed.
Streamflow in the Poudre River near the canyon mouth was measured at 103% of average over
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the summer season; however, peak streamflow measured well above average. Water quality
indicators measured at key long-term monitoring sites along the CLP River were within the
range of values observed over the baseline period of record (2008 – 2012) suggesting normal
water quality conditions over the summer season. In several instances, precipitation events over
the Cameron Peak burn scar impacted water quality and required the water treatment plant to
shut down their Poudre River raw water intake for a brief period. Real-time water quality meters
installed upstream of the City’s Poudre River raw water intake detected these events and
provided staff with an early warning to effectively respond and minimize impacts to the City’s
drinking water quality.
CC: Kendall Minor, Utilities Executive Director
Jill Oropeza, Senior Director of Water Sciences & Planning, Utilities
Leslie Hill, Water Quality Services Director, Utilities
Richard Thorp, Watershed Program Manager, Utilities
Diana Schmidt, Watershed Specialist, Utilities
Water Commission
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Upper Cache la Poudre Watershed Collaborative Monitoring Program
SUMMER 2023 WATER QUALITY UPDATE
Source Water Monitoring
The Upper Cache la Poudre (CLP) Watershed Collaborative Water Quality Monitoring
Program is a partnership between the cities of Fort Collins, Greeley, Thornton, and Soldier
Canyon Water Treatment Authority. The goal of the program is to help these water providers
meet present and future drinking water treatment goals.
Water quality monitoring of our raw, CLP River drinking water supply is conducted from
April through November. Monitoring sites are strategically located throughout the Upper CLP
watershed. Water quality data provide valuable information about the health of our source
watershed and the quality of our raw water supply.
The Summer 2023 Water Quality Update provides a seasonal summary of watershed
conditions in the Upper CLP watershed by highlighting weather, drought, streamflow, and
water quality conditions over the summer season (June – August).
Water quality begins to stabilize following spring snowmelt runoff and routine monitoring
is reduced to monthly sampling. Routine water quality monitoring results are reported for
six key monitoring sites located throughout the CLP watershed. Monitoring sites capture
water quality conditions above and below major tributaries and near water supply intake
structures (Figure 1). Current water quality conditions are compared to baseline water quality
conditions over the period of 2008 to 2012.
Figure 1 – Upper Cache la Poudre
Watershed Collaborative Monitoring
Program water quality sampling
sites and real-time water quality
instrument locations.
JWC - Joe Wright Creek above the
confluence with the Poudre River
PJW - Poudre River above the
confluence with Joe Wright Creek
PBR - Poudre River below Rustic
PSF - Poudre River below the
confluence with the Little South Fork
PNF - Poudre River above the
confluence with the North Fork at
the City of Fort Collins’ Intake
PBD - Poudre River below the
confluence with the North Fork at
the Bellvue Diversion
Indian Meadows
WQ Instrument Manners Bridge
WQ Instrument
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Temperature
Air temperature measured at the Joe Wright Snowpack Telemetry (SNOTEL) station over the 2023 summer season was 1.1°F warmer than
the long-term average and ranked as the 14th warmest summer on record (out of 34 years). The monthly mean air temperature was below
average in June and above average in July and August. The month of July ranked as the ninth warmest on record and the month of August
ranked as the fifth warmest on record (Table 1).
Temperature
2023
(ºF)
Average
(ºF)
Departure
(ºF)2023 Rank
June 45.8 47.1 -1.3 12th (C)
July 54.1 52.5 +1.6 9th (H)
August 53.5 50.5 +3.0 5th (H)
Summer 51.1 50.0 +1.1 14th (H)
Precipitation
Precipitation measured at the Joe Wright SNOTEL over the 2023 summer season was above average and ranked as the 12th wettest
summer on record (out of 45 years). Precipitation was well above average in June and August and near average in July (Table 2). Due to the
above-average precipitation over the summer season, drought conditions were nonexistent across the Upper CLP watershed (Figure 2).
Total Precipitation
2023
(inches)
Average
(inches)
% of
Average 2023 Rank
June 3.1 2.2 139%11th (W)
July 2.0 2.1 94%21st (D)
August 2.9 2.2 130%12th (W)
Summer 8.0 6.6 122%12th (W)
Table 1 – Monthly mean air temperatures measured at Joe
Wright SNOTEL over the summer months of 2023 compared to
the long-term average (1991 – 2020).
Note: H = hottest and C = coldest
Table 2 – Monthly accumulated precipitation totals measured
at the Joe Wright SNOTEL over the 2023 summer season
compared to the long-term average (1991 – 2020).
Note: W = wettest and D = driest
Figure 2 – Drought conditions for the state of Colorado as monitored by the United States Drought Monitor on May 30, 2023 (left) and August 29,
2023 (right). (Map source: https://droughtmonitor.unl.edu/)
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Streamflow Conditions
Streamflow at the Cache la Poudre River near the Canyon Mouth (CLAFTCCO) stream gage measured 174,912 acre-feet of water over
the summer season, which was 103% of the long-term average (calculated over the 1881 – 2022 measurement period). Peak streamflow
was observed on June 17th and measured 2,520 cubic feet per second – 126% of average. The timing of the 2023 peak occurred six days
later than the long-term average. Streamflow slowly receded following peak streamflow and by the end of the summer season was
approaching baseflow (low flow) conditions. The total amount of water was slightly higher than average in all summer months (Figure 3).
Figure 3 –
Streamflow
conditions on the
Poudre River over
the 2023 summer
season (left) and
monthly total
water volume
measured over the
summer season
(right).
Water Quality Indicators
The Upper CLP Collaborative Water Quality Monitoring Program uses several key water quality indicators, including pH, conductivity,
temperature, and turbidity, which act as surrogates for other parameters (Table 3). These indicators provide a snapshot of water quality
conditions and are useful for identifying trends or changes in water quality. Significant changes in these water quality indicators may
provide an early warning of potential water pollution.
Water Quality Indicator Explanation
Temperature
Water temperature influences other water quality parameters and is a
major driver of biological activity and algal growth in rivers, including
certain phytoplankton species that produce the taste and odor
compounds, geosmin and 2-methlyisoborneol.
pH
pH is an important water quality parameter to monitor, because
it influences the solubility and biological availability of chemical
constituents, including nutrients and heavy metals. pH near 7 is
considered neutral, with more acidic conditions occurring below 7 and
more basic, or alkaline, conditions occurring above 7.
Specific Conductivity
Conductivity is an index of dissolved ionic solids in water. Conductivity
is used as a general measure of water quality. Significant increases in
conductivity can be used as an indicator of increased pollution.
Turbidity
Turbidity is monitored to track changes in water clarity. Clarity
is influenced by the presence of algae and/or suspended solids
introduced to surface waters through various land use activities,
including runoff and erosion, urban stormwater runoff and drainage
from agricultural lands. For water treatment, turbidity is an important
indicator of the amount of suspended material that is available
to harbor pollutants, such as heavy metals, bacteria, pathogens,
nutrients and organic matter.
Table 3 – Water
quality indicators
measured as part of
the Upper Cache la
Poudre Collaborative
Water Quality
Monitoring Program.
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Summer monitoring captures water quality conditions during the Poudre River’s highest flow levels (peak streamflow) and when flow
levels gradually decrease (the falling limb of the hydrograph) in the months following peak streamflow. Water quality conditions generally
stabilize during this time of year. Constituents that were once diluted by high streamflow begin to concentrate as streamflow recedes.
In general, specific conductivity, the ability of water to conduct electrical current, and water temperature increase, while turbidity and
pH levels decrease. The summer season also marks the beginning of the summer monsoon, which can lead to increased frequency and
intensity of rain events. An active monsoon season, in combination with a post-fire landscape, can lead to flash flooding, debris flows, and
severe impacts to water quality.
Joe Wright Creek Canyon Mouth
All water quality indicators at key sites along the CLP River were within
the baseline range of values over the 2023 summer season (Figure 4).
Water temperature was near normal in Joe Wright Creek (JWC) and in
the CLP River above Joe Wright Creek (PJW) – normal is defined as the
median value over the baseline period of record. Water temperature
was slightly warmer than normal at all other key monitoring sites and
increased from Joe Wright Creek (JWC) downstream to the City of
Greeley’s diversion (PBD). pH levels were near normal at all key
monitoring sites. Specific conductivity values were higher than normal
at all key sites, except in Joe Wright Creek (JWC) where values were
normal. Turbidity levels were near normal at all key monitoring sites and
measured less than 5 nephelometric turbidity units (NTU).
Water quality indicator data are collected using a multi-parameter
water quality meter from the North Fork below Seaman Reservoir.
Figure 4–Water quality
indicator data collected
at key monitoring sites
over the 2023 summer
monitoring season
compared to baseline
fall water quality.
conditions.
Summer
2023
Median
Maximum
Median
Minimum
Graphic Explanation
Baseline data
range based
on long-term
data record
2008-2012
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Post-Cameron Peak Wildfire Water Quality Impacts
Water quality monitoring instruments were installed at two locations upstream of the Poudre supply intake facility in early April. The
Poudre at Indian Meadows site is located one mile downstream of the Town of Rustic and the Manners Bridge site is located approximately
one mile upstream of the City’s raw water intake (Figure 1). The Water Quality Alert System provides water treatment operations near
real-time water quality data to quickly respond to changes in Poudre River water quality that result from runoff from the Cameron Peak
burn area or other upstream events.
High-intensity precipitation events driven by the summer monsoon continued to cause several post-fire erosion, sedimentation, and
flooding events on the Poudre River over the summer season (Figure 5). These events briefly impacted water quality and required water
treatment plants to shut down their raw water intakes on the Poudre River.
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Figure 5 – Daily average turbidity measured in the Poudre River at the Manners Bridge Water Quality Alert System over the summer
season. Daily average values were calculated from 15-minute data.
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