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HomeMy WebLinkAboutMemo - Mail Packet - 7/31/2018 - Memorandum From Jared Heath Re: 2018 Spring Water Quality Update - Upper Cache La Poudre WatershedUtilities electric · stormwater · wastewater · water 700 Wood Street PO Box 580 Fort Collins, CO 80522 970.221.6700 970.221.6619 – fax 970.224.6003 – TDD utilities@fcgov.com fcgov.com/utilities M E M O R A N D U M DATE: July 23, 2018 TO: Mayor Troxell and Councilmembers FROM: Jared Heath, Watershed Specialist THROUGH: Darin Atteberry, City Manager Jeff Mihelich, Deputy City Manager Kevin R. Gertig, Utilities Executive Director RE: 2018 Spring Water Quality Update – Upper Cache la Poudre Watershed Bottom Line: In the shared interest of monitoring the Upper Cache la Poudre (CLP) River drinking water supply, the City of Fort Collins, the City of Greeley, and the Tri-Districts partnered in 2008 to implement the Upper CLP Collaborative Watershed Monitoring Program. The goal of this 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 snowpack, streamflow, and water quality conditions monitored in the Upper CLP watershed during the spring months of April and May in 2018. 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 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. All water quality reports and seasonal updates are made publicly available on the Fort Collins Utilities website, fcgov.com /source-water-monitoring. Spring 2018 Highlights: The Upper CLP watershed continues to be a reliable, high quality drinking water source. Snowpack conditions were normal over the 2018 water year with peak snow water equivalent measured at 103 percent of normal. Streamflow began later than normal in 2018, and peak DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 streamflow was observed two weeks early at 106 percent of normal. Water quality during snowmelt runoff in the spring is typically more variable than other times of the year. Normal water quality conditions were observed throughout the Upper CLP watershed during the spring of 2018. CC: Carol Webb, Water Resources and Treatment Operations Manager, Utilities Jill Oropeza, Water Quality Services Manager, Utilities Richard Thorp, Watershed Program Manager, Utilities DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 Water Quality Update | Spring 2018 fcgov.com/water-quality Monitoring and Protecting Our Water Sources SOURCE WATER MONITORING 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 the Town of 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 The Upper Cache la Poudre (UCLP) Watershed Collaborative Monitoring Program was established in 2008 between the City of Fort Collins, the City of Greeley and Soldier Canyon Water Authority, to help meet present and future drinking water treatment goals. Water quality monitoring of our raw, Cache la Poudre River drinking water supply is conducted from April through November. Monitoring sites are strategically located throughout the UCLP. Water quality data provide valuable information about the health of our source watershed and raw water supply. The Spring 2018 Water Quality Update provides a seasonal summary of watershed conditions in the UCLP watershed by highlighting snowpack and streamflow conditions, as well as water quality information collected over the months of April and May. Water quality during spring snowmelt runoff is highly variable. To better capture this seasonal variability, monitoring is conducted two times per month from April through June. Results are reported for six key monitoring sites located throughout the UCLP watershed, which capture water quality conditions above and below major tributaries and near water supply intake structures (Figure 1). Present water quality conditions are compared to baseline water quality conditions collected over the period of 2008 to 2012. Figure 1 - Upper Cache la Poudre Collaborative Monitoring Program sampling locations DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 SNOWPACK CONDITIONS IN 2018 WATER YEAR Snow water equivalent (SWE), the amount of water held in the snowpack, measured at Joe Wright snow telemetry station near Cameron Pass, was below the long-term median for most of the snow accumulation season (Figure 2a). The snow accumulation season began several weeks later than normal in 2018. The start of the winter season experienced above average precipitation (Figure 2b), but any snow that accumulated in early October was completely melted out by late-October (Figure 2a). Above average precipitation in November helped improve SWE conditions in the UCLP watershed, but average precipitation in December and January (Figure 2b) was not enough to increase SWE to normal conditions. Precipitation was above average from February through April, and over these months SWE rebounded to normal. Dry and warm weather returned in May and the snowpack began to melt initiating spring snowmelt runoff in the Poudre watershed (Figure 2). The maximum amount of water contained in the snowpack, referred to as peak SWE, was observed at the Joe Wright SNOTEL on April 23 measured at 23.6 inches– 99 percent of the historical median (Figure 2a). Based on the 30- year period of record, peak SWE at Joe Wright SNOTEL normally occurs on April 29. Peak SWE for the Upper CLP basin was measured at 103 percent of the median for the 2018 water year (Figure 3). Peak SWE was near or above the long-term median at higher elevations and only 60 – 69 percent of median at lower elevations. The North Fork CLP watershed received slightly more snow than the Mainstem and South Fork CLP watersheds with peak SWE measured at 109 percent of median. The Mainstem and South Fork CLP watersheds were slightly below the long-term median at 95 percent and 92 percent, respectively. Water Quality Update | Spring 2018 fcgov.com/water-quality Figure 2 – Snowpack conditions (left) in the Poudre River watershed over the 2018 water year and monthly accumulated precipitation totals (right). Sep Aug Jul Jun May Apr Mar Feb Jan Dec Nov Oct 25 20 15 10 5 SWE (inches) Median (1981-2010) WY2018 May Apr Mar Feb Jan Dec Nov Oct 6 4 2 0 PRECIPITATION (INCHES) Av erage (1981-2010) WY2018 (a) (b) DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 Water Quality Update | Spring 2018 fcgov.com/water-quality SNOWPACK CONDITIONS CONTINUED Figure 3 – Percent of median peak snow water equivalent at snow monitoring sites throughout the Upper Cache la Poudre River watershed. DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 Water Quality Update | Spring 2018 fcgov.com/water-quality STREAMFLOW CONDITIONS Streamflow, as measured at the Canyon Mouth, began later than normal in 2018 compared to the long-term average. Streamflow was below average for most of April before rapidly rising in early-May. Cooler weather slowed streamflow after the initial rise in the hydrograph, but hot weather in late May melted the remaining snowpack at Joe Wright SNOTEL resulting in an early snowmelt peak. Peak streamflow was observed on May 28 at 2,120 cfs – 106 percent of the average peak streamflow and two weeks earlier than normal (Figure 4a). Mean spring streamflow was 624 cfs – 118 percent of the long-term average (Figure 4b). Figure 4 – Streamflow conditions on the Poudre River over the 2018 water year and mean streamflow measured over the spring season. Sep Aug Jul Jun May Apr Mar Feb Jan Dec Nov Oct 2400 1800 1200 600 0 STREAMFLOW (CFS) Historic Av erage (135 Year Record) WY2018 Spring WQ Sampling 600 450 300 150 0 MEAN STREAMFLOW (CFS) Historic Av erage WY2018 (a) (b) DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 The Upper Cache la Poudre 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 1). These indicators provide a snapshot of water quality conditions and are useful for indentifying trends or changes in water quality. Significant changes in water quality indicators may provide an early warning of potential water pollution. Water Quality Update | Spring 2018 fcgov.com/water-quality WATER QUALITY INDICATORS 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 compound, geosmin. Water Quality Indicator Explanation 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. 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. Spring water quality monitoring captures water quality conditions from the start of snowmelt runoff to peak streamflow. Water quality conditions vary with changes in elevation and contributing watershed area. All water quality indicators at key sites were measured within the range of baseline conditions indicating normal water quality conditions on the Poudre River during the 2018 snowmelt runoff season (Figure 4). Table 1 - Water quality indicators measured as part of the Upper Cache la Poudre Collaborative Water Quality Monitoring Program. DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 Water Quality Update | Spring 2018 fcgov.com/water-quality Spring 2018 Median Maximum Median Minimum Baseline data range based on long-term data record 2008 – 2012 Graphic Explanation Graphic Explanation Data range based on long-term data record 2008-2012. Figure 5 – Water quality indicator data collected at key monitoring sites over the 2018 spring monitoring season (April and May) compared to baseline spring water quality conditions. Spring Median (2018) Figure 5 – Water quality indicator data collected at key monitoring sites over the 2018 spring monitoring season (April and May) compared to baseline spring water quality conditions. Joe Wright Creek Canyon Mouth Joe Wright Creek Canyon Mouth JWC PJW PBR PSF PNF PBD 20 15 10 5 0 DEGREES CELSIUS JWC PJW PBR PSF PNF PBD 9 8 7 6 pH JWC PJW PBR PSF PNF PBD 150 100 50 CONDUCTIVITY (uS/cm) JWC PJW PBR PSF PNF PBD 16 12 8 4 0 TURBIDITY (NTU) The following lists the range of values measured throughout the Mainstem watershed during spring water quality monitoring in 2018: • Water temperature = 0.48oC – 13.1oC • pH = 6.61 – 8.19 • Specific conductivity = 23.8 µS/cm – 124.8 µS/cm • Turbidity = 0.7 NTU – 11.0 NTU WATER QUALITY INDICATORS CONTINUED DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 Water Quality Update | Spring 2018 fcgov.com/water-quality fcgov.com/water-quality TOTAL ORGANIC CARBON AND ALKALINITY Figure 6 – Alkalinity and total organic carbon concentrations measured at PNF and PBD during the 2018 spring monitoring season (April and May) compared to baseline spring water quality conditions. Red lines indicate removal requirement threshold concentrations. Total organic carbon (TOC) is a measure of the total concentration of dissolved and particulate organic matter in water. Water treatment requires the effective removal of TOC because the interaction between residual TOC and chlorine can form regulated disinfection by-products (DBPs). Higher concentrations of TOC in source waters require additional removal requirements at the water treatment facility based on alkalinity levels. The higher concentrations of TOC and low alkalinity, often observed during spring runoff, create challenges for water treatment. Alkalinity is a measure of the effective acid buffering capacity of water, and is derived from the dissociation of mineral carbonates, bicarbonates, and hydroxides. Alkalinity is influenced by local geology, as well as other dissolved constituents derived from land use practices throughout the watershed. Total organic carbon and alkalinity concentrations measured near the City of Fort Collins’ and City of Greeley’s raw water intakes (PNF and PBD, respectively) were within the baseline range of concentrations. Alkalinity concentrations were slightly higher than median baseline concentrations. The higher concentrations were likely caused by lower than average streamflow in April. Alkalinity concentrations measured over the spring 2018 monitoring season ranged from 14.2 – 35.2 mg/L at PNF and 18.8 – 49.6 mg/L at PBD, and TOC concentrations ranged from 3.08 – 9.34 mg/L at PNF and 3.08 – 8.20 mg/L at PBD. PNF PBD 60 40 20 ALKALINITY (mg/L) PNF PBD 10 8 6 4 2 TOC (mg/L) Charlie Beasley, Watershed Technician, collects water quality indicator data on Joe Wright Creek in early Spring using a multi-parameter water quality sonde. DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49 Water Quality Update | Spring 2018 fcgov.com/water-quality TASTE AND ODOR COMPOUNDS Geosmin and 2-Methylisoborneol (MIB) are naturally occurring organic compounds which introduces an earthy odor to water that can be detected by the most sensitive individuals at concentrations as low as 4 nanograms per liter (ng/L) or 4 parts per trillion (ppt). These compounds do not pose a public health risk, but it is of concern because its detectable presence can negatively affect customer confidence in the quality of drinking water. Geosmin and MIB are monitored at PBR and PNF during routine UCLP monitoring events. Geosmin was detected slightly above the taste and odor threshold on May 7, 2018 (Table 2). Table 2 – Poudre River geosmin and MIB concentrations (ng/L or ppt) during the spring of 2018 at Poudre above the North Fork (PNF) and Poudre below Rustic (PBR) monitoring locations. 2017 Upper Cache la Poudre Watershed Water Quality Trends Report The Upper Cache la Poudre Watershed Collaborative Monitoring Program recently released its 2017 Water Quality Trends Report. Trend reports are produced every five years and provide an in-depth analysis of long-term trends in the climate, hydrology and water quality of the Upper CLP watershed. Water quality reports can be found online at fcgov.com/source-water-monitoring. Monitor Date 4/9/2018 5/7/2018 2.13 2.46 BDL BDL PBR PNF Geosmin (ng/L) MIB (ng/L) Geosmin (ng/L) MIB (ng/L) 2.37 4.43 BDL BDL DocuSign Envelope ID: 8569B6DB-F01F-458D-A96D-101A07EADC49