Henderson Watershed WRIA 13. Chapter Includes: Tanglewilde Stormwater Outfall Woodard Creek Woodland Creek

Transcription

1 Henderson Watershed WRIA 13 Chapter Includes: Tanglewilde Stormwater Outfall Woodard Creek Woodland Creek 146

2 Tanglewilde Stormwater Outfall PART OF HENDERSON WATERSHED PRIMARY LAND USES: Urban residential Commercial GENERAL TOPOGRAPHY: The Tanglewilde outfall is a stormwater outfall that discharges into Woodland Creek. The stormwater system collects runoff from the Tanglewilde neighborhood and portions of Martin Way and Carpenter Road. It also carries shallow ground water that infiltrates into the stormwater conveyance system during wet periods of the year. OTHER DATA: Thurston County Environmental Health Division, (360) Washington Department of Ecology, Water quality data from Henderson TMDL study, (360) Thurston County Resource Stewardship Department, Water Resources Program. (360) GENERAL WATER QUALITY: (Excellent, Good, Fair, Poor) Fair Often fails the fecal coliform standard. Nitrate concentrations are very high in base flows due to shallow groundwater contamination. 147

3 Tanglewilde Stormwater Outfall The water quality standard for fecal coliform bacteria has two parts: Part 1 the geometric mean shall not exceed 50 colonies/100 ml and Part 2 no more than 10% of the samples shall exceed 100 colonies/100 ml. Part 1 of the water quality standard for fecal coliform was violated in Water Year. Part 2 for the fecal coliform standard was violated in both Water Year and. In addition, this outfall/station is often dry, as such, limited data points per water year may statistically skew the available data. The water quality standard for dissolved oxygen is a lowest one-day minimum of 9.5 mg/l. No violations occurred in Water Years and. Since 2005 there has only been one measurement below the dissolved oxygen standard. The standard for ph requires the ph to be within the range of 6.5 to 8.5. There have been no violations for Water Years and. 148

4 Tanglewilde Stormwater Outfall Discussion: The Tanglewilde stormwater outfall was added to the ambient monitoring network in This stormwater outfall discharges into Woodland Creek, which is the largest tributary to Henderson Inlet. Woodland Creek is listed on the 303d Section of the Clean Water Act for fecal coliform, temperature, and dissolved oxygen standards violations. A Total Maximum Daily Load (TMDL) study completed by Washington Department of Ecology in March 2006 identified the Tanglewilde stormwater outfall as one of the major sources of bacteria and nitrogen pollution to Woodland Creek. The Tanglewilde data set for the and Water Years is limited due to the absence of stormwater discharges especially during the summer months. During the and Water Years, a total of two and five samples were collected from this site, respectively. The outfall is usually dry during summer months. The water quality standard for fecal coliform bacteria at this site is as follows: Part 1 - the geometric mean shall not exceed 50 colony forming units (CFU) per 100 milliliters of sample, and Part 2 - no more than 10 percent of the samples shall exceed 100 colonies per 100 ml of sample. For the aforementioned water years, the outfall exceeded Part 1 of the fecal coliform standard in, and failed Part 2 in both Water Years and. Nitrate results are consistently very high in the Tanglewilde stormwater outfall. While there is no water quality standard for nitrates in surface water, a US EPA study determined that the reference condition for nitrate+nitrite concentrations in streams and rivers of the Puget Sound Lowland ecoregion is 0.26 mg/l (EPA Publication 822-B ). The annual average nitrate/nitrite concentrations for and were and 6.37 mg/l, respectively. In this stormwater system, shallow ground water infiltrates into the pipe. The high nitrate values reflect local contamination of the shallow ground water, primarily from on-site sewage systems. The total phosphorus regional reference condition is mg/l, according to the above-referenced EPA report. The average annual total phosphorus concentrations were above the reference condition of mg/l, in Water Years and with concentrations of and mg/l, respectively. Major Issues: Stormwater discharged from this outfall is a major source of bacteria and nutrient pollution to Woodland Creek. On-site septic systems and other urban activities are contributing to contamination of the shallow ground water in the area, which is infiltrating into the stormwater system. Elevated nitrate+nitrite and total phosphorus above their respective regional reference condition was noted for Water Years and 2015/15. Funding Sources: Local Storm and Surface Water Utility 149

5 Water Quality Summary Conventional Parameters Tanglewilde Outfall to Woodland Creek Parameter Units WQ Standard WAC A Water Year Water Year Data: and Mean Range # samples violating standard Cumulative Data: Mean Range Temperature º C Highest 7-DAD Max of 16 º C Dissolved Oxygen mg/l Lowest one-day minimum of of 1 0 of Conductivity μmhos/cm ph * 6.8* of 2 0 of * Turbidity NTU not to exceed 5 NTU over background of 2 0 of Fecal Coliform Total Phosphorus colonies/ 100 ml mg/l GMV: < 50 and < 10% not to exceed ** 18** % exceeding % 20% 21 ** Nitrate + Nitritenitrogen mg/l * Median ** Geometric mean value (GMV) 150

6 Thurston County Water Resources Monitoring Report Tanglewilde Outfall to Woodland Creek Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/21/ :50:00 Dry. 11/19/ :00:00 Dry. 12/10/ :20: Samples only: too low for flow or field parameters. 02/10/ :00: /11/ :30: Q (discharge) uncertainty 6.1%. No DO measurement due to equipment malfunction, DO did not post calibrate. 04/15/ :30:00 Dry. 05/11/2015 Dry. 06/17/ :30:00 Dry 07/15/ :30:00 Dry. 09/15/ :00:00 Dry. 151

7 Thurston County Water Resources Monitoring Report Tanglewilde Outfall to Woodland Creek Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/13/ :40:00 Dry. 11/17/ :30: /09/ :15: FC reported as < /13/ :10: FC reported as <5. 02/08/ :40: Q (discharge) uncertainty 31%. FC reported as <5. Ammonia reported as < /09/ :00: Q (discharge) uncertainty 6.9%. 04/12/ :15:00 Dry. 05/16/ :15:00 Dry. 06/07/ :15:00 Dry. 07/11/ :00:00 Dry. 09/14/ :45:00 Dry. 152

8 Woodard Creek #0012 PART OF HENDERSON WATERSHED LENGTH OF CREEK: 7.5 miles BASIN SIZE: 5,090 acres STREAM ORDER: 2 PRIMARY LAND USES: Urban residential, Rural residential Commercial FISHERIES RESOURCES: (From A Catalog of Washington Streams and Salmon Utilization, WDOF) Coho Chum GENERAL TOPOGRAPHY: The length of the creek is characterized by wetlands and wooded terrain. The gradual rises and depressions of land contain many small wetlands. GENERAL WATER QUALITY: (Excellent, Good, Fair, Poor) Fair-to-Poor Failed both parts of the Fecal Coliform Standard in Water Years and. The water quality standard for dissolved oxygen was violated three times in water year. The water quality standard for ph was violated once in water year. Nitrate and total phosphorus levels exceed their respective regional reference conditions. This creek is listed as an impaired water body for violations of fecal coliform & dissolved oxygen standards. OTHER DATA: Thurston County Environmental Health Division, (360) Thurston County Resource Stewardship Department, Water Resources Program, (360) (flow data) 153

9 Woodard Creek #0012 The water quality standard for fecal coliform bacteria has two parts: Part 1 the geometric mean shall not exceed 50 colonies/100 ml and Part 2 no more than 10% of the samples shall exceed 100 colonies/100 ml. Woodward Creek failed both parts of the Fecal Coliform Standard in Water Years and. Woodard Creek has a history of failing the bacteria standard. The water quality standard for dissolved oxygen is a lowest one-day minimum of 9.5 mg/l. The standard was met in water year. Three measurements were below the standard for water year. The standard for ph requires the ph to be within the range of 6.5 to 8.5. One measurement was outside the standard during water year (March). 154

10 Woodard Creek #0012 Discussion: Woodard Creek has been monitored by Thurston County since Pollution reduction efforts have been underway for several years, and particularly since formation of the Henderson Shellfish Protection District in Some of the pollution reduction activities include construction of stormwater treatment facilities, septic system inspections and repairs, farm planning and installation of agricultural best management practices, installation of pet waste collection stations, and public education/outreach. The headwaters of the creek are a wetland complex within the urban area of Olympia and Lacey, where stormwater has the greatest potential to impact water quality. The mid-reaches of the creek are in a rural area where agriculture, livestock-keeping, and septic systems are the most likely pollution sources. The creek is listed on the Washington Department of Ecology list of impaired water bodies for fecal coliform & dissolved oxygen. The Washington Department of Ecology completed a Total Maximum Daily Load (TMDL) study of the Henderson Inlet watershed, including Woodard Creek, in March 2006, which establish pollutant reductions that are necessary in order for the creek to meet water quality standards. The water quality data are summarized and compared against the state water quality standards in the table on the following page and graphed for trends on the previous page. Both parts of the Fecal Coliform Standard were violated in Water Years and. The water quality standard for dissolved oxygen was violated three times in water year. The water quality standard for ph was violated once in water year. This creek is listed as an impaired water body for violations of fecal coliform & dissolved oxygen standards. While there is no water quality standard for nitrate in surface water, a US EPA study determined that the reference condition for nitrate+nitrite concentrations in streams and rivers of the Puget Sound Lowland Ecoregion is 0.26 mg/l (EPA Publication 822-B ). The average nitrate concentrations for Woodard Creek for Water Years and are and mg/l, respectively, which are both above the aforementioned regional reference condition. The total phosphorus regional reference condition is mg/l, according to the above-referenced EPA report. The average total phosphorus concentrations for Water Years and are and 0.044, respectively, which is also above the regional reference condition. Major Issues: Impacts from stormwater runoff in the urban area reaches and from agricultural practices and septic systems in the rural area reaches. Continuing development within the urban growth area makes efforts to reduce pollution and meet the water quality standards challenging. The mean concentrations of total phosphorus and nitrate for Water Years and were above the regional reference conditions of both constituents. Failed both parts of the Fecal Coliform Standard in Water Years and. The water quality standard for dissolved oxygen was violated three times in water year. 155

11 Woodard Creek #0012 Funding Source: Local Storm and Surface Water Utilities 156

12 Water Quality Summary Conventional Parameters Woodard 4100 blk Libby Rd Parameter Units WQ Standard WAC A Water Year Water Year Data: and Mean Range # samples violating standard Cumulative Data: Mean Range Temperature º C Highest 7-DAD Max of 16 º C Dissolved Oxygen mg/l Lowest one-day minimum of of 11 3 of Conductivity μmhos/cm ph * 7.1* of 12 1 of * Turbidity NTU not to exceed 5 NTU over background of 12 0 of Fecal Coliform Total Phosphorus colonies/ 100 ml mg/l GMV: < 50 and < 10% not to exceed ** 76** % exceeding % 27% 55 ** Nitrate + Nitritenitrogen mg/l * Median ** Geometric mean value (GMV) 157

13 Thurston County Water Resources Monitoring Report Woodard 4100 blk Libby Rd Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/21/ :00: Duplicates labeled "Libby". 11/19/ :20: Q (discharge) uncertainty 3.5%. 12/10/ :00: Q (discharge) uncertainty 4.2%. 01/14/ :50: Q (discharge) uncertainty 6.3%. 02/11/ :00: Q (discharge) uncertainty 4.8%. No DO measurement due to equipment malfunction, DO did not post calibrate. 03/18/ :40: Q (discharge) uncertainty 5.0% 04/15/ :15: Q (discharge) uncertainty 5.9%. 05/13/ :30: Q (discharge) uncertainty 4.0%. 06/17/ :20: Q (discharge) uncertainty 7.7%. 07/15/ :15: Q (discharge) uncertainty 8.4%. Duplicates labeled "Libby 08/12/ :45: Q (discharge) uncertainty 5.5%. Resampled FC's on 8/19/15. FC /15/ :20: Q (discharge) uncertainty 8.2%. 158

14 Thurston County Water Resources Monitoring Report Woodard 4100 blk Libby Rd Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/13/ :20: Q (discharge) uncertainty 5.4%. 11/17/ :00: No FC's recorded: Dups labeled "Libby Lab" were TNTC, sample was /09/ :10: /13/ :45: /08/ :00: Q (discharge) uncertainty 3.4%. 03/09/ :30: Q (discharge) uncertainty 3.1%. 04/12/ :10: Q (discharge) uncertainty 5.2%. 05/16/ :00: Q (discharge) uncertainty 4.0%. 06/07/ :40: Q (discharge) uncertainty 8.1% 07/11/ :45: Q (discharge) uncertainty 6.8%. 08/15/ :30: Q (discharge) uncertainty 13.9%. 09/14/ :00: Q (discharge) uncertainty 21.3%. Duplicates. 159

15 Woodland Creek #0006 PART OF HENDERSON WATERSHED LENGTH OF CREEK: 11 miles BASIN SIZE: 18,900 acres STREAM ORDER: 2 PRIMARY LAND USES: Urban residential Rural residential Commercial FISHERIES RESOURCES: (From A Catalog of Washington Streams and Salmon Utilization, WDOF) Coho, Chum GENERAL TOPOGRAPHY: The stream originates in a lakes system in the Lacey environs in the southern portion of the Henderson watershed. The lake chain empties into a series of wetlands on St. Martin's campus. The creek crosses under I-5 and flows through rolling hills before discharging into Henderson Inlet. 160 GENERAL WATER QUALITY: (Excellent, Good, Fair, Poor) Fair to Poor The Draham Rd. sampling site met Part 1 of the water quality standard for fecal coliform in Water Years and, but failed Part 2 in. The water quality standard for dissolved oxygen is routinely violated at the Draham Rd. sampling site. The Pleasant Glade sampling site failed both parts of the water quality standard for fecal coliform in and. This creek is listed on the 303 d list for violations of fecal coliform & dissolved oxygen. Nitrate and total phosphorus are high. OTHER DATA: Thurston County Environmental Health Division, (360) or Washington Department of Ecology, Water quality data from Henderson TMDL study, (360) Thurston County Resource Stewardship Department, Water Resources Program, (360) or

16 Woodland Creek #0006 Woodland Creek at Draham Rd. The water quality standard for fecal coliform bacteria has two parts: Part 1 the geometric mean shall not exceed 50 colonies/100 ml and Part 2 no more than 10% of the samples shall exceed 100 colonies/100 ml. Woodland Creek at Draham Rd. met Part 1 of the bacteria standard in Water Years and, but failed Part 2 in. The water quality standard for dissolved oxygen is a lowest one-day minimum of 9.5 mg/l. In Water Years and the water quality standard for dissolved oxygen was exceeded 7 out of 12 and 9 out of 12 months, respectively. The water quality standard for ph requires the ph to be within the range of 6.5 to 8.5. The water quality standard for ph was violated once in December

17 Woodland Creek #0006 Woodland Creek at Pleasant Glade The water quality standard for fecal coliform bacteria has two parts: Part 1 the geometric mean shall not exceed 50 colonies/100 ml and Part 2 no more than 10% of the samples shall exceed 100 colonies/100 ml. Woodland Creek at Pleasant Glade failed both parts of the water quality standard for fecal coliform in Water Years and. The standard for ph requires the ph to be within the range of 6.5 to 8.5. There have been no violations since The water quality standard for dissolved oxygen is a lowest one-day minimum of 9.5 mg/l. For water years and, only one violation of dissolved oxygen was recorded in June 2016 at 9.17 mg/l, otherwise during the entire data record there have only been a few measurements below the dissolved oxygen standard. 162

18 Woodland Creek #0006 Discussion: Woodland Creek at Pleasant Glade (the mouth station) has been monitored by Thurston County since There have been numerous intensive study efforts, including DNA ribotyping of E. coli in 2000 and a Total Maximum Daily Load (TMDL) study by Washington Department of Ecology completed in A shellfish harvesting area downgrade in October 2000 due to bacterial pollution triggered a legal requirement to form a shellfish protection district. In December 2001, Thurston County created the Henderson Shellfish Protection District and a stakeholder committee was convened to consider the actions needed to improve water quality and reopen the shellfish beds. This report was completed in July 2003 and can be found on-line at Some of the resulting pollution reduction activities include construction of stormwater treatment facilities, septic system inspections and repairs, farm planning, and installation of agricultural best management practices (BMPs), installation of pet waste collection stations, and public education. In 2005, the Thurston County Board of Health created an area of special concern called the Henderson Watershed Protection Area, which established inspection requirements for all on-site sewage systems within the area. The requirements went into effect in In 2010, water quality improvements in the marine waters of the Inlet resulted in an upgrade of 240 acres of commercial shellfish harvest areas to approved status. Monitoring at a second site on Woodland Creek (Woodland at Draham), resumed in January The water quality data are summarized and compared against the state water quality standards in the table on the following page and graphed for trends on the previous page. While there is no water quality standard for nitrate in surface water, a US EPA study determined that the reference condition for nitrate+nitrite concentrations in streams and rivers of the Puget Sound Lowland ecoregion is 0.26 milligrams per liter (mg/l) (EPA Publication 822-B ). The average nitrate concentrations for Woodland Creek at Pleasant Glade for and are 1.23 and 1.41 mg/l, respectively, which are substantially above the regional reference condition. The average nitrate concentrations at the Draham Road site is 1.12 and 1.18, & 1.06 mg/l, for Water Years and, respectively, also well above the regional reference condition. A pollutant load reduction study attributed much of the nitrate pollution to impacts from older, highdensity development served by on-site sewage systems contaminating groundwater. Since the source of the water for the base flow in the creek is springs, the high nitrate values reflect the groundwater quality condition. The total phosphorus regional reference condition is mg/l, according to the above-referenced EPA report. The average total phosphorus concentrations were above the reference condition for Water Years and at the Draham Road station at and mg/l, respectively. Total mean phosphorus concentrations at the Pleasant Glade site are also above the reference condition at and mg/l for Water Years and, respectively. Major Issues: Urban stormwater discharges, failing on-site sewage systems, and poor livestock-keeping practices are a source of pollution in the Woodland Creek watershed, resulting in average total phosphorus and nitrate conditions above the above-referenced EPA reference conditions for the aforementioned constituents. Mean annual concentrations for nitrate+nitrite and total phosphorus were above their regional reference conditions for the water years addressed in this report at both sampling stations. Violations of the fecal coliform standards occurred at both stations for the water years addressed in this report. Funding Source: Local Storm and Surface Water Utilities 163

19 Water Quality Summary Conventional Parameters Woodland Draham Rd. Parameter Units WQ Standard WAC A Water Year Water Year Data: and Mean Range # samples violating standard Cumulative Data: Mean Range Temperature º C Highest 7-DAD Max of 16 º C Dissolved Oxygen mg/l Lowest one-day minimum of of 11 9 of Conductivity μmhos/cm ph * 6.85* of 12 0 of * Turbidity NTU not to exceed 5 NTU over background of 12 0 of Fecal Coliform Total Phosphorus colonies/ 100 ml mg/l GMV: < 50 and < 10% not to exceed ** 45** % exceeding 100 8% 17% 35 ** Nitrate + Nitritenitrogen mg/l * Median ** Geometric mean value (GMV) 164

20 Thurston County Water Resources Monitoring Report Woodland Draham Rd. Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/21/ :15: Staff gage '. 11/19/ :30: Q (discharge) uncertainty 2.8%. Staff gage Two fish in stream. 12/10/ :00: No flow measurement: salmon spawning. Counted 4 in culvert area. Heavy rain overnight. 01/14/ :40: Q (discharge) uncertainty 2.3%. Staff gage '. 02/11/ :00: No flows: too deep. No DO measurement due to equipment malfunction, DO did not post calibrate. Staff gage /18/ :00: Q (discharge) uncertainty 2.2%. Staff gage /15/ :15: Q (discharge) uncertainty 1.7%. Staff gage - 0.8'. 05/13/ :15: Handcalculated as correction factor was incorrect at one station. 06/17/ :20: Q (discharge) uncertainty 3.4%. 07/15/ :40: Q (discharge) uncertainty 2.8%. Staff gage (est.) '. 08/12/ :30: Q (discharge) uncertainty 3.1%. Duplicates labeled "Culvert". 09/15/ :15: Hand calculated due to error in depth recording. 165

21 Thurston County Water Resources Monitoring Report Woodland Draham Rd. Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/13/ :20: Q (discharge) uncertainty 9.2%. USGS staff in creek at cross section on arrival. Obtained data from USGS. 11/17/ :20: No flows: too deep to wade. 12/09/ :45: Duplicates labeled "Truck". No flows: too high and fast. 01/13/ :00: No flows: too fast. 02/08/ :00: Q (discharge) uncertainty 2.1%. Staff gage '. 03/09/ :20: Q (discharge) uncertainty 1.5%. No staff gage data recorded. 04/12/ :30: Q (discharge) uncertainty 1.4%. Staff gage '. 05/16/ :30: Q (discharge) uncertainty 2.3%. Staff gage '. 06/07/ :30: Q (discharge) uncertainty 3.5%. Staff gage /11/ :20: Q (discharge) uncertainty 1.8%. Staff gage '. 08/15/ :00: Q (discharge) uncertainty 12.1%. Staff gage '. 09/14/ :30: Q (discharge) uncertainty 7.3%. Gage:

22 Water Quality Summary Conventional Parameters Woodland Pleasant Glade Parameter Units WQ Standard WAC A Water Year Water Year Data: and Mean Range # samples violating standard Cumulative Data: Mean Range Temperature º C Highest 7-DAD Max of 16 º C Dissolved Oxygen mg/l Lowest one-day minimum of of 11 1 of Conductivity μmhos/cm ph * 7.1* of 12 0 of * Turbidity NTU not to exceed 5 NTU over background of 12 0 of Fecal Coliform Total Phosphorus colonies/ 100 ml mg/l GMV: < 50 and < 10% not to exceed ** 64** % exceeding % 27% 59 ** Nitrate + Nitritenitrogen mg/l * Median ** Geometric mean value (GMV) 167

23 Thurston County Water Resources Monitoring Report Woodland Pleasant Glade Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/21/ :30: Staff gage '. 11/19/ :00: No flow measurement, fish throughout stream. Staff gage '. 12/10/ :20: Q (discharge) uncertainty 3.2%. Staff gage '. 01/14/ :45: Q (discharge) uncertainty 2.1%. Staff gage '. 02/11/ :20: Q (discharge) uncertainty 2.3%. No DO measurement due to equipment malfunction, DO did not post calibrate. 03/18/ :45: Q (discharge) uncertainty 2.6%. Staff gage /15/ :40: Q (discharge) uncertainty 2.5%. Staff gage '. 05/13/ :15: Q (discharge) uncertainty 4.1%. Staff gage '. 06/17/ :40: Q (discharge) uncertainty 11.2%. Staff gage '. 07/15/ :50: Q (discharge) uncertainty 3.1%. 08/12/ :00: Q (discharge) uncertainty 12.8%. 09/15/ :45: Q (discharge) uncertainty 7.4%. 168

24 Thurston County Water Resources Monitoring Report Woodland Pleasant Glade Date Time Temp ph DO FC Turb Flow TP NOx COMMENTS C mg/l umhos/cm cfu/100ml NTU cfs mg/l mg/l 10/13/ :30: Q (discharge) uncertainty 2.3%. Staff gage '. 11/17/ :00: No flows: too deep to wade. FC's TNTC. 12/09/ :00: /13/ :10: Staff gage '. 02/08/ :00: Q (discharge) uncertainty 1.5%. Staff gage '. 03/09/ :50: Q (discharge) uncertainty 3.8%. Staff gage '. 04/12/ :50: Q (discharge) uncertainty 2.5%. Staff gage '. 05/16/ :45: Q (discharge) uncertainty 2.7%. Staff gage '. 06/07/ :30: Q (discharge) uncertainty 3.3%. 07/11/ :40: Q (discharge) uncertainty 5.4%. Staff gage /15/ :45: Q (discharge) uncertainty 9.2%. 09/14/ :45: Q (discharge) uncertainty 7%. Gage: