King County Streams Monitoring Update for August 2018

King County environmental field scientists wore protective respirators while sampling in August due to an inundation of wildfire smoke. The South Fork of the Skykomish is pictured above.

Thank you for your interest in the Streams Monitor, a monthly update from King County's Routine Stream and River Monitoring Program, which samples water quality at 74 sites on streams each month.

August 2018 was hot and smoky. For the second summer in a row, the region was inundated in smoke from wildfires. The image to the right depicts the concentration of smoke on August 22, 2018. The smoke threatened public and wildlife health through respiratory stress. For this Stream Monitor, we consider how wildfire smoke can impact stream water quality.

September 26, 2018

Up in Smoke: How Wildfires Can Impact Streams

A forest fire reflected in Okanagan Lake, British Columbia, Canada. Getty.

During mid-August our region was inundated with smoke from wildfires in eastern Washington and British Columbia resulting in air quality advisories initially for sensitive groups and eventually all residents. As water quality scientists, we are asked “how do these wildfires impact streams?” In this issue we discuss how streams can be impacted by wildfires in their local watershed first, followed by what we know about how smoke from distant fires can impact streams.

How do wildfires impact nearby streams?

Wildfires can greatly impact local streams over both short and long time scales. The impacts will vary based on the intensity, duration, and distribution of the wildfire. Wildfires reduce vegetation, change soil characteristics, and alter the water quality of a stream. Burned-out vegetation no longer captures rainfall and cannot readily retain soils through their root structures. Erosion, flooding, and landslides are exacerbated by wildfires, leading to increased sediment in the stream and shifting the pathways of flow.

During a wildfire, temperatures at the soil surface can approach 900 °C (1,652 °F); and heat this intense will increase temperature in streams, greatly harming, and even killing, thermally sensitive aquatic life and wildlife in the immediate area. Streams below wildfire- September 26, 2018

impacted areas often have elevated fine sediment, nutrients, and metal concentrations. Changes in the physical and chemical properties of streams likely impacts the biologic communities downstream of fires, including insects, fish, algae, and terrestrial animals relying on streams.

The ecological impacts of wildfires are not purely negative and may benefit certain types of ecosystems. A study1 found that the occurrence of wildfires in the Wentatchee River subbasin would have a net-positive effect on spring Chinook salmon habitat. Wildfires have the potential to increase the quality of adult and overwintering juvenile habitat through increased delivery of woody debris. However, the quality of egg and fry habitat is decreased by the introduction of fine sediments. The authors determined that, because there is less high-quality juvenile habitat than habitat for other life stages, wildfires in the subbasin would generally improve spring Chinook habitat.

How does wildfire smoke impact streams?

Few studies have examined the effects of wildfire smoke on stream ecosystems. While streams near wildfires are heated by the nearby blaze, wildfire smoke may obscure solar radiation and lessen the warming of streams far away. A study2 in the lower Klamath River Basin in Northern California found that wildfire smoke resulted in measurable cooling of air and water temperatures commensurate with the density of smoke in the air.

Wildfire smoke has been shown to impact the activity of wildlife, especially birds, but little research has examined the long-term impacts of wildfire smoke exposure on terrestrial animals, let alone aquatic life. The sensitivity of aquatic insects to smoke exposure has not been evaluated, but some

1 Flitcroft, R. L., Falke, J. A., Reeves, G. H., Hessburg, P. F., McNyset, K. M., & Benda, L. E. (2016). Wildfire may increase habitat quality for spring Chinook salmon in the Wenatchee River subbasin, WA, USA. Forest Ecology and Management, 359, 126-140. 2 David, A. T., Asarian, J. E., & Lake, F. K. (2018). Wildfire Smoke Cools Summer River and Stream Water Temperatures. Water Resources Research, 54. September 26, 2018

insects are likely to benefit from the decreased bird predation during smoky periods. Decreased solar radiation may be expected to hamper organisms relying on photosynthesis, including stream algae, which in turn could impact the benthic

invertebrates who graze on growth on rocks. In general, the resilience of aquatic life to handle the impacts of smoke is not known at this time.

Further Reading:

Hallema, D. W., Sun, G., Bladon, K. D., Norman, S. P., Caldwell, P. V., Liu, Y., & McNulty, S. G. (2017). Regional patterns of postwildfire streamflow response in the Western United States: The importance of scale‐specific connectivity. Hydrological Processes, 31(14), 2582- 2598.

Ice, G. G., Neary, D. G., & Adams, P. W. 2004. Effects of wildfire on soils and watershed processes. Journal of Forestry, 102(6), 16-20.

Minshall, G. W., Royer, T. V., & Robinson, C. T. (2001). Response of the Cache Creek macroinvertebrates during the first 10 years following disturbance by the 1988 Yellowstone wildfires. Canadian Journal of Fisheries and Aquatic Sciences, 58(6), 1077- 1088.

Oregon Health Authority and Oregon Department of Forestry. 2014. Impacts of the Pole Creek Wildfire on Fish, Wildlife and Aquatic Habitat, and on Public Health

Smith, H. G., Sheridan, G. J., Lane, P. N., Nyman, P., & Haydon, S. (2011). Wildfire effects on water quality in forest catchments: a review with implications for water supply. Journal of Hydrology, 396(1-2), 170-192.

US Forest Service. 2017. Stream Water Quality Concerns Linger Long After the Smoke Clears.

September 26, 2018

Summary of August 2018 Observations for King County Monitored Streams

 Sampling dates o Aug. 13 – North Lake Washington and Pipers Creek (Water Resources Inventory Area [WRIA] 8), Green River and Vashon–Maury Island (WRIA 9), and Boise Creek (WRIA 10). o Aug. 14 – East Lake Washington and Lake Sammamish (WRIA 8). o Aug. 15 – South Lake Washington (WRIA 8). o Aug. 20 – Streams of Snoqualmie and Skykomish rivers (WRIA 7).  Rainfall, snowmelt, and flow o A trace amount of rain fell on Aug. 11. o Stream flows in King County were generally normal to below normal. Some streams had much lower flow than normal, including the Issaquah Creek, Raging River, Lyon Creek, Newaukum Creek, Miller Creek, Mill Creek, and Sammamish River.

A description of the water quality standards may be found at the end of this email.  Water quality Fecal coliforms o Twenty-six sites (accounting for 24 streams) had high fecal coliform levels above the state peak criteria: . Pipers Creek draining to the Puget Sound in northwest Seattle; . Longfellow Creek draining to the West Waterway of the Duwamish Estuary; . Forbes, Juanita, Lyon, McAleer, and Thornton creeks draining into Lake Washington (Thornton had the highest concentration at 1,300 colonies per 100 milliliters); . Eden, Idylwood, Laughing Jacob, Lewis, and Pine Lake creeks draining into Lake Sammamish; . Bear, Little Bear, North, and Swamp creeks draining into the Sammamish River; . Mill and Soos creeks draining to the Green River; . Rock and Covington creeks draining to Soos Creek; . Boise Creek draining to the White River; and . Fisher, Gorsuch, and Mileta creeks on Vashon Island. o Twenty-three sites (accounting for 19 streams) have had ongoing high fecal coliform levels that are above the state geometric mean criteria. . Over a third of monitored streams in WRIA 8 have fecal coliform geometric means over the state standards (16 of 40 sites). . Longfellow, Springbrook, Fisher, Gorsuch, Judd, and Tahlequah creeks in WRIA 9 and Boise Creek in WRIA 10 also had geometric means above the state criteria.

September 26, 2018

Dissolved oxygen, Temperature, and pH o The North and Middle forks of the Snoqualmie River (WRIA 7), Cedar, Evans, Forbes, Juanita, Kelsey, Issaquah-North Fork, Lyon, Sammamish, Swamp, Thornton, Tibbetts, and Yarrow creeks (WRIA 8), and Lower Green, Springbrook, Mill, Little Soos, Rock, Mill, and Mileta creeks (WRIA 9) was below the state criteria for dissolved oxygen. o Bear, Cedar, Cherry, Issaquah, and Swamp creeks were above the state criteria for pH. o Many streams had sample temperatures that were above the state standard. However the state standards are based on a seven-day moving average of daily maximum temperatures. Not all streams have continuous temperature monitoring. The following streams have continuous temperature monitoring and exceeded the state standard. . WRIA 7: Patterson Creek, Griffin Creek, Cherry Creek. . WRIA 8: Cedar River, Issaquah Creek (mainstem and North Fork), Lewis Creek, Laughing Jacobs Creek, Sammamish River, Bear Creek, Evans Creek, Little Bear Creek, Swamp Creek, North Creek, Lyon Creek, McAleer Creek, Thornton Creek, May Creek, and Juanita Creek. . WRIA 9: Lower Green River, Little Soos Creek, Jenkins Creek, Soos Creek, Mill Creek, Newaukum Creek, and the Duwamish River. Nutrients o Stream nutrient (phosphorus and nitrogen) levels at all sites were similar to the typical historic values for the time of the year.

Click Here to Explore King County Stream Water Quality Data

September 26, 2018

Purpose of Updates As part of its routine stream monitoring program, King County monitors water quality at 73 sites within streams in WRIAs 7, 8, 9, and one stream, Boise Creek, in WRIA 10. Typically these updates will be completed one month after the streams are sampled once all laboratory analysis and quality assurance procedures are completed.

These updates serve several purposes: 1. To alert interested parties when the most recent King County routine stream monitoring data is uploaded and publicly available on the Streams Water Quality Monitoring Data webpage. 2. To provide initial quality assurance and control of the routine data by identifying outliers and anomalies with regards to historic stream conditions and regional observations. 3. To provide a cursory, snapshot narrative of regional stream conditions based on the observed stream quality measurements, stream gage data, and meteorological data. This analysis is not comprehensive and is meant to serve as a starting point.

To provide context and a relative scale, water quality data may be compared to Washington State Water Quality Standards. These comparisons should not be used to determine impairment and are for interpretive purposes only.

Brief Background of Washington State Water Quality Standards  The Washington State legislature has established water quality standards (WAC 173-201A) for the protection of human health and aquatic life.  For the protection of aquatic life, standards are established for temperature, dissolved oxygen, pH, total dissolved gas, turbidity, and toxic chemicals (e.g., metals, polychlorinated biphenyls or PCBs, and pesticides).  The routine water quality data collected by King County allow for the comparison of temperature, dissolved oxygen, pH, and un-ionized ammonia. The standards for each of these are dependent on the designated aquatic life use (e.g., salmon spawning and core summer habitat).

Fecal coliform bacteria are used as indicators of pathogens associated with fecal material from warm-blooded animals. The standards for fecal coliforms are dependent on the designated recreational use:  extraordinary primary contact — swimming and tributaries to lakes or shellfish harvest;  primary contact — swimming or water skiing; and  secondary contact — fishing or wading. The fecal coliform criteria include both a geometric mean criterion and a statistical threshold value (or peak). The geometric mean is defined as the nth root of the product of n numbers. The statistical threshold is based on the 90th percentile of observed levels.

September 26, 2018