Freshwater Water Quality

Freshwater Environment

About this indicator: King County's Freshwater Water Quality Index is derived from two main groupings of results describing the conditions of lakes and rivers & streams. Wetland conditions do not factor into the index at this time because of inadequate data. Due to the budget cuts, several indicators in this index have been removed from data collection in 2010 and possibly future years.

Status: Overall below standard, though with some areas of lesser concern.

Influencing factors: The impacts of development, landowner practices in areas close to the shoreline and pollutants are the dominant drivers determining the health of freshwater bodies in King County. Less forest cover and increases in impervious surfaces result in higher stream temperatures and more urban runoff. Phosphorus from blended stormwater and wastewater that bypasses the treatment process during significant storm events, failing septic systems, pet wastes and water bird droppings reduce dissolved oxygen levels and increase water temperatures.

What you can do:

• Properly dispose of unused pharmaceuticals, harmful chemicals and paints, instead of pouring them down the drain or allowing them to run off on the ground.
• Minimize the use of fertilizers and pesticides by practicing natural yard care.
• Wash your car on the grass or gravel instead of on the street or driveway, or take it to a car wash.
• Properly dispose of or manage pet and livestock wastes.

More information about King County's Freshwater water quality is available by continuing below for these measures:

• Phosphorus in Large Lakes
• Stream Temperature
• Streams Water Quality Index
• Nitrates in Groundwater on Vashon-Maury Islands

---

Phosphorus in Large Lakes

About this measure: The people of King County have made significant investments in water quality improvement and protection to lakes Washington, Sammamish and Union beginning with the diversion of wastewater effluent out of Lake Washington and Lake Sammamish in 1968.

Water quality improvements continue with efforts to:

• Reduce the discharge of combined sewer overflows
• Improve King County's wastewater treatment system (including construction of Brightwater treatment facility)
• Expand effluent reuse programs

These gains in water quality are constantly threatened by increasing amounts of phosphorus entering the watersheds as a result of increased development.

Status: Lake water quality results vary annually, depending on the climate effects and biological interactions that combine to create unique conditions in each lake annually. For example, the 1994-2010 results for both Lakes Sammamish and Washington show phosphorus concentrations fluctuated between low to moderate productivity from year to year, indicating water quality varies from good to moderate with low potential for nuisance algal blooms. Lake Union typically has phosphorus concentrations within the moderate water quality range, with the exception of 2007. In 2007 high phosphorus levels put Lake Union in the poor water quality range. Overall the Total Phosphorus - Trophic State Index scores for Lakes Washington and Sammamish, appear to be somewhat lower in recent years.

Lake Sammamish is the only one of the three lakes with an approved management plan that includes designated water quality goals. The plan calls for an annual volume weighted total phosphorus concentration (VWTP) of 22 µg/L or less. Water from both the north and south lake stations met this goal in 2010 with a VWTP of 12 µg/L and 13 µg/L, respectively.

Influencing factors: In this region, phosphorus is most often the nutrient that promotes algal growth in freshwater. The more phosphorus that can be stopped from entering lakes, the less chance that a potentially toxic cyanobacteria bloom will occur. Phosphorus can be managed through well-designed drainage systems, maintenance of sewer infrastructure, changing homeowner and business behaviors (to use no phosphorus fertilizers on lawns), education and incentives, and replacing watershed septic systems with sewers.

Existing DNRP response: King County will continue to monitor these lakes as part of its ongoing Major Lakes Ambient Monitoring Program. This program is designed to track how lakes respond over time to various activities and inputs from the watersheds through influent streams, lake nutrient cycles, ecological interactions, and seasonal or year-to-year variability in weather. The goal of 100 percent of the three major lakes being within the range of moderate to low risk of potential algal blooms was met in 2010. If the lakes begin to show serious deterioration in terms of their beneficial uses, actions will be taken to further investigate causes and plans will be made.

Priority new actions: King County recently adopted an ordinance, which will not take effect until 2011, that limits the non-agricultural use of phosphorus fertilizers in unincorporated King County. The state is currently considering similar fertilizer control legislation.

---

Stream Temperature

About this indicator: This indicator is based on the stream temperature standards established by the state of Washington. The stream temperature standards were established for the protection of designated beneficial uses — particularly for the protection of freshwater spawning, rearing and migration habitat for salmon. For this particular indicator, the focus is on the moving average of the daily maximum stream temperature based on continuous (every 15 minutes) observations of stream temperature conducted at routine monitoring locations by King County, the U.S Geological Survey and the Seattle District of the U.S. Army Corps of Engineers.

While observed exceedances of the stream temperature standard suggest impairment of designated uses, the Washington State Department of Ecology makes this determination under the Clean Water Act Sections 303(d) and 305(b) based on data collected by Ecology and additional data submitted by others. The result of Ecology's assessment includes placement of stream segments in one of five categories that range from Category 1 (meets standards) to Category 5 (polluted waters that require a Water Cleanup Plan — also known as a Total Maximum Daily Load (TMDL). Stream temperature TMDLs typically include the collection of additional data and the development of a stream temperature model to establish the magnitude of impairment relative to an idealized condition where riparian vegetation (and sometimes other factors) is restored to its maximum historic potential.

Status: Continuous temperature data from 65 stream and river sites in King County were measured and the moving 7-day average of the daily maximum temperature was calculated for 2010 and all other years for which data were available going back as far as 2000.

This indicator suggests that many streams and rivers throughout the county exceed the 16°C standard established for the protection of core summer salmonid habitat, with the exception of a few streams found in rural areas and less developed areas within the urban growth boundary.

A stream temperature TMDL has been completed for the Bear-Evans Creek Basin, Newaukum Creek, the mainstem Green River below Howard Hanson Dam and the Snoqualmie River; and temperature TMDLs are under development for the Soos Creek Basin.

Influencing factors: Extensive development can substantially alter the extent of riparian shade that moderates daily peak stream temperatures. Development can also alter summer low flows through reduced groundwater recharge from impervious areas and by water management activities within the basin such as groundwater extraction and export via potable water supply and regional wastewater conveyance systems. Development induced increases in high flows combined with the loss of riparian tree cover can also cause the stream to become wider and shallower, which also contributes to higher peak stream temperatures. Climate change, particularly predicted increases in air temperature are expected to result in warmer stream conditions without substantial investment in restoring riparian shade and summer flow conditions.

Existing DNRP response: King County has a range of regulatory, educational, and on-the-ground programs to reduce the impacts of development on streams and protect and restore riparian vegetation. More attention is also being paid to how development and basin water management activities affect summer stream flow and approaches are being explored to restore and improve flows in streams where historical flow declines have been observed.

Priority new actions: The potential extent of impairment of streams for the designated use as core summer salmon habitat highlights the need for a more comprehensive and coordinated approach to identifying stream reaches that would most benefit from measures such as riparian shade restoration and improved summer stream flows. As noted in the Streams Water Quality Index, King County will work with Ecology, Puget Sound Partnership, and other regional stakeholders to advocate a regional scale water quality assessment, cleanup planning and implementation effort.

---

Streams Water Quality Index

About this indicator: King County's Streams Water Quality Index (WQI) integrates key factors into a single number that can be compared over time and across locations. This index compares monthly temperature, pH, fecal coliform bacteria, dissolved oxygen, turbidity, total suspended solids, and nutrients (phosphorus and nitrogen) relative to state standards and guidelines. This index was originally based on the Oregon Water Quality Index and work by the Washington Department of Ecology. In 2009, Ecology modified the WQI to reflect revised state water quality rules for the protection of native fish and aquatic resources. In addition to modifications for revised state criteria, the WQI was further modified in 2009 by Ecology to more directly reflect conditions in Puget Sound lowland streams. For purposes of year-to-year comparison, results from previous years were recalculated using the new Puget Sound Lowland Stream WQI.

Due to budget cuts, the Stream and River Monitoring Program was significantly reduced in 2009 from 63 sites on three rivers and twenty-eight streams to 24 sites on three rivers and eighteen streams. Four of these 24 stream sites are Vashon Island streams that are monitored through funding sources not associated with the Ambient Stream and River Monitoring Program. The Stream and River Monitoring Program now targets major rivers and streams that will best characterize potential sources of pollutant loading to a major water body. The 2009 Ambient Stream and River Monitoring Program reductions represent a significant loss of a long-term data set for many stream stations that have been monitored since the inception of Metro's monitoring programs in the early 1970s.

Status: The 2009-10 WQI scores indicated that 83 percent of the 24 sampling sites were of moderate or high water quality concern (poor to moderate water quality) and 17 percent were rated of low concern (good water quality). Two of the six sites rated high concern were are in WRIA 9 -- Springbrook Creek was affected by low dissolved oxygen, high phosphorus, and high fecal coliform bacteria, and Newaukum Creek was affected by high phosphorus and nitrogen, as well as high fecal coliform bacteria. Four WRIA 8 creeks were rated high concern — Thornton Creek was affected by high fecal coliform bacteria and high TSS. Juanita Creek was affected by high fecal coliform bacteria, high TSS, and low dissolved oxygen. North Creeks was also affected by high fecal coliform bacteria and low dissolved oxygen. Pipers Creek was affected by high phosphorus and high fecal coliform bacteria.

Influencing factors: Overall stream water quality in King County is impacted by increased development in our region — primarily stormwater runoff. Four of the 24 streams monitored had declining WQI scores compared with the previous year. Juanita, North, and Newaukum creeks WQI scores dropped from moderate concern to high concern, and Soos Creek changed from low concern to moderate concern. All of these creeks were impacted by rainfall events with high fecal coliform bacteria, and in most cases, total suspended solids measured in samples collected in September and January both following a significant rain event. Three of the four streams with improved WQI scores (Shinglemill, Fisher, and Judd) are on Vashon Island. Jenkins Creek also had an improved conditions going from the "moderate concern" rating in 2008-09 to back to "low concern" as in the previous five years.

Stormwater, combined sewer overflows (CSO's), waterfowl and pet wastes are the most likely sources of bacteria in urban streams. Poor livestock manure management and failing septic systems can be a potential source of bacteria in agricultural and suburban areas. In wetlands, wildlife excrement and stagnant water conditions can lead to elevated bacteria counts. High phosphorus concentrations are found in fecal material and elevated concentrations are often linked to similar sources as bacteria. In addition, elevated phosphorus concentrations are linked to areas undergoing development primarily due to erosion.

Low dissolved oxygen concentrations can be associated with low flows, wetlands, high temperatures (colder water holds more oxygen), and high levels of organic matter (bacteria use up oxygen in the process of decomposing).

Existing DNRP response: King County is responsible for preserving water quality and preventing and repairing damage to its waterways and water bodies. Attention is given to high concern sites to improve water quality. This can involve properly maintaining facilities, constructing or engineering solutions, identifying where or how pollutants are entering the stream, and/or educating adjacent property owners about the impacts of pesticides and fertilizers on streams.

Priority new actions: Results from 2009-2010 King County's Streams Water Quality Index highlight the need for a comprehensive and coordinated approach to resolving in-stream flow management, since lower summer flows and increased stormwater runoff inflate every water quality measurement of the index. In 2010, King County worked with local jurisdictions and Washington State Department of Ecology on in-depth bacterial investigations for Issaquah and Idylwood creeks. In 2011, efforts will be focused on further identifying sources in Juanita, Idylwood, Issaquah, and Boise creek basins. King County will work with the Puget Sound Partnership to advocate a coordinated effort in the planning at a regional scale.

---

Nitrates in Groundwater on Vashon-Maury Islands

	Nitrates in Groundwater on Vashon-Maury Islands 2010 Findings

About this indicator: King County has been tracking groundwater quality on Vashon-Maury Island since 2001. Nitrate is used to track groundwater quality because it is a good indicator of changes caused by human activities, such as land-use development. King County's goal is to ensure high water quality through effective land-use and on-site septic regulations.

The groundwater quality indicator uses a nitrate index, defined as the maximum concentration of the annual sampling results divided by the maximum contaminant level (MCL) of Nitrate (10 mg/L). This method yields one number. The closer this index gets to 1 (or over 1) the greater concern. The nitrate index has been less than 0.5 since 2003. The nitrate index for 2010 is below 0.5 with a value of 0.46.

Status: Of the 25 well/spring sites monitored, all have tested below the drinking water standard (Maximum Contaminant Level, MCL of 10 mg/L) and all are less than 5 mg per liter of nitrate present. Less than half the sites tested have seen above average nitrate increases since testing began.

Influencing factors: Poor drainage systems, improperly maintained septic systems and improper fertilizer use can increase nitrate levels.

Existing DNRP response: King County plans to continue monitoring Vashon's wells and springs annually for nitrate concentrations.

Priority new actions: Additional locations have been sought to increase our understanding of island aquifers. King County intends to produce Vashon-Maury Island-wide water table, contour maps with seasonal variability that will be reported every year.

Back to top