Habitat monitoring
Implementation Progress Report 2006-2015
The historic and ongoing destruction of habitat is the most significant threat to Chinook salmon recovery in WRIA 8 as well as throughout Puget Sound. Therefore, the monitoring of habitat conditions is crucial to track our progress in conserving and restoring salmon habitat. In WRIA 8, we monitor changes in forest cover, stream habitat conditions, and water quality throughout the watershed.
Forest cover
Healthy, intact forests support natural watershed processes and high water quality necessary for salmon survival. Especially important is intact forest cover next to streams where salmon migrate, spawn, and rear. Forests buffer the stream from human impacts and provide shade and cover for fish. In addition, areas draining to Chinook streams can heavily influence conditions further downstream. WRIA 8 monitors overall forest cover throughout the watershed, as well as forest cover specifically next to salmon-bearing streams. Starting with 2011 forest cover data, technological advances now allow a much finer assessment of forest cover over a broader area than in past years. As subsequent years are processed, we will be able to report on trends in forest cover along our salmon-bearing streams.
Using high-resolution data and not counting streams in the upper Cedar River Municipal Watershed (where they are protected from development), we estimate that in 2011, 32.6% of the area within 200 feet of WRIA 8 salmon streams was forested. We will be able to compare future years to this benchmark, and track changing conditions over time.
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On the broadest habitat scale, change in the amount of forest cover is a good surrogate for overall watershed conditions, because intact forests can indicate that the hydrology of the watershed is also fairly intact. For this reason, WRIA 8 reports on the overall acres of forest cover in the watershed using information collected by satellite and reported every five years by NOAA. The most recent satellite imagery reported for the Puget Sound region was collected in 2011.
We report on forest cover area separately for inside and outside the urban growth area (UGA) boundaries. We do this because land management strategies inside the UGA boundaries are different than those strategies outside – we would expect to see a much lower rate of forest cover decline outside UGA boundaries, except for areas with commercial forestry operations. (There are currently few forestry operations in WRIA 8.)
Between 1991 and 2011, overall forest cover in our highest priority salmon basins inside the UGA boundary declined by 35%. The majority of that decline (about 19%) occurred during the period from 2006-2011. Forest cover decline inside the UGA is to be expected, since areas inside the UGA take the majority of development pressure throughout the area. Our expectation, however, is that streamside areas, protected by local sensitive areas ordinances, should have stable or growing forest cover. However, a recent study indicates that forest cover along streamside areas inside the UGA is still declining.
Forest cover inside Urban Growth Area boundaries. Source: NOAA Coastal Change Analysis Program and King County.
Source: Jensen 2012.
Outside the UGA boundary, forest cover in WRIA 8 declined by 4.75% between 1991 and 2011. The majority of that decline (4.5%) occurred during the latest reporting period, from 2006-2011.
Forest cover outside Urban Growth Area boundaries. Source: NOAA Coastal Change Analysis Program and King County. NOTE: Tier 2 forested acres total does not include the Cedar River Municipal Watershed.
Stream habitat conditions
WRIA 8 monitored habitat status and trends in and along small streams in the watershed between 2010 and 2013 (King County, 2015). Some stream habitat conditions considered important for salmon (wood volume and water temperature) were found to be below standards considered supportive of salmon use, even in rural areas of the watershed. Wood volume was consistently below standards, and summer water temperatures frequently exceeded state standards. Other important indicators of stream habitat quality, such as pool area, riparian cover and sediment composition, were also assessed, though regional standards for these are not currently available. This monitoring project indicated that salmon recovery priority areas inside Urban Growth Area boundaries are most at risk of further degradation in the short term. Further degradation of these areas will impair their ability to support Chinook salmon.
Habitat status and trends monitoring is currently unfunded in WRIA 8. A power analysis of monitoring requirements indicates that a small program will need ten to twenty years of annual monitoring to reliably detect watershed-wide trends in habitat conditions.
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Water quality
WRIA 8 relies on the Clean Water Act and efforts of state and local jurisdictions to protect and improve water quality for salmon. Likewise, WRIA 8 relies on monitoring efforts by King County and others to provide information on the status and trends in water quality in the watershed. One metric commonly used to report water quality is the Water Quality Index.
The Water Quality Index (WQI) incorporates eight water quality parameters that include temperature, pH, fecal coliform bacteria concentration, dissolved oxygen concentration, sediment load and nutrient levels. A higher number indicates better water quality. In general, stations scoring 80 to 100 meet expectations for water quality and are of "lowest concern;" scores of 40 to 80 indicate "marginal concern." Water quality at stations with scores below 40 does not meet expectations and these streams are of "highest concern." The last two water years (incorporating the summers of 2014 and 2015) saw a large increase in stations reporting the lowest category of water quality. These two summers were also among the hottest on record; many of the additional stations reporting poor water quality had results indicating effects of higher water temperatures and lower streamflow volumes.
Water Quality Index scores (by water year) for priority WRIA 8 streams. Source: King County Science and Technical Support Section.