The large bar graph in this piece shows Skykomish River discharge (the volume of water) from mid July to late September in 2023. The decrease in water over the dry, hot summer period is evident. The line graph that makes up the mountain above the bars shows the temperature of the river at this same time, highlighting heat wave events. When the temperature spikes, and when the river levels drop, a critical threshold is reached for salmon and other species. This highlights the importance of glaciers in acting as a buffer during drought and heat events.
In 1958 the Skykomish River Basin was home to nineteen glaciers or perennial snow and ice bodies exceeding 0.1 km2 in area, with a combined area of 5.7 km2 (Post and others, 1971). It was the third most glaciated west side basin in the North Cascades behind the Nooksack and Skagit River. These glaciers provided significant runoff to the basin in late summer (Fountain and Tangborn, 1980). We have monitored the mass balance of two glaciers in this basin from 1984-2026, and the changing area and dynamic characteristics of six other glaciers during this period. The Skykomish River Basin has experienced rapid glacier loss leading to the loss of six of its nine glaciers, and over a 40% area reduction of the remaining three.
The North Cascade Glacier Climate Project has maintained an annual mass balance monitoring on the two largest glaciers in the basin from 1984-2026; Columbia and Lynch Glacier. The mean annual mass balance on these two glaciers was –0.4 m/year from 1984-2013, decreasing to –1.5 m/year from 2014 to 2025. This represents the average water equivalent thickness of ice lost from the glacier.
In the field between 1984 and 1986 we identified nine glaciers in the basin that had active crevassing and sufficient area to be classified as a glacier. During the 2005-2023 period we observed six of these glaciers to have disappeared. Lynch and Columbia Glacier now comprise 88% of the total glaciated area in the basin in 2023, up from 37% of total glaciated area in 1958. Foss Glacier, the third remaining glacier in the basin, has lost 85% of its area since 1958 and has almost disappeared. We will check on this glacier later this summer to see if it still is a glacier. The basin is on a trajectory to lose all its remaining glaciers in the next 2-3 decades; this transition to a non-glacier fed watershed will lead to further reductions in summer discharge and increased summer water temperatures.
In 2026 the approach to Columbia Glacier via the Blanca Lake trailhead was lenghtened by bridge and road washouts from the December atmospheric river event. In 2026 the Columbia Glacier will thin by at least 2 m. The lack of avalanche snowpack indicates the warm winter conditions that prevented buildup of snowpack in the 5000-6500 foot range that feeds this glacier. Lynch Glacier had substantial snowpack remaining in its upper basin above 7200 feet. This indicated that the December atmospheric river event deposited snow not rain on the upper Lynch. This was partly due to the embedded cold air east of the divide that Lynch Glacier sits on. Our approach and exit from Mount Daniel and Lynch Glacier was impacted by smoke from the Three Queens fire.
Foss Glacier continues to fragement and disappear.
In glaciated watersheds glacier runoff is of particular importance to aquatic life in late summer and early fall when other water sources are at a minimum, increasing minimum flow and reducing maximum temperatures, thus providing crucial drought buffering capacity (Ultee and others, 2022). In the Skykomish River Chinook salmon are a threatened species with the fall runs being sensitive to lower flows and higher temperatures.
Stream discharge and temperature are observed at the USGS Skykomish River gaging station at Gold Bar. This gaging station is downstream of the confluence of the North and South Fork of the Skykomish River. The basin above Gold Bar has an area of 1386 km2, the average elevation of the basin is 1050 m. A key threshold of in-stream flow levels considered insufficient to maintain short term survival of fish stocks is below 10% of the mean annual flow, for Skykomish River that threshold is 14 m3s-1 (~490 cfs). In the Skykomish River from 1958 to 2023 there were 390 melt season days with discharge below 14 m3s-1. Of these only three occurred before 1985, and 74% have occurred since 2000. The loss of significant glacier runoff is a key reason for the increase of low flow days. Of more concern for aquatic life is the occurrence of extended periods (7+ days) of low flow-below 14 m3s-1 during the melt season, 1986, 1987, 1992, 1998, 2003, 2005, 2006, 2007, 2015, 2017, 2019, 2021, 2022, 2023, 2024, 2025 and 2026.
These low flows are associated with higher stream temperatures.The Skykomish River was listed as having a water quality standard impairment for water temperature in a 2008 303(d) listing and proposed 2010 303(d) listing, under the Clean Water Act[11]. Several segments of the Skykomish River as well as its tributaries consistently exceed water quality temperature standards today. The TMDL(total maximum daily load) for the Skykomish River indicates the maximum temperature should not exceed 16oC for seven consecutive days.
A water temperature sensor became operational in early July 2022 at the USGS Gold Bar site. The temperature exceeded 18oC for the first time on July 27. It surpassed 18oC diurnally on 37 of 42 days from July 27-September 7. In 2022 the 16oC threshold was exceeded continuously from July 26th to August 4th, August 14th-August 28th, and August 29th to September 4th. In 2023 the 16oC threshold was exceeded continuously from July 27th to August 21st, coinciding with the period of low streamflow from August 11to August 21. In 2025 stream temperature remained above 16C from August 22nd to Sept. 14th.
In 2026 stream temperature rose above 16C on Aug. 5th and as of Aug. 22nd has remained above this threshold. During this same interval discharge has reamined below the adequate flow threshold declining to 360 CFS. The low flow and high stream temperatures will continue to stress salmon and limit recreational uses of the river.
From a Glaciers Perspective 