Monthly Kachemak Bay Report, June 2026
Summary
After an unusually cold spring, deep waters of Kachemak Bay were colder than normal in June 2026, continuing a marine cold spell that began in December 2025. Surface waters, however, had warmed up to and beyond the seasonal mean, resulting in a temperature difference of over 7 °C between surface and deep waters in the inner bay. Chlorophyll concentrations were higher than the extremely low values observed in May, and approached the seasonal mean. The unusually low oxygen saturation levels recorded may have been due to sensor issues.
A complete set of up-to-date graphs can be found on this Google Drive: section plots and time sections (request access from martin.renner@noaa.gov).
Conditions
After a cold spring, temperatures were back to the seasonal mean in the weeks leading up to this June survey (Figure 1). After an unusually wet May, precipitation in June 2026 was close to the long-term mean (which is usually the driest time of the year). Since mid-May, no remaining snowpack has been reported at any of the SNOTEL stations around Kachemak Bay.
The June 22, 2026 Kasitsna Bay Lab oceanographic survey was conducted by Hans, Kris and Martin in calm conditions.
Physical oceanography
Temperature
Water temperatures during the June survey ranged from a minimum of 4.9 °C at station AlongBay-12 (69 m depth), in the inner bay, to a maximum of 12.7 °C at station AlongBay-11 (1 m depth) in the inner bay. Vertical stratification observed throughout the bay, with a 10-20 m layer of warmer, fresher surface water over cooler, more saline waters below (Figure 2 (a), top-left panel). Mid- depth outer bay waters were slightly warmer in the inner bay, but the distinct horizontal differences seen in May between inner and outer bay were no longer present. Satellite sea surface temperature data showed the larger patterns, with warmer waters found in the shallower areas of inner Kachemak Bay and upper Cook Inlet than in lower Cook Inlet and the Gulf of Alaska (Figure 3).
Throughout the bay, deep waters were still cooler than normal, by up to one standard deviation (Figure 2 (a), top-right panel, Figure 5). In contrast, the surface waters were close to normal (Figure 2, Figure 4, Figure 6), with some areas of the thin surface layer in the inner bay up to 7 °C warmer than bottom waters, and up to two standard deviations above the long-term mean for this month (Figure 2 (a), top-right panel). The large warm-up in surface temperatures, compared to May, reflects warmer air temperatures, strong vertical stratification and light wind conditions leading up to the survey. Surface waters of the Gulf of Alaska and Bering Sea also remained colder than normal in June 2026, as shown by satellite sea temperature anomaly data, in contrast to warmer than normal conditions in the central North Pacific (Figure 7).
Salinity
Salinity values during the May survey ranged from 23.6 PSU at station AlongBay-13 (1m depth) in the inner bay to 31.5 PSU at station AlongBay-1 (56m depth) in the outer bay. The water column was strongly stratified throughout the bay, with fresher waters in a 10-20 m surface (Figure 2). Along the mid-bay transect, the fresher water was deeper on the north than on the south side of the bay, indicative of outflows of inner bay waters freshened by rain and snowpack melting (Figure 2 (b)).
Compared to the long-term means, Kachemak Bay waters below the surface layer were less saline than seasonally expected, by over 1.5 standard deviation in some places (Figure 2, Figure 8). This deviation was more pronounced in deep waters than in shallow waters, some of which showed slightly positive anomalies (Figure 2). Kachemak Bay has been fresher than normal in spring/early summer for most of the past three years now (Figure 8, Figure 9).
Turbidity
Inner bay waters were more turbid than outer bay waters, with higher turbidity at depth in the outer bay (Figure 2 (a)). Areas of higher surface turbidity were found in some areas of transient fresher surface water plumes, Compared to the seasonal mean, outer bay waters were slightly less turbid than expected.
Biological conditions
Phytoplankton
Highest chlorophyll concentrations were found in the outer bay with elevated subsurface centrations near the bottom of the surface layer (pycnocline), in both the inner and outer bay (Figure 2 (a)). Integrated over the entire water column, chlorophyll concentrations were higher than the extremely low concentrations in May, but approached the seasonal mean (Figure 10). Our partners from the Kachemak Bay National Estuarine Research Reserve detected potentially toxic Pseudo-nitschia spp. and Alexandrium spp. cells as “present” (on a scale of present, abundant and bloom) in samples from outer and inner bay (Kim Schuster, The Phyto Times, 25 June 2026).
Oxygen
Oxygen values were substantially lower than seasonally expected (Figure 2 (a)). Additional quality control will be conducted to determine if these unusual values are due to issues with the oxygen sensor.
Wildlife
No marine mammals, other than sea otters were observed. Common murres and tufted puffins had returned in numbers to Gull Island and surrounding waters.
Mailing list
Please email Martin at martin.renner@noaa.gov if you would like to be added to or removed from this mailing list.
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