Lake Sammamish Research Articles

Stability of Lake Sammamish phosphorus despite land use changes

Welch EB, Bouchard D, Frodge J, Jacoby JM. Stability of Lake Sammamish phosphorus despite land use changes. Lake Reserv Manage. 35:167–180.Total phosphorus (TP) concentration in Lake Sammamish has not changed significantly following recovery in the 1970s from wastewater diversion, despite increases in developed land and impervious area of 100% and 60%, respectively, from 1980 to 2011. Annual mean, whole-lake TP has remained constant at about 18 µg/L. Summer mean TP and chlorophyll a (Chl-a) have not changed either, and transparency increased from 3.8 m in the 1970s to consistently around 5 m since the 1980s. Reasons for the stability of annual mean TP through the 1980s were (1) hypolimnetic TP had declined by nearly 50% since the 1970s, due to 62% less internal loading; (2) water residence time increased slightly since the 1970s, allowing more settling of particulate matter; and (3) hypolimnetic TP content at turnover did not persist. In 1992, annual TP was predicted to increase from 18 to 28 µg/L if the watershed was developed to 64% from 36% as projected, without substantial forest retention and runoff controls. Developed land increased to half the watershed, but lake TP remained unchanged. Reasons for the continued stable TP over the subsequent 2 decades are that (1) use of land for agriculture ceased; (2) runoff controls were installed; and (3) more forest was retained (64% of the watershed that supplies 70% of the lake’s inflow remained 68% forested). With the implementation of runoff controls, concomitant with increased forest retention and decreased agriculture in the watershed, lake TP and water quality were more stable than originally predicted without these measures.

Phototaxic Behavior of Subyearling Salmonids in the Nearshore Area of Two Urban Lakes in Western Washington State

AbstractWe conducted field experiments in the nearshore area of two urban lakes (Lake Washington and Lake Sammamish) in western Washington to test the attractive quality of artificial nighttime lighting to subyearling salmonids Oncorhynchus spp. In both lakes, experimental trials were conducted along a uniform 156‐m shoreline section twice a month (one night with lights and one control night without lights) from March to May to correspond with peak nearshore rearing of subyearling salmonids. We examined the effects of three light intensities on nearshore fish abundance: (1) no light, (2) dim light (maximum, 5.0 lx), and (3) bright light (maximum, 50.0 lx). These were compared with abundances from control nights without light treatments. Beach seining was used to determine fish abundance. For each month, the total number of subyearling salmonids (Chinook Salmon O. tshawytscha, Coho Salmon O. kisutch, and Sockeye Salmon O. nerka combined) was greater on the lighted nights (all treatments combined) than it was on the control nights. In both lakes, the most subyearling salmonids were collected in the bright‐light treatments, an intermediate amount in the dim‐light treatments, and few in the no‐light treatments. In some instances, subyearling salmonid abundances in the bright‐light treatments were more than 10 times greater than in the no‐light treatments. The effect of nighttime artificial lighting was generally more pronounced in March than in April or May. The results support our hypothesis that subyearling salmonids exhibit nocturnal phototaxic behavior when exposed to elevated nighttime lighting. A major concern of artificial nighttime lighting for subyearling salmonids is the potential for an increased predation risk, and we believe the prudent management goal would be to minimize artificial nighttime lighting.Received October 23, 2016; accepted March 7, 2017 Published online May 26, 2017

Use of Nonnatal Tributaries for Lake-Rearing Juvenile Chinook Salmon in the Lake Washington Basin, Washington

Abstract Ocean-type juvenile Chinook salmon (Oncorhynchus tshawytscha) can be present in the nearshore areas of Lake Washington and Lake Sammamish, WA for 4–5 months (January–June) and may encounter nonnatal tributaries. The use of these tributaries is not well known. We determined the presence of juvenile Chinook salmon in 12 tributaries through nighttime snorkel surveys from March to June. At one heavily-used tributary, we determined their temporal and spatial distribution by conducting surveys every two to three weeks from February to June. Additionally, we determined whether delta areas of tributaries are used by juvenile Chinook salmon by comparing their density and diet to other lakeshore sites. Of 12 streams surveyed, juvenile Chinook salmon were observed in eight. The abundance of Chinook salmon appeared to be related to a variety of factors including proximity to the natal stream, stream gradient, and stream size. In an intensively-monitored stream, juvenile Chinook salmon were found primarily in...

Mercury Accumulation in Sediment Cores from Three Washington State Lakes: Evidence for Local Deposition from a Coal-Fired Power Plant

Mercury accumulation rates measured in age-dated sediment cores were compared at three Washington state lakes. Offutt Lake and Lake St. Clair are located immediately downwind (18 and 28 km, respectively) of a coal-fired power plant and Lake Sammamish is located outside of the immediate area of the plant (110 km). The sites immediately downwind of the power plant were expected to receive increased mercury deposition from particulate and reactive mercury not deposited at Lake Sammamish. Mercury accumulation in cores was corrected for variable sedimentation, background, and sediment focusing to estimate the anthropogenic contribution (Hg(A,F)). Results indicated lakes immediately downwind of the power plant contained elevated Hg(A,F) levels with respect to the reference lake. Estimated fluxes to Lake Sammamish were compared to measured values from a nearby mercury wet deposition collector to gauge the efficacy of the core deconstruction techniques. Total deposition calculated through the sediment core (20.7 μg/m²/year) fell just outside of the upper estimate (18.9 μg/m²/year) of total deposition approximated from the wet deposition collector.

Differing Forage Fish Assemblages Influence Trophic Structure in Neighboring Urban Lakes

Lakes Sammamish and Washington are two large, urban lakes in close proximity to Seattle, Washington. The two lakes have similar assemblages of apex predators, but differences in lake size, species richness, and forage fish assemblages contribute to contrasting trophic relationships. We used stable isotope and diet analyses to assess lake-specific differences in the trophic structure of fish and invertebrates from these lakes. Estimates of δ15N-based trophic elevation revealed that the food web in Lake Sammamish was truncated by approximately one complete trophic level relative to that of Lake Washington. The shorter food chain in Lake Sammamish reflected the absence of longfin smelt Spirinchus thaleichthys and minimal consumption of threespine stickleback Gasterosteus aculeatus, emphasizing the importance of these species as primary forage fishes and trophic links between invertebrates and piscivores in Lake Washington. As two highly 15N-enriched and 13C-depleted energy sources, longfin smelt and threespine sticklebacks effectively stretched the isotopic endpoints of the Lake Washington food web by contributing to more pronounced ontogenetic shifts in isotope values for piscivores in Lake Washington than for those in Lake Sammamish.

Structure of the Eastern Seattle Fault Zone, Washington State: New Insights from Seismic Reflection Data

We identify and characterize the active Seattle fault zone (SFZ) east of Lake Washington with newly acquired seismic reflection data. Our results focus on structures observed in the upper 1 km below the cities of Bellevue, Sammamish, Newcastle, and Fall City, Washington. The SFZ appears as a broad zone of faulting and folding at the southern boundary of the Seattle basin and north edge of the Seattle uplift. We interpret the Seattle fault as a thrust fault that accommodates north–south shortening by forming a fault-propagation fold with a forelimb breakthrough. The blind tip of the main fault forms a synclinal growth fold (deformation front) that extends at least 8 km east of Vasa Park (west side of Lake Sammamish) and defines the south edge of the Seattle basin. South of the deformation front is the forelimb breakthrough fault, which was exposed in a trench at Vasa Park. The Newcastle Hills anticline, a broad anticline forming the north part of the Seattle uplift east of Lake Washington, is interpreted to lie between the main blind strand of the Seattle fault and a backthrust. Our profiles, on the northern limb of this anticline, consistently image north-dipping strata. A structural model for the SFZ east of Lake Washington is consistent with about 8 km of slip on the upper part of the Seattle fault, but the amount of motion is only loosely constrained.

Microsatellite DNA Data Indicate Distinct Native Populations of Kokanee, Oncorhynchus nerka, Persist in the Lake Sammamish Basin, Washington

Microsatellite DNA Data Indicate Distinct Native Populations of Kokanee, Oncorhynchus nerka, Persist in the Lake Sammamish Basin, Washington

Cyanobacterial toxicity and migration in a mesotrophic lake in western Washington, USA

In fall 1997, the toxic cyanobacterium Microcystis aeruginosa was documented in Lake Sammamish (western Washington, U.S.A.) for the first time. Cyanobacterial activity and environmental conditions that may promote toxic cyanobacteria were investigated during summer and fall 1999. Development of toxic Microcystis was hypothesized to be due to runoff of nutrients from the watershed (external loading hypothesis) or from vertical migration of dormant cyanobacteria from the nutrient-rich sediments into the water column (cyanobacterial migration hypothesis). Microcystins were detected using an enzyme-linked immunosorbent assay during late August and early September 1999 despite low cyanobacterial abundance. Microcystin concentrations ranged between 0.19–3.8 μg l−1 throughout the lake and at all depths with the exception of the boat launch where concentrations reached 43 μg l−1. Comparison of the conditions associated with the toxic episodes in 1997 and 1999 indicate that Microcystis is associated with a stable water column, increased surface total phosphorus concentrations (> 10 μg l−1), surface temperatures greater than 22 °C, high total nitrogen to phosphorus ratios (> 30), and increased water column transparency (up to ∼5.5 m). Migration of the cyanobacteria, Microcystis and Anabaena, occurred in both the deep and shallow portions of the lake. Microcystis dominated (89–99%) the migrating cyanobacteria with greater migration from the shallow station. External loading of nutrients due to the large rainfall preceding the 1997 toxic episode may have provided the nutrients needed to fuel that bloom. However, toxic Microcystis occurred in 1999 despite the lack of rain and subsequent external runoff. The migration of Microcystis from the nutrient-rich sediments may have been the inoculum for the toxic population detected in 1999.

ANABAENA AND MICROCYSTIS IN THE PACIFIC NORTHWEST: A TALE OF PLASTICITY

The molecular marker, cpcBA‐IGS, was used to examine the biogeography of representatives of Anabaena and Microcystis collected from Pacific Northwest lakes and their phylogenetic relationship to isolates from the UTEX and CCAP culture collections. cpcBA‐IGS contains portions of the alpha and beta subunit of cyanophycocyanin with an intergenic spacer (IGS) of ∼100 base pairs situated between the subunits. The use of this cyanobacteria specific marker and primers allowed us to amplify cpcBA‐IGS DNA from uni‐cyanobacterial field samples. The morphology and habit of specimens were documented by photomicroscopy. Single filaments or colonies of field material and 3–4 filaments of culture material were then amplified using the polymerase chain reaction (PCR). Results include analysis of non‐toxic summer and toxic winter blooms of Anabaena from 1989–1997 in American Lake, WA and a comparison of non‐toxic and toxic Microcystis from Lake Sammamish, WA. A preliminary phylogenetics analysis of Pacific Northwest and UTEX isolates also was performed using parsimony, maximum likelihood and distance methods. The results of this analysis suggest that revision of Anabaena and Microcystis taxonomy may be needed.

Storm Water Pollutant Removal by Two Wet Ponds in Bellevue, Washington

Two wet detention ponds were investigated for their ability to remove pollutants, primarily phosphorus, from storm water runoff. The two ponds lie within the Phantom Lake watershed, a subbasin of the Lake Sammamish watershed in Bellevue, Wash., which is developed as a commercial and residential area with impervious surface area as high as 57%. There are design differences between the two ponds, yet both are comparable to design recommendations set forth by local agencies. One pond was built for flow attenuation and water quality treatment; the other serves only to improve water quality. Fifteen storms and two baseflows were successfully sampled during the Northwest's wet season from October 1996 through March 1997. Pollutant removals varied between one-fifth and one-half for phosphorus, and greater than one-half for total suspended solids and most of the analyzed metals. Removal efficiencies were consistently better in the pond designed primarily for water quality.

A Zero Degree of Freedom Total Phosphorus Model; 2. Application to Lake Sammamish, Washington

ABSTRACT Current mean annual whole-lake total phosphorus (TP) concentration is about 20 mg·m−3, and mean June through September epilimnion TP is approximately 13 mg·m−3 in Lake Sammamish. Water quality is referenced to mean June through September chlorophyll a (chl a) and Secchi disk transparency. Currendy, these two parameters are at approximately 2.8 mg·m−3 and 4 meters, respectively. A dynamic deterministic TP simulation model indicates that lake water quality will decline, and future water quality in the lake is dependent upon die extent of land development and stormwater controls. The model simulated a lake that: 1) is seasonally stratified, 2) receives seasonal internal loading, and 3) receives seasonal variations in both external TP loading and hydraulic loading. TP movement into, out of, and within the lake was estimated based upon measured values for all of the major pathways. Past, present, and future water quality were estimated based upon the simulated TP concentrations and empirical relationships developed from both literature and in-lake relationships.

The geochemical cycling of stable Pb, 210Pb, and 210Po in seasonally anoxic Lake Sammamish, Washington, USA

The geochemical processes controlling the behavior of stable Pb, 210Pb, and 210po in seasonally anoxic Lake Sammamish, Washington were identified from water column distributions and box model calculations. Total (sum of dissolved and particulate) inventories of stable Pb, 210Pb, and 210Po increased in the whole lake during the latter part of the oxic stage of the lake and were attributed to diffusion from sediments. Large decreases in the total inventories of these elements occurred during the transition from oxic to anoxic conditions, and the lowest inventories were observed during the sulfidic stage of stratification. The cycling of stable Pb and 210Pb during oxic periods appeared to be linked to Fe cycling while 210Po cycling was more closely linked to the cycling of Mn. The behavior of stable and radioactive Pb and, possibly, 210Po during anoxia was influenced by sulfur cycling. Thermodynamic calculations indicated that dissolved Pb concentrations might be controlled by PbS precipitation during anoxia. Flux balance calculations during stratification indicated that atmospheric deposition was the major source of both 210Pb and 210Po to the lake and fluvial input was more important for 210Po than for 210Pb. 210Pb and 210Po supplied by atmospheric deposition were scavenged and removed by sedimentation from the epilimnion. Residence times with respect to scavenging and sedimentation in the epilimnion were 1–3 and 617 days, respectively, for 210Pb and 9–22 and 9–26 days for 210Po. Model results in the hypolimnion indicated that at certain times the radionuclides diffused out of the sediments and at other times into the sediments. Residence times with respect to sedimentation of particulate nuclides in the hypolimnion were 2–124 days for 210Pb and 8–48 days for 210Po. The behavior of 210Pb and 210Po in Lake Sammamish was compared to that in B~' kford Reservoir, Massachusetts. Although the comparison indicated similarities (e.g., links to Fe and Mn cycling, larger scavenging rates for 210Pb than for 210Po), the major differences between the systems were that atmospheric inputs were greater than fluvial inputs, activities of the radionuclides were lower, and the presence of sulfide in the hypolimnion during anoxia affected the cycling of stable Pb, 210Pb, and 210Po in Lake Sammamish.

The biogeochemical cycling of trace metals in the water column of Lake Sammamish, Washington: Response to seasonally anoxic conditions

Total acid-soluble and dissolved Cd, Co, Cr, Cu, Ni, Pb, and Zn concentrations in the water column of a seasonally anoxic lake (Lake Sammamish, Washington) were measured on a monthly basis during the course of a year. These data, in conjunction with Fe, Mn, sulfide, and nutrient data, are used to assess the biochemical processes controlling the distribution of trace metals in the lake and how the importance of these processes varies with time. Thermodynamic calculations are used to examine changes in dissolved metal speciation in the bottom waters during the year and to assess the saturation state of metal-sulfide phases. Spatial and temporal changes in the redox conditions of the bottom waters result in increases in dissolved Co and Ni concentrations, peaks in particulate Co profiles, decreases in dissolved Cu and Cr concentrations, and significant changes in dissolved metal speciation during stagnation. The rcdox-driven cycling of Fe and Mn in the hypolimnion has a dramatic effect on Co distributions, a slight effect on Ni concentrations, and virtually no effect on Cd, Cu, Cr, and Zn concentrations. Biological uptake and regeneration processes result in a correlation between Zn and silicate concentrations throughout the water column, and it appears that biological cycling may also influence the distribution of Cd. During the sulfidic phase of stagnation dissolved Cd concentrations in the bottom waters may be controlled by metal-sulfide precipitation, Cr(V1) is probably reduced to more particle-reactive Cr(II1) and removed by settling particles, and Cu(H) is most likely reduced to Cu(1) and precipitated as a metal-sulfide phase.

The cycling of iron and manganese in the water column of Lake Sammamish, Washington

Processes controlling the distribution and mobility of Fe and Mn in Lake Sammamish, Washington, a seasonally anoxic lake, are deduced from a year‐long monthly study of physical, chemical, and biological parameters in the lake. Inventories of dissolved Mn and Fe in the bottom waters increase as the redox potential lowers with dissolved Mn inventories during stagnation being much larger than inventories of dissolved Fe. The shapes of the dissolved metal profiles indicate that dissolved Fe is supplied to the hypolimnion during stratification by diffusion of Fe(II) from the sediments into the overlying anoxic water as well as reduction of Fe oxide particles settling through the anoxic water column, while the dominant source of dissolved Mn to the anoxic bottom waters during most of the stratification period appears to be reduction of settling Mn‐oxide particles. Inventories of particulate Fe in the hypolimnion during the latter stages of stratification are significantly larger than inventories of particulate Mn. Peaks of particulate Fe and Mn occur in the water column from July through November and particulate Mn peaks always occur at shallower depths than peaks of particulate Fe. Flux calculations suggest that there is a sufficient supply of both oxygen and reduced metal to the particulate zones for metal‐oxide precipitation to occur. Thermodynamic calculations suggest that during the sulfidic phase of stagnation dissolved Fe concentrations in the very bottom waters may be controlled by FeS precipitation.

The Political Survival of Landless Puget Sound Indians

SEVERAL PUGET SOUND INDIAN TRIBES have been placed in a double bind by legal decisions and ethnological field studies. Some recent court decisions suggest that certain Puget Sound tribes no longer exist (United States v. State of Washington, 1979; United States v. State of Washington, 1981), and many anthropologists suggest that they never were tribes (i.e., beyond local village level). Both views are based on a dearth of political data. Indeed, Judge Canby (1982: 1375) criticized courts' contention that such Puget Sound tribes as Duwamish and Snoqualmie were essentially assimilated on grounds that Judge Boldt decision lacked data on their aboriginal political organization and their subsequent political continuity. Moreover, in a recent summary of fifteen ethnographic sources on Puget Sound Indians, Onat (1984: 87) concludes that the term tribes is misleading since native peoples of Puget Sound were not politically organized beyond framework of kinship obligations. These studies casually dismiss significant historical data as the imagination of whites (Underhill 1944: 174) and ignore significant ethnological data such as Haeberlin and Gunther (1930). Recent studies on Duwamish and Snoqualmie Indians indicate that both tribes were organized as political chiefdoms in 1850s and survived in small economic communities into latter half of twentieth century (Tollefson and Pennoyer 1986: 1-450; Tollefson 1987a: 121-136; Tollefson 1987b: 1-411). Four such economic communities described in this study are as follows: Sackman, Lake Sammamish Snoqualmie, Meadowbrook, and Dewatto. The current composition of Duwamish and Snoqualmie Tribal Councils is based upon their former chiefdom political organization. The following section suggests that these tribes survived through political integration of small scattered economic communities that existed in their aboriginal lands. A later section explains changes that occurred in political organization of these two tribes since treaty times.

RESPONSE OF LAKE SAMMAMISH TO URBAN RUNOFF CONTROL

ABSTRACT A seasonal phosphorus model was used to predict the effect of proposed watershed development on water quality in Lake Sammamish, Wash. The model was calibrated and verified using daily loadings from two separate annual data sets. Phosphorus yields were scaled from literature values using actual loadings. Results indicate that substantial runoff controls should be applied to maintain water quality at its present, near oligotrophic state and prevent its return to a prewastewater diversion mesotrophic–eutrophic state.

Nitrogen and phosphorus recycling in Lake Sammamish, a temperate mesotrophic lake

This paper presents nitrogen and phosphorus budgets for spring and summer for the trophogenic (0–9 m) and tropholytic (9–27 m) zones of Lake Sammamish. The objective of constructing the budgets is to evaluate the efficiency of nutrient recycling and increase knowledge of the overall nutrient dynamics.

Lake Sammamish response to wastewater diversion and increasing urban runoff

Lake Sammamish has shown a decrease in its mean annual concentration of phosphorus following diversion of about one third of the external loading in 1968. During 1971–1975 the P concentration averaged 27 μg l −1, in contrast to the prediversion (1964–1966) concentration of 33 μg l −1, and may be equilibrating near the predicted steady state concentration of 22 μg l −1. Neither phytoplankton biomass or Secchi visibility has changed following diversion, however the blue green component of the phytoplankton decreased by nearly 50%. The failure of biomass and visibility to improve is probably a result of similar pre- and postdiversion winter spring epilimnetic P concentrations. The marked reduction in P since diversion occurred during and prior to fall overturn and may have represented a supply of P for later summer early fall blue green algal populations that declined after diversion. Runoff from a rapidly developing westside portion (18%) of the watershed is contributing substantially to P loading of the lake. Development to a density of about ten dwellings ha −1 has increased loading possibly on the order of 14%. Future development of the eastside portion (26% of watershed) may increase loading by 20% and be equivalent to nearly one half of the P previously diverted in 1968.

Nitrogen fixation in lakes of the Lake Washington drainage basin

Biological nitrogen fixation rates have been measured periodically in the epilimnetic waters of four Washington lakes using the acetylene reduction technique. Nitrogen fixation was detected regularly during the summer in the mesotrophic lakes, Lake Sammamish and Lake Washington, but only occasionally in the oligotrophic lakes, Lake Chester Morse and Findley Lake. The contribution of fixed nitrogen in these lakes was estimated to be less than 1% of the total annual nitrogen input from other sources. Comparison of these lakes with others for which appropriate data are available suggest that the low rate of fixation is consistent with the types and abundance of the algal flora and the trophic conditions of the lakes.

Plankton secondary productivity and biomass: Their relation to lake trophic state

The biomass and production of the most important zooplankton species were followed for two years in three lakes of varying trophic status in the Lake Washington watershed. Cladocerans and copepods were of equal importance in the biomass of lakes Findley and Chester Morse (both oligotrophic), whereas, copepods were the main biomass component in Lake Sammamish (mesotrophic). Cladocerans dominated production in lakes Sammamish and Chester Morse, while in Findley Lake their productive role, like that of biomass, was equal to that of the copepods. Rotifers contributed a relatively small biomass and production.