Nutrient budgets in the lakes of the Cedar River Watershed

Aquatic mineral measurements and sediment characterization of the Cedar River basin lakes and streams reveals two largely distinct physical and chemical environments. Near the headwaters of the Cedar River Watershed the composition of lakes and streams reflect adjacent rocks but the effects of forest and agricultural practices and of processes occurring downstream very quickly alter the composition to a type largely responsive to the urbanization in the lower reaches of the watershed. The relative ionic composition in the watershed is: Ca > Mg ≥ Na > K and HCO₃ > Cl ≥ S0₄. A 2- to 10-fold increase in concentration is measured with most chemical parameters when comparing upper watershed to lower watershed. The lowest increase is observed with total phosphorus reflecting perhaps identical phosphorus solubility control mechanisms. Annual nutrient budgets for Lake Sammamish suggest a reduction in sedimented phosphorus since diversion, but little change in the quantity of phosphorus released from anaerobic sediment. Although the sediment phosphorus supply during the summer and fall months is nearly three times higher than the external phosphorus supply its relative contribution to the trophogenic layer phosphorus is a function of lake mixing. An iron precipitation mechanism appears to control the mean winter phosphorus contents of Lake Sammamish. The prevailing anoxic conditions in the lake during late summer and fall bring about large increases in hypolimnetic iron concentrations which upon destratification precipitate phosphorus as an iron (111) hydroxy complex. Lake sediment characterization indicate differences between lakes with respect to carbon/nitrogen, nitrogen/phosphorus and particle size distribution reflecting drastic variations in the depositional environments and trophic status of the upper and lower watersheds. Higher carbon/nitrogen and nitrogen/phosphorus ratios and coarser sediments are measured in oligotrophic Findley Lake. With the exception of Findley Lake, all sediments appear to have the same composition with respect to Fe, Mn, Ca, Mg, Na, and K contents. Simulation of sediment phosphorus release at the sediment-water interface In enclosed in situ Lake Sammamish sediment-water columns appears to parallel the phosphorus release measured in the lake hypolimnion at the peak of the lake stagnation period. Preliminary studies indicate that it will be possible to relate the nutrient release results from the in situ columns to those of laboratory studies, arriving thus at a faster more economically obtained elucidation of the nutrient exchange mechanisms and potentials at lake sediment-water interface

Phosphorus cycling during the stratified period in Lake Sammamish

A steady-state phosphorus cycle was determined for the stratified period May to November in Lake Sammamish, Washington. A steady-state. condition for this period is considered at this time since data on some important processes are only sufficient to estimate average values for the stratified period. Nevertheless, such a cycle is instructive in indicating the relative magnitude of recycling to maintain productivity in the epilimnion and associated turnover rates

Grazing and production by zooplankton in lakes of contrasting trophic status : a progress report

Grazing rates and density of the crustacean zooplankton were measured in Findley and Chester Morse Lakes and Lake Sammamish, Washington. Sample analysis is incomplete at reporting time, thus estimates of production from examination of life stage biomass changes was not possible. Maximum density of crustacean zooplankton was about 10/1 in the water column of oligotrophic Findley and Chester Morse Lakes and 70/1 in mesotrophic-eutrophic Lake Sammamish during 1972. Densities averaged about 10 times greater in Lake Sammamish than in the other lakes. Copepods comprised most of the numbers in all three lakes. Grazing apparently represents a sizable loss to phytoplankton in the three lakes feeding rates experimentally determined in situ from changes in ¹⁴C tagged phytoplankton ranged from nearly one half to over six times the algal biomass per day. However, feeding rate was always less than phytoplankton productivity

Phytoplankton productivity and response to altered nutrient content in lakes of contrasting trophic state

Lakes Findley, Chester Morse and Sammamish, Washington, are characterized by one major outburst of phytoplankton productivity and biomass (mainly diatoms) with usually no or low fall activity. Vernal outbursts were often delayed in some lakes and years probably by unfavorable climate (snow cover and cloudy rainy conditions). Mean spring-summer productivity ranged from 270 mgC/m² day in the most oligotrophic lake, Findley, to nearly 1000 mgC/m² day in mesotrophic-eutrophic Lake Sammamish. The range in mean Chlorophyll a content was 0.8 to 10 ug/l for the same lakes respectively. Mean biomass within and between the lakes was related to winter phosphorus content but not to nitrogen. However, nitrogen (N) and phosphorus (P) were simultaneously limiting productivity increase in the three lakes in summer. Carbon assimilation in response to added P showed increasing half-saturation constants for the natural phytoplankton progressing from oligotrophy to eutrophy. While diversion of over 1/2 the phosphorus from nearby Lake Washington during 1963-1967 was followed by reduction in winter mean P content and a rapid shift from eutrophy to mesotrophy (Edmondson 1970), mean winter P content and measured characteristics of plankton response have not changed significantly in Lake Sammamish following a diversion of similar magnitude. P availability in the water column (winter mean content) appears to be controlled by precipitation with Fe to a greater extent than in Lake Washington

Phytoplankton productivity and growth rate kinetics in the Cedar River Lakes

Sample collection to define the phytoplankton biomass and productivity in Lakes Findley, Chester Morse, and Sammamish was conducted according to the schedule In Figure 1. Methods and procedures are the same as those used in 1972 (Welch et al. 1972). The purpose of such sampling is to provide validation data of productivity, biomass and growth rate (P/B) of phytoplankton to evaluate the fit of models constructed from experimentally determined parameters. Also, productivity and biomass on a seasonal mean basis serve as a measure of lake response to the incoming nutrient supply rate

Geochemical equilibria and primary productivity in natural lakes

The objectives for year have been the gathering of existing information, initiation of monitoring water quality, evaluation of analytical methods and procedures for measuring nutrient regeneration in the sediment-water interface, and the study of growth-environment correlations in Findley Lake, Chester Morse Reservoir, and Lakes Sammamish and Washington. Progress was made in all phases. An annual budget of total chemical elements entering and leaving Lake Sammamish should he largely completed during 1971. Preliminary data indicate that years after the major portion of phosphorus was directed from Lake Sammamish, the chemical and biological characters are showing only slight and probably insignificant changes compared to what has been observed in Lake Washington. The chemical and biological characteristics of the lakes reveal a graded sequence in chemical composition and productivity. A 4- to 20- fold increase in concentration is observed with most chemical and biological parameters when Findley and Chester Morse Lakes are compared to Lake Washington. Phytoplankton productivity (carbon assimilation rate) and total biomass (chlorophyll) show a progressive increase from Findley Lake (extreme oligotrophy) to Lake Washington (moderate eutrophy). Based on particle-size distribution and carbon: nitrogen rations in surface sediments, the sediments of Findley and Chester Morse Lakes appear to be different from those at Lake Sammamish and Washington. Higher ratios of carbon to nitrogen and coarser sediments are observed in the upper Cedar River drainage lakes

Findley Lake watershed a terrestrial-lake interface program

One of the major objectives of the Western. Coniferous Biome is to understand the relation between terrestrial ecosystems and the chemical and biological properties of drainage waters. The first year of study on such a program has been completed and has primarily entailed a year of descriptive studies.Includes supplemental reports 25-A, B & C

A guide to peppermint insect and mite identification and management

Published May 1993. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo