Water quality data for Green Lakes Valley, 2000 - ongoing.

This dataset contains water quality measurements made on Green Lakes
1, 2, 3, 4, 5, and Lake Albion. Green Lake 4 was initially sampled
in 2000 and is ongoing. Ongoing sampling of Green Lakes 1 was
started in 2014 and ongoing sampling of Lake Albion was started in
2016. Water samples were collected for analysis of chlorophyll a and
nutrient analysis (which is available in glvwatsolu.dm.data) and
field measurements for pH, temperature, specific conductivity,
dissolved oxygen (DO), % saturation, secchi depth, PAR. Secchi depth
is recorded at the 0m row however it is a measurement of depth and
so the units are meters. Most samples were collected between 0800
and 1200 MST. The first sampling date each summer occurs shortly
after the ice had melted. Data are collected from an inflatable raft
at the point of deepest depth or from the lake inlet and outlet when
surface flow is present. The majority of chlorophyll-a the
measurements were taken at the surface (0m), the metalimnion (3m),
and the hypolimnion nine (usually 8-11m). However, additional
measurements were taken for side projects of the long-term dataset
during several of the years and are included in this dataset. Water
samples from the metalimnion or hypolimnion were collected using a
Van Dorne sampler, and surface samples were collected as grab
samples from the water column surface, the inlet and outlet. Field
measurements were conducted using a YSI either DO or multiple probe
meter (2014-2017, YSI MPS 556)(2018-ongoing, YSI ProPlus) and a
Li-Cor meter with a quantum sensor. Chlorophyll-a was extracted from
filtered samples and absorbance was measured before and after
acidification to quantify chlorophyll a concentration.