This is a long-term monitoring dataset of surface temperature, surface oxygen, water clarity, water chemistry and phytoplankton chlorophyll a from weekly to fortnightly sampling at Grasmere in Cumbria, England that began in 1968 for some variables. The data were initially collected by the Freshwater Biological Association but have been collected by the Centre for Ecology & Hydrology (CEH) and its predecessor Institute of Freshwater Ecology since 1989. The data available to download comprise surface temperature (TEMP) in degree Celsius, surface oxygen saturation (OXYG) in % air-saturation, Secchi depth (SECC) in metres, alkalinity (ALKA) in µg per litre as CaCO3 and pH. Ammonium (NH4N), nitrate (NO3N), soluble reactive phosphate (PO4P), total phosphorus (TOTP), dissolved reactive silicon expressed as SiO2 (SIO2) and phytoplankton chlorophyll a (TOCA) are all given in µg per litre. Measurements are made from a boat at a marked location (buoy) at the deepest part of the lake. When it was not possible to visit the buoy, samples were taken from the shore, thus water samples were not integrated on these occasions, marked as Flag 2. All data are from June 1968 until the end of 2013. Full details about this dataset can be found at https://doi.org/10.5285/b891c50a-1f77-48b2-9c41-7cc0e8993c50

The dataset contains spectrophotometrically measured chlorophyll absorbance data from lake and river samples incubated with different nitrogen, phosphorus, silica or combined nutrients, as bioassays, either ex situ for phytoplankton or in situ for periphyton. These data were collected from sites in the English Lake District, Norfolk Broads and Greater Glasgow area in 2017 and 2018 as part of the NERC funded Freshwater Highlight Topic 'Hydroscape'. The work was supported by the Natural Environment Research Council (Grant NE/N00597X/1). Full details about this dataset can be found at https://doi.org/10.5285/2ea22f99-242c-4524-a5dc-3067a5f97a72