This dataset represents land cover mapping, physical habitat measurements, continuous hydrology measurements, salt tracer measurements, and benthic macroinvertebrate sample scores from nine small streams in unincorporated King County within the Puget Sound region of Washington State. These data were collected during two periods, 2008 – 2012/2013 and 2018 – 2022, as part of a study to evaluate the performance of King County’s land use regulations at protecting stream ecosystems. Six of the streams drained watersheds that were developed or developable and were subject to King County’s land use regulations. Three of the streams drained watersheds that were largely protected from development and served as references for comparison. The initial data collection (2008 – 2012/2013) is described in a report titled, “Assessing Land Use Effects and Regulatory Effectiveness on Streams in Rural Watersheds of King County, Washington,” published in 2014. An analysis of the two combined datasets is described in a report titled, “The Effects of the Land Use Regulatory Framework on Stream Ecosystems in Unincorporated King County Watersheds,” published in 2025. See these reports for details about the sampling methods, study results, and what these data represent. Below we briefly describe the types of data included in this dataset. For questions about these data, please contact James Bower (james.bower@kingcounty.gov), Aaron David (adavid@kingcounty.gov), Ian Higgins (ihiggins@kingcounty.gov), or Rebekah Stiling (rstiling@kingcounty.gov). All data were collected by the King County Water and Land Resources Division, Science and Technical Support Section.

Land cover mapping of the nine study watersheds was conducted once at the beginning and end of the first period (2007 and 2012) and once at the beginning and end of the second period (2017 and 2022). The land cover data are represented by ‘Land_cover.csv’.

Physical habitat measurements were collected once a year within a defined and consistent section of each stream. Physical habitat measurements are represented by ‘Pools.csv’, ‘Reach_lengths.csv’, ‘Substrate.csv’, ‘Thalweg_depths.csv’, and ‘Wood.csv’.

Continuous hydrology measurements of stream discharge, water temperature, and conductivity were collected in each stream throughout most years of the study. Continuous hydrology measurements were summarized into daily values and are represented by ‘Hydrology_daily.csv’.

Samples of the benthic macroinvertebrate community were collected in each stream during late summer or early fall across all study years. These samples were used to calculate Puget Sound lowlands Benthic-Index of Biotic Integrity scores for each stream and year. Benthic macroinvertebrate sample scores are represented by ‘BIBI.csv’.

Salt tracer measurements were conducted in each stream across multiple flows within each year. Salt tracer measurements are represented by ‘Tracer_measurements.csv’.

The ‘Variable_names.csv’ file contains a list of each of the variable/field names within each data file, the variable type for each field, and a brief description of what each variable/field represents.