Overview #
Pro bono remote sensing analysis conducted for the National Audubon Society’s Saline Lakes Program to assess whether artificial wildlife habitat — specifically ponds and canals — had ever been constructed at River’s End Reservoir (River’s End Ranch) near the mouth of the Chewaucan River in Lake County, Oregon. Construction of that habitat was a condition of both a 1991 Oregon water use permit and a 1993 lease agreement with USFWS governing the property. The analysis was undertaken to support potential legal action by Audubon.
Three independent lines of evidence were examined. All three reached the same conclusion: the required habitat infrastructure was never built.
Region & Ecosystem #
The study area centers on River’s End Reservoir and the lower Chewaucan River corridor where it enters Lake Abert — a shallow, hypersaline terminal lake in the northern Great Basin, Lake County, south-central Oregon. Lake Abert is one of the largest saline lakes in the western United States and a critical migratory stopover for shorebirds and waterfowl. The adjacent riparian corridor is semi-arid, with wetland and emergent vegetation confined to the immediate floodplain. The region has experienced significant hydrological stress from upstream water diversions, making the non-delivery of compensatory habitat particularly consequential for wildlife.
Methods #
Global Surface Water (Pekel et al. 2016). The JRC Global Surface Water dataset (Landsat-derived, 30 m resolution, 1984–2018) was used to characterize surface water extent, occurrence frequency, seasonality patterns, and long-term change at and around the reservoir. This dataset provided the longest continuous temporal record available and allowed detection of any persistent or seasonal water bodies that could represent constructed ponds.
NDVI Time Series (Robinson et al. 2017). A Landsat-derived NDVI time series product was used to assess vegetation change before and after the permit and lease dates. Persistent increases in greenness in the expected construction area — consistent with irrigated pond margins or riparian revegetation — would have been detectable in this record. No such signal was observed.
Historical Aerial Imagery (NAIP/NAPP). NAIP and NAPP 4-band aerial imagery at multiple acquisition dates (1994, 2001, 2009, 2014, 2016) provided high-resolution visual and near-infrared inspection of the property. Earthworks, berms, canal corridors, and ponded areas would be readily identifiable at these resolutions. None were found at any date.
Permit and Lease Map Overlay. Scanned maps from the 1991 water use permit and 1993 lease agreement were georeferenced and overlaid against current aerial imagery in ArcGIS Pro 2.4.0. This established the precise locations where construction was legally required and confirmed the spatial scope of the absence finding. NHDPlus HR served as a hydrography reference layer.
Outputs #
- Documented absence finding across three independent evidence streams
- Georeferenced permit and lease map overlays
- Surface water occurrence and change maps (Global Surface Water products)
- NDVI change analysis outputs
- Historical aerial imagery annotation panels
- Final analytical report
My Role #
Originated the research design in direct response to a question from Marchelle Shoop, National Director of Audubon’s Saline Lakes Program. Proposed the multi-source methodology, conducted all data collection, processing, and analysis independently, and wrote the report. This was pro bono consulting work.