Parson's Creek is an intermittent stream that drains into the Russian River. Approximately 3,000 acres, or 56%, of HREC is in the Parson's Creek Watershed. Winter flows for Parson's Creek can exceed several hundred cfs and the creek supports a steelhead trout population, which is presently at risk due to detrimental impacts to the watershed. Small portions of HREC drain into Morrison Creek, a perennial stream, and Dooley Creek, an intermittent stream, both tributaries to the Russian River. Common riparian tree and bush species include, valley oak (Quercus lobata), California bay (Umbellularia californica), elderberry (Sambucus mexicana), and arroyo willow (Salix lasiolepis). Understory plants include chain fern (Woodwardia fimbriata), California horsetail (Equisetum laevigatum), California grape (Vitis californica) and common monkey-flower (Mimulus guttatus).
- Area: 180 - 3,069 m2
- Elevation: 1,080 - 2,960 ft
- Water depth: 0 - 120 cm +
- Percent shade: 0 - 40
- Total plant species: 105
- Introduced species: 33
- Vernal pool obligates: 8
Lake Biological Area contains three sag ponds created by the Mayacama fault line. The upper two of these natural retention basins are continuously fed through underground springs, and are permanent ponds. These ponds and their wetlands vegetation have been protected from grazing since the 1950s. They provide very important wildlife habitat, and are the site of the largest and probably most intensely utilized archaeological site at HREC.
Since 1993, the lower section of Parson's Creek has been included in a restoration/demonstration project funded by the California Department of Fish & Game. The restoration project consists of twelve treatments:
- no livestock/no deer/planted (4 replications)
- no livestock/no deer/not planted (4 replications)
- livestock and deer admitted (control areas), 2 planted and 2 not planted