2021 Groundwater Sustainability Plans:
- Tolley, D., L. Foglia, T. Harter, 2019. Sensitivity Analysis and Calibration of an Integrated Hydrologic Model in an Irrigated Agricultural Basin With a Groundwater-Dependent Ecosystem. Water Resour. Res., doi:10.1029/2018WR024209 (open access)
- NOTE: The above article includes a full update to the 2018 version of the Scott Valley Integrated Hydrologic Model, SVIHM, with embedded links to data and software sources.
Cantor, A., D. Owen, T. Harter, N. G. Nylen, and M. Kiparsky, 2018. Navigating Groundwater-Surface Water Interactions under the Sustainable Groundwater Management Act, Center for Law, Energy & the Environment, UC Berkeley School of Law, Berkeley, CA. 50 pp., https://doi.org/10.15779/J23P87
- Owen, D., A. Cantor, N. Green Nylen, T. Harter, and M. Kiparsky, 2019. California groundwater management, science-policy interfaces, and the legacies of artificial legal distinctions. Env. Res. Lett. 14(4). https://doi.org/10.1088/1748-9326/ab0751
Foglia, L., J. Neuman, D.G. Tolley, S.B. Orloff, R.L. Snyder, and T. Harter, 2018. Modeling guides groundwater management in a basin with river-aquifer interactions. California Agriculture 72(1):84-95.
- Foglia, L., A. McNally, and T. Harter, 2013. Coupling a spatio-temporally distributed soil water budget with stream-depletion functions to inform stakeholder-driven management of groundwater-dependent ecosystems. Water Resour. Res. 49:7292-7310, doi:10.1002/wrcr.20555 (open access).
- Supplemental Material: Estimating Streamflow into Scott Valley
Reports and Online Webinars:
- Summary of the Scott Valley private water level monitoring program, 2006-2018.
Figure: Water level hydrographs for currently active wells in the Scott Valley water level monitoring program, 2006 through October 27, 2021.
Table: 2020 (blue) and 2021 (green) summer and fall depth to water (ft) in the Scott Valley monitoring network. Tables on the left show all wells, tables on the right show only data for wells on the Valley Floor (near the Scott River). On the right of each table, columns show differences in water table depth between months. "AVG": average of all wells. The bottom table (red) is the difference between depth to water in 2020 and 2021. On the Valley Floor wells (right tables), water levels in the most recent month (November 2021) have risen 1.7 feet. Last year, water levels came up 1.5 feet over the same period (late Oct - late Nov).
Summer levels in 2021 were quite a bit lower than in 2020. But starting in September, Valley Floor well water levels rose more than last year: 2.2 ft instead of 1.6 ft in September, and 1.4 ft instead of 0.6 ft in October. In November, water level rose about the same in 2021 compared to 2020. But as a result of the faster rise in water level during September and October 2021, current water levels are, on average 1.3 ft higher this year than last year (average depth is 14.2 ft this year and was 15.5 ft last year in late November).
Relevant to the development of the Scott Valley GSP, it is interesting to note the following: At the end of October 2021, four days after an unusual atmospheric river provided enough rain to connect the entire length of the Scott River and generated a peak flow of over 800 cfs, the average depth to water level in Valley Floor wells was 15.9 ft. In contrast, late November 2020 featured average depth to water level of only 15.5 ft (the first major 2020 rain occurred just before Thanksgiving). Despite the higher aquifer water levels at the end of November 2020 (when compared to late October 2021), the Scott River would not connect until more storms occurred in mid-December. This shows that water levels are difficult to interpret with respect to inferring instream flows.
- Groundwater-dependent ecosystems: Scott Valley (UC Davis webinar, 2015)
- Understanding Groundwater-Surface Water Interactions (AGI webinar, 2015)
- Dynamics of Scott Valley water table surface (movie), 1953-2015
- Scott Valley Pumping Test Report (2014)
- Scott Valley Integrated Hydrologic Model: Data Collection, Analysis, and Soil Water Budget (4/2013)
- Scott Valley Integrated Hydrologic Model: Data Collection, Analysis, and Soil Water Budget Appendix A (4/2013)
- Scott Valley Community Groundwater Study Plan (2008)
- Comments provided on the draft plan, October 2007 (4.5 MB pdf file)
- or: same comments, but including 2005 TMDL Draft Comments by QVIC
Thomas Harter [contact for technical comments/questions]
The Scott Valley is an agricultural groundwater basin in Northern California, within the Scott River watershed and part of the much larger Klamath Basin watershed straddling the California-Oregon border. The Scott River provides important habitat for salmonid fish, including spawning and rearing habitat for coho and fall-run Chinook salmon and steelhead trout. Sufficient flows at adequately low temperatures during summer, for rearing, and fall, for spawning, are critical for healthy fish habitat in the mainstem and tributaries.
We are currently working with the Groundwater Sustainability Agency for Scott Valley, the Siskiyou County Flood Control District, and its Technical Advisory Council, to develop a Groundwater Sustainability Plan under the regulations of the Sustainable Groundwater Management Act, passed by the California legislature in 2014. These efforts are following significant prior technical development by UC Cooperative Extension and its groundwater program in the Scott Valley:
The April 2013 Scott Valley Integrated Hydrologic Model data report presents the data assembled and the methods used for data analysis and data modeling to prepare the Scott Valley Integrated Hydrologic Model Version 2, which is currently under development. The report includes precipitation data analysis, streamflow data analysis and modeling, geology and groundwater data review and analysis, evapotranspiration and soils data analysis, and preparation of relevant watershed, land use, topography, and irrigation data. The data collection and analysis efforts culminate in the development of a spatio-temporally distributed soil water budget model for the Scott Valley. The soil water budget model is used to determine spatially and temporally varying groundwater pumping rates, surface water diversion rates, and groundwater recharge across the groundwater basin. The spatial resolution of the soil water budget model is by individual fields (land use polygons). Temporal discretization is in daily time steps for the period from October 1, 1990 to September 30, 2011. This period includes several dry years, average years, and wet year periods. Methods and results of the soil water budget model are presented in this report. This report represents the next step toward a better understanding of the interactions between groundwater, surface water, landuse, and agricultural practices with a specific focus on the seasonal impacts
Data, information, and analysis are needed through studies to understand the groundwater hydrology of the Scott River system and its relationship to surface hydrology, especially in areas where groundwater could affect Scott River water temperatures, potential riparian vegetation, and habitat connectivity for anadromous fish. Without knowledge of the overall groundwater hydrology of Scott Valley, solutions to specific issues outlined in the TMDL Action Plan and the Scott River Groundwater Management and Enhancement Plan will not be possible. It will be more cost effective to discover and prevent problems before they occur. Baseline data will be needed to determine the best approach in the design and implementation of water projects and water management alternatives and strategies to protect anadromous fish while also protecting the other beneficial uses, including the needs of agricultural operations. Much of this information will need to be developed over a period of time necessary to have a sufficient record from which to discover and test feasible and effective management strategies.
The GW Study Plan and the Integrated Hydrologic Model are developed by the University of California at Davis (UC Davis) with the voluntary assistance of communities, landowners, the SRWC, the Groundwater Advisory Committee, and the Siskiyou Resource Conservation District (SRCD). The GW Study Plan is intended to be a living blueprint of the hydrologic, ecologic, water resource management, and agricultural management research needs and of the investigative approaches that can be taken to develop management practices that meet the mandate for protection of water, agricultural, and ecological resources in the Scott Valley. The GW Study Plan summarizes the 2008 status of knowledge about the hydro-agro-eco-geography of the Scott Valley and outlines potential approaches to addressing critical current research needs. Individual study projects and tasks are described and scheduled in a way that is most efficient and timely to make the best use of funds to collect the information and data needed.