1. Surface Water & Groundwater Interactions Middle Reach of Russian River
Marcus Trotta, PG, CHg Water Agency Hydrogeologist

2. Riverbank Filtration System
Russian River
Riverbank Filtration System
One of the largest riverbank filtration systems in the world
Treatment accomplished via natural filtration.
Only chlorine added as a disinfectant
6 Collector Wells
7 Vertical Wells
5 Infiltration Ponds
Inflatable Dam

3. Groundwater Movement Between Recharge and Discharge
U.S. Geological Survey Circular 1139

4. Groundwater Basin Characteristics
Unconfined alluvial aquifer filled with highly transmissive sands and gravels
Hydraulically connected with Russian River
Alluvial sediments Up to ~100 feet thick near River
Bounded on West by low permeability Franciscan bedrock
Bounded on East by older and less transmissive fluvial deposits (correlative with Glen Ellen Fm)

5. US Geological Survey Circular 1139
Gaining
and
Losing
Streams
Stream gains water from
groundwater
Stream loses water to
groundwater
Groundwater
Mounds beneath
the stream
US Geological Survey Circular 1139

6. Assessment Techniques and Methods
Temperature based streambed conductance estimates
Water-Level measurements & vertical gradient analysis
Seepage meters
Surface and groundwater quality studies
Riverbed sediment sampling program
In-situ microsphere studies
Geophysical Methods to Evaluate SW-GW Interactions
Electrical Resistivity
Spontaneous Potential

7. Measurement of Temperature to Characterize Surface and Groundwater Interactions
Since 1998, SCWA/USGS have measured temperature
trends of Russian River & shallow groundwater
Estimate hydraulic conductivity & streambed
conductance using VS2DH (USGS)
Able to evaluate seasonal trends
Cost-effective method
Results compare favorably with seepage meters

12. Temperature data showing upward gradient
Water level data showing upward gradient

15. Groundwater Flow Models

16. Questions/Discussion