1. Land Use Influences on Water, Sediment and Nutrients in the Napa Valley Watershed: Conceptual Models and Examples Lester McKee (PhD) Watershed Program Manager San Francisco Estuary Institute (SFEI)

2. Presentation Outline Historic conceptual model for water and sediment Historic conceptual model for water and sediment Modern conceptual model for water and sediment Modern conceptual model for water and sediment Examples of impacts Examples of impacts Conceptual models for nutrients Conceptual models for nutrients Examples of nutrient impacts Examples of nutrient impacts San Francisco Estuary Institute

5. Overview of Changes Channel have been: Channel have been: Straightened Straightened Strengthened or lined Strengthened or lined Connected Connected Drainage density has been increased Drainage density has been increased Result Result More water drains of faster More water drains of faster Sediment supply is more connected Sediment supply is more connected Nutrients and other chemical residues drain off faster Nutrients and other chemical residues drain off faster San Francisco Estuary Institute

6. Soda - Realignment of Road and Creek

7. Lower Soda Creek Silverado-Napa R. Reach

8. 19421999 Lower Soda Creek Silverado-Napa R. Reach

9. St. Helena San Francisco Estuary Institute

13. Storage of large volumes of sediment Discontinuation of gravel mining in 2002 Aggradation and potential flood risks Sulphur - Alluvial Fan Reaches

14. Highly affected by the town of St. Helena Entrenched Large amount of bank revetment Water quality affected by runoff Invasive species, primarily Arundo donax Some areas with no riparian vegetation Sulphur - Lowest Reaches

15. Carneros Ck. Revetment

16. Carneros Ck. Bank Erosion

18. Nutrients San Francisco Estuary Institute

19. Null Hypothesis H(0) Land use or human population have no influence on nitrogen or phosphorus concentrations in flowing water bodies within the Napa River watershed. Accept H(0) if there was reasonable doubt that anthropogenic factors strongly influence water quality Accept H(0) if there was reasonable doubt that anthropogenic factors strongly influence water quality If reject H(0) then we would need to develop and test alternate hypotheses (i.e. develop monitoring/management questions) If reject H(0) then we would need to develop and test alternate hypotheses (i.e. develop monitoring/management questions) San Francisco Estuary Institute

20. Conceptual Models to Test Null Hypotheses Against Nutrient concentrations should be below WQ standards Nutrient concentrations should be below WQ standards Seasonal variation should be minor (<10x) Seasonal variation should be minor (<10x) Little spatial variation either between subwatersheds or in a downstream direction Little spatial variation either between subwatersheds or in a downstream direction Nitrate << organic nitrogen Nitrate << organic nitrogen Phosphate << organic phosphorus Phosphate << organic phosphorus San Francisco Estuary Institute

21. Sampling Locations *selected for beneficial uses and coverage

22. WQ Guidelines NOx 1,129 µg/L TDN 500 µg/L Phosphate 30 µg/L TDP 30 µg/L

23. Seasonal Variation San Francisco Estuary Institute

24. Downstream Variation

25. NOxNO 2 - NH 3 Turb Total_POP0.483**.0.397*. Total_COMM.0.435*0.629***. Total_URBA0.434*... Total POPden0.444*... Total_OPEN%-0.533***... Total_URBA%0.367*... 5km_AREA0.509**... 5km_POP0.561***.0.399*. 5km_AGRI0.570***... 5km_COMM0.535**0.546**0.667***. 5km_URBA0.505**... 5km_POPden0.420*... 5km_COMM%0.552**.0.474*0.454* 5km_INDU%..0.417*0.446* 5km_URBA%0.393*... 50m_buffer_POP0.500**.0.397*. 50m_buffer_AGRI0.380*... 50m_buffer_URBA0.412*... 50m_buffer_POPden0.444*... 50m_buffer_COMM%0.431*... 50m_buffer_OPEN%-0.483**...

26. Reasons for Rejecting H(0): Except in headwater reaches, concentrations of NOx, NH3 and PO43- were high relative to expected concentrations in pristine watersheds. Except in headwater reaches, concentrations of NOx, NH3 and PO43- were high relative to expected concentrations in pristine watersheds. Concentrations of NOx varied greatly between sampling locations and increased in a downstream direction in relation to anthropogenic factors. Concentrations of NOx varied greatly between sampling locations and increased in a downstream direction in relation to anthropogenic factors. Total dissolved nitrogen was dominated by NOx and total dissolved phosphorus was dominated by PO43-. Total dissolved nitrogen was dominated by NOx and total dissolved phosphorus was dominated by PO43-. Approximately 85% of the sampling locations exceeded EPA guidelines in Level III Eco-Region 6 for TN (500 µg/L) and ~92% of the sampling locations exceeded EPA guidelines in Level III Eco-Region 6 for TP (30 µg/L). Approximately 85% of the sampling locations exceeded EPA guidelines in Level III Eco-Region 6 for TN (500 µg/L) and ~92% of the sampling locations exceeded EPA guidelines in Level III Eco-Region 6 for TP (30 µg/L). NOx concentrations were highest during the winter months indicating considerable seasonal variation greater than would be expected in a natural system. NOx concentrations were highest during the winter months indicating considerable seasonal variation greater than would be expected in a natural system. NOx correlated significantly with population and urban environmental variables during the winter, spring and early summer and during the wet season only with agricultural and commercial land use variables NOx correlated significantly with population and urban environmental variables during the winter, spring and early summer and during the wet season only with agricultural and commercial land use variables

27. Conclusions Work to-date on water, sediment, and nutrients in the Napa River watershed suggests a level of impact associated with historic and current human land and water use Work to-date on water, sediment, and nutrients in the Napa River watershed suggests a level of impact associated with historic and current human land and water use The questions that stakeholders and the public have to answer is: The questions that stakeholders and the public have to answer is: Is this acceptable given multiple societal needs? Is this acceptable given multiple societal needs? What goals do we set for the future? What goals do we set for the future? San Francisco Estuary Institute