Water Quantity and Quality in Chaparral Region Streams

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1 Water Quantity and Quality in Chaparral Region Streams Christopher Solek, Council for Watershed Health 2 nd Southern CA Chaparral Symposium, June

2 Creeks Named Chaparral in USA Bonneville Co., ID (lat , long ) Blaine Co., ID (lat , long ) Yakima Co., WA (lat , long ) Wallowa Co., OR (lat , long ) Humboldt Co., CA (lat , long )

3 Chaparral defines California as a place in terms of its native landscape This landscape includes not just the upland habitat, but the stream network as well

4 Kilometers Estuarine Flowing Streams / 3rd Order Streams Streams Spreading Grounds Lakes San Gabriel River Watershed

5 Chaparral, Watersheds, and Ecosystem Services Chaparral provides essential ecosystem services: protection against soil erosion (supporting) moderating local climate (regulating) providing important habitat for wildlife, incl. riparian (supporting) recreation (cultural) water supply and groundwater recharge (provisioning) streams move water, sediment, nutrients, and debris through the stream network and provide hydrologic connectivity within the larger watershed (supporting)

6 For Today Climatic setting Hydrologic regime-role of flooding and drying Regional watershed monitoring Effect of fire on water quality and quantity Recreation and water quality in so CA streams

, local geomorphology, edaphic features, human impacts - may vary spatially irrespective of climatic conditions Sequential, predictable,

7 Characteristics of Streams in Chaparral Regions Products of their climate and geomorphic setting - water quality conditions influenced by streamspecific attributes e.g., local geomorphology, edaphic features, human impacts - may vary spatially irrespective of climatic conditions Sequential, predictable, seasonal events of flooding and drying over an annual cycle physically, chemically, and biologically shaped by these events Often associated with topographically complex areas of high relief Exception is Australia (region of moderate relief)

8 Mediterranean Climates Distinct cool-wet season followed by warm-dry season Seasonality and variability of rainfall (and flooding) 65-80% of rain falls within 3 month period (winter) Most rain falls during a few major storm events, accompanied by intense flooding (episodicity) Seasonal rain pattern highly predictable, but extreme intra-annual variability in rainfall possible Pronounced orographic effects and climate cycles in southern CA El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO)

9 Flashy hydrographs Flooding/peak discharges shortly after storm begins and decline to normal flow shortly after storm ends Could occur within hours if soil saturated and/or in high gradient topography Local geomorphology may play a major role in hydrograph dynamics Volume (m 3 /sec.) Jan 1991 Jan 1993 Jan 1995 Jan 1997 Jan 1999 Jan 2001 Jan 2003 Jan 2005 Jan 1967 Jan 1969 Jan 1971 Jan 1973 Jan 1975 Jan 1977 Jan 1979 Jan 1981 Jan 1983 Jan 1985 Jan 1987 Jan Year/Month Mean monthly discharge (m 3 /sec.) in the San Gabriel River, Jan t (Source: Los Angeles Department of Public Works)

10 Mesic-climate Streams Least flashy- extensive tributary networks and floodplains drying over an annual cycle can be interrupted by rain Chaparral-climate Streams Much flashier than mesic streams but less flashy than desert streams continuous, gradual drying process over dry summer period-more gradual impact on the biota than is typical of more arid streams. Desert-climate Streams Most flashy - often restricted by steep bedrock canyons or alluvium drying over an annual cycle can be interrupted by rain

Continuum of Stream Type Based on Watershed zone

predominate Transfer (Sediment Transfer) Discontinuous

Compound channels and alluvial fans predominate e.g.

11 Continuum of Stream Type Based on Watershed zone Erosional (Sediment Production) Single-thread channels predominate Transfer (Sediment Transfer) Discontinuous channels predominate Depositional (Sediment Deposition) Compound channels and alluvial fans predominate e.g., headwaters may occur at high elevations and not be in chaparral 11

Gradient of Hydrologic Permanence Perennial short-term non-perennial

months 2 months > 1 month Typical flow duration Streams can be perennial,

Streams may alternate between perennial flow in rainy years and intermittency

t years - surface water limited to isolated pools - e.g.

12 Gradient of Hydrologic Permanence Perennial short-term non-perennial Intermittent (seasonal) long-term non-perennial Ephemeral 12 months 8 months 6 months 2 months > 1 month Typical flow duration Streams can be perennial, seasonal (intermittent), or ephemeral - seasonal creeks common in CA chaparral Streams may alternate between perennial flow in rainy years and intermittency in drought years - surface water limited to isolated pools - e.g., coastal mountain streams in CA chaparral Seepage of groundwater, agricultural water, and effluent discharge may maintain flow in lower reaches of some streams during dry, summer period 12

13 Deviations In regions of karst geology, large amounts of water may be stored in subterranean aquifers, which may moderate seasonal fluctuations in flow (e.g. Spain, Israel) Portions of catchment located high elevation areas with subfreezing winter temperatures and snow accumulation may exhibit a bimodal mean flow pattern -highest discharges following onset of rain (e.g. in fall) and after snow melt in spring Although the occurrence of floods during fall, winter, or spring is predictable in mediterranean-type streams, the intensity and frequency of the floods vary greatly from year-to-year depending on frequency and intensity of rainfall.

Flooding Period Watershed-stream interactions most pronounced during the relatively short wet season - physical effects of flooding = habitat expansion First floods usually flush tributaries of

14 Flooding Period Watershed-stream interactions most pronounced during the relatively short wet season - physical effects of flooding = habitat expansion First floods usually flush tributaries of accumulated debris and carry a high load of dissolved and suspended matter from the drainage basin into stream channel Throughout wet season: - water quality conditions in stream are least variable - concentration of total dissolved solids is usually relatively low - concentration of suspended solids relatively high - diurnal ranges in temperature and dissolved oxygen are usually lowest

Drying Period Process of drying involves a gradient of events - reductions in flow, to formation of isolated pools, to complete drying of substrate - diurnal fluctuations in water quality conditions

15 Drying Period Process of drying involves a gradient of events - reductions in flow, to formation of isolated pools, to complete drying of substrate - diurnal fluctuations in water quality conditions highest - physical effect of drying = habitat contraction During dry season: - highly fluctuating oxygen concentrations due to elevated temperatures - high daytime photosynthesis and nighttime respiration - high biochemical oxygen demand associated with increased algal production and microbial respiration - reduced dilution of effluents in streams and reduced turbulence - reduced dilution of nutrients - increased salinity - increased deposition of fine sediments - increase in concentration of dissolved minerals due to increased evapotranspiration

16 Effect of Droughts Droughts can exaggerate average drying sequence - elimination or reduction of scouring flows - alteration of temporal and spatial dynamics of habitat structure - fluctuations of mean monthly discharge ranging from 100% above to 50% below the multiannual average not a typical Consecutive drought years may have similar effect to that of water diversion - accrual of fine sediments and expansion of deposition zones - bank erosion and vegetation encroachment into channel - produce major changes in channel morphology In regions where beaches build, coastal streams may become seasonally or annually disconnected from ocean during drought years because there is insufficient water to wash away deposited sand -formation of closed lagoons

18 15 management units = watersheds

20 Fire in California Fire is a regular occurrence in California Frequency of fires increasing Fire alters runoff patterns Higher flows More sediment More nutrients Little is known about effect of post-fire runoff on water quality

21 Post-fire Sources of Pollutants Gasses, aeriallydeposited particulates Fire retardants/fire suppression chemicals Sediment ASH and partially burned organic matter

22 Downstream Water Quality Effects of Fire Fires often occur in watersheds with water bodies of concern Impaired waterbodies Sensitive areas Recreational areas Estuaries Ports and harbors Contaminated sediment

23 Study Locations km 2 catchments Min burn area = 100 km 2 Indirect Effects

24 Sampling Approach Continuous flow monitoring Pollutograph sampling How does post-fire runoff affect contaminant flux? Focus on metals, Polycyclic Aromatic Hydrocarbons 0.1 (PAHs), and nutrients o 5 burn sites ( ) o o 13 storm-events 16 unburned, natural sites 27 storm-events 6 urban, unburned sites 16 storm-events Rain (in) :58 13:38 14:18 14:58 15:38 16:18 16:58 17:38 18:18 18:58 19:38 20:18 20:58 21:38 22:18 22:58 23:38 0:18 0:58 1:38 2:18 2:58 3:38 4:18 4:58 5:38 6:18 6:58 7:38 8:18 8:58 9:38 10:18 10:58 11:38 12:18 12:58 13:38 14:18 14:58 15:38 16:18 16:58 17:38 18:18 18:58 19:38 20:18 20:58 21:38 22:18 22:58 23:38 0:18 0:58 1:38 2:18 2:58 3:38 4:18 4:58 5:38 6:18 6:58 7:38 8:18 8:58 9:38 Time Rain Flow Sample Taken Bottle 1 Sample Taken Bottle 2 Sample Taken Bottle 3 Sample Taken Bottle Flow (cfs)

25 How Does Fire Affect Flux? Direct effects

26 Fire Produces Higher Runoff and Sediment 500 2/25-2/26/04 Burned Site Unburned Site 400 Flow (cfs) Fire October 2003 Total Suspended Solids Unburned Burned EMC (mg/l) 16:00 22:00 04:00 10:00 16: Dec 25, 2003 Feb 25, 2004 Jan 7, 2005

27 Increased Metal Flux (Zinc) unburned

28 Increased PAH and Nutrient Flux

29 Flashier Response Natural, unburned 0.49 Urban 0.69 Burned 0.84 Avg. Runoff Ratio

30 Conclusions Post fire runoff may contribute to increased metals and PAHs flux Greater than ten-fold increase in mass and concentration in many situations, can be up to 100 fold increase Effects appear to be relatively short-live Levels generally return to pre-fire levels within one year Event rainfall influence persistence of effects Indirect effects associated with ashfall can also lead to higher metals and PAHs Need additional sampling to better understand biological effects and recovery

31 San Gabriel Mountain Streams San Gabriel Mts. provide over 70% of L.A. County's open space 346,177 acres designated as a National Monument in Oct Provide 30% of LA County s drinking water supply Includes portions of Los Angeles and San Gabriel River Watersheds 17 million people within an hour's drive (urban-proximate) Over 3 million visitors a year

32 Water-based Recreation Is Extremely Popular in the San Gabriel Mountain Streams!

33 Exceedance of REC-1 standards at swimming sites in the upper LA watershed

streams, lakes, and human health in the San Gabriel Mountains Provide resource managers with the tools and information needed to

34 Opportunity: Healthy Streams for Angelenos Initiative to improve human and watershed health through applied research, education and community engagement Focus on positive health impacts of water-based recreation and negative impacts pollution can have on streams, lakes, and human health in the San Gabriel Mountains Provide resource managers with the tools and information needed to accurately assess the public health risks associated with stream-based recreation when water quality safety standards are exceeded

35 Closing Remarks Seasonal streams in California and other Mediterranean climate areas are among the aquatic habitats most altered by human actions and by invasions by alien species. Managers need to recognize this reality to find ways to direct change towards novel ecosystems with desirable features, including native species. Where more or less intact systems persist, it is usually because extreme environmental conditions restrict both alien invaders and human use. This pattern appears to be fairly typical of streams in Mediterranean climate areas Concept of reconciliation ecology as practical approach to living with a new reality

36 Acknowledgements Eric Stein and Rafael Mazor, SCCWRP Karin Patrick, ABC Consulting, Inc.

37 Thank You

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