19th Annual Review of Research

February 18, 2009
University of Washington

(See and hear Annual of Review presentations here)

Abstracts

The Fate of Onsite Septic System Nitrogen Discharges in Groundwater of the Hood Canal Basin

Julie Horowitz
Research Analyst, William D. Ruckelshaus Center

Nitrogen loading from onsite septic systems (OSSs) may degrade the ecological health of aquatic systems by causing or accentuating eutrophication leading to hypoxia or anoxia.  OSSs do not typically remove nitrogen within the septic tank; therefore, denitrification is the primary mechanism controlling nitrogen loading from OSSs to surface water systems. Hood Canal, located in the Puget Sound region of Washington, has been severely affected by low dissolved oxygen concentrations due to excess nitrogen loading. Onsite septic systems are the primary wastewater treatment process in this watershed and may be an important source of nitrogen to Hood Canal.

The purpose of this study was to determine how much denitrification occurred in OSS effluents in the Hood Canal basin, a glacially-formed, geologically complex system. Shallow sampling wells (0.5 – 2 m) were installed around five OSS drainfields and deep sampling wells (6 m) at one OSS drainfield. Well samples were analyzed for nitrogen, chloride, bromide, and dissolved organic carbon concentrations. The extent of nitrogen reduction varied among the field sites and between two years at one field site. A study site, located in a riparian floodplain, was found to have nearly complete denitrification. Shoreline sites, located near rocky intertidal zones, were found to have little denitrification. And sites located in upland areas were found to have partial denitrification.


Evaluation of peak pricing on single-family residential water consumption in Seattle

David Hsu
Graduate Student, College of Urban Planning and Architecture

Public water utilities have increasingly turned to increasing block rate price structures to reduce water consumption and signal the high environmental costs of water supply. This paper evaluates the impact of a new and substantially higher price block added to the existing block rate price structure in Seattle { often referred to as a `shock rate' { which only a ected those who consume very high quantities of water. The public water utility in Seattle added such a rate to its existing price structure in 2001, and has subsequently seen significant decreases in per capita water demand.

Rigorous evaluation of policies such as the shock rate is often constrained by the limited avail- ability of appropriate data that describes individual consumption decisions. Much of the previous literature of water demand relies upon aggregated data which often results in theoretically im- plausible results such as price elasticities with the wrong signs. As a result of these empirical data limitations, there has also been limited application of theoretically appropriate models such as DCC models within the literature of demand for water and other resources.

This paper applies a DCC model to a new, rich source of observational micro-data to evaluate changes in water consumption in Seattle as a result of the new pricing structure. A comprehensive billing database of water consumption for individual households in the period from 1991 to 2007 was obtained from Seattle Public Utilities. The DCC model was developed as a theoretically appropriate model to describe realistically the e ect of inclined block rate price structures on water consumption.


Monitoring spatiotemporal heterogeneity of arid wetlands

L. Monika Moskal
Assistant Professor of Remote Sensing & Biospatial Analysis
College of Forest Resources

Wetlands are valuable ecosystems that benefit society. They allow for gradual recharge of groundwater, provide critical habitat for plants, fish and wildlife, control erosion, mitigate water pollution, provide food and recreational bases for people and contribute to healthy water cycles and lake levels (Tiner 199). This research combines the use of NASA Landsat and ASTER satellite imagery, aerial photographs, and climate data to improve remote sensing techniques for monitoring the spatiotemporal heterogeneity of arid wetlands. The results of this technique will give more detailed information on wetland dynamics by creating a unique signature for each wetland based on its spectral, spatial and temporal characteristics. This technique can be used to help with wetland habitat selection for preservation or to understand how wetland policies and land use decisions affect wetland dynamics.
 

Migrations of salmon and trout in Puget Sound:  New approaches to old questions

Tom Quinn
Professor, School of Aquatic and Fishery Sciences

The migrations of salmon and trout are an integral part of their basic biology and are also important for their conservation because migrations define critical habitat and control patterns of fishery exploitation.  Decades of tagging with a variety of techniques has yielded many insights but the ability to follow individual fish is of special value.  This presentation describes a collaborative project involving many entities in the Puget Sound region, using ultrasonic tracking to describe the movements of individual salmon and trout.  Tracking includes species that differ in their hypothesized reliance on Puget Sound as habitat: steelhead (believed to migrate directly to the ocean as smolts), Chinook and coho salmon (some infividuals reside in Puget Sound and other inland waters whereas other migrate to the coastal ocean), and cutthroat trout and bull trout (believed to remain near their natal streams during their period in marine waters).  Examples of the kinds of data are presented to illutrate some of the patterns that we are seeing, including diel activity rhthms, home range, and exploratory behavior.

Evaluation of Precipitation Scaling Using Snow Cover Disappearance Date

Mark Raleigh
Graduate Student, Department of Civil and Environmental Engineering

Snowfall is a critical component of the hydrologic cycle of mountainous regions in the Western United States as snowfall accounts for the majority of annual precipitation.  Point scale precipitation measurements of snowfall are often inaccurate due to wind effects, quality control and improper gage calibration, and spatial estimates between these precipitation gauges are challenging in complex terrain.  There is a need to improve spatial distributions of winter precipitation for snow, hydrology, and climate models but existing methods of precipitation estimation struggle to accurately simulate precipitation on finer spatial scales.  As applied in previous studies, the snow depletion date and a snowmelt runoff model can be used jointly to provide an improved indication of winter precipitation.  Peak snow water equivalent (SWE) can be reconstructed at a location by calculating the total melt from ablation energetics and subtracting the solid precipitation during the melt season.  We call this SWE reconstruction technique the Snow Depletion Date Scaling (SDDS) method.  The SDDS method has seen application in the Himalayas, the Swiss Alps, and the Rio Grande headwaters in the San Juan Mountains of Colorado but the method has yet to receive rigorous testing of its accuracy.

This study evaluates the SDDS method at 144 surface meteorological stations in Washington, Oregon, and California between water year 1996 and 2004.  The SDDS method is implemented with the Snow-17 model by iteratively adjusting a snow correction factor (SCF) until the simulated snow disappearance date matches the observed disappearance date.  The preliminary results using Snow-17 indicate that the SDDS method underestimates peak SWE by 17% and SWE volume by 16% on average, however, significant spread exists in the results.  Lower elevation stations tended to overestimate SWE while higher elevation stations generally underestimated SWE.  A sensitivity analysis indicated that these results did not change when the date of snow depletion was incorrect by ±2 days.  Further work is required with the Snow-17 since the sites were not calibrated to region-specific Snow-17 state variables.  Future work also includes evaluating the SDDS method with a full energy balance snow model that requires less calibration and may represent ablation energetics more accurately, thus improving the performance of the SDDS method.  In the application setting, the snow depletion date can be observed by remote sensing satellites or buried temperature sensors, and the SDDS method can be implemented using simulated or measured data and a snow model.


Historical and Future Trends in Precipitation Extremes and Their Impacts on the Stormwater Infrastructure of Washington State

Eric Rosenberg
Graduate Student, Department of Civil and Environmental Engineering

The design and performance of stormwater infrastructure is based on a probability distribution of precipitation extremes, together with an underlying assumption that this distribution is statistically stationary.  This assumption is called into question by climate change.  We therefore examined both historical precipitation records and simulations of future rainfall to evaluate changes in the probability distributions of precipitation extremes across Washington State.  Precipitation data downscaled from two global climate models were also used as input to a hydrologic model to project future streamflow in two urban watersheds in central Puget Sound.  Few statistically significant changes in extreme precipitation were observed in the historical records, but simulations generally indicate future increases in the magnitudes of extreme rainfall and streamflow.  Although the range of these projections is too large to predicate engineering design, and actual changes may be difficult to distinguish from natural variability, the evidence suggests that drainage infrastructure designed using mid-20th century rainfall records may be subject to a future rainfall regime that differs from current design standards.


From Shelf to Sound:  Hidden and Hazardous Chemicals in Everyday Consumer Products

Anne C. Steinemann
Professor, Civil and Environmental Engineering, and Public Affairs

Fragranced consumer products (such as cleaners, air fresheners, laundry supplies, and personal care products) are widely used in homes, businesses, institutions, and public places.  While prevalent, these products can contain chemicals that harm human and environmental health, and that are found in stormwater, wastewater, and water bodies such as Puget Sound.  Moreover, these chemicals are typically not disclosed on product labels or material safety data sheets.  This presentation provides results from an analysis of fragranced consumer products, the hazardous and undisclosed chemicals in those products, and their presence in water systems in the region.  Among 24 best-selling products tested (including ones called "green" or "organic"), more than 150 volatile organic compounds were identified, many of which are classified as toxic or hazardous, but virtually none of which were listed on any product label or material safety data sheet.  Results point to a need for improved understanding and disclosure of product constituents, and their fate and transport in water systems, and effects on human and environmental health.


Efficacy and potential for non-target effects of larvicides for West Nile Virus control in Seattle catch basins

Morgan Sternberg
Graduate Student, School of Aquatic and Fishery Sciences and
Loveday Conquest
Professor, School of Aquatic and Fishery Sciences

In anticipation of the spread of West Nile Virus, Seattle officials promoted a city-wide research effort over the summers of 2006 and 2007 designed to investigate the efficacy and fate of four common larvicides: Mosquito Dunks® and Bits®  (Bacillus thuringiensis [Bti]), VectoLex® WSP (Bacillus sphaericus [Bs]), VectoLex® CG (Bs), and Altosid® Briquets (Methoprene).  All treatments resulted in a rapid reduction in number of pupae (Bti and Bs treatments) or emergence success of pupae (Methoprene).  The Bs treatment was the most efficacious in 2006.  From these results, VectoLex® CG was chosen for city-wide application in 2007.  Efficacy was realized in most cases for 7 weeks, though a relatively high number of precipitation events confounded the direct effect of the larvicide.  The larvicide was detected above background levels at least one week post-treatment in each of the basins chosen to monitor larvicide fate; subsequent precipitation events likely decreased the Bs concentrations.  Larvicide was detected in three urban creeks (Longfellow, Pipers, Thornton) connected to treated basins.  Results from toxicity tests suggest that concentrations of Bs and Bti detected in each of the watersheds pose little hazard to juvenile salmonids.