ADEQ Lakes Classification ADEQ Lakes Classification ADEQ Lakes Classification Project Project Project Update on the Update on the Update on the Narrative Nutrient Criteria Narrative Nutrient Criteria Narrative Nutrient Criteria Development Project Development Project Development Project
Water Quality Standards Water Quality Standards Water Quality Criterion Designated Antideg. Use Policy
Designated Uses… Designated Uses… Aquatic & wildlife-coldwater Drinking water supply Agricultural uses: irrigation, livestock watering Aquatic & wildlife-warmwater Full or partial body contact
Nutrients most common causes of Nutrients most common causes of lake/reservoir impairment… lake/reservoir impairment…
Problems with nutrients Problems with nutrients � Nuisance Nuisance � algal/macrophyte macrophyte algal/ growths growths – Unaesthetic Unaesthetic – – Toxic Toxic – – Taste & odor problems Taste & odor problems – – Low dissolved oxygen Low dissolved oxygen – – Food quality impacts Food quality impacts – – Habitat degradation Habitat degradation –
USEPA’s National Nutrient National Nutrient USEPA’s Strategy Strategy � As of 1995, most states did not have effective As of 1995, most states did not have effective � nutrient standards nutrient standards � USEPA’s USEPA’s National Strategy document published National Strategy document published � in 1998 in 1998 � Technical guidance manuals published in 2000 Technical guidance manuals published in 2000 � � Nutrient criteria in 2001 Nutrient criteria in 2001- -2002 2002 � – Causal variables: TN, TP Causal variables: TN, TP – – Response variables: Chlorophyll Response variables: Chlorophyll a a , and , and Secchi Secchi depth depth – � States required to adopt standards in 2004 States required to adopt standards in 2004- -2007 2007 � timeframe timeframe
USEPA’s default criteria are default criteria are USEPA’s ecoregional… … ecoregional
AZ Narrative Nutrient Standard AZ Narrative Nutrient Standard � � R18 R18- -11 11- -108A. A surface water shall be free from pollutants ( 108A. A surface water shall be free from pollutants (nutrients nutrients in this case in this case) in amounts that: ) in amounts that: – – Settle to form bottom deposits Settle to form bottom deposits that inhibit or prohibit the habitation, growth, that inhibit or prohibit the habitation, growth, or propagation of aquatic life; or propagation of aquatic life; – Cause objectionable odor Cause objectionable odor in the area in which the surface water is located; in the area in which the surface water is located; – – Cause off Cause off- -taste taste or odor in drinking water; or odor in drinking water; – – Cause off Cause off- -flavor flavor in aquatic organisms; in aquatic organisms; – – Are toxic Are toxic to humans, animals, plants, or other organisms; to humans, animals, plants, or other organisms; – – Cause the growth of algae or aquatic plants that inhibit or proh Cause the growth of algae or aquatic plants that inhibit or prohibit the ibit the – habitation or other aquatic life or that impair recreational uses s; ; habitation or other aquatic life or that impair recreational use – Cause or contribute to Cause or contribute to a violation of an aquifer water quality standard a violation of an aquifer water quality standard…; …; – – Change the color Change the color of the surface water from natural background levels of the surface water from natural background levels –
Project Goals Project Goals � To help develop flexible To help develop flexible narrative nutrient criteria narrative nutrient criteria � and associated implementation procedures associated implementation procedures for for and Arizona’s lakes that will maintain a consistent, Arizona’s lakes that will maintain a consistent, scientifically- -based means of compliance based means of compliance scientifically assessment. assessment. � Avoid “one Avoid “one- -size fits all” numeric criteria; i.e., size fits all” numeric criteria; i.e., � consider how variability lake/watershed consider how variability lake/watershed Lake Pleasant characteristics affects trophic trophic responses. responses. characteristics affects � Link criteria/numeric targets with Link criteria/numeric targets with � designated uses. designated uses.
Overview of Approach Overview of Approach Compile Statistical/ Lake Lake/Reservoir Modeling Classification Data Analysis 2005 Triennial Review Implementation Numeric for public review Procedures Targets and comment
Project Overview Project Overview � 74 Lakes in the Study � 138 Sampling Sites � Water Quality Data spanning 20 Years collected by: • ADEQ, • U of A, • Southern Nevada Water Authority • Game and Fish, • Fish and Wildlife, • EPA, • USBR, • USGS
Statistical Analysis Design Statistical Analysis Design Graphical analysis � � Graphical analysis – Exploration of important correlations – Exploration of important correlations – Determine need for transformations – Determine need for transformations � Multivariate analysis � Multivariate analysis – Principal components analysis (PCA) – Principal components analysis (PCA) – Seek useful linear combination of lake/water – Seek useful linear combination of lake/water characteristics variables to “explain” water quality characteristics variables to “explain” water quality � Classification and regression tree (CART) � Classification and regression tree (CART) – Use most powerful variables to classify lakes. – Use most powerful variables to classify lakes.
Project Status Project Status � Water quality and GIS databases compiled and linked Water quality and GIS databases compiled and linked � (Spring 2003 - - Winter 2004); Winter 2004); (Spring 2003 � Descriptive statistics, PCA, CART & phosphorus load Descriptive statistics, PCA, CART & phosphorus load � modeling performed (Spring 2004); modeling performed (Spring 2004); � Algae species data analyzed, TSI re Algae species data analyzed, TSI re- -worked for AZ & worked for AZ & � project re- -scoped (Summer 2004); scoped (Summer 2004); project re � Refined statistical analyses performed (Fall 2004); Refined statistical analyses performed (Fall 2004); � � Matrix completed for implementation of narrative nutrient Matrix completed for implementation of narrative nutrient � standard for lakes & reservoirs (Spring 2005); standard for lakes & reservoirs (Spring 2005); � Survey of recreational use attainment (Spring 2005) Survey of recreational use attainment (Spring 2005) � � Implementation proposed in 2005 Triennial Review Implementation proposed in 2005 Triennial Review �
Modeling concept Modeling concept Eutrophic zone Reservoir Category A : Unlikely to meet coldwater Summer mean A&W uses chlorophyll a ( µ g/L) Phosphorus 120 loading (g/m 2 yr) 100 60 30 Reservoir Category B : 15 Likely to meet coldwater A&W uses 5 Oligotrophic zone Mean depth/hydraulic residence time (m/yr) Figure 1 : Conceptual application of generalized model results. Basic chart form after Rast and Lee (1978).
Preliminary results suggests that other variables Preliminary results suggests that other variables may complicate this approach… may complicate this approach… I refuse to draw a regression line through these points.
Model Results Model Results � Lack of a clear predictive relation between the normalized Lack of a clear predictive relation between the normalized � annual aerial phosphorus load (NAAPL) and the water annual aerial phosphorus load (NAAPL) and the water quality of Arizona’s lakes and reservoirs…why? quality of Arizona’s lakes and reservoirs…why? – errors in model parameter estimates and uncertainty of the true errors in model parameter estimates and uncertainty of the true – seasonal average concentrations seasonal average concentrations – Limitation by factors other than phosphorus Limitation by factors other than phosphorus – – Sequestering of nutrients by Sequestering of nutrients by macrophytes macrophytes or or periphyton periphyton – – – Deposition of nutrients Deposition of nutrients – Internal recycling of nutrients Internal recycling of nutrients – – High or variable proportions of non High or variable proportions of non- -bioavailable bioavailable nutrients in the nutrients in the – annual load annual load – Top Top- -down biological controls (i.e., grazing). down biological controls (i.e., grazing). –
Confirmed some expected relations Confirmed some expected relations between water quality variables between water quality variables Chlorophyll-a v. total phosphorus Chlorophyll-a v. secchi depth …albiet with a lot of scatter.
Insight into how water quality Insight into how water quality varies within lakes/reservoirs varies within lakes/reservoirs “Lakes” have more “Reservoirs” display Uniform water quality longitudinal variations
Water quality correlates with Water quality correlates with agricultural and urban land use agricultural and urban land use Secchi depth v. percent agricultural land TP v. percent agricultural land
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