Who is the Colorado Nutrient Who is the Colorado Nutrient Who is - PowerPoint PPT Presentation

Who is the Colorado Nutrient Who is the Colorado Nutrient Who is the Colorado Nutrient Who is the Colorado Nutrient Coalition and Why are we Coalition and Why are we here? here? h h ? ? John C. Hall John C. Hall William T. Hall William T. Hall William T. Hall William T. Hall Tad S. Foster Tad S. Foster

The Science The Science Where does it stand? Where does it stand? Where does it stand? Where does it stand?

Review of Mechanisms Review of Mechanisms Review of Mechanisms Review of Mechanisms I nfluencing Nutrient I nfluencing Nutrient Dynamics in Lakes and D D Dynamics in Lakes and i i i i L k L k d d Streams Streams

EPA GUI DANCE ON ALGAL EPA GUI DANCE ON ALGAL GROWTH RELATI ONSHI P “ The difficulty associated with understanding predictive relationships between nutrient loading and algal biomass is perhaps the biggest challenge to establishing meaningful nutrient criteria.” (Nutrient Criteria Technical Guidance Manual–Rivers and ( Streams at 73)

CLARK FORK RI VER (MT) ( ) NUI SANCE ALGAE (CLADOPHERA) Relative Cladophora abundance in the Clark Fork River, MT. Abundance Scores: VA = very abundant, A = Abundant, VC = Very Common, C = Common, R = Rare, N = not present. (Dodds et al. 1997)

NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A DEVELOPMENT CONSI DERATI ONS DEVELOPMENT CONSI DERATI ONS • Nutrients (N, P) not toxic in classical sense Nutrients (N, P) not toxic in classical sense – No direct effect on invertebrates directly No direct effect on invertebrates directly – Stimulate plant growth Stimulate plant growth  adverse effects adverse effects • EPA Nutrient Criteria Guidance (2000) EPA Nutrient Criteria Guidance (2000) EPA Nutrient Criteria Guidance (2000) EPA Nutrient Criteria Guidance (2000) – Define relationship to plants, D.O., pH, etc. Define relationship to plants, D.O., pH, etc. – Set causal (TP) and response (Chl ‘a’) criteria Set causal (TP) and response (Chl ‘a’) criteria ( ( ) ) p p ( ( ) ) • Recent Regulatory Actions Recent Regulatory Actions – Stressor Stressor-Response Empirical Analysis Stressor Stressor Response Empirical Analysis Response Empirical Analysis - SAB Response Empirical Analysis SAB SAB SAB – Florida WQS Problems Florida WQS Problems

NUTRI ENT CRI TERI A MUST NUTRI ENT CRI TERI A MUST NUTRI ENT CRI TERI A MUST NUTRI ENT CRI TERI A MUST CONSI DER PLANT GROWTH CONSI DER PLANT GROWTH [F]ish and macroinvertebrates do not directly respond to nutrients, and therefore may not be as sensitive to changes in nutrient concentrations as algal assemblages. It is recommended that relations l l bl d d h l between biotic integrity of algal assemblages and nutrients be defined and then related to biotic integrity of macroinvertebrate and fish assemblages in a stepwise, mechanistic fashion. assemblages in a stepwise, mechanistic fashion. (EPA. 2000. Nutrient Criteria Technical Guidance Manual - Rivers and Streams at 85)

SAB CONCLUSI ON OVERVI EW SAB CONCLUSI ON OVERVI EW SAB CONCLUSI ON OVERVI EW SAB CONCLUSI ON OVERVI EW • Regression Approach Not Scientifically Defensible for Regression Approach Not Scientifically Defensible for g g pp pp y y Nutrient: Invertebrates; Lacks Cause/Effect Demonstration Nutrient: Invertebrates; Lacks Cause/Effect Demonstration • Need to Confirm “Impairment” Thresholds Are Biologically Need to Confirm “Impairment” Thresholds Are Biologically p p g g y y Significant Significant • Need to Account for Factors Influencing Nutrient Dynamics Need to Need to Need to Account for Factors Influencing Nutrient Dynamics ccou t o ccou t o acto s acto s ue c g Nut e t ue c g Nut e t y a y a cs cs and Invertebrate Metrics (Habitat, DO, pH, Scour/Sediment) and Invertebrate Metrics (Habitat, DO, pH, Scour/Sediment) • Loading Approach May Be a Better Than Concentration Loading Approach May Be a Better Than Concentration Loading Approach May Be a Better Than Concentration Loading Approach May Be a Better Than Concentration • Failure to Consider Site Failure to Consider Site- -specific Data May Yield Inappropriate specific Data May Yield Inappropriate Results Results Results Results

EVALUATI ON OF EVALUATI ON OF COLORADO’S COLORADO’S NUTRI ENT CRI TERI A NUTRI ENT CRI TERI A PROPOSAL PROPOSAL PROPOSAL PROPOSAL

BASI C CONCERNS WI TH BASI C CONCERNS WI TH COLORADO APPROACH COLORADO APPROACH • No demonstrated need for TN control in all No demonstrated need for TN control in all Lakes and Streams Lakes and Streams • Lakes Lakes – – regression approach fails to reflect regression approach fails to reflect multiple factors controlling plant growth multiple factors controlling plant growth u t p e acto s co t o u t p e acto s co t o g p a t g o t g p a t g o t • Streams Streams – – regression approach alone regression approach alone contrary to SAB findings contrary to SAB findings – no cause and contrary to SAB findings contrary to SAB findings no cause and no cause and no cause and effect effect

NO NEED FOR UNI VERSAL NO NEED FOR UNI VERSAL TN CONTROL TN CONTROL When evaluating the relationships among nutrients and algal response When evaluating the relationships among nutrients and algal response within stream systems, it is important to first understand which nutrient is limiting. Once the limiting nutrient is defined, critical nutrient concentrations can be specified and nutrient and algal biomass relationships can be examined to identify potential criteria to avoid nuisance algal levels. EPA. 2000. Nutrient Criteria Technical Guidance Manual – Rivers and Streams, at 74. (Emphasis added) at 74. (Emphasis added) Many natural factors combine to determine rates of plant growth in a waterbody. First of these is whether sufficient phosphorus and nitrogen exist to support plant growth. The absence of one of these nutrients i t t t l t th Th b f f th t i t generally will restrict plant growth. I n inland waters, typically phosphorus is the limiting nutrient of the two, because blue-green algae can “fix” elemental nitrogen from the water as a nutrient source. g EPA. 1999. Protocol for Developing Nutrient TMDLs First Edition at t 2- 4. EPA 841-B-99-007 (Emphasis added)

LAKES LAKES S

SAB CONLCUSI ON RELEVANT TO SAB CONLCUSI ON RELEVANT TO LAKES PROPOSAL LAKES PROPOSAL Plant biomass is driven by nutrient supply rates (i.e., nutrient mass loads). Plant biomass is driven by nutrient supply rates (i.e., nutrient mass loads). Ambient nutrient concentrations are not necessarily good surrogates for Ambient nutrient concentrations are not necessarily good surrogates for nutrient mass loads. Relationships between nutrient mass loads and nutrient mass loads nutrient mass loads Relationships between nutrient mass loads and nutrient mass loads. Relationships between nutrient mass loads and Relationships between nutrient mass loads and ambient nutrient concentrations are highly system ambient nutrient concentrations are highly system- -specific and depend specific and depend on many factors including inflows, hydrology, bathymetry, sediment on many factors including inflows, hydrology, bathymetry, sediment- - water exchanges and chemical water exchanges and chemical- -biological processes. biological processes. Consequently, there Consequently, there may be many systems for which nutrient concentrations will not be may be many systems for which nutrient concentrations will not be may be many systems for which nutrient concentrations will not be may be many systems for which nutrient concentrations will not be appropriate stressor variables appropriate stressor variables . For such systems it may be more For such systems it may be more appropriate, and scientifically defensible, to use site appropriate, and scientifically defensible, to use site- -specific mechanistic specific mechanistic models incorporating loading to determine the nutrient controls required to models incorporating loading to determine the nutrient controls required to attain designated uses (at 11) attain designated uses (at 11) attain designated uses. (at 11) attain designated uses. (at 11)

LAKE CRI TERI A LAKE CRI TERI A LAKE CRI TERI A LAKE CRI TERI A Use Class Use Class TP TP TN TN Chl Chl- -a a Cold Cold Cold Cold 24 ug/L 24 ug/L 24 ug/L 24 ug/L 490 ug/L 490 ug/L 490 ug/L 490 ug/L 8 ug/L 8 ug/L 8 ug/L 8 ug/L Warm Warm 82 ug/L 82 ug/L 960 ug/L 960 ug/L 20 ug/L 20 ug/L • Cold Lakes: Chl Cold Lakes: Chl- -a optimal for most salmonids a optimal for most salmonids • Warm Lakes: Chl Warm Lakes: Chl-a optimal for game fish Warm Lakes: Chl Warm Lakes: Chl a optimal for game fish a optimal for game fish a optimal for game fish • TP/TN: linear regression of cold/warm lakes to TP/TN: linear regression of cold/warm lakes to achieve chl achieve chl-a criterion. achieve chl achieve chl a criterion. a criterion. a criterion.