August 19, 2009
Agenda Aquatic Life Use Refinement Nutrient Criteria – Rivers and Streams Nutrient Criteria – Lakes and Reservoirs Nutrient Criteria – Direct Use Water Supply Res CMA issues
Recap – rivers and streams Refined Aquatic Life Uses (and Nutrient Criteria for Rivers and Streams) depend on bioassessment tools and biocriteria Bioassessment tools methods of quantifying the biological condition of an aquatic community Biocriteria Describe the biological condition that must be present to support the use Serve as the threshold against which assessment results are compared
Bioassessment Tools How to describe the condition of the elephant height weight temperature blood pressure
Bioassesment Tools A method of quantifying the biological condition of an aquatic community
Multi-Metric Bioassessment Tool Statistical analysis of stressed and reference sites Select metrics that discriminate well between the good and bad sites MMI Macroinvertebrates Recalibration complete (see website for report)
Biocriteria Setting thresholds Are any of these elephants “ impaired ” ?
Longterm view… Embarking on new territory Incremental Progress Refinement in the years to come
The thresholds we are about to discuss are the Division’s preliminary thresholds. We are still in the process of checking our math and making sure the logic and concepts are sound. The thresholds will change.
August 19, 2009
Topics Terminology WQCC Policy 2010-1 Tool Limitations Determining MMI Score Threshold Development Decision Framework Approach Next Steps
Terminology Reference and Stressed The ID of reference and stressed was a scientific exercise using anthropogenic influences. Attained and Impaired The ID of attained and impaired is a regulatory exercise based on direct measurement of aquatic community. Biotype Refers to the conceptual biological groupings defined by cluster analysis. Class Refers to Aquatic Life Use Classifications Cold and Warm I and II.
WQCC Policy 2010-1 Division will not propose revisions to the aquatic life use classification descriptions in the Basic Stds. The Division’s proposal will be made in WQCC Policy 2010- 1 titled “ Aquatic Life Use Attainment, Methodology to Determine Use Attainment for Wadeable Rivers and Streams”. This document will: Provide a description of methodology Record the WQCC’s policy decisions for MMI thresholds for use attainment
Tool Limitations The Division is defining “wadeable streams” as streams with a natural drainage less than 7,000 km 2 or 2,700 mi 2 . The limit on stream size is driven by practical concerns related to: Sampling methodology Data treatments in MMI development (“limitations of the model”) Examples: South Platte River at Waterton = 2,621 mi 2 Arkansas River at Canon City = 3,117 mi 2
Tool Limitations cont. The MMI tool was calibrated and validated with data treatments for consistency in analysis. Therefore, not all samples will match this data treatment. Tool Usage Criteria: Drainage area must be less than 7,000 km 2 or 2,700 mi 2 Sample must include 150 or more total individuals 1 Sample must include 10 or more taxa 1 1 Target sub-sample size is 300 individuals.
Determining MMI Score “Ingredients to Determine MMI Score” Metrics Germane to Hi Primary or Lo Index Biotype High or Low MMI Score Elevation (0-100) MMI
Initial Threshold Development Thresholds for each biotype developed based upon the reference dataset distribution of MMI scores.
Step 1 Example – Biotype 2 (Reference Sites): 25 th percentile=66, IQR=14.4 Midpoint = 66 – 1.5 x 14.4 Midpoint = 66 – 21.6 = 44.4 or 44 Inter-Quartile Range 25 th Percentile
Step 1 Illustrated Midpoint=44
Step 2 Upper Bound (+6) Midpoint=44 Yellow Zone Lower Bound (-6)
Initial Thresholds Initial Thresholds for Aquatic Life Use Classification Threshold MMI score MMI Colorado Biotype (MMI Group) Index Impaired Attainment High Mountains High elevation, steeper High <38 >50 (biotype 2) slopes, moist Mountains Mid-elevation, flatter slopes, High <34 >46 (biotype 1) moderate precipitation Mountain Edges Mid-elevation, steeper High <26 >38 (biotype 3) slopes, drier Transition Low elevation, flatter slopes, Low <22 >34 (biotype 4) drier Plains and Xeric Low elevation, flatter slopes, Low <16 >28 (biotype 5) drier
Decision Framework Approach The distinction between Class 1 and Class 2 relies on the phrase “a wide variety of warm/cold biota including sensitive species”. The Division proposes using a decision framework approach that relies upon auxiliary metrics that measure diversity and sensitivity.
Example of Class 1 Water Attainment Threshold 50 38 Impairment Threshold
Example of Class 1 Water MMI Score of 46.5 Attainment Threshold 50 • 38 Impairment Threshold
Example of Class 2 Water 38 Impairment Threshold
Example of Class 2 Water MMI Score of 46.5 • 38 • Impairment Threshold MMI Score of 20.0
Next Steps The Division is still investigating auxiliary metrics and their potential thresholds. The Division is still examining the issue of secondary biotype membership and will be assessing its implications for threshold development. The Division will start exploring other options for streams/rivers that don’t meet the Tool Usage Criteria.
Questions?
R IVERS AND S TREAMS N UTRIENT C RITERIA U PDATE Sabin Room--CDPHE 1:30pm--August 19, 2009
B ACKGROUND 2001 304(a) Criteria Colorado’s use -based approach to numeric nutrient criteria for rivers and streams Recreation — 150 mg/m 2 Chl a (attached) Based on recreational user surveys ( http://www.umt.edu/watershedclinic/algaesurveypix.htm ) Aquatic Life — numeric values to be determined Based on Colorado’s Multimetric Index (MMI) thresholds and Total Phosphorus/Total Nitrogen
C OLORADO ’ S A QUATIC L IFE U SE L INKAGE MMI Scores Nutrient (ug/L)
T ABLE V ALUE S TANDARDS Nutrient criteria will be adopted into the Basic Standards (Reg. 31) via numeric table value standards (TVS) Nutrient Criteria for Rivers and Streams Total Total Phosphorus Nitrogen (ug/L) (ug/L) Cold water biota AA BB Warm water biota CC DD
R IVERS AND S TREAMS 304(a) C RITERIA Summary of the 2001 304a Nutrient Criteria for Rivers and Streams by Subecoregion That Would be Applicable to Colorado EPA Portion Total Total Chlorophyll a Turbidity Ecoregion of Phosphorus Nitrogen (ug/L) (FTU) Designation Colorado (ug/L) (ug/L) Xeric westslope, 21.87 368 1.78 4.2 Wyo Basin Plateau north (III.18) Xeric westslope, 20 553 1.78 2.79 Colo Plateau west (III.20) Xeric westslope, 15 228 1.78 5.13 Az/NM Plateau south (III.22) Mountains central 6.34 90 1.08 0.8 So Rockies mountains (II.21) So Great Plains eastern plains, 90 840 2.5 9.01 W High Plains northeast (V.25) Great Plains eastern plains, 25 450 3.4 4.96 SW Tablelands southeast (IV.26)
C URRENT N UTRIENT DATABASE + 51,000 total phosphorus records +35,000 total nitrogen records 911 MMI Scores (Colorado EDAS) Includes data from Storet NWIS Riverwatch 23 other 3 rd party sources
I NITIAL R ESULTS Total Phosphorus 100 90 80 70 MMI Score 60 50 40 30 20 10 0 0.01 0.1 1 10 TP (mg/L)
I NITIAL R ESULTS Total Nitrogen 100 90 80 70 MMI Score 60 50 40 30 20 10 0 0.02 0.2 2 TN (mg/L)
M OVING T OWARDS N UMERIC C RITERIA Explore various statistical methods to define the linkage between biological thresholds (MMI) and nutrient concentrations in order to develop numeric nutrient TVS LOWESS Change-point analysis Break-point analysis Quantile regression Conditional probability http://n-steps.tetratech-ffx.com/statisticalTool-method.cfm
LOWESS E XAMPLE (f = 0.8)
Total Phosphorus 100 90 80 70 MMI Score 60 50 40 30 20 10 0 0.01 0.1 1 TP (mg/L)
A TTAINMENT T HRESHOLD E XAMPLE
N EXT S TEPS Data Complete nutrient database Pair remaining EDAS MMI sites and nutrient data Process 3 rd party macroinvertebrate data Table Value Development Explore methods for use in defining linkage between biological community and nutrients Develop thresholds for nutrient concentrations Propose numeric nutrient table values
Q UESTIONS AND C OMMENTS Blake W. Beyea blake.beyea@state.co.us 303.692.3656
B REAK
WQ Impacts of High Chlorophyll Transparency pH DO demand Cyano-toxins DBPs Fish species
Chlorophyll and Transparency Transparency high 0 1 only at low 2 chlorophyll Secchi Depth, m 3 Transparency also 4 may be reduced by 5 6 factors other than 7 chlorophyll Warm Lakes 8 9 1 10 100 1000 Chlorophyll, ug/L
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