Jordan River TMDL Update

Transcription

1 Jordan River TMDL Update 2010 Watershed Symposium August 4 th, 2010 Hilary N. Arens Utah Division of Water Quality

2 Jordan River TMDL Outline What is a TMDL and what is the Jordan impaired for? Evaluation of existing information Pollutant sources and loading Permissible Loads and Needed Reductions Load Allocation Scenarios Next Steps

3 What is a TMDL? If a waterbody (stream, lake, reservoir, etc.) fails to meet water quality standards, the state places the waterbody on the 303(d) list of impaired waters. State must then prepare a plan to restore water quality called a Total Maximum Daily Load study (TMDL). The Clean Water Act requires this study to determine how much a pollutant of concern has to be reduced to meet water quality standards and support an impaired waters designated beneficial uses.

4 Jordan River TMDL A TMDL establishes the maximum amount of a pollutant allowed in the water while supporting all of its designated beneficial uses. A TMDL is the sum of nonpoint sources (NPS), point sources (PS), and a margin of safety, that support water quality standards. TMDL = LA + WLA + MOS LA - Load Allocations from Non-Point Sources WLA - Waste Load Allocations from Point Sources MOS - Margin of Safety

5 Jordan River Beneficial Use Classes Class 2B: Protected for secondary contact recreation such as boating, wading, or similar uses. Class 3A: Protected for cold water species of game fish and other cold water aquatic life, including the necessary aquatic organisms in their food chain. Class 3B: Protected for warm water species of game fish and other warm water aquatic life, including the necessary aquatic organisms in their food chain. Class 4: Protected for agricultural uses including irrigation of crops and stock watering.

6 Utah Water Quality Standards and Pollutant Indicator Values Pollutant or Indicator Allowable or Recommended Limit Dissolved Oxygen (DO) (1) Total Dissolved Solids (TDS) (1) Temperature (1) Biochemical Oxygen Demand (BOD) (2) 30-day average 5.5 mg/l Aug-Apr instantaneous 4.0 mg/l May-July instantaneous 4.5 mg/l 1,200 mg/l for irrigation 2,000 mg/l for livestock 20 C for cold water fishery 27 C for warm water fishery 5 mg/l Total Suspended Solids (TSS) (2) 90 mg/l Total Phosphorus (2) 0.05 mg/l (1) Utah state water quality standard (2) Not a water quality standard but an indicator of water quality

7 Jordan River Segments and Water Quality Impairments

8 Evaluation of Existing Information Water quality and flow data available for use in the study EPA-STORET Data Warehouse: USGS-National Water Information Server: Wastewater Treatment Plants (DMR data, additional monitoring) Salt Lake City (municipal watersheds) Division of Water Rights (diversions) Salt Lake County (gaged tributaries and stormwater monitoring) Four basic types of data (routine, continuous, synoptic, diurnal) Data archived in MS Access database (currently more than 500,000 records of water quality and flow).

9 Significant Pollutant Sources Tributary Streams and Utah Lake Some streams not significant due to limited flow and diversions. Permitted discharges Central Valley WRF, South Valley WRF, South Davis WWTP. Storm water Storm water catchments from Salt Lake and Utah counties, none located in Davis County. Direct surface runoff Areas outside of storm water catchments that drain directly to Jordan River. Groundwater Flow based on USGS Salt Lake Valley model Considered all wells within 2 miles of Jordan River.

10 Pollutant Loads Pollutant loads were calculated using average monthly flows and water quality values. Water quality stations selected based on proximity to flow gages and length and frequency of the data record.

11 Updated Existing Loads Rationale Ensure that TMDL is based on most current data Include recent measurements of BOD and Total P Incorporate minor corrections Purged suspect data Results Minor changes in total loads Increased NH 4 -N in mainstem Significantly higher BOD 5 at CVWRF Increased TSS in small tributaries All data used in permitted discharge loads provided by facilities

12 Previous Distribution of Annual Pollutant Loads to Jordan River

13 Updated: Distribution of Annual Pollutant Loads to Jordan River

14 Percent Change in Average Annual Load due to Update

15 Future Loads Percent Change in Total Pollutant Loadings by 2030 Pollutant TDS TSS BOD NH4 TP DWQ Segment % 0% -2% 12% 11% -3% -5% 2% 104% 5% 7% 32% 39% 71% 407% 0% 62% 4% 14% 59% 24% 320% 290% 1% 58% 5% 14% 36% 24% 2067% 43% 0% 58% 16% 10% 35% 18% 1364% 6% 1% TOTAL 3% 15% 56% 76% 59% Increases from existing loads Calculate the total reduction required for any new point source or non-point source load that is anticipated within the planning horizon For example, the Jordan Basin WWTP in Riverton under construction.

16 TMDL Compliance Points Monitoring locations where permissible loads are measured. Considerations: Location with respect to impaired segments Data history Group segments of similar impairment Monitoring points above impairment

17 Determine Permissible Loads and Necessary Reductions Identify Critical Conditions Establish Endpoints Assign Permissible Loads Definitions Temperature TDS DO

18 Definition: Critical Condition Combination of environmental factors (e.g., flow, temperature, etc.) that represent the worst case scenario Low flow (7Q10) Time period (seasonal, daily) Continuous simulation using models

19 Definition: Endpoints A measured value that represents a desired environmental condition. Hickey (2002) enforceable by law, indicative of ambient water quality, of ecological or anthropogenic significance, measurable in the field, predictable using a water quality model, of stakeholder concern.

20 Definition: Permissible Load The greatest amount of pollutant loading a water can receive without violating water quality standards

21 Percent Exceedance (%) Temperature ( C) Temp: Critical Conditions Percent Temperature Exceedance of 20 C Standard and Average Monthly Temperatures Upper Jordan River ( ) 100% 25 80% 20 60% 15 40% 10 20% 5 0% Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 0 Seg South Seg South Seg 7 - Bluffdale Rd Seg 7 - Narrows Seg S Temp Seg S Temp Seg 7 - Bluffdale Temp Seg 7 - Narrows Temp

22 Temp: Endpoints Average and maximum water temperatures at the Narrows and within Segments 5-7 modeled (QUAL2Kw) under different shading scenarios for August. Maximum Temp ( C) Average Temp ( C) At Segment At Segment Description Narrows Narrows Baseline: August % shading Segment 8, 60% shading Segments Practical alternative: 33% shading Segments 5-8, decrease SVWRF to 20 C Practical alternative in July

23 Temp: Endpoints Only three significant sources of thermal loading in the upper Jordan River (two can be modified.) Solar radiation = largest thermal load, (reduce by increasing shading) Natural hot spring: Temps from well = ~72 ºC SVWRF = anthropogenic thermal source Discharge average 21.8 C in July and 22.3 C in August.

24 Temp: Permissible Load Even under very aggressive alternative, would not reach water quality standard. Permissible loads not calculated for temperature Unlikely that any reasonable strategy could achieve the State water quality standard. Assess the status of the aquatic biota and composition that could be achieved by reasonable efforts to limit high water temperatures. Yield a site specific criteria or a new subclass of beneficial use.

25 TDS: Critical Conditions Conservative substance Impairments listed in 4 segments Weak overall seasonal effect Seasonal pattern varies geographically Linked to Utah Lake

26 TDS: Utah Lake Critical Low levels in Utah Lake Condition Low precipitation, lake management 42% evaporation loss concentrates TDS Pumping for downstream water rights increases TDS concentration to Jordan River

27 Endpoint: TDS

28 TDS: Site Specific Criteria Effect of Endpoints and Permissible Loads Segment Segment 8 Segment 7 Compliance Point Narrows Bluffdale Road Significant TDS Sources (tons/yr) Utah Lake (627,980) Groundwater (7,645) Segment 8 (503,400) Groundwater (36,360) Segment 7 (180,854) Endpoint Site Specific Criterion: 1,300 mg/l Site Specific Criterion: 1,300 mg/l Sum of Monthly Exceedances of Endpoint (tons/yr) N/A (< 10% exceedances) N/A (< 10% exceedances) Segment 6 Segment 5 Segment South 5400 South 2100 South Groundwater (157,128) Irrigation Return Flow (14,197) Segment 6 (364,739) Site Specific Criterion: 1,300 mg/l 13,429 Site Specific SVWRF (39,915) Criterion: 143 Groundwater 1,300 mg/l (16,223) Not impaired: Only 4% of measurements last 5 years exceed 1,200 mg/l.

29 TDS: Permissible Loads

30 DO: Critical Conditions DO most critical in August, but varies significantly year to year. DO result of many interacting processes. DO exceedances may be linked to low levels of Utah Lake (concentrated detritus and algae). Use QUAL2Kw to explore reaction to changing pollutant loads at 2100 South.

31 DO: Endpoint Reducing nutrients alone at 2100 South does not resolve DO impairment. Significant reduction in organic matter can resolve DO impairment. Nutrients upstream may still contribute to organic matter at 2100 South.

32 QUAL2Kw Tool for Understanding Complex Chemical, Physical and Biological Interactions

33 Critical Pollutant Affecting DO Average DO (mg/l) Minimum DO (mg/l) Scenario Cudahy Lane Burnham Dam Cudahy Lane Burnham Dam August 2009 Synoptic Period Baseline TP = TP = 50% TP = 0.05 mg/l TP = 0.05 mg/l and NO3-N = 4 mg/l NO 3 = 4 mg/l NH 4 -N (only) = 0.08 mg/l Pollution Indicator Condition w/ NH 4 Limit ScBOD = 50% Eliminate Prescribed SOD Meet WQ Standard (min DO > 4 mg/l and mean DO > 5.5 mg/l) with Prescribed SOD and Detritus at 70% 12. Meet WQ Standard with all components of TSS and prescribed SOD at 75% baseline Meet WQ Standard + 2 mg/l with all components of TSS and prescribed SOD at 25% baseline (to protect diurnal swings)

34 DO: Permissible Loads Reducing TSS is one way to improve DO in the lower Jordan River. The mechanisms are two-fold: Reduce Organic Matter (OM): Reduces the DO demand from bacterial decomposition in both the water column and bottom sediment Reduce light attenuation: Allows benthic algae to produce DO during photosynthesis

35 Organic Matter Insoluble OM (or VSS) represented as detritus and chlorophyll-a

36 3 Load Allocation Scenarios Maximum allowable pollutant load accounts for both existing and future pollutant loads. 1. Proportional Allocation: Pollutant sources contribution of OM entering the lower Jordan River. Contribution of pollutant sources upstream of 2100 South Reduction distributed between pollutant sources based on their percent contribution to the Jordan River below 2100 South after losses have been accounted 2. Least Cost Allocation: Least expensive method for achieving load reductions that meet the permissible load. Costs for implementing BMPs and BATs to determine the cost per kg reduction for each source. 3. Most Practicable Allocation: Considers the constraints imposed by existing political and social settings or future trends that may influence implementing water quality improvements.

37 Existing Loads and Load Reductions 1. VSS Pollutant Loads at the Source 2. Residual VSS Source Loads Downstream of 2100 South 3. VSS Load Reductions Downstream of 2100 South 4. Proportional Load Allocation 5. VSS Load Reductions at the Source

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39 VSS Loads From Different Sources * Tributaries contribute 53 percent of the VSS load to the lower Jordan River under existing conditions, while WWTPs contribute 19 percent of the load.

40 Next Steps Revise and update QUAL2Kw model based on Chapra review Inform permitted community of TMDL and load reduction scenarios Define elements of phased approach to TMDL development First phase submitted to EPA April 2011

41 Thank you! Hilary N. Arens