REVIEW OF PHASE I WATER QUALITY DIAGNOSTIC STUDY OF LAKE AUBURN AND ITS WATERSHED LAKE AUBURN WATERSHED PROTECTION COMMISSION PUBLIC MEETING

Transcription

1 REVIEW OF PHASE I WATER QUALITY DIAGNOSTIC STUDY OF LAKE AUBURN AND ITS WATERSHED LAKE AUBURN WATERSHED PROTECTION COMMISSION PUBLIC MEETING In collaboration with: Comprehensive Environmental, Inc. and Dr. Ken Wagner, Water Resources Services, LLC February 13, 2013

2 Agenda Introduction Dave Jones/John Storer, LAWPC Background and Current Status Jim Pescatore, CDM Smith Phase I Watershed Diagnostics and Recommendations Rebecca Balke, Ben Lundsted and Eileen Pannetier, CEI Phase I Lake Diagnostics and Recommendations Bernadette Kolb, CDM Smith Management Options for Lake Auburn Dr. Ken Wagner, Water Resources Services Questions and Answers Closing

3 AWD/LWD Water Management Philosophy Follows a Multiple Barrier Approach Risk Prevention Watershed management for high quality source water Risk Management Effective water treatment Proper distribution system maintenance Monitoring and Compliance Individual Action

4 History of Meeting Drinking Water Regulations EPA promulgated Safe Drinking Water Act (SDWA) amendment Performed a watershed study Established watershed control program Received an exemption to the filtration requirement Created the Lake Auburn Watershed Protection Commission (LAWPC) Initiated watershed protection measures, such as Septic system surveys Zoning and ordinances Land preservation Forestry management Lake restrictions Watershed surveys Boat inspections

5 History of Meeting Drinking Water Regulationscontinued Met SDWA disinfection requirement for Giardia and viruses by upgrading the chlorination system Performed a study of coliform bacteria and turbidity in Lake Auburn Designed and constructed a 900-ft long intake pipe extension to serve both communities jointly Updated the 1993 coliform bacteria and turbidity study for Lake Auburn and implemented a waterfowl control program

6 History of Meeting Drinking Water Regulationscontinued Performed an SDWA Compliance Study 2007 Completed a ultraviolet light (UV) Concept Design Report Initiated design-build project to construct a UV disinfection facility to meet SDWA requirements for Cryptosporidium

7 History of Meeting Drinking Water Regulationscontinued Completed Comprehensive Watershed Management Plan 2011 Constructed UV treatment facility including raw and finished water pumping Completed Phase II/III chemical, laboratory and admin building Initiated Lake Auburn Water Quality Study

8 Lake Auburn UV Treatment Facility

9 Lake Auburn Water Quality Overview Historically, a clear, high quality drinking water supply with few algae problems Long-term turbidity levels average well below 1 NTU Supported cold water fishery of Togue and salmon Managed by State Department of Inland Fisheries & Wildlife

10 Lake Auburn Water Quality Overview 2011 Water Quality Changes Mid-August 2011, significant bloom of blue-green algae Gloeotrichia, followed by Microcystis and Anabaena Dissolved oxygen decreased below thermocline September through November - lake below 13 meters had minimal oxygen Turbidity levels peak at 4.41 NTU Allowable limit 5 NTU Maine Volunteer Lake Monitoring Program was consulted, winter sampling increased & watershed phosphorus contributions reviewed

11 Lake Auburn Water Quality Overview continued 2012 Water Quality Changes Surface water at above average to record warm temperatures Summer algal blooms of Gloeotrichia and Anabaena By mid-september, dissolved oxygen decreased so that below 9 meters had low/no oxygen In September, a fish kill occurred 200 dead lake trout found a follow-up survey found surviving trout Turbidity levels peak at 3.55 NTU Allowable limit 5 NTU

12 Effect of DO Loss on Coldwater Fishery in Lake Auburn High Oxygen/Warmest Water Thermocline Cooler Water/Moderate Oxygen Coldest Water/Very Low Oxygen By late August, 2012, dissolved oxygen levels had dropped to near zero below this depth. Lake Trout had no refuge in which water temp was cool And oxygen remained at healthy concentrations. *This slide is an excerpt from a presentation by Scott Williams to the Lewiston City Council on October 9, 2012

13 Days Maximum Turbidity Over 1 NTU Raw Water Turbidity Trend

14 Lake Auburn Water Quality Overview continued Status Since September 2012 Sampling program in lake and watershed redefined sampling increased Tried flushing water/algae by releasing water from the lake Algae have continued to cause problems including Floating algal scum in fall Some increases in winter turbidity Some households with filters experienced clogging New Microlab used to WQ staff for speciation of algae

15 Current Study Scope of Work Overview: Phase I Phase I Data Collection Analysis and Findings Diagnostics Short-term Management Actions Schedule Phase I draft report nearly complete Executive Summary posted following the meeting today

16 Current Study Scope of Work Overview: Phase II Phase II Management Options Watershed Actions In-lake Actions Public Participation Grants and Permitting Reports Schedule Draft Phase II Recommended Actions by May 2013 Phase II Completion - by December 2, 2013

17 Lake Auburn Diagnostic Study Results Watershed Findings & Next Steps February 13, 2013

18 Objective & Scope Identify possible drivers of recent water quality degradation Develop water budget Develop nutrient budget Identify pollution sources in watershed Also developed Phase 2 next steps to remedy problem areas

19 1/1/2000 7/1/2000 1/1/2001 7/1/2001 1/1/2002 7/1/2002 1/1/2003 7/1/2003 1/1/2004 7/1/2004 1/1/2005 7/1/2005 1/1/2006 7/1/2006 1/1/2007 7/1/2007 1/1/2008 7/1/2008 1/1/2009 7/1/2009 1/1/2010 7/1/2010 1/1/2011 7/1/2011 1/1/2012 7/1/2012 Lake Elevation (ft) Precip. (inches), TP/10 ug/l Water Budget Significant Precipitation Events Lake Elevation Weir Precipitation

20 Water Budget Findings Increasing precipitation more frequent, higher intensity storms Higher inflows Higher average water levels

21 Nutrient Budget Findings High winter/spring loads

22 Nutrient Budget Findings 13 acres new development since 2006 High winter loads in 2010 & 2011 High spring loads in 2012 The timing of these higher loads may contribute to more abundant 2012 algal blooms

23 Watershed Evaluation 1) Larger, more frequent storms lead to higher runoff velocities and erosion 2) June 2012 storm may have fueled algal blooms 3) Field investigations performed to identify potential source areas

24 Watershed Source Evaluation 1) Surveyed shorelines of Lake Auburn, The Basin, Little Wilson Pond and Mud Pond 2) Sampled sediment deltas at inlets and outlets 3) Reviewed tributary roadway crossings 4) Reviewed roadway drainage between crossings 5) Walked high priority tributaries 6) Identified potential BMP locations for the watershed

25 Field/Source Findings 36 deltas sampled Biggest sediment deltas: Spring Rd & Route 4 corridor (direct discharges from Route 4) Large sediment deposits in Little Wilson Pond/Skillings Corner Brook Highest P/N: The Basin & Lake Auburn at Basin Dam Gravel Pit Wetland and Mud Pond - high P/N

26 Watershed Contributors Area 1. Spring Road Area 2. Holbrook Road Area 3. The Basin Dam Area 4. Lakeshore Drive Area 5. Townsend Brook Area 6. Route 4 Corridor Area 7. Lower Watershed 7

27 Spring Road & Basin Dam Steep slopes and Spring Road drainage The Basin Dam sediment source Sediment deltas Findings & Concerns

28 Holbrook Rd Findings & Concerns Holbrook Rd drainage Evidence of historical erosion and washouts

29 Lakeshore Drive Findings & Concerns Un-treated direct stormwater discharges Spill potential Shoreline and roadway shoulder erosion

30 Townsend Brook Findings & Concerns Large flow contributor Additional phosphorus inputs

31 Route 4 Drainage Large impervious area Busy road increased maintenance needs Un-treated direct discharges Spill potential Findings & Concerns

32 Lower Watershed Area Findings & Concerns Additional phosphorus inputs

33 Next Steps 1. Complete Phase 2 Report Identify short and long-term measures a. Identify regulatory improvements b. Identify monitoring enhancements c. Identify public education needs 2. Develop site specific data for the six key areas to construct controls

34 Lake Auburn Diagnostics: Key Questions What was the source of the high turbidity? What was the driver for increase in area of bottom waters with very low oxygen? What causes phosphorus increase in surface waters? Were differences due to current year drivers or long-term changes? Will this continue? Lake Auburn Diagnostics

35 Lake Auburn Diagnostics: Outline What was measured What we know/determined What we hypothesize What this means What needs to be done now Next steps

36 What was Measured A look at data for the following, with emphasis on changes in 2011 and 2012 Precipitation Water temperature Phosphorus concentrations in surface water Extent of low dissolved oxygen in bottom water Phosphorus concentrations in sediment Secchi depth

37 Annual Precipitation was Average; 2012 Monthly Rainfall was Not Monthly Precipitation Annual Precipitation Lake Auburn Diagnostics: What was measured

38 Temperature ( C) Intake Water Temperature had Near Record Highs Median, J F M A M J J A S O N D Lake Auburn Diagnostics: What was measured

39 Total Phosphorus (μg/l) Surface Water Phosphorus at the Deep Hole Is Increasing Desirable Caveat: Limited data with more scatter at other locations A M J J A S O N D Lake Auburn Diagnostics: What was measured

40 Low DO in Bottom Waters Extensive Does Not Occur: 2000, , Area of bottom where dissolved oxygen < 2 mg/l results in: Release phosphorus from sediments into water No habitat for fish and other aquatic life Lake Auburn Diagnostics: What was measured

41 2012 Sediment Samples 10-m depth Below 10-meters depth, sufficient iron-bound phosphorus in sediment to: Move into water column under low oxygen conditions, and Then support algal blooms Lake Auburn Diagnostics: What was measured

42 Secchi Depth (m) Secchi Depth: include Shallowest Measurements on Record 0 2 Range of Measurements Average A M J J A S O N D Lake Auburn Diagnostics: What was measured

43 What We Know or Determined About the watershed Land use is little changed More intense storms increasing Delivers more pollutants than average intensity storm Stratification can be disrupted Sediment deltas appear recently increased About algae Gloeotrichia first measured in Lake Auburn in 2006 Can bring phosphorus from bottom to enrich surface water Turbidity related to late summer-fall algal bloom Apparent shift to blue-greens problematic Control buoyancy, reduce transparency and cause taste and odor Lake Auburn Diagnostics: What we know or determined

44 Algal Concentration (colonies/l) Raw Water Turbidity (NTU) Relationship between Algae and Turbidity , ,000 60,000 50,000 40,000 30,000 Gloeotrichia presence Maximum Turbidity Hurricane Irene Peak Total Algae Total Blue-Green Microcystis Anabaena , , Jun-11 Jul-11 Aug-11 Sep-11 Oct-11 Nov-11 0 Algal data from Drs. Ewing, Weathers, and Cottingham under NSF grants NSF DEB NSF EF m NSF EF , NSF EF Lake Auburn Diagnostics: What we know or determined

45 What We Hypothesize Several sources for increased phosphorus in surface water: Inputs from watershed Higher phosphorus released from sediment migrating to surface water, requires Low dissolved oxygen in bottom Source of sediment phosphorus Mechanism to migrate phosphorus past thermocline Brought with Gloeotrichia rising from the sediments Other algae migrate to deep waters with higher phosphorus to feed Lake Auburn Diagnostics: What We Hypothesize

46 Typical Clean Lake Phosphorus-Algal Cycle Add More Phosphorus Discharge out of Lake Watershed Phosphorus Load Phosphorus in Surface Water Phosphorus in Bottom Water Phosphorus Released from Sediments Large Algal Algal Blooms Blooms Algae Low Oxygen Settle to in Bottom Lake Bottom Water Lake Auburn Diagnostics: What We Hypothesize Deep Burial

47 Lake Auburn Mid- to late Summer Gloeotrichia Bloom Late Summer/Fall Algal Bloom High Turbidity Watershed Phosphorus Load Phosphorus in Surface Water Phosphorus in Bottom Water Phosphorus released from Sediment when no DO Low DO in Bottom Water Some Lake Trout Died Storms cause mixing Lake Auburn Diagnostics: What We Hypothesize June 3 Storm Watershed Organic Load Temperatures Near Record 2012

48 What We Hypothesize: Findings Several sources for apparent increased phosphorus in surface water: Watershed loads alone do not fully explain the increase Sediment phosphorus can explain the increase Gloeotrichia can explain the increase but limited data suggest it is coincident and not causative Other blue-green algae do not appear to explain increase Lake Auburn Diagnostics: What We Hypothesize

49 What This Means Available data suggest that the lake is responding to both Forcing factors in current year (storm loads) Apparent trends in increased phosphorus Data insufficient to determine which is more significant Ultimately, it all starts in the watershed Poor water quality in lake could recur, but not certain Management measures will need to be implemented in both The watershed The lake Lake Auburn Diagnostics

50 What Needs to be Done Now Implement revised monitoring program in lake and key tributaries Continue discussions with Maine DEP about permitted use of algicide as a contingency measure if algal blooms are large and turbidity rises Make recommendations on in-lake management options Lake Auburn Diagnostics

51 Possible In-lake Management Options Algal Control by Algicides Dredging Aeration/Oxygenation Phosphorus Inactivation

52 Algal Control by Algicides Blue-greens Diatoms Goldens Copper-based compounds are by far the most widely applied algicides Peroxides gaining popularity Used before bloom fully forms Requires weekly algal monitoring Minimal risk to nontarget organisms at normal New England doses

53 Algal Concentration Phases of Algal Growth Normal Senescence/ Death Phase Cycle may be Interrupted by Treatment with Algaecide Lag Phase Time (Hours or Days)

54 Algal Control by Dredging

55 Algal Control by Oxygenation/Circulation Methods to Oxygenate or Circulate a Lake

56 Oxygenation with Pure Oxygen Diffusion Combines simplicity of diffuser system with high efficiency oxygen transfer Before (left) vs. after (right)

57 Algal Control by Phosphorus Inactivation Phosphorus inactivation: anti-fertilizer treatments Aluminum compounds most often applied to lake to Strip P from water column Bind P in surficial sediments

58 Summary The following initial actions for 2013 are recommended Implement a revised more intensive monitoring program in both the lake and watershed Prepare for possible algicide application Permits Equipment and chemicals Track algae growth and decide on the need to apply an algicide and the timing

59 Summary The ongoing Phase II study will provide recommended longterm holistic watershed and lake management measures including: Structural and Management Controls for high phosphorous areas Changes to watershed monitoring programs and regulations In-lake management measures to control phosphorous The recommended actions are intended to help improve the water quality in Lake Auburn The benefits will be Safe drinking water that is affordable A robust cold water fishery