# Presentation: 053786

## TMDL of Nutrients for Lake Nockamixon, PA

- Public Meeting
- January 30, 2003
- Conshohocken, PA

## Objectives

- General overview of TMDL program
- Present TMDL analysis for Lake Nockamixon
- Receive feedback

## Presentation Format

- Introduction & General TMDL Program – Pennsylvania DEP
- TMDL Analysis and Results – Tetra Tech
- Describe problem
- Outline technical approach
- Describe results and TMDL allocations
- Q & A

## What is a TMDL?

- A Total Maximum Daily Load (TMDL) is the amount of pollutant loading that a waterbody can assimilate and meet our water quality standards.

- The TMDL process is a planning tool to help states develop pollution reduction goals that will improve impaired waters to meet water quality standards.

## The Watershed Management Cycle

- A stream/watershed assessment
- Waterbodies that are impaired are put on the 303(d) list.
- TMDL Scheduled.
- The TMDL is completed to address the impairments.
- Implementations are developed.
- Remediation activities
- The watershed will be re-surveyed.

## Legal Background

- Section 303(d) of the Federal Clean Water Act
- States must identify, list and prioritize all waters where technology-based treatment requirements will not attain and/or maintain applicable water quality standards.
- Total Maximum Daily Loads (TMDLs) must be established for these waters to ensure attainment of water quality standards.

## DEP Plan of Action

- Assess all unassessed streams within 10 years
- Assess 100 significant lakes within 10 years
- Establish TMDLs for the 1996 303(d) listed waters (575 segments) – in 10 years for Non-AMD; 12 years for AMD
- Also, prepare TMDLs for newly listed waters (403 in 1998)

## The Assessment Process

- One of Pennsylvania’s objectives is to assess every stream in the Commonwealth.
- Unassessed Waters biological surveys
- Macro-invertebrates
- Habitat and the watershed landscape
- Chemical analysis

## Unassessed Waters Action Summary through Year 2002

| Pennsylvania Total Miles of Streams: | 83,161 miles |
| --- | --- |
| Assessed: | 52,889 miles
(63.6%) |
| Supporting uses: | 44,504 miles |
| Impaired: | 8,385 miles |

## Current Categories for TMDL Development in PA

- Non-Point Source Impairment
- Lakes
- Point Source Impairments
- Fish Consumption Advisories
- Acid Mine Drainage

## TMDL Development Procedure

- 1.  Model selection
- 2.  Source loading analysis
- 3.  In-stream analysis
- 4.  Model testing
- 5.  Source response evaluation (optional)

**TMDL Development Procedure**

**TMDL**
**Submittal**
**Components**

**I.  Problem Understanding**
- 1. Waterbody characterization
- 2.  Water quality standards & target limit
- 3.  Impairment analysis
- 4.  Source Assessment

- 1.  Problem Understanding
- 2.  Water Quality Standards / Targets
- 3.	Source Assessment

- 4	Loading Capacity/TMDL
- 5.  	WLA
- 6.  	LA
- 7.  	MOS
- 8.  	Seasonality

- 3.	Summary of Technical Approach

**III.  Allocation Analysis**

**IV.  Monitoring & Implementation**
- 1.	Monitoring plan
- 2. 	Implementation plan addressing reasonable assurance

**V.  Public Review and Comment**
- 1.  Public notice
- 2.  Post draft TMDL (via web and hard copy by request)
- 3.  Public meeting (optional)
- 4.  Response to comments

- 9.	Monitoring
- 10.	Implementation

**VI.  Submittal to EPA**

- 12.	Submittal Letter

- 11.	Public Participation

- Delist if
- demon-strated

## Problem Understanding

- Lake Location: Bucks County, PA
- Watershed encompasses about 46,700 acres in Bucks County
- Major land uses
- Forest – 63%
- Agricultural/Hay/Pasture – 25%
- Lake
- Surface Area – 1450 acres
- Storage Volume – 39,900 acre feet

## Slide 13

## Problem Understanding

- Point Sources
- 16 NPDES permits in watershed
- 4 facilities have not yet been constructed
- 1 facility closed

## Problem Understanding

- 303(d) listing
- Listing Basis – Lake classified as hypereutrophic  from Clean Lakes Project (Phase I & II) and Trophic Status Index studies by Pennsylvania DEP

## Problem Understanding

- Eutrophication – Process of gradual accumulation of sediment and nutrients that causes high algal production and decreased water quality such as:
- Decreased clarity, aesthetic displeasure
- Low dissolved oxygen and aquatic life impacts
- Decreased recreational opportunities
- Foul odors, taste problems
- Ecosystem alterations

## Problem Understanding

- Trophic States
- Oligotrophic- good clarity and water quality
- Mesotrophic- moderate clarity and water quality
- Eutrophic- poorer clarity and water quality
- Hypereutrophic- floating algae, very poor clarity and water quality, fish kills
- Chlorophyll-a used as indicator of trophic state

## Problem Understanding

- Designated Uses: warm water fishes, potable water supply, industrial water supply, livestock water supply, wildlife water supply, irrigation, boating, fishing, water contact sports, and aesthetics, designated trout fishery
- Water Quality Standards – No numeric water quality criteria for nutrients, only general narrative criteria
- Water Quality Target – Achieve meso-eutrophic status based on achieving in-lake chlorophyll-a concentrations of 10 ug/l
- Chlorophyll-a is easy to measure, is a valuable surrogate for algal biomass, and is desirable as a water quality target because algae are either the direct (nuisance algal blooms) or indirect (high/low dissolved oxygen, pH, and high turbidity) cause of most problems related to excessive nutrient enrichment (US EPA, 1999(a)).

## Problem Understanding

- Impairment confirmation –
- Bucks County Conservation District water quality reports (1996 – 2000) confirm continued elevated chlorophyll-a and eutrophic status
- Pennsylvania DEP Trophic Status Index studies (1999 – 2001) confirm elevated chlorophyll-a levels and eutrophic status
- Phosphorus limited

## Technical Approach

- Consider phosphorus loading processes from precipitation driven, overland sources
- Account for point source phosphorus loadings and other sources such as groundwater, septic systems, and stream bank areas
- Consider nutrient dynamics such as nutrient limitation, partitioning, and sedimentation
-  Diverse land uses in moderate size watershed

## Technical Approach

- Linked watershed/in-lake water quality model
- Watershed model - ArcView Generalized Watershed Loading Function (AVGWLF)
- Developed by Penn State specifically for Pennsylvania
- Simulates runoff and nutrient loadings from watershed of variable size and land uses, considers septic systems and groundwater, and incorporates point sources
- Driven by climatological data such as daily rainfall and temperature
- Has been used for EPA approved TMDLs throughout Pennsylvania including TMDLs of Nutrients and sediment for Conewago Creek, Conodoguinet Creek, Quittapahilla Creek, and North Branch Mahantango Creek.

## Technical Approach

- In-lake water quality model – BATHTUB
- Developed by U.S. Army Corps of Engineers
- Incorporates nutrient loadings from tributaries, direct point sources, and nonpoint sources
- Considers nutrient limitation, nutrient partitioning, nutrient cycling, and nutrient sedimentation kinetics
- Capable of predicting in-lake, nutrient water quality responses to various nutrient loading scenarios
- Has been used for EPA approved TMDLs in West Virginia including TMDLs of phosphorus and sediment in Bear Lake, WV and Ridenour Lake, WV

## Technical Approach	

- Watershed and in-lake water quality models calibrated and validated to observed data
- Linked watershed/water quality model used to perform source loading analysis and determine in-lake water quality response
- Used to calculate total allowable load of phosphorus to lake that ensures a seasonal chlorophyll-a average of 10ug/l

## Technical Approach

- Reductions of phosphorus loading will help:
- Reduce chlorophyll-a concentrations
- Improve trophic status
- Lead to improved water quality
- Lead to improved water clarity, aesthetics
- Decrease likelihood of algal blooms and macrophyte growth

## Allocation Analysis

- TMDL = WLA + LA + MOS
- WLA = wasteload allocations
- LA = load allocations
- MOS = margin of safety

## Allocation Analysis

- Point sources - all point sources already meeting 0.5 mg/l concentration for phosphorus discharge
- Nonpoint sources -  diverse land uses
- Forest – represent natural background
- Groundwater – difficult, if not impossible to control
- Urban/Unpaved roads/transitional – less than 3.5% of total phosphorus load to lake
- Agriculture/hay & pasture/streambank – focus of allocation analysis

## Allocation Analysis

- Equal Marginal Percent Reduction (EMPR)
- Baseline analysis – each discharge is evaluated independently against water quality target
- Multiple discharge analysis – cumulative impact of all discharges is evaluated against water quality target

## Allocation Analysis (lbs/month)

## Allocation Analysis (lbs/month)

## Allocation Analysis

## Allocation Analysis

## Allocation Analysis

## The data and all supporting information used to develop the proposed TMDL are available from the Department.  To request a copy of the proposed TMDL and an information sheet, contact:Jennifer Fields, P.E., Section Chief, Permits SectionPennsylvania Department of Environmental ProtectionSoutheast Regional OfficeLee Park Suite 555 North LaneConshohocken, PA 19428    phone: (610)-832-6094email: jefields@state.pa.usWritten comments will be accepted at the above addresses and must be postmarked by February 12, 2003.  The TMDLs can also be viewed and printed on this Website:http://www.dep.state.pa.us/watermanagement_apps/tmdl/