lake independence phosphorus tmdl critique stephanie koerner & zach tauer bbe 4535 fall 2011

Lake Independence Phosphorus TMDL Critique

Stephanie Koerner & Zach Tauer

BBE 4535 Fall 2011

Watershed Description

Pioneer-Sarah Creek Watershed

851 – acre lake / 7631 – acre watershed

North Central Hardwood Forest ecoregion

Deep lake – max depth: 58ft

15 miles West of Minneapolis

Uses: Recreation

Aesthetic viewing

Contains portion to Municipalities Medina

Independence

Loretto

Watershed Shoreline

Receives 7,631 acres of runoff

Uses of shoreline: Agriculture

Commercial

Park and Recreation

Residential

298 animal units are on the shoreline, mostly of Horses on Single Family Property.

History of Watershed

Prior to 1850 the surroundings were predominantly Forests and Wetlands.

July 4, 1854 settlers found the lake giving it’s name Lake Independence for the day it was found.

Area slowly developed with lakeshore homes and agriculture

Drainage systems were then put in place which drastically changed the hydrologic system

Recently seasonal lake homes on the lake were converted to year round homes

Water Quality

Monitored biweekly from 1990 except in 1992

Phosphorus and chlorophyll data show no significant trends of improving or declining since 1990 but Secchi disk data showed a reduction in clarity.

Water Quality – Aquatic Vegetation

Curlyleaf pondweed and Eurasian watermilfoil cause water clarity and recreational problems from the lake.

Curlyleaf pondweed grows under ice and forms dense growth by late spring and dies in mid July causing increase in nutrients.

303(d) Listing

Total phosphorus concentration exceeded 40ppb 11 of 12 years from 1990 to 2003. Calculated from a minimum of 9 samples a year

Placed on 303(d) list as impaired waterbody for its recreational uses in 2002.

Modeling

MINLEAP, BATHTUB and Canfield and Bachman models were. MINLEAP quantified the feasibility of the target goal

Canfield and Bachman estimated TP reduction to achieve target

BATHTUB estimated nutrient flows from subwatersheds

Canfield and Bachman was used based on field monitoring and computer model which resulted in 2,381 lbs/yr assuming normal precipitation.

Model predicted reduction of 1300 lbs/yr to reach 36ppb.

MINLEAP

Calculated with “typical” nutrient inflows to unimpaired lakes in central Minnesota

Target concentration is likely attainable.

BATHTUB with GIS

GIS for Livestock Contribution

Bachman and Canfield

Sources of phosphorus

TMDL

TMDL = WLA + LA + MOS

TMDL Continued

Seasonal Variability

MOS – 35 lbs/yr was incorporated into TMDL for rainfall Variability

Final Phosphorus TMDL

Non-degradation Policy Future land development requires to meet strict guidelines

to protect water quality and prevent increases in runoff and nutrient loading.

Public Participation

Funding for the study was provided by the Three Rivers Park District and Lake independence Citizens Association provided many hours of volunteer work.

Efforts between the Three Rivers Park District, local municipalities, and MPCA the diagnostic feasibility evolved into the Lake Independence Phosphorus TMDL Estimated associated costs, expected effectiveness,

predicted longevity, and technical feasibility.

Target goal, WLA and LA were discussed by a large group of stakeholders.

Committee met monthly for two years

Decided WLA and LA would be based on source instead of municipal or subwatershed basis.

Implementation

Reducing movement of phosphorus into Lake Independence.

45% reduction (1081lbs/yr)

872 lbs/yr decrease from each identified external source

209 lbs/yr decrease of internal loading due to reduction of external sources.

Source Implementation Plan

Continue water quality monitoring program

Water sample collection

Inflow monitoring during and after implementation

Cost and Implementation

Ranked in highest priority, Time lines, Estimated costs, responsible parties and tasks are explained Goal reduction and possible reduction

Agriculture – Buffer Strips 300 acres can be installed

$150,000 to $500,000

Goal reduction 284lbs possible reduction 288lbs

Animal Waste – BMPs 33 feedlots

$330,000 to $825,000

Goal reduction 378lbs possible reduction 435lbs

Urban Development – urban runoff Goal reduction 146lbs possible reduction 202lbs

Failing Sewage Treatment – inspections $500,000

Goose Removal – reduce goose population $2,500

Loretto Wastewater Treatment

Example of Implementation Plan

Critique

Overall capable reduction

Effort and time put behind implementation plans

Local involvement was helpful

Useful and long record of data

Water Quality was not monitored for the year of 1992 but was not explained.

Sediment cores were used from four other lakes in the area of Lake Independence but not from the lake to estimate historical phosphorus loads.