Best Hills Lake Remediation Recommendations

Jordanne Holst, Nathan Rosenau, and Monique Crumb

Introduction

Massive Macrophyte Growth

Possible Issues

• Phosphorous maybe contributing significantly to the growth of macrophytes– External loading– Internal loading

• Depth of the system allows light to penetrate much of the water column, possibly stimulating macrophyte growth as well

Macrophytes from Best Hills reservoir

Hypothesis• We hypothesize that external phosphorous

loading from developed land may be significantly contributing to macrophyte growth in Best Hills Lake

Hypothesis

• Different buffers may abate nutrient runoff more effectively than others

• Obtain information about internal phosphorous loading using chemical profiles

Methods

• To determine the profiles of the lake we used a YSI 85 oxygen meter.

Methods• TP (total phosphorous) samples taken at the

developed shore, pelagic area, and undeveloped shore, and also in front of different buffers

T1 T2 T3 T4

No Buffer Rock SandRock+ Sand

DAMS1

S2

S3

Phosphorous Results

1 2 30

5

10

15

20

25

30

35

40

45

50

Transect 1Transect 2Transect 3Transect 4

Site

TP (u

g/L)

Profile Results

7 8 9 10 11 12 130

0.5

1

1.5

2

2.5

3

TempDO

Temp( C)/DO (mg/L) ̊

Dept

h (m

)

Discussion

• Goals of recommendations– Clear water– Lower macrophyte growth– More aesthetically pleasing

Summary

• Profiles • anoxic periods• Resulting in increased amounts of readily available

phosphorous• Phosphorous concentrations

– developed shoreline may not be abating nutrient runoff effectively

– one may be more effective than the others

Recommendations

• Lake aeration may help to reduce internal phosphorous loading

• Buffer strips may help abate nutrient runoff

Aeration

• Hypolimentic oxygenation may stop anoxia and limit internal phosphorous loading

• $2000 will purchase a small aerator that covers 5 acre– http://www.dripworksusa.com/ev_store/ev_pond

aer.php– Quiet– Timer– Self installation is possible

Buffer Strips

• Buffer Strips or “Set Asides”– The US Department of Agriculture defines conservation buffers or “buffe strips”

as small areas or strips of land in permanent vegetation, designed to intercept pollutants and manage other environmental concerns.

– The most commonly referenced size for the buffer strip is 10m, or approximately 33 feet (Ryding et al. 1989).

– Can remove up to 50% of TP (USDA &NRCS)

Buffer Strips (cont..)

• A narrow strip of shrubs (5-6 ft.)

• Decreased fertilizer application in back yards

• Several local landscapers, probably $2500-$3500

Riparian Buffer (cont…)

• Why is it important to use native plants?– Don’t require fertilizers– Don’t require pesticides– Require less water– Provide shelter and food for wildlife...

• http://www.epa.gov/glnpo/greenacres/nativeplants/factsht.html

Riparian Buffer (cont…)• The City of Coeur d'Alene Water Department has teamed up

with the NIC Workforce Training Center. • City residential customers who live in their home and who

take the "Landscaping with Native Plants" class at NIC this Spring (March 11 and March 18, 2010) can receive a utility bill credit for the cost of the class and the workbook.

For More Information: http://northidaho.augusoft.net/index.cfm?method=ClassListing.ClassListingDisplay

Questions?