Aquatic Macrophyte Survey with Remediation Suggestions for Best

Hills RanchBrad Kalb

Tyson FehringerMarie Pengilly Kristen Pilcher

Montana SkovlinJohn SchiselTim Barbier

Estimate amount of aquatic vegetation in the lake

Estimate phosphorus in the lake Estimate phosphorus stored in the plants Explore options for remediation

◦ Cost efficient◦ Reduce aquatic vegetation

Objectives

Study Site•Best Hill Ranch, Coeur d’Alene, Idaho•Sampled October 7 and 14, 2009

Aquatic vegetation ◦Collected from 14 areas◦Macrophyte sampler◦Dried in oven for 48 hours◦Weighed◦Analyzed for phosphorus

Methods

Aquatic vegetation

◦~2,700 kg (~6,000 lbs) dry mass for entire lake

◦~93 kg (~205lbs) phosphorus in the plants

Results

Estimated 659 kilograms (~1,500 lbs) total phosphorus in sediment

Plants are storing large amounts of phosphorus

Summer pump is only adding 23 grams (0.05 lbs)

Most of the phosphorus most be coming from runoff

Discussion

Physical removal◦Harvest in a striped pattern ◦Raking and hand pulling◦Harvest when growth is at its highest◦160 hours of work◦~$2,000 annually

Remediation

Use strips to keep the sediment down and the water clear

Removing plants could cause an algae bloom

Use chemicals to keep algae down

Remedation

Chemicals◦Aquashade◦$70 for a gallon bottle◦4 bottles◦$280 annually

Macrophyte Remediation

Before Aquashade

After Aquashade

Decrease nutrient loading Manual removal of macrophytes

◦ Long term removal of nutrients from system

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