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CCeeddaarr LLaakkee ““SSttaattee ooff tthhee LLaakkee”” ((22001155))

RReeppoorrtt && 22001166 MMaannaaggeemmeenntt

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Cedar Lake “State of the Lake” Report

(2015)

Restorative Lake Sciences 18406 West Spring Lake Road Spring Lake, Michigan 49456

Email: info@restorativelakesciences.com Website: http://www.restorativelakesciences.com

Table of Contents

Section 1: Cedar Lake Summary (2015) .................................. 4

Section 2: Cedar Lake Water Quality Data (2015) .................... 5

Section 3: Cedar Lake Aquatic Vegetation Data (2015) ......... 10

Section 4: Management Recommendations for 2016 ............. 15

4

Cedar Lake “State of the

Lake” Summary

The following information is a summary of key lake findings collected during the spring and summer of 2015.

he overall condition of Cedar Lake is ranked in the top 30% of developed lakes of similar size in the state of Michigan. Invasive species such as hybrid Eurasian Watermilfoil (EWM) and Curly-leaf Pondweed (CLP) are able to grow in moderate nutrient waters and thus are a challenge to the Cedar Lake

ecosystem. It has been particularly a challenge since the milfoil in Cedar Lake had been recently genetically determined to be HYBRID, which makes it much more resistant or tolerant to aquatic herbicides and thus much higher doses will be needed for effective control in the future. Both EWM and CLP were treated during 2015 and were not problematic later in the season. The invasive macro alga, Starry Stonewort was also found in the lake and promptly treated in 2015. The implementation of laminar flow aeration (LFA) in the lake in 2016 may also reduce aquatic vegetation over-dominance in many areas.

In regards to water quality, total phosphorus was highest at the bottom of the deepest basin during late July. All ortho-phosphorus concentrations were below the level of detection which is favorable. Chlorophyll-a was also very low during 2015 and water clarity was moderate at 9.0 feet. The dissolved oxygen was favorable in early May but declined rapidly with depth during late July. A summary of all lake data collected in 2015 is displayed below in this report along with 2016 recommendations.

Section

1

T

5

Cedar Lake Water Quality Data (2015)

Water Quality Parameters Measured

There are hundreds of water quality parameters one can measure on an inland lake but several are the most critical indicators of lake health. These parameters include water temperature (measured in °F), dissolved oxygen (measured in mg/L), pH (measured in standard units-SU), conductivity (measured in micro-Siemens per centimeter-µS/cm), total alkalinity or hardness (measured in mg of calcium carbonate per liter-mg CaCO3/L), total dissolved solids (mg/L), secchi transparency (feet), total phosphorus and total nitrate nitrogen (both in µg/L), chlorophyll-a (in µg/L), and algal species composition. Water quality is measured in the deep basins of Cedar Lake in spring and late summer of each year. Table 1 below demonstrates how lakes are classified based on key parameters. Cedar Lake would be considered eutrophic (relatively productive) since it does contain ample phosphorus, nitrogen, and aquatic vegetation growth but has good water clarity and modest algal growth. 2015 water quality data for Cedar Lake is shown below in Tables 2-5.

Lake Trophic Status

Total Phosphorus

(µg L-1)

Chlorophyll-a (µg L-1)

Secchi Transparency

(feet) Oligotrophic < 10.0 < 2.2 > 15.0

Mesotrophic 10.0 – 20.0 2.2 – 6.0 7.5 – 15.0

Eutrophic > 20.0 > 6.0 < 7.5

Table 1. Lake trophic classification (MDNR).

Section

2

Did You Know? Cedar Lake has a maximum depth of 27 feet

DB #1

DB #2

6

Depth ft.

Water Temp

ºC

DO mg/L

pH S.U.

Cond. µS cm-1

TSS mg/L

Total Phos. mg/L

Ortho-P mg/L

TDS mg/L

Chl-a µg/L

0 18.8 10.0 9.1 435 <10 <0.010 <0.010 218 --

7.5 15

16.3 12.0

8.9 7.3

9.0 8.8

437 447

<10 <10

0.016 <0.010

<0.010 <0.010

218 220

0 --

Table 2. Cedar Lake water quality parameter data collected in the deep basin #1 (May 12, 2015).

Depth ft.

Water Temp

ºC

DO mg/L

pH S.U.

Cond. µS cm-1

TSS mg/L

Total Phos. mg/L

Ortho-P mg/L

TDS mg/L

Chl-a µg/L

0 18.9 9.7 9.1 434 <10 0.018 <0.010 217 --

13 26

11.0 8.2

8.9 6.2

8.9 8.2

443 446

<10 <10

0.010 0.011

<0.010 <0.010

221 222

0 --

Table 3. Cedar Lake water quality parameter data collected in the deep basin #2 (May 12, 2015).

Depth ft.

Water Temp

ºC

DO mg/L

pH S.U.

Cond. µS cm-1

TSS mg/L

Total Phos. mg/L

Ortho-P mg/L

TDS mg/L

Chl-a µg/L

0 28.4 7.3 8.2 468 <10 0.017 <0.010 304 --

7 14

24.5 24.8

7.1 3.3

8.0 7.7

400 404

<10 <10

0.014 0.020

<0.010 <0.010

275 275

0 --

Table 4. Cedar Lake water quality parameter data collected in the deep basin #1 (July 28, 2015).

Depth ft.

Water Temp

ºC

DO mg/L

pH S.U.

Cond. µS cm-1

TSS mg/L

Total Phos. mg/L

Ortho-P mg/L

TDS mg/L

Chl-a µg/L

0 28.4 7.7 8.3 396 <10 0.014 < 0.010 266 --

11 22

26.3 16.6

5.1 0.8

7.9 7.3

392 463

<10 <10

0.023 0.051

<0.010 <0.010

279 328

0 --

Table 5. Cedar Lake water quality parameter data collected in the deep basin #2 (July 28, 2015).

7

Dissolved Oxygen Data

Dissolved oxygen is a measure of the amount of oxygen that exists in the water column. In general, dissolved oxygen levels should be greater than 5 mg/L to sustain a healthy warm-water fishery. Dissolved oxygen concentrations may decline if there is a high biochemical oxygen demand (BOD) where organismal consumption of oxygen is high due to respiration. Dissolved oxygen is generally higher in colder waters. Dissolved oxygen is measured in milligrams per liter (mg/L) with the use of a dissolved oxygen meter and/or through the use of Winkler titration methods. Dissolved oxygen concentrations ranged from 10.0–6.2 mg/L from top to bottom over the deep basins in May but declined with depth rapidly by late July in both basins.

Water Clarity (Transparency) Data

Elevated Secchi transparency readings allow for more aquatic plant and algae growth. The transparency throughout Cedar Lake is adequate (7.5-13 feet) to allow abundant growth of algae and aquatic plants in the majority of the littoral zone of the lake. Secchi transparency is variable and depends on the amount of suspended particles in the water (often due to windy conditions of lake water mixing) and the amount of sunlight present at the time of measurement. The secchi transparency was 9.0 feet in both May and July of 2015.

Total Phosphorus and Ortho-Phosphorus

Total phosphorus (TP) is a measure of the amount of phosphorus (P) present in the water column. Phosphorus is the primary nutrient necessary for abundant algae and aquatic plant growth. TP concentrations are usually higher at increased depths due to higher release rates of P from lake sediments under low oxygen (anoxic) conditions. Phosphorus may also be released from sediments as pH increases. The dissolved oxygen levels at the bottom of Cedar Lake are low and are likely causing release of phosphorus from the bottom which is fueling aquatic plant and algae growth each season. TP ranged from <0.010-0.018 mg/L in May and from 0.014-0.051 mg/L in late July.

Ortho-phosphorus or “soluble reactive phosphorus” refers to the proportion of phosphorus that is bioavailable to aquatic life. Higher concentrations of ortho-phosphorus concentrations in the lake result in increased uptake of the nutrient by aquatic plants and algae. The ortho-phosphorus concentrations in the deep basins of Cedar Lake were all ≤ 0.010 mg/L in May and July, which are quite low.

8

Total Suspended and Dissolved Solids

Total dissolved solids (TDS) are another measure of combined inorganic and organic solids dissolved in the water that pass through a 2µm sieve. In general, the higher the turbidity of the water, the greater the quantity of TDS. The TDS present in Cedar Lake water ranged from 217-222 mg/L for all samples collected in May of 2015 and from 275-328 mg/L on July 28, 2015. Most aquatic ecosystems can tolerate TDS levels up to 1,000 ppm (Boyd, 1999). The water quality standard for drinking waters in the United States is 500 ppm.

Total suspended solids (TSS) refers to the amount of solids suspended in the water column at a given time. In general, the higher the TSS, the higher the turbidity of the lake water and reduced water clarity. All of the TSS concentrations in Cedar Lake in May and late July were <10 mg/L which is quite favorable.

pH

Most Michigan lakes have pH values that range from 6.5 to 9.5. Acidic lakes (pH < 7) are rare in Michigan and are most sensitive to inputs of acidic substances due to a low acid neutralizing capacity (ANC). Cedar Lake is considered “slightly basic” on the pH scale. The pH of Cedar Lake ranged from 7.3-9.1 S.U. which is ideal for an inland lake but represents a wide range of values.

Conductivity

Conductivity is a measure of the amount of mineral ions present in the water, especially those of salts and other dissolved inorganic substances. Conductivity generally increases as the amount of dissolved minerals and salts in a lake increases, and also increases as water temperature increases. The conductivity values for Cedar Lake are moderately high and ranged from 400-468 µS/cm. Severe water quality impairments do not occur until values exceed 800 µS/cm and are toxic to aquatic life around 1,000 µS/cm.

Chlorophyll-a and Algal Species Composition

Chlorophyll-a is a measure of the amount of green plant pigment present in the water, often in the form of planktonic algae. High chlorophyll-a concentrations are indicative of nutrient-enriched lakes. Chlorophyll-a concentrations greater than 6 µg L-1 are found in eutrophic or nutrient-enriched aquatic systems, whereas chlorophyll-a concentrations less than 2.2 µg/L are found in nutrient-poor or oligotrophic lakes. Chlorophyll-a concentrations were negligible in Cedar Lake during 2015 and the reason for this is not known.

Algal genera from a composite water sample collected over the deep basin of Cedar Lake were analyzed under a compound bright field microscope. Genera are listed here in the order of most abundant to least abundant. The genera present

9

included the Chlorophyta (green algae): Chlorella sp., Scenedesmus sp. Euglena sp., Haematococcus sp., Rhizoclonium sp., Gleocystis sp., Pediastrum sp., Spirogyra sp., and Chloromonas sp. the Cyanophyta (blue-green algae): Oscillatoria sp.; the Bascillariophyta (diatoms): Navicula sp., Synedra sp., Cymbella sp., Fragilaria sp., and Tabellaria sp. The aforementioned species indicate a moderately diverse algal flora and represent a relatively balanced freshwater ecosystem, capable of supporting a strong zooplankton community in favorable water quality conditions. The waters of Cedar Lake are rich in the Chlorophyta (green algae) but contain less diatoms. If the dissolved oxygen levels of the lake were increased, diatoms may increase and be beneficial for a healthy fishery.

A Green Alga (Good)

A Diatom (Good)

A Blue-Green Alga (Bad)

10

Aquatic Vegetation Data (2015)

Status of Native Aquatic Vegetation in Cedar Lake

The native aquatic vegetation present in Cedar Lake is essential for the overall health of the lake and the support of the lake fishery. The May 12, 2015 survey consisting of 50 sampling locations determined that there were a total of 25 native aquatic plant species in Cedar Lake. These include 17 submersed species, 3 floating-leaved species, and 5 emergent species. This indicates a very high biodiversity of native aquatic vegetation in Cedar Lake. The native aquatic plant communities in Cedar Lake should be preserved (i.e. not treated) to protect the lake fishery and to leave the lake less vulnerable to further infestations from incoming exotics.

The most common native aquatic plants included the following: 1) The macro alga, Chara, which is light green in color and has a strong, skunky odor, 2) Large-leaf Pondweed, which has brown leaves that are large and the plant grows tall into the water column, 3) Illinois Pondweed which has lance-shaped light brown/red leaves that curl slightly and the plant also grows tall in the water column, and 3) White Water Lily pads which produce a showy white flower and the plant forms mats of pads on the lake surface. The pads serve as valuable cover for snails and other macroinvertebrates.

A list of all native aquatic plant species found in Cedar Lake on May 12, 2015 is shown in Table 6 below.

Section

3

11

Native Aquatic Plant Species Name

Aquatic Plant Common Name

Abundance in/around Cedar Lake

Aquatic Plant Growth Habit

Chara vulgaris Muskgrass 5.0 Submersed, Rooted Potamogeton pectinatus Thin-leaf Pondweed 0.1 Submersed, Rooted Potamogeton amplifolius Large-leaf Pondweed 9.5 Submersed, Rooted Potamogeton zosteriformis Flat-stem Pondweed 0.1 Submersed, Rooted Potamogeton gramineus Variable-leaf Pondweed 0.1 Submersed, Rooted Potamogeton robbinsii Fern-leaf Pondweed 0.1 Submersed, Rooted Potamogeton illinoensis Illinois Pondweed 4.5 Submersed, Rooted Potamogeton pusillus Small-leaf Pondweed 0.1 Submersed, Rooted Myriophyllum sibiricum Northern Watermilfoil 0.1 Submersed, Rooted Myriophyllum verticillatum Whorled Watermilfoil 0.1 Submersed, Rooted Zosterella dubia Water star grass 0.1 Submersed, Rooted Ceratophyllum demersum Coontail 0.1 Submersed, Non-Rooted Utricularia vulgaris Bladderwort 6.1 Submersed, Non-Rooted Utricularia minor Mini Bladderwort 0.1 Submersed, Non-Rooted Ranunculus sp. Buttercup 0.1 Submersed, Rooted Najas flexilis Slender Naiad 1.0 Submersed, Rooted Scirpus subterminalis Submersed Bulrush 1.5 Submersed, Rooted Nymphaea odorata White Waterlily 5.0 Floating-Leaved, Rooted Nuphar variegata Yellow Waterlily 8.0 Floating-Leaved, Rooted Brasenia schreberi Watershield 0.2 Floating-Leaved, Rooted Typha latifolia Cattails 2.0 Emergent Scirpus acutus Bulrushes 1.8 Emergent Sagittaria sp. Arrowhead 0.2 Emergent Pontedaria cordata Pickerelweed 0.5 Emergent Iris sp. Wild Iris 0.1 Emergent

Table 5. Cedar Lake native aquatic plants (May 12, 2015). Relative abundance displayed as a percentage.

12

Invasive (Exotic) Aquatic Plant Species

The amount of Eurasian Watermilfoil present in Cedar Lake varies each year and is dependent upon climatic conditions, especially runoff-associated nutrients. 2015 was the wettest year on record and many lakes experienced nuisance milfoil and algal outbreaks even given the two consecutive harsh winters. The spring 2015 survey revealed that approximately 7.75 acres of hybrid milfoil was found throughout the entire lake. On June 24th, 2015, the milfoil was treated with high dose granular Triclopyr (Renovate OTF®) at a dose of 160 lbs. /acre. The treatment was successful overall with no milfoil found at the end of the 2015 season.

In addition to the milfoil, there were approximately 1.25 acres of invasive Curly-leaf Pondweed (CLP) that necessitated treatment with the contact herbicide Aquathol-K®. Also, the invasive Starry Stonewort was found to occupy approximately 7.5 acres of area and was treated with flumioxazin (Clipper) at a dose of 200 ppb. Both the CLP and the Starry Stonewort treatments were also successful with no viable growth remaining at the end of the 2015 season.

Treatment maps for the each of the invasives and nuisance lily pads are shown on the next page.

Eurasian Watermilfoil

Eurasian Watermilfoil

Starry Stonewort

13

.

Cedar Lake 2015 Milfoil Distribution Map

Cedar Lake 2015 CLP Distribution Map

14

Cedar Lake 2015 Starry Stonewort Distribution Map

Cedar Lake 2015 Nuisance Lily pad Distribution Map

15

Management Recommendations for 2016

Continuous aquatic vegetation surveys are needed to determine the precise locations of EWM, CLP, Starry Stonewort, or other problematic invasives in Cedar Lake. These surveys should occur in late-May to early-June of each year and again post-treatment after each treatment. Due to the healthy native pondweed population in Cedar Lake, the treatment of these species with aquatic herbicides is not recommended (one exception is the overgrowth of the invasive pondweed, Curly-leaf Pondweed in the canals which can also be harvested). The plan for 2016 and beyond should include the use of high doses of systemic aquatic herbicides due to the genetically determined strains of hybrid milfoil that require such doses for effective treatment. Triclopyr (Renovate OTF®) has been very effective for the reduction of EWM in Cedar Lake. Mechanical harvesting is recommended for the removal of nuisance aquatic plant biomass in the canals. Water quality parameters in the lake and inlets should also be monitored and compared to data after the implementation of the aeration system.

Section

4

16

Glossary of Scientific Terms used in this Report

1) Biodiversity- The relative abundance or amount of unique and different biological life forms found in a given aquatic ecosystem. A more diverse ecosystem will have many different life forms such as species.

2) CaCO3- The molecular acronym for calcium carbonate; also referred to as “marl” or mineral sediment content.

3) Eutrophic- Meaning “nutrient-rich” refers to a lake condition that consists of high nutrients in the water column, low water clarity, and an over-abundance of algae and aquatic plants.

4) Mesotrophic- Meaning “moderate nutrients” refers to a lake with a moderate quantity of nutrients that allows the lake to have some eutrophic qualities while still having some nutrient-poor characteristics

5) Oligotrophic- Meaning “low in nutrients or nutrient-poor” refers to a lake with minimal nutrients to allow for only scarce growth of aquatic plant and algae life. Also associated with very clear waters.

6) Sedimentary Deposits- refers to the type of lake bottom sediments that are present. In some lakes, gravel and sand are prevalent. In others, organic muck, peat, and silt are more common.