The New York City Lakes and Ponds Harmful Algal Bloom Program

Home , Alley Pond Park, Crotona Park, Gerritsen Creek, Pelham Bay Park, Prospect Park (Brooklyn), Van Cortlandt Park

Ellen Kracauer Hartig and Katie Friedman NYC Department of Parks and Recreation

February 28, 2019 New York City Natural Areas

1,600 acres of freshwater wetland 1,500 acres of salt marsh

Alley Pond Park, Queens Gerritsen Creek, Brooklyn

Pelham Bay Park, Bronx Van Cortlandt Park, Bronx 1,600 acres of grassland 5,300 acres of forest Aquatic Habitat Benefits

Recreational opportunities—accessible by mass transit—for a dense urban population • Rowing, canoeing, sailing • Fishing, where permitted • Birdwatching • Aesthetic enjoyment Essential habitat for fish, birds and other wildlife Ecosystem services including flood storage and water quality improvement

3 4 Lakes and Ponds Inventory (2015)

• 37 lakes and ponds inventoried

• Approximately 360 acres total

• Shallow depth (<10 ft)

• Shoreline armor varies:

o 13% lakes have predominantly armored shoreline

o 60% have entirely natural shoreline • Water sources include drinking water, untreated stormwater, and naturally occurring streams

• Many lakes are eutrophic due to high phosphorus levels Top: Bowne Pond, Queens. Bottom: Wolfe’s Pond, Staten Island. 5 Management Concerns

• Harmful Algal Blooms (HABs)

• Fish kills

• Invasive plants, including Phragmites australis

• Fouling by Canada Geese

Actions

• Use of chemical products, including herbicide

• Fountain aerator installation

• Mechanical harvesting

• Shoreline restoration Top: Canada geese at lake edge Bottom: Weedoo at Indian Lake, Crotona Park, Bronx 6 Lakes and Ponds Bioblitz (August 6, 2015)

Shoreline Metrics • Type of shoreline (armored or natural), • Location of natural inlets, pipes and culverts • Extent of shoreline vegetation • Public access points

Water Quality Metrics • Maximum and average depth • Turbidity (Secchi depth) • Temperature, pH, salinity, dissolved oxygen (multiparameter meter) • Chlorophyll a readings • Nutrients (nitrogen and phosphorous) • Total Phosphorus, Chlorophyll-α • Phosphate, ammonium, nitrate • Aquatic vegetation

7 Top: Bowne Pond, Queens Bioblitz results—Total Phosphorous Total Phosphorous (TP) concentration Higher numbers suggest poorer conditions

0.60 0.50 0.40 0.30

TP (mg P/L) TP 0.20 0.10 0.00

Phosphorous eutrophic threshold (0.024 mg/L) Hatching indicates lakes inspected for HABs

8 NYC Parks Harmful Algal Bloom (HABs) Program (2015 to Present)

• 28 waterbodies inspected in 2018

• NYC Parks staff and partners (Central Park Conservancy, Prospect Park Alliance, Friends of Van Cortlandt Park) conduct the inspections

• Gobler Laboratory, SoMAS/Stony Brook University conducts the analysis to confirm HABs

• NYS Department of Environmental Conservation sponsors the NYC Parks HABs program

Source: NY Lake Federation and NYSDEC. 2009. Diet for a Small Lake. (Photo credit: Chris Cooley) 9 HABs Monitoring Process

• Inspectors trained in early April

• Inspections performed from late April to October (preferably Mondays)

• Where bloom is suspected, inspectors:

o Photograph and collect a water sample o Overnight samples (on ice) for lab analysis • NYSDEC disseminates results each Friday

• NYC Parks posts signs to inform public where HABs is suspected or confirmed

Prospect Park Lake form and image by Marty Woess, Prospect Park Alliance

10 Example Results for Prospect Park and Central Park Blue green Date Chl-α Microcystin (2018) Water Body Status Extent (µg/L) (µg/L) Genus The Lake in Confirmed with Widespread/ Microcystis, 9-Oct 3,267 >1,000 Central Park High Toxins Lakewide Anabaena Confirmed with Small 9-Oct Harlem Meer 15,451 27 Planktothrix High Toxins Localized Prospect Park Widespread/ Microcystis, 9-Oct Confirmed 129,888 16 Lake Lakewide Planktothrix Small Microcystis, 9-Oct Turtle Pond Confirmed 19,598 2 Localized Anabaena No Bloom 9-Oct The Pool No Bloom Present Conservatory No Bloom 9-Oct No Bloom Water Present No Bloom 9-Oct The Pond No Bloom Present Highlighted cells indicate presence of HABs confirmed by laboratory analysis NYSDEC thresholds are: • Confirmed algal bloom: >25 μg/L blue green chlorophyll-α • Confirmed algal bloom with high toxin (HABs): >20 μg/L microcystin

Source: Rebecca Gorney, NYSDEC 11 Results from the 2018 HABs season Number of Number inspections

12 Results for Prospect Park Lake, Brooklyn, and The Lake in Central Park, Manhattan