Seasonal care calendar
June pond care in Pennsylvania
Harmful algal bloom season begins and invasive shoreline plants start to flower.
- Safety
Harmful algal blooms are caused by cyanobacteria ("blue-green algae") and can produce toxins that harm people, pets and other animals. If you suspect one, keep people and pets out of the water and do not swallow or breathe in spray from it. Only a laboratory test can confirm a bloom. Report a suspected bloom to the Pennsylvania HABs Task Force (HABs@pa.gov). Blooms are most common from mid-June to early September.
Checked Oct 4, 2026 · Source: Harmful Algal Blooms (HABs hub) This may be outdated
- Care
Purple loosestrife flowers from about late June into September. Cut off the flower heads, bag and destroy them, and pull young plants with their roots.
Source: Purple Loosestrife: A Noxious Weed; DCNR invasive plant fact sheet: Purple loosestrife
- Care
Net or rake algae mats and pile them well away from the water so the nutrients don't wash back in.
Source: Filamentous Algae
- Care
Aeration can raise dissolved oxygen during blooms and hot spells, when fish kills are most likely.
- Permit timing
Planning a fall drawdown? Over 1 acre (or with another state permit): PFBC drawdown permit, 30+ days ahead, no fee.
Checked Oct 4, 2026 · Source: Apply to Draw Off Water from Impoundments This may be outdated
- Care
Watch for floating rosettes of toothed, triangular leaves: European water chestnut. Pull it before it flowers in mid-July and report it.
Source: European Water Chestnut Range Expands to 15 Pennsylvania Counties
This calendar repeats every year. Permit reminders show the date we last checked the rule.
The Seasonal Pond Letter
Free, four times a year: mid-February, May 1, mid-August and November 1: what to do and file before each season. Sign up.