LeTort Spring Run
Carlisle · Classic Limestone Spring Creek
Central Pennsylvania, USA
Open live forecast →Target species: Brown.
Stream gauge: 01569800. Flow and water temperature update on every refresh.
Weekly AI Outlook as of 06/05/26
Sulphur season peaks on the LeTort with stable limestone spring conditions and perfect hatching temps in the mid-50s. Evening emergence windows from 6-8pm should be prime with calm nights following warm 80s+ afternoons. This is technical dry fly fishing at its most demanding — long leaders, drag-free drifts, and precise presentations over spooky browns in gin-clear water.
- Conditions: Classic limestone spring stability with consistent 54-58°F water temps — perfect sulphur hatching zone through the week
- Hatches: Peak sulphur emergence expected 6-8pm with warm afternoons triggering good activity. CDC Sulphur #16-18 and Comparadun patterns
- Water Temp: Steady mid-50s from spring source — ideal sulphur emergence trigger temp maintained regardless of air temperature swings
- Best Window: Evening rise 6-8pm when sulphurs emerge. Early morning for terrestrials as temps climb into the upper 80s later in week
Generated weekly from live USGS gauge readings, weather forecasts, and recent fly shop reports. Updates Friday mornings.
About this Water
- Limestone
- Best months: May–Sept; peak June–July (terrestrial season). Also excellent spring Sulphur hatch
The LeTort Spring Run near Carlisle is the most historically significant trout stream in American fly fishing — the clear limestone creek where Vince Marinaro and Charles Fox revolutionized dry fly fishing in the 1950s, developing terrestrial patterns and upstream dry fly presentation techniques that transformed the sport worldwide. Today the LeTort flows through Carlisle and the surrounding farmland with remarkably little changed. The creek is shallow, clear, and mercilessly demanding — large wild brown trout feeding on tiny insects in slow, transparent water.
The LeTort Spring Run is where Vince Marinaro developed the 'Jassid' pattern — a tiny imitation of leafhoppers and Japanese beetles — establishing the entire terrestrial fishing tradition that is now practiced on trout streams worldwide.
January Outlook
January on the LeTort Spring Run — hallowed ground for technical fly fishing, open year-round from its limestone springs. The 52–58°F constant temperature keeps the ultra-selective brown trout feeding all winter. Winter midge and scud fishing at its most technical.
Productive Patterns
- Zebra Midge (size 24)
- Scud
- Cress Bug
- RS2
Tips
January on the LeTort is an extraordinary experience for the technical angler. The limestone springs maintain perfect temperature year-round. Fish size 22–26 midges on 7X tippet. Approach on hands and knees — the fish are as selective in January as July. The Marinaro Meadows section is accessible year-round.
Water Notes
Spring creek flows 20–80 cfs. Water 52–58°F year-round. The LeTort never freezes. Genuine January technical fishing.
February Outlook
February technical fishing on the LeTort Spring Run. The limestone springs maintain constant temperature through Pennsylvania winter. Scud, cress bug, and midge patterns for incredibly selective brown trout.
Productive Patterns
- Scud
- Cress Bug
- Zebra Midge (size 24)
- WD-40
Tips
February on the LeTort is for the technical specialist. The river never freezes and the fish feed year-round. Tie size 22–26 imitations and approach with extreme stealth. The fish in the Marinaro Meadows section have seen every pattern tied by the finest tiers in America.
Water Notes
20–80 cfs. Water 52–58°F. Limestone spring constant. Year-round technical fishing.
March Outlook
March on the LeTort — early Baetis hatches begin as spring approaches but the limestone spring character means the creek has been fishing well all winter. First dry fly activity of the year.
Productive Patterns
- Blue Winged Olive (size 20)
- Baetis Nymph
- Cress Bug
- Midge Dry
Tips
March Baetis hatches on the LeTort begin weeks before surrounding Pennsylvania freestone streams see activity. The glassy flat water sections near Carlisle produce the most consistent early-season dry fly activity. Long leaders, fine tippet, and perfect presentations.
Water Notes
20–80 cfs. Water 52–58°F. First dry fly activity. Limestone spring advantage.
April Outlook
April on the LeTort Spring Run — early Sulphur and Hendrickson nymph activity building toward the prime season. The limestone spring creek is one of Pennsylvania's most technical early-season fisheries.
Productive Patterns
- Hendrickson
- Sulphur Nymph
- Cress Bug
- Blue Winged Olive
Tips
April on the LeTort builds toward the Sulphur season. The creek is already fishing on dry flies while nearby Penns Creek and Yellow Breeches are just starting. The Marinaro Meadows section above Carlisle Springs is the prime water.
Water Notes
20–80 cfs. Water 52–58°F. Spring approaching. Early Sulphur nymph activity.
May Outlook
The LeTort Spring Run near Carlisle is hallowed ground in American fly fishing. Vince Marinaro perfected his thorax tie and jassid patterns here for the ultra-selective brown trout. One of the most technical fisheries in North America.
Productive Patterns
- Jassid
- Sulphur Thorax Dry
- Cress Bug
- Trico Spinner
Tips
The LeTort demands the finest presentations. Fish are large (to 28 inches) and incredibly selective — sipping tiny naturals from glassy flat water. 7X tippet is standard. Approach on hands and knees if necessary.
Water Notes
Spring creek flows 20–80 cfs. Water 52–58°F year-round. Limestone geology provides perfect constant temperatures.
June Outlook
Sulphur and Trico season on the LeTort. The most challenging dry fly fishing in the East.
Productive Patterns
- Sulphur Thorax
- Trico Spinner
- Cress Bug
- Ant
Tips
June on the LeTort is the pinnacle of technical dry fly fishing. The Marinaro Meadows section above Carlisle Springs is the most famous water. Book access to private sections through local fly shops.
Water Notes
20–80 cfs. Water 54–60°F. Consistent limestone spring character.
July Outlook
Terrestrial season on the LeTort. Ants, beetles, and grasshoppers supplement the always-present Trico spinner fall.
Productive Patterns
- Ant (size 20)
- Beetle
- Trico Spinner
- Jassid
Tips
The LeTort's terrestrial fishing in summer is exceptional. Ants falling from streamside vegetation produce consistent rises. Size 18–22 ants on 7X tippet. The morning Trico spinner fall continues through July.
Water Notes
20–70 cfs. Water 54–60°F. Stable limestone spring conditions — fishing well in summer heat.
August Outlook
August on the LeTort — terrestrial season at peak. Ants, beetles, and jassids produce the most consistent results. The limestone spring constant temperature makes this one of Pennsylvania's finest summer fisheries.
Productive Patterns
- Ant (size 20–22)
- Beetle
- Jassid
- Trico Spinner
Tips
August on the LeTort is excellent. The limestone springs maintain 52–58°F regardless of air temperature. Terrestrials account for most August fish. The Marinaro Meadows section produces rising fish to precise small-fly presentations all day.
Water Notes
20–70 cfs. Water 52–58°F. Limestone spring thermal stability. Excellent August fishing.
September Outlook
September fall fishing on the LeTort. Trico spinner falls continue at dawn. BWO hatches begin on overcast afternoons. The limestone spring character maintains consistent conditions.
Productive Patterns
- Trico Spinner
- Blue Winged Olive
- Ant
- Cress Bug
Tips
September on the LeTort is excellent. Dawn Trico spinner falls continue and BWO hatches appear on overcast afternoons. The fish remain as selective as ever. Fine tippet and careful presentations are the year-round requirements on this technical spring creek.
Water Notes
20–70 cfs. Water 52–58°F. Consistent limestone character. Excellent fall fishing.
October Outlook
October on the LeTort — brown trout spawning activity and reliable BWO hatches. The limestone spring character provides consistency when surrounding streams fluctuate. Streamers for pre-spawn fish.
Productive Patterns
- Blue Winged Olive
- Streamer
- Egg Pattern (small)
- Cress Bug
Tips
October on the LeTort produces aggressive pre-spawn brown trout alongside reliable BWO hatches. The Marinaro Meadows section is beautiful in fall. Fish the deeper pools with streamers for the largest fish.
Water Notes
20–70 cfs. Water 50–58°F. Limestone spring consistent. Brown trout spawning season.
November Outlook
November late-season on the LeTort. Brown trout spawning concludes and the creek transitions to winter midge fishing. The limestone spring character keeps fish active year-round.
Productive Patterns
- Midge Dry
- Cress Bug
- Scud
- BWO (early month)
Tips
November on the LeTort transitions from fall to winter mode. The limestone springs keep the creek open and productive. Late BWO activity on mild afternoons. Transition to scud and cress bug patterns as temperatures drop.
Water Notes
20–70 cfs. Water 52–58°F. Limestone spring constant. Late season fishing.
December Outlook
December on the LeTort Spring Run — the limestone spring constant temperature maintains 52–58°F water year-round. The most technical winter fishing in the East. Size 24 midges and 7X tippet.
Productive Patterns
- Zebra Midge (size 24)
- Scud
- Cress Bug
- WD-40
Tips
December on the LeTort is an extraordinary winter experience for the technical fly fisher. The limestone springs never freeze and the ultra-selective fish feed year-round. Approach on hands and knees in December as in June — these fish know no off-season.
Water Notes
20–70 cfs. Water 52–58°F year-round. The LeTort never closes. December fishing is real.
Hatch Calendar
| Insect | Peak | Active | Size | Productive Patterns |
|---|---|---|---|---|
| Trico Tricorythodes spp. |
Jul, Aug, Sep | Jul, Aug, Sep, Oct | #22–26 |
|
| Blue Winged Olive Baetis spp. |
Apr, Oct | Apr, May, Sep, Oct, Nov | #18–22 |
|
| Sulphur Ephemerella dorothea |
May, Jun | May, Jun | #16–18 |
|
Access & Approach
Carlisle, PA (just off I-81, exit 52). Parking along Bonny Brook Road near the famous meadow section. Pennsylvania Fish and Boat Commission manages access. Pennsylvania fishing license required. Special regulations apply to most of the creek.
Nearby Fly Shops
- Relentless Fly Fishing
- TCO Fly Shop
- Backwater Angler
Regulations & License
Fishing in Pennsylvania requires a current license. Always verify season dates, bag limits, and any special-regulation waters before you fish.
Pennsylvania fishing regulations & license →
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About Current
LeTort Spring Run conditions on Current combine real-time flow data (USGS, WSC, CDEC, CEHQ), weather, tide predictions, hatch probabilities calibrated to this specific water, and recent fly shop reports from the area.
LeTort Spring Run is one of 245 hand-curated waters in Current. The app and web forecast also generate AI outlooks for any unlisted river, lake, or saltwater flat anywhere in the world — drop a pin or paste a name and Current produces a fresh seasonal outlook with weather, flow context, and recommended techniques.
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