Lancaster County is within minutes of one of Pennsylvania's best big-bass lakes.

Can you guess which one it is?

Lake Marburg?

No.

Blue Marsh Reservoir?

No.

Lake Redman?

No.

Those lakes are quality fisheries, no doubt.

But a recent survey of largemouth bass numbers in Chester County's Marsh Creek Lake produced historic results.

The catch rates recorded by Pennsylvania Fish and Boat Commission biologists during a survey in October of the 535-acre lake near Downingtown were the fifth-highest ever logged in the state on any lake over 500 acres for largemouth bass measuring 12 inches and over, and the seventh-highest ever for largemouths measuring 15 inches and over.

"Some of our data goes back to the 1970s," said Mike Kauffman, southeast regional fisheries biologist for the PFBC. "So we're talking about comparing results over a long period of time, and these were the fifth and seventh highest we've ever seen."

It was the night of Oct. 19 that PFBC fisheries biologist Greg Murphy led a survey team to Marsh Creek Lake.

The expedition was prompted by complaints from a local bass club that Marsh Creek's bass population was suffering from years of heavy stockings of tiger muskellunge.

True enough, the PFBC has a long history of stocking the toothy predators in Marsh Creek Lake.

But were muskies gobbling up an inordinate number of largemouths?

Murphy said a study done in Wisconsin of the stomach contents of muskies indicated bass represent a small fraction of a muskie's diet.

"But we had no data to refer to on that issue as far as Marsh Creek was concerned," he said.

And it had been about 13 years since the lake's bass population was surveyed for any reason.

So teams set out with electrofishing gear to shock three areas they always survey on the lake.

The abundance of bass was determined by catch per hour of electrofishing effort.

A total of 142 largemouths were collected, ranging in size from 6 to 19 inches.

(Biologists also netted four muskies measuring 18-40 inches long.)

The catch rate of bass equal to or greater than 12 inches was 39.3 fish per hour.

On all lakes in the southeast region, the average is 12.3 fish per hour.

The Marsh Creek catch rate of bass equal to or greater than 15 inches was 17.3 fish per hour.

On all lakes in the southeast region, the average is 3.6 fish per hour.

Of all the sampling ever done on all the lakes in the southeast, the PFBC has recorded only two higher catch rates for bass equal to or greater than 15 inches.

One was in 2001 on Chambers Lake, also in Chester County, when biologists netted 19 fish per hour.

The other was in 1995 on Nockamixon Lake in Bucks County, when biologists caught 18.9 bass per hour.

And here's the kicker.

Both Kauffman and Murphy said the Marsh Creek numbers probably would have been higher if the sampling had been done in the spring, rather than fall.

"Spring is typically when we do our sampling because bass move into the shallows to spawn, where they are more susceptible to our gear," Murphy said.

And many of the catch rates logged in the PFBC database, against which the recent Marsh Creek sampling was compared, were recorded during in spring.

"It probably would have ranked even higher" had the sampling been done in the spring, Kauffman said.

Biologists on Oct. 19 didn't catch any largemouths over 20 inches, although Murphy said he's certain they exist in the lake.

And the catch rate of young bass was low, although Murphy noted the areas shocked primarily encompass adult bass habitat.

"We know that we had a good sampling of multiple year classes, which means reproduction in the lake is excellent," he said.

• • •

Marsh Creek Lake is a Big Bass Lake, which means only bass measuring 15 inches and longer can be creeled.

Elsewhere, the minimum length is 12 inches during the prime summer and fall fishing season.

The increased minimum length was enacted on Marsh Creek back in 1991, making it one of the state's first Big Bass Lakes.

Samplings were done every year from 1994-97.

Those samplings did not show a significant change in the number of bass 15 inches and over.

"The numbers were actually pretty low back then," Murphy said.

Along comes the 2011 sampling and the old numbers were blown out of the water.

The 2011 catch rate on bass 15 inches and over was 518 percent higher than the rate observed in the 1990s, according to Murphy's report on Marsh Creek Lake, which was published last week on the PFBC's website —fish.state.pa.us.

Why is the lake's largemouth population so healthy?

According to Kauffman and Murphy, it's got excellent forage for bass, there's plenty of cover and the water clarity is good.

"From what we observed, it certainly appears predation from muskies is not impacting the population," Murphy said.

Murphy suspects that it took a few years for the effects of the big-bass regulations on Marsh Creek to impact the bass population.

Also, he said biologists know catch-and-release angling is much more popular now than it was 20 years ago.

"It has become the norm among black-bass fishermen," he said. "Not everyone practices it, but it certainly seems the majority do."

As Kauffman noted, huge numbers of bass in the water don't necessarily translate to successful days on the water for anglers.

"Studies have shown that bass do learn," he said. "And with catch-and-release angling becoming more popular, that means anglers must improve their tactics if they want to keep catching those fish."

A recent study by the U.S. Fish and Wildlife Service found Pennsylvania ranked in the top five states in the nation for the annual number of angling trips for bass, according to Kauffman.

"Our bass lakes in Pennsylvania get a lot of pressure," he said. "Pressure makes the bass harder to catch, and certainly Marsh Creek — in the southeast region where there are a lot of people — gets a lot of pressure."

I've been fishing Marsh Creek Lake since I was 16 years old in 1984.

Compared to some of the anglers in this area, I am by no means an expert bass fisherman.

But if I can catch largemouths as regularly as I do on Marsh Creek, there have to be a ton of fish in the water.

And not just smart ones.

P.J. Reilly is the Sunday News' outdoors writer. Email him at preilly@lnpnews.com.