Like many curious anglers, I am always discovering new topics of interest. Recently, a friend asked me about the difference between limestone and freestone streams. He wanted to know what they are and why guys like me are so interested in the limestone streams of Pennsylvania. Here is my brief overview on this topic.

Consistency in water temperature and flow combined with a relative neutral Ph is what make limestone streams so vigorously alive.

The Black Forest trail located in north central, Pennsylvania encircles a sparkling wild trout stream, named Slate Run. Slate Run is a freestone stream; this means it is made by water running off the surface of the land. It does get a few shots of spring water along the way, provided by seeps located in the cliff walls and small spring tributaries, but its life primarily depends on surface water run-off. This means that it lives and dies, by the snow and rain. Through the course of the year, Slate’s temperature, Ph, alkalinity, and water flow fluctuate dramatically. This fluctuation can have very negative effects on the environment, both biomasses within the water, as well as the surrounding micro and macro environments. Of course I know you’re totally aware of the how tightly integrated all of this stuff really is; hence the ominous issue regarding environmental fragility that looms around it. I’ve heard that before the first wave of lumbering, there was a deep dark forest, so heavy the canopy that only sprinkled shards of sunlight touched the wet mulch-like floor. It’s named the Black Forest and I would like to find out if this is because of the great proportion of German settlement or because the woods were so dark and dense. Back then streams like Slate Run were hardier and healthier, they didn’t drastically fluctuate in temperature, they produced thick clouds of mayflies in dozens of varied species – it was extremely alive. That is a smidgen of information about Freestone streams in northern Pennsylvania. I’m trying to find out why they call them runs instead of streams or creeks. Is it because they flow quickly down a mountain?

Contrastingly, Limestone streams are usually found in valleys. Limestone streams are born in places where it is wet and prone to collect water. This water then filters through a stratum of limestone; agricultural England is also known for this type of environment. In central Pennsylvania, which is an extremely lush agricultural region, one can find sink holes throughout the cozy farm valleys. These small pond-like areas called sink holes are found near the streams. They are funnels to the labyrinth below which are underground limestone aquifers. Limestone has the wonderful acidic buffering quality. Limestone streams are products of this natural Ph balancing process. One can find roiling springs rising to the surface throughout the region. Think of the output equaling Limestone streams to the input equaling sink holes. Another analogy is the underground water table is like a tree, one sees the trunk, branches and leaves, but there is a vital nurturing root system below. It’s always a pleasure to travel through this area and see the sturdy chalk greyish brick homes, made from Limestone, scattered about the hillsides. I find myself anxious when looking at the farm houses knowing what resides in the meandering waters behind the barn. These streams are such a treat for guys like me because of their consistency in temperature and Ph. This consistency provides a healthy breeding ground for numerous micro-invertebrates; which in-turn feed the entire food chain.

I recently fished Spring Creek for an afternoon outing. During my trip I snagged a few tree branches that rested along the bottom. They were just big enough to pull ashore and remove my lodged nymph. It always surprises to see just how many nymphs can cling to one branch. In almost every square inch of the branch there were roughly 5 to 15 nymphs crawling about. A quick look at the bark and you’d swear it was alive and moving; the proverbial bug factory. There are many types of fishing waters, each providing unique characteristics. I hope you find the chance to enjoy the fantastic Limestoners here in beautiful Pennsylvania.

~ Leo

Additional References:
Limestone Collection on Amazon

Trout Tactics: An excellent book written by Joe Humphreys including a great chapter on Limestone and Freestone characteristics.

This entry was posted on Friday, June 23rd, 2006 at 11:10 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.