Catchy Ideas: Reading Watersheds

vegetation vegetation
Riparian vegetation, such as these willows along the San Lorenzo River, provides food, shade, and safety for fish. Fish will often select lies beneath or close to overhanging vegetation, where they can feed on high-calorie meals such as beetles and caterpillars that drop from the branches and leaves.

There are plenty of articles that explain how to read the water, helping you figure out where the fish are and what they are feeding on. This skill can take a while to learn, but is well worth the effort. For most folks, this is all the reading they want to do. However, this is not the only useful story on nature’s bookshelf. There’s another one that starts at the edge of the water. It’s the story told by the watershed, and it can take your fishing to another level.

A watershed is all of the land that drains to a particular body of water. For a small, high-Sierra lake or a neighborhood pond, it may be no more than a few dozen acres, while bodies of water such as the Sacramento River may have watersheds covering thousands of square miles. It may not be readily apparent, but every creek, river, pond, or lake is simply the wettest bit in a much larger and more complex ecosystem. To keep things simple, we’ll break the watershed down into easily identifiable features.

The Water’s Edge

The water’s edge is the easiest zone to recognize, since one side is water and the other is damp or dry. Transition zones such as this are called “ecotones” and often feature a greater species diversity than in the adjacent habitats. Take time to look closely at this zone, and you’ll likely find fish food.

Late spring and summer are when you’ll see the empty husks of dragonfly, damselfly, and stonefly nymphs clinging to rocks or bankside vegetation. Dragons and damsels frequent lakes and streams, while stoneflies are usually found in moving waters. A typical dragonfly nymph weighs twenty times more than a Hexagenia nymph, so it represents a good chunk of calories for hungry fish. A study at Castle Lake in the Trinity Alps showed that dragonfly nymphs comprised more than half the diet of the lake’s rainbow trout. Dragonfly and stonefly nymphs typically move across the bottom toward the shore to exit the water, so you’ll want your fly to do the same. You’ll be fishing in shallow water, so it’s best not to use heavily weighted patterns.

Other fish food that can be found along the water’s edge on hot days includes bees, wasps, beetles, ants, and spiders. A number of these critters inevitably will end up in the water. Like dragonflies, damselflies, and stoneflies, they can represent a good-sized meal. On most creeks and lakes, simple patterns such as foam beetles in brown or black will match the hatch.

The best time to fish the shallows is usually around dawn or dusk, but regardless of the time, it never hurts to make a few casts before you wade out. Fish stationed near the shore will be alert to threats, so approach with care and keep a low profile. Stay as far back as you can, and start by dropping your fly just a few feet out from the shore. I’ve caught plenty of trout and bass in water that’s under a foot deep and have scared way too many by stupidly forgetting to cast to the shallows first.

If you are lucky, you may see the fish or their wakes and be able to cast to individual fish. This is one of the more intense forms of fly fishing. One wrong move or a flubbed cast, and you’ll watch your target and any unseen companions make surging bow waves as they bolt for deeper water. This type of fishing is not uncommon on many mountain lakes. It also occurs in lakes and ponds at lower elevations, especially for bass and carp. A friend caught a big largemouth beneath a recently flooded picnic table in water that was barely a foot deep. The fish was probably hunting crayfish scavenging bits of bread or tortilla.

The Riparian Zone

Just inland beyond the water’s edge is the riparian zone, an area that usually features water-loving plants such as sedges, blackberries, and willows. This is another highly productive habitat. The adult stage of many aquatic insects such as mayflies, caddisflies, stoneflies, and chironomids use riparian vegetation as habitat and in some cases for mating. One neat way to figure out what aquatic insects you should match is by checking out what’s caught by spider webs in the riparian zone.

Riparian vegetation that extends over the water provides shade that helps hide fish, possibly reduces water temperature in the summer and fall, and also creates a prime feeding location. In fact, riparian invertebrates such as beetles, caterpillars, and spiders sometimes represent the dominant food source for trout during the summer, especially during the daytime, when aquatic insect hatches can be limited.

Research has shown that overhanging riparian vegetation influences the foraging behavior and local abundance of trout in streams. The fish often will select lies that are directly beneath or near this vegetation to take advantage of the larger morsels dropping from the branches. If you can cast with reasonable accuracy, drop your fly as close to the vegetation as possible. Otherwise, look for gaps and make your best shot.

You don’t have to worry too much about super-delicate deliveries. The fish are used to having fat caterpillars and clunky beetles making a bit of a splash. Riparian vegetation can be important in ponds and lakes, too. I know a spot where largemouth bass will lie in wait for birds to take a drink. One minute you are looking at a tranquil scene, and the next, all hell breaks loose. I’m still trying to figure out how to tie and present a drinking bird fly. (Editor’s note: “Teethmarks on the Rod Tip,” by Harry Smith, printed way back in our September/October 1995 issue, covers fishing for bass with a bird pattern.)

Meadows

If you have ever hiked California’s mountain ranges, you no doubt will have come across alpine meadows. Varying in size and plant species, these features generally require a shallow water table, which also means they are likely fed by the same groundwater system that helps support nearby streams and still waters. One might even say that still waters are the natal stage of meadows.

Meadows are biologically rich places that support a wide variety of insects, including beetles and spiders, and these can supply adjacent streams and lakes with plenty of food. On windy days, grasshoppers can get blown out of grassy meadows and onto the water. Trout often will attack the struggling insects with aggressive, splashy rises. Even on windless days, a high-floating hopper pattern often will be greeted enthusiastically. Bumblebees occur in natural meadows with plenty of flowering plants, and these fat insects will get the attention of trout, too. A black foam-bodied beetle pattern provides a reasonable facsimile of a bumblebee.

forested
Forested watersheds are essential to the health of many rivers and lakes. Their soils absorb rainfall, reducing winter runoff and recharging shallow groundwater, which augments streamflows during the dry summer months. Forest insects can get blown onto the water during windy days, to the advantage of the fish that live there.

Forests

Many of California’s rivers, creeks, and lakes are surrounded by forests, or at least have their headwaters in forested areas. These tree-dominated ecosystems interact with bodies of water in many ways. The most obvious parts of trees are their leaves and branches, which help reduce soil temperatures through shading and lessen the impact of rain on the soils, thereby reducing erosion. The leaves are also where photosynthesis creates sugars that feed the tree and numerous other organisms.

Leaves that fall to the ground create duff, which further reduces soil erosion and also acts like a giant sponge. This slows runoff and reduces moisture loss from the underlying soils, which helps regulate shallow groundwater f lows to streams and still waters. Below ground, the tree’s roots help stabilize the soils and also have a symbiotic relationship with fungi and bacteria. The relationship with fungi is especially important. The tree supplies large underground mats of fungi with sugars, and in return, the fungi provide the tree with nutrients such as nitrogen and phosphorus. These subterranean fungal mats can cover a wide area (the largest organism on the planet is a fungus) and provide food for numerous invertebrates such as worms, beetles, pill bugs, and millipedes.

A common phenomenon in mountain forests and the treeless alpine zone are upslope and downslope winds caused by daytime heating and nighttime cooling of the land. Upslope winds can waft terrestrial bugs such as grasshoppers, ants, beetles, bees, and wasps into creeks and lakes. If you f ind yourself f ishing a creek and the wind is blowing, try a high-floating beetle pattern on a short (6-foot) leader. The short leader will help make casting in the wind a bit easier, but accuracy isn’t all that important. Try to get the fly close to seams that are carrying leaves and other wind-blown debris. This is where the fish likely will be expecting something fat and juicy. The rises to these patterns can be spectacular. And don’t curse at the leaves that occasionally mess up your presentation, because they provide a significant food source for the nymphs that feed the trout.

Anglers who fish mountain lakes and streams can sometimes find themselves in what appears to be a biblical flying-ant plague. These swarms are caused by carpenter ants, which form large colonies in dead and decaying wood. While we may see ants as pests, they are an integral part of the forest ecosystem, feeding on insects and beetles that attack trees and also helping to create topsoil. They typically range from a quarter of an inch to half an inch long, with black, brown, or red-and-black bodies.

From the spring through the early fall, winged adult ants form large swarms that can end up f lying over the water. They aren’t particularly strong fliers, and the surface can quickly become littered with ants. The fish seldom ignore them. Ants, of course, are a completely natural food, but I wonder if recently stocked hatchery f ish might mistake them for food pellets. When it comes to flies, the good old foam ant is hard to beat.

Often enough, you’ll see fish rising to ants, but it’s easy to underestimate the number of fish in an area based solely on the number of rises. If you look very carefully, you may be able to spot the subtle wrinkles in the water’s surface that betray trout moving just below. If there is a slight breeze, the fish usually will travel upwind, but on a calm day, they can move quite haphazardly. By all means, cast to where you think a fish will be, but sometimes it’s better just to leave the fly in the water and wait for a fish to come by.

A significant number of ants sink, and it’s possible some fish will be selectively feeding on these. You can cover your bases by fishing an ant version of the hopper-dropper setup, with a wet ant pattern suspended just below a foam ant.

Fire

As has become painfully obvious to pretty much everyone in California, forested areas are subject to fire. Federal data show that over the past 60 years, there’s been a steady increase in forest fires in the West, and over 60 percent of those fires have occurred since 2000. It also shows that mega fires (more than 100,000 acres) increased in the past two decades. In fact, no mega fires were documented prior to 1970. Regardless of whether you believe this increase in number and size of wildfires is just part of a long-term natural cycle or the result of climate change and decades of fire suppression, there’s no denying these events affect the fish and the creeks, rivers, or lakes they inhabit.

As discussed above, forests and riparian areas provide food for fish and countless other animals. When these areas burn, the food they supply can diminish or disappear, affecting the entire aquatic ecosystem. In addition, extreme fire events may change the makeup of the soils, creating a waxy layer that repels water. This means the soil can no longer act like a giant sponge, resulting in increased runoff and reduced percolation. More runoff means the fish will have to deal with higher than normal f lows during rain events, while reduced percolation means less recharge of shallow groundwater, resulting in lower-than-normal flows during the dry heat of the summer. Increased runoff also means greater erosion of unprotected soils, which can affect water quality and also the composition of the streambed. A study at Angora Creek in South Lake Tahoe showed an eightfold increase in fine sediments and a sevenfold reduction in cobbles. This effect extended several miles downstream and lasted for over two years. Since the nymphs of many mayfly, stonefly, and caddisfly species require clean-flowing streams, excess sediments will reduce the abundance of these insects.

For higher-elevation creeks and lakes with limited aquatic productivity, the impact of fire in the watershed can be especially hard. The reduction in food coming from the watershed will reduce the number and size of the fish. The time it takes for things to get back to normal depends on how quickly the forest recovers. For particularly intense fires, this might take decades.

If you’ve been near a wildfire, you’ll be familiar with the gray carpet of ash that coats everything. With particularly large fires, ash can travel for many miles, affecting unburned watersheds. A wildfire ash study in the Gila watershed in New Mexico showed dramatic impacts on nymphs and other aquatic invertebrates in areas with heavy ash deposits.

These effects lasted for almost a full year. Wildfire ash has also been shown to increase nitrogen and phosphorus concentrations rapidly by as much as sixtyfold over the background levels. This can fuel rapid growth of algae and bacteria, potentially leading to lowered dissolved oxygen levels at night.

Wildfire suppression activities can also affect water chemistry. One of the common fire retardants contains ammonium polyphosphate, which can also act as a fertilizer. When rains wash the stuff into the water, it adds to the fertilizing effects of the ash fall. As if ash and fire retardants aren’t enough of a headache, smoke can affect fish, too. The study at Castle Lake found that trout abandoned the shallows they normally inhabit when the air was full of smoke.

Dams

Many of California’s reservoirs were formed by placing a dam across a river. If you have fished these lakes, you’ll know how productive they can be. In addition, a number of dams have created incredible tailwater fisheries, where cold water from behind the dam is released downstream. These flows can vary, however, across the course of a day, or many days, or months, and these variations can affect how well a tailwater will fish (Editor’s Note: See Ryan Johnston’s story in this issue on fishing the lower Sacramento River). You can often get f low information and its effect on fishing from fly shops in the area, and an internet search might also turn up useful advice.

dams
Hundreds of small dams block the passage of salmon and steelhead on many of California’s smaller streams. A lot of these dams no longer serve any purpose, such as this dam that is filled to the brim with trapped sediments (on which the photographer is standing). The removal of small dams is politically and technically much simpler than the removal of big dams. By eliminating them we can help salmon and steelhead gain access to thousands of miles of ancestral habitat.

Although dams can sometimes enhance downstream fisheries, they don’t come without an environmental cost. An obvious cost is that they block the spawning runs of anadromous salmon and steelhead, which can have a severe impact on the sustainability of these fish. Also, while it’s a bit of an oversimplification, rivers generally transport nutrients away from their watersheds and into the ocean. Nature reverses this process when salmon return to the watershed to spawn after several years at sea. Nitrogen is an important nutrient, since it is essential for proteins and DNA. A study in an Alaskan stream showed the majority of nitrogen in aquatic plants and animals was of marine origin. Put another way, more than half of every non-anadromous trout in that stream was made of salmon. Other essential marine nutrients, such as phosphorus, sulfur, magnesium, copper, iron, and sodium, are also delivered by salmon. Just how dependent a watershed is on marine nutrients is influenced by its geology and biology. That said, it’s not hard to see how eliminating salmon can have an effect on the productivity of the river and its watershed. This is what happens when rivers are dammed, especially when those dams are not fitted with effective fish ladders. Without a compensatory delivery of nutrients, the stream and its watershed will become less productive. Studies have shown that the reduction in salmon runs in California has reduced nitrogen and phosphorus inputs to watersheds to just 7 percent of their historic levels.

Dams now block salmon from more than 90 percent of their historical spawning habitat. We hear about the removal of large dams such as those on the Klamath, and such big projects are incredibly important. However, many of the state’s large dams provide critical flood protection and water storage, with an economic value of more than $40 billion a year. Improving fish passage at these dams is probably a more realistic goal than removal.

While big dams get the majority of our attention, California is riddled with small dams that block salmon (and steelhead) from accessing thousands of miles of spawning and rearing habitat in numerous rivers and creeks. These dams were built long ago, and many no longer serve any purpose. The removal of these dams is politically and technically far less challenging and represents a very real opportunity to make a big difference.

Dam Busters

This is where you can get involved. Type “California Fish Passage Assessment Database” into your search engine of choice, and you’ll get directed to the California Department of Fish and Wildlife’s page of known and potential barriers to fish passage. The map viewer allows you to click on specific barriers, and a table at the bottom provides details on the barrier, the landowner, and a recommendation for action. The page also provides a 2011-to-2019 list of fish-passage priority sites that shows barriers the CDFW believes have willing partners, land access, and political support for removal.

If you find a listed barrier on a river or creek that’s important to you, take a few minutes to search online to see if the state or a local government is planning to remove it. If not, contact folks who share your passion for the water and arrange for everyone to send emails to the appropriate political representative. You’d be surprised how responsive local government can be when a good environmental cause is brought to their attention.

Another option is to support groups that are involved with the watershed. I’ve been on the board of the local Resource Conservation District (RCD) for a number of years. Along with federal and state government departments and local nonprofits, RCD staff have worked with private landowners who voluntarily have allowed the removal of several dams in Santa Cruz County. After many fishless decades, these creeks are once again home to steelhead and coho salmon. I can’t begin to tell you how rewarding this feels.

I hope this simple overview of watersheds will make all your fishing trips more productive. And if there is a special river or creek in your life that is blocked by a dam, get involved and be part of bringing the damn thing down.  

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