Science of the Seasons: Stone cold crazy in love

It snowed again this week and spring seems to have been put off again. After a long winter, many of us are ready to see a color change from pure white snow (perhaps with a little gray volcanic ash as an accent) to the shades of green that spring offers.

Various trees are showing bulging catkins that are preparing to pop open, and swelling leaf buds will soon give rise to the next generation of leaves. A postponement of what we think of as spring may occur, but changes are ongoing in the streams, whether we know it or not.

If we could see underneath the ice cover of streams and rivers today, there are subtle changes happening. A fair number of aquatic insects have been feeding and growing during the winter months, and some will emerge as adults within a couple weeks. One of the early emerging insects from the Kenai River is a group of small stoneflies (Plecopterans), commonly called winter flies or winter stoneflies. They get these names because they can often be seen crawling on the snow and ice in the late winter or early spring.

Two weeks from now there will be thousands of tiny black, Capnidae stoneflies emerging from gravel substrate areas. If you happen to walk along the river, perhaps near Slikok Creek, every large rock along the stream edge will be crawling with slender, half-inch long stonefly adults. A close examination will reveal that these little insects have transparent wings folded flat on their backs, indicating they are in fact adults and no longer nymphs.

They aren’t very strong fliers so they prefer to crawl. You’ll find them crawling all over you if you sit down for any length of time or even stand still for a few seconds. They do not feed as adults and will see you as a tall, drumming platform and a possible place to find a mate. One might argue that they are “looking for love in all the wrong places,” but there will be lots of them using you as their personal dating service.

In some years the Kenai River ice cover has been melted away by now. This year it seems that the ice cover could remain intact during their chosen emergence period; but that will not deter their massive emergence. Most of these insects use light duration as their “zeitgeber” or timing cue, and they don’t really care if there is still ice cover or not.

Hidden from our view are air-filled spaces beneath the ice because of lowering river levels. There are lots of exposed rocks or even ice surfaces for the insects to use as an emergence platform. Winter stoneflies can emerge underneath the ice cover, find a mate, lay eggs and die, all hidden from the gaze of curious entomologists or insect predators.

For shortlived aquatic insects, and these stoneflies might only survive for two weeks, synchronous emergence of the entire population is important. By having most members of the population becoming an aerial insect at the same time, there is a high likelihood of everyone finding a mate. Since they are emerging early in the spring, very few avian predators are around to disrupt their party.

Along the Kenai River, various shore birds, like lesser yellowlegs, will work the shoreline, feeding on as many stoneflies as they can, but they cannot eat them all. These winter stoneflies will emerge by the tens of thousands so the predators that do appear will soon become satiated. The surviving flies will be able to complete their reproductive duties.

Because of a diverse number of microhabitats in the Kenai River, there are a fair number of different species of stoneflies. This species diversity probably comes from the variety of possible food sources available for stoneflies. Many, like the winter stoneflies we’ll be seeing in a few weeks, are leaf shredders. They feed on leaves, mostly those from riparian trees that are infested with nutrient-rich bacteria and fungi. The nymphs (immature stoneflies) chop the leaves into fine fragments and pass them through their gut. Because their guts are relatively inefficient — they can only extract about 5 percent of the nutrients they take in — they process a lot of leaves. Now you know why we don’t find many leaves in the river after the ice melts.

Another guild of stoneflies are active predators on smaller aquatic insects. These predators target the most abundant stream insects, the midge larvae and young mayflies. Some stoneflies combine the two lifestyles by starting their nymphal careers as a detritivore but slowly change into omnivores and eventually become predators.

Perhaps one of the most interesting aspects about many stoneflies is their novel approach to finding a mate. The males will crawl into a nearby shrub or tree and begin to “drum” on the limb with their abdomen. A receptive female, upon sensing the drumming, will answer with her own abdomen tapping and crawl toward the male virtuoso. Eventually the male will find the responding female and they mate. Each stonefly species uses a unique drumming cadence so inappropriate species are not attracted. Eggs are then laid on the stream surface or along the shoreline on submerged structures like a rock or tree limb. Soon stonefly nymphs hatch out and start the yearly cycle again.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River watershed.

Science of the Seasons: Little insects have huge role in Kenai River ecosystem

Over the past couple weeks, the Kenai River channel has been slowly opening.

Initially there was only a patch of thin ice at the outlet of Skilak Lake and then a few small areas of open water about a half-mile downstream. A number of overwintering swans and a few mergansers used these open-water areas to forage for food and find a little protection from predators.

Then the river channel opened up about a mile farther downstream. This slow downstream opening of the river will continue as the days lengthen and temperatures rise. Usually in April, the entire river will have an open channel with slabs of ice along each bank.

As the river opens and spring seems to be arriving, a number of aquatic insects will start to appear along the shore. Some of the very first insects will be a number of species of the dipteran family called chironomidae or “midges.”

These insects start emerging from the water when it reaches about 0.5 degrees Celsius. A large number of species of midges will emerge throughout the summer and fall until the water temperatures fall back down toward freezing again in late October or November.

We know at least 88 different species of midges live in the Kenai River. They are certainly the most abundant group of insects in this river, and probably the most abundant group in any freshwater river of the world. Not only are there more species of chironomidae than any other aquatic insect in the river, they are also going to be the group of insects with the largest number of individuals. It would surprise most people to know that there are probably around 100,000 midges that grow, develop and emerge from every square meter of river surface area. That equates to some staggeringly large numbers of insects emerging from the river each year.

Anyone who has traveled along the river in summertime has probably seen swarms of tiny bugs along the shoreline on a sunny day. These swarms of miniature, mosquitolike insects are mating swarms of midges. The males form the swarm and use a species-specific pitched sound to attract females. The females enter the swarm, mate and fly off to lay their eggs. Females can lay thousands of eggs in masses that stick to twigs, rocks or debris along the shore.

The eggs may hatch immediately into tiny larvae or may delay their development until many months later. These young larvae feed on algae, diatoms or fine detritus in the stream or river. Once they reach a certain size, they become pupae. After only a few days as pupae, they emerge and fly away as aerial insects. The adults usually do not feed, although a few are known to take in some sugar-rich fluids from flowers. The adults quickly mate and die within a week or two.

When the pupa becomes an adult, the pupal skin is left floating on the water surface. These pupal skins, called exuviae, remain on the water surface for a couple days and can be collected and identified to species. By collecting these exuviae, I was able to identify which midges were found in the Kenai River and when they emerged.

Even though these insects are only a couple millimeters long, they are a very important component of the aquatic community. They are a favorite food for virtually every species of fish. Young salmon fry feed heavily on midge larvae, pupae and adults. Many of the aquatic insect predators, like stoneflies, frequently feed on midges, too.

If you have ever seen swallows flying back and forth over the river or along most streams, you have seen another predator feeding heavily on midges. Because the adult midges are so small, we rarely recognize what the swallows are capturing. Dragonflies are well-known for feeding on mosquitoes, but they are also a major predator of adult midges.

While midges are certainly some of the smallest aquatic insects in the river, they play a disproportionately large role in the food web because of their high diversity and enormous numbers.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River watershed.

Science of the seasons: Stream debris can be good for fish, insects

The first raft or boat trip on the Kenai River each spring is a new adventure because the river will have changed significantly since the last trip in the fall. There will be new channels and unknown shallows that have to be noted in order to avoid costly repairs to the boat bottom or prop. Along with the substrate changes are the arrival or removal of large logs and, sometimes, entire trees. Sections of a river with significant numbers of logs and stumps are usually given a wide berth by boaters.

Logs and stumps are transients in the river until a large flood or ice jam washes them downstream. Eventually they will end up in the inlet and can create their own hazard out there. While in the river, however, the logs can have a significant impact on surrounding substrates and can become a temporary microcosm of riverine organisms, especially fish.

Most floating trees and logs are the result of normal bank erosion as the river meanders within its flood plain. “Sweepers” are frequently seen on the outside of river bends as the tree-supporting substrate is slowly washed away and trees bend over the river. As more and more of their support washes away, they dangerously skim the river surface until being completely uprooted. Once floating free, the strong current carries them downstream to the first shallow section. The limbs and branches are lighter and have more surface area than the stump and trunk end. Because of this, the heavier stump end tends to get dragged, begrudgingly, downstream.

Once a log or tree becomes “grounded” in the river, it starts changing the river substrates nearby. Water washing up against the unmoving trunk or stump will create a deeper hole below or to the side. Other areas along the log will slow the current so that sand, gravel and cobbles will be deposited there. By deflecting parts of the current, new channels will be created around the log. Some of the substrate and channel changes will in turn cause the log to be washed farther downstream. The process begins again as soon as the tree stops.

Once one log gets solidly lodged in the current, others seem to be attracted. In a fairly short period of time, with the arrival of new trees, large logjams can develop. As the numbers of logs build, so does the impact on the original water-flow pattern. Logjams can cause water to be diverted far from the original course and new side channels can be formed. These side channels create a variety of new pathways for the water to flow downstream.

Streams with numerous side channels are much more difficult to navigate with a motorboat than those with a clearly defined channel. However, rivers with more logjams, as well as an increased number of side channels, seem to have much fewer flash floods compared with rivers that have had logjams removed. By diverting water into numerous areas of the flood plain, the water moves downstream more slowly and is less able to erode away constraining lateral banks.

Various aquatic insects will use trees and stumps for an in-stream residence. Since many insects feed on fine, drifting organic particles found in the water , a spot on a tree limb with water drifting past is the best seat in the house. Some, like hydrospychid caddisfies, build filtering nets on these wooden substrates. Others, like black fly larvae, attach their abdomen to the limbs and filter out fine particles with special antennal fans. Because algae and diatoms will grow on the submerged wooden substrates, algal grazers will also be attracted to the logjam. In streams with soft, muddy bottoms, logjams and submerged trees can be some of the only available insect attachment sites.

For fish, and the astute fisherman, logs and stumps along a river are attractive areas. Because of the deeper channels around the logs, fish can find passageways if they are moving upstream. There are usually sections underneath the logjam where the current is slower than the surrounding stream and these areas are used as a fish refuge. Other fish will remain in the deeper sections underneath the log and wait for drifting or dislodged insects to wash right to them. Light shadows created by the tree or its limbs will also camouflage fish from potential predators. It’s kind of like an all-you-can-eat buffet for the fish in a sheltered restaurant.

Like virtually every other part of a stream or river, there are constant changes in the submerged trees and logs, as well as the rocky substrates around them. While these dynamic habitats can be dangerous for boaters, they can be a blessing for aquatic insects, fish and fishermen.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River watershed.

Wading into debate over arsenic risks — Many factors to consider in finding safe level of contaminant in area water supply

Editor’s note: This is a continuation of an examination of arsenic levels in drinking water. For last week’s story, on March 4.

By Jenny Neyman
Redoubt Reporter

When Susan Bulkow, the local Alaska Drinking Water Program coordinator with the state Department of Environmental Conservation, gets a phone call from a central Kenai Peninsula resident asking about arsenic in the water supply, the question is usually straightforward:

Should I be concerned?

Her answer isn’t straightforward. In most cases, there is no simple “Yes” or “No” to that question, because there are no simple answers to many questions regarding arsenic.

The best Bulkow can do is offer information, wade carefully into the debates that swirl around arsenic contamination, and let residents decide the answer for themselves.

Epidemic or not?

A few things are widely agreed upon when it comes to arsenic — it’s here, and it’s bad for you. It’s been linked to cancer, and can contribute to a slew of other health problems, including fatigue, skin damage and problems with the circulatory system. Some level of arsenic routinely shows up in water samples across the central peninsula, in city and private wells.

What does that mean for peninsula residents? Is arsenic an epidemic that warrants a run on bottled water and filtration systems, where every glass of tap water is a tumor waiting to happen?

Or is it less dramatic than that — more a cause for routine concern, like replacing smoke detector batteries and making sure the garage door is open when warming up the car?

It’s a difficult question to answer, because some of the information necessary to make the leap from “if this” to “then that” is missing.

The biggest hole is in records, as a result of regulation. The Environmental Protection Agency regulates and monitors arsenic levels in public water supplies — from cities and other municipalities — but there is no oversight of private wells. Banks require water quality tests on nitrates and coliform bacteria levels in private wells when homes are bought and sold, but no entity requires arsenic testing.

As a result, and since arsenic is undetectable by taste, sight and smell, many homeowners on private wells simply don’t know how much arsenic is in their water. And there are no comprehensive records of arsenic levels in private wells on the central Kenai Peninsula to accurately gauge how widespread contamination is.

There is anecdotal information available, but some points to arsenic being an epidemic problem, and some points the other direction.

Dr. Robert Thompson, with a practice in Soldotna, said he has recommended over 1,000 patients get hair mineral analysis done in the past five years, which in part measures the level of arsenic in their systems. He believes arsenic is a significant concern.

“It’s a huge problem on the peninsula. About 80 percent of the wells, based on the testing I’ve seen, have high arsenic levels,” Thompson said. “I’m more surprised when they’re not elevated than when I see them when they are elevated.”

Mike Polocz, who offers arsenic testing with Culligan Water, said he’s routinely found high levels of arsenic in private wells he’s tested —up to 70 parts per billion or more. He agrees with Thompson that high levels occur particularly in certain areas, including Sterling, along Kalifornsky Beach Road and near Sports, Longmere and Mackey lakes.

Mike Tauriainen, owner of Tauriainen Engineering and Testing, in Soldotna, which is certified to conduct water analysis and forwards water samples to Anchorage for arsenic testing, said arsenic isn’t a huge concern.

“It varies from nondetectible — below the detection limit, probably down under 1 part per billion, which is an incredibly small amount — to over 100 parts per billion. But that’s uncommon. We have seen a few samples come in at over a hundred,” he said.

Tauriainen estimated that 1 percent to 5 percent of the water samples he sees test high for arsenic.

“We are blessed with pretty good water on the peninsula, as far as health concerns go,” Tauriainen said. “My personal opinion is that it’s generally not a very significant factor, but some people are more sensitive to different minerals, including arsenic. At the allowable level of 10 parts per billion, I don’t think that there’s any significant cause for concern.”

He also said he hasn’t seen evidence of arsenic showing up in higher concentrations in some areas than others. Arsenic levels, and water quality in general, can vary by area, but well depth probably has more to do with arsenic than location, he said.

“We really haven’t done a study of it, but I haven’t really noticed that one particular area has more than others,” Tauriainen said.

“Typically, the deeper the well, the more likely it is to have arsenic, because water has been in residence longer with arsenic. But it’s not a hard and fast rule.”

A rising tide?

A misperception Bulkow has heard is the level of arsenic in the water supply is rising.

“I’m not aware of there being an increase associated with arsenic,” she said.
There has been a concern that earthquakes and seismic activity lead to an increase of arsenic in water, but that’s probably not the case, she said. Probably.

“It is possible that some earthquakes could loosen deposits, and you could temporarily see an increase. We don’t know. We haven’t actually done that kind of testing to substantiate those claims. We have had other people tell us that they believe there is a correlation,” Bulkow said.

Tauriainen said he doesn’t think the typical magnitude of earthquakes felt on the central peninsula cause long-term changes in water quality.

“We don’t have evidence of that. We have not done a study, but normally the levels will stay roughly the same,” he said.

Maybe if the central peninsula contained more bedrock, earthquakes might fracture the rock and introduce more arsenic-bearing sediments into underground aquifers. But central peninsula communities sit on 1,000 feet of unconsolidated sediments, Tauriainen said, which may shift around during earthquakes, but don’t crack or undergo a large amount of upheaval.

However, aquifers can and do change, and wells can go dry or produce more water, or bring up new sediments if pumped hard. All of which could potentially affect water quality.

“If you’ve never tested private wells for (water) quality, you should, and if you have tested it in the past, it doesn’t hurt to get tested again to make sure you’re comfortable with those test results,” Bulkow said.

She said the increased buzz about arsenic is more likely due to increased attention on arsenic than increasing arsenic levels. The increased attention has come because the Environmental Protection Agency lowered the limit of arsenic contamination allowed in public water sources.

The maximum contaminant level was lowered from 50 parts per billion to 10 parts per billion in 2006. The lower limit meant an increased number of water sources exceeded the allowed level of arsenic, but it doesn’t mean the amount of arsenic changed, Bulkow said. It’s just that 40 ppb was considered fine prior to 2006, and over the limit post 2006.

Reaching the limit

How much is too much is a basic question in determining a resident’s risk from arsenic, but debate swirls over what that level should be.

Prior to 2006, the EPA’s maximum contaminant level of 50 ppb was thought to be the difference between safe and not. And some people still think it is, even after the maximum contaminant level was lowered to 10 ppb.

“There’s a lot of conflicting data on arsenic. People believe the mcl is too high, and there are some that say the mcl is low,” Bulkow said.

“EPA is constantly looking at new research data that’s available to determine whether their current standards are consistent with what is being discovered in the lab and through reporting of discoveries and through the CDC (Centers for Disease Control and Prevention) and other agencies. If they look at the data and decided the mcls were set too high, they revisit them and lower them. That’s what they did with arsenic,” she said.

Opponents of the lower mcl level point out that many of the studies done on arsenic took place in Third World countries, where poverty, poor sanitation and other factors already contributed to compromised health, Bulkow said.

She also said the arsenic limit assumes a sole water source, which typically isn’t the case.

“The mcl is set on the idea people drink the same water source every day all your life — 2 liters a day out of the same source. Most people don’t drink all their water all their whole life from one source,” she said.

Arsenic exposure of 200 ppb is toxic to a human. But arsenic is bioaccumulative, meaning even low-level exposure over time can build up to the point where it impacts health. Having over 10 ppb arsenic in a person’s system can increase their cancer risk by 30 percent, Thompson said.

But people, just like their wells, are different. Some people are more susceptible to effects from arsenic than others, just as some may drink more water than others. Even among the heavy water drinkers, some get more from their home water source, while others drink it from work, bottled from the store or from other sources.

All those variables make it difficult to determine one standard limit that is theoretically safe for all, whether it’s 10 ppb, 50 ppb or somewhere in between.
“We have to set the level someplace, so EPA is saying 10 is the level you should be concerned about. We have to draw the line somewhere, and the lines move,” Bulkow said. “It’s always based on more evidence and study and EPA is trying to do the best we can to protect public health with data we have at the time.”

Rather than being concerned over where the limit is set, Bulkow recommends residents use the 10 ppb limit as a guideline for considering their own individual arsenic exposure risk and deciding what they should do about it.

“I think what they should be concerned about is whether they have arsenic in the water and whether it should be treated,” Bulkow said.

She said people should have their water tested by a certified lab, discuss those results with their physician and a water treatment professional and decide from there whether, and how extensively, they should filter their water.

“They can look at the overall exposure risks that they have and look at their treatment options. I don’t want people to overreact because they all of a sudden find out they have arsenic in their water. But nobody ever feels like they’re overreacting to public health risks. I just want people to take it into perspective,” Bulkow said.

In the absence of regulations extending to private water sources, individual choice comes to the fore.

“Between 10 and 50 parts per billion, according to the EPA, is a concern,” Tauriainen said. “I’m not sure that it is, but for some people it is a concern. If somebody isn’t sleeping well at night because they’re worried about their water, it’s worth putting some kind of treatment on it.”

Bugging out: Mayflies will soon spring into action

March may seem a little early in the spring to talk about mayflies, but they are currently active on the bottom of virtually all of our streams, rivers and lakes.

Resident trout and whitefish here in Alaska use the many species of mayflies for food all year long. Because of this, mayflies are well-known to fly-fishermen, since they are the model for a large number of dry and nymph fly patterns.

It is also well-known that nymph patterns attract fish more frequently than dry flies. This is easily understandable since most mayfly species spend almost the entire year underwater in a nymphal form, and only a day or two as an aerial insect. The mayfly order name, Ephemeroptera, comes from the Greek “ephemeros,” which is a referral to the short-lived adult stage. While many mayflies can survive a couple days as an adult, some members of the group have adult stages lasting less than two hours. During that short aerial life stage, they have to molt once, find a mate, migrate to a water body and lay eggs. Talk about having a lot to do in a short time.

Most mayfly nymphs, or naiads, feed on fine particulate detritus or algae in the water. Some filter the tiny food particles out of the water column with hairs on their legs while others scrape the surface of rocks and gravel. Some species have brushlike mouth parts to scrub algae and detritus from almost any submerged substrate. The grazing of mayflies has been shown to significantly reduce and actually control the algal cover on submerged rocks.

With a very short time to find a mate and reproduce, most mayfly species choreograph their emergence so everyone emerges together. When the proper light and temperatures cues occur, the entire population can emerge in a matter of a few days.

My father used to tell of using snow shovels in the 1930s to clear walks and roads in July after the Hexagenia mayflies emerged en masse from the Mississippi River near La Crosse, Wis. Several years ago there was such a large emergence of these same mayflies from Lake Erie that the swarm was picked up on radar and were thought to be unidentified airplanes in the area.

Once the females have mated, they head to a stream, river or lake and fly just above the water surface to drop small packets of eggs. The flying female will often fly up and down over the water, each time touching her abdomen to the water surface and releasing a few more eggs. This behavior will go on until all her eggs, 500 to 3,000, are released. Incidentally, this is when trout rise and start taking insects off the surface of the water or start jumping out of the water after aerial insects. Because the female mayfly is carrying masses of energy-rich eggs, it is a sought-after meal by many fish species.

Mayfly eggs immediately start to absorb water once they are deposited. They become sticky and end up bound to rocks, leaves, twigs or vegetation. Depending on the species, they may hatch right away or possibly remain in diapauses for several months.

Depending on the species and the temperature regimes, some species can produce several generations a year. In colder climates like here in Alaska, most mayflies have only one generation per year. Sometimes, in cold years or very old habitats, it may take two years to complete one generation.

In the fast-moving current of streams, mayflies use a couple strategies to keep from being washed downstream.

Since currents are much reduced right up against a rock, one approach is to have their thorax, head and legs flattened so they can remain very close to the substrate. Others have modified thoracic gills that act like a giant suction cup, which then holds them against the solid substrate. Yet another group of mayflies use a disk of fine hairs on their abdomen that can also act like a suction cup to hold the insect in place in spite of the current. Incidentally, there are several species using this approach in the Kenai River.

Another survival approach for these aquatic insects is being streamlined or torpedo-shaped.

This shape allows fast-moving water to pass by the mayflies without washing them downstream. By wriggling their abdomen they can swim much like a fish and move about in fast-moving water. This same technique enables mayflies in lakes to quickly move to hiding places and escape predators.

Mayflies are one of the most common aquatic insect orders, and they are found in fresh water all over the world. Apparently their many adaptations for survival in different habitats have enabled them to survive for millions of years. They are among the oldest of the insects and date back to the Carboniferous period.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River watershed.

Guest column: Following a murky trail

Storm water may lead to pollutants muddying up Kenai creeks

The Kenai Watershed Forum has discovered that in the past several years, No Name Creek and another unnamed creek in Kenai have shown a trend of elevated turbidity levels. Turbidity is a way of measuring the cloudiness of water and can be caused by natural sources, like glaciers, or human sources, such as storm drains. Extremely high turbidity levels can kill salmon, and elevated levels can make it difficult for salmon to find food or migrate.

So where exactly is all the turbidity coming from? To answer that question, KWF employees spent last summer walking the streets of Kenai to establish where water travels during a rainy day before it enters creeks. As one astute observer pointed out, water flows downhill. Indeed, Kenai does not have any pumping stations, so all storm water travels by gravity to the outlets. However, Kenai’s storm-water system was implemented in pieces as the city grew, so storm water sometimes follows more of an illogical pattern, depending on the construction of roads rather than natural topography.

To find out the path of storm water and the pollutants it can carry, KWF used a Global Positioning System unit to determine the coordinates of culverts, manhole covers and storm-drain inlets and outlets.

A construction level and observations on rainy days were utilized to clarify which direction storm water travels through ditches and gutters that eventually drain into No Name Creek and the unnamed creek.

Once the series of storm drains and gutters were mapped out, this data was used to build a drainage network in a Geographic Information System. This digital drainage network provides a better understanding of how the different areas of Kenai are linked to No Name Creek and the unnamed creek. In a few weeks, monitoring equipment will be placed where the storm water connects to the stream and water samples will also be collected. Using the GIS, monitoring equipment and water-quality collection in unison will help narrow down potential sources of water pollution that are being flushed into two of Kenai’s creeks and harming salmon habitat.

Jennifer McCard is a watershed scientist at the Kenai Watershed Forum.

Science of the seasons: Rocks star in creating good fish habitat

If you think about your favorite trout streams, or perhaps the secret fishing holes you only share with your very best and most trusted friends, there are probably some strong similarities between these streams.

These similarities are most likely going to be related to stream substrates. While stream substrates may seem to be an entirely esoteric subject, it is the characteristic and diversity of stream substrates that salmon check carefully when deciding where they will spawn. Not only do salmon use the gravels, cobbles and boulders as a determinant for spawning, but these same substrates are home to the community of aquatic insects that trout and salmon fry feed upon.

It is well-documented that aquatic insects prefer to be in streams with a mixture of various-sized stones. Insects are most abundant in streams with heterogenous substrates, but their numbers decline dramatically when the fine particles make up more than 20 to 30 percent of the substrate material. These fine particles are defined as being various-sized sands — 0.8 millimeters to 0.12 millimeters — or silt and clay particles — 0.006 millimeters or smaller.

As you can imagine, glacier outflow streams here in Alaska with high levels of fine sediment are poor habitats for most aquatic insects, and salmon don’t like to spawn there, either.

The amount of fine sediments in the substrate mixture is referred to as “embeddedness.” Spawning salmon look for stream areas with low embeddedness and prefer areas with large gravel, cobble and small boulder substrates. The most sought-after spawning areas are those just above a riffle section where water percolates down — downwelling — into the gravel substrates below. This water flowing through gravel brings oxygen to growing salmon eggs that settle into the lower, or deeper, substrates. The spaces between the larger gravel bits provide a home for aquatic insects that alevins and young salmon fry can feed upon. While seemingly unimportant, there is a lot of activity in the stream substrates that we don’t get to see.

The downwelling water flow can also carry fine sediments that fill in the spaces between gravel, especially if there were large amounts of fine sediments present. Too much fine sediment material would entomb and kill the young salmon residing deep in the gravel.

Over a period of years, fine sediment will clog the gravel below and make it less attractive to spawning salmon or trout. Fortunately, periodic high-water flows and stream flooding will wash out the fine sediments and re-sort the gravel. Then the area will become attractive as a spawning site once again.

Stream sediment composition can vary due to a large number of situations. Local geology and geomorphology plays a major role. Streams like the Kenai River that flow through old, well-washed glacier moraine gravel seem to have great substrate diversity. Next time you visit the Kenai River, notice the mixture of big cobbles, boulders, large gravel, smaller gravel and only a very small amount of fine substrates.

Unfortunately, there are a large number of ways that we as humans can change the mixture of substrate sizes in a stream. Some of the most problematic human activities are poor farming (tilling) techniques, road building, logging and large-scale mining. If poorly planned or improperly executed, all of these activities allow fine particles to wash into nearby streams.

In efforts to reduce the escape of fine particles from construction sites, low, black plastic fences and straw bales are placed in neat rows. These are arranged specifically to trap fine particles and prevent them from washing into a nearby stream.

While fine sediments in a stream can drastically reduce the aquatic insect population, at the other end of the spectrum, streams with only huge boulders also have reduced insect populations too. This interesting phenomenon usually occurs when there is a high gradient stream that has washed out most of the smaller gravel and cobbles. The major reason for this reduction in stream organisms is that the boulder substrates are fairly uniform and support only a small number of insects. The overall reduction in the insect population can then only support a small population of trout or salmon.

Diverse mixtures of stream substrates are critically important for the survival of a whole host of aquatic insects. These same rocky substrates create habitats below the surface of the stream that salmon search out for spawning. If these gravel, cobble and boulder substrates are changed, particularly with additions of fine sediments, salmon will avoid the area or have limited success in spawning.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the biology of the Kenai River watershed.

Something to chew on: Circle of life, beaver style

Every school-age child knows that beavers dam up streams, and it is a compliment to be described as being “busy as a beaver.”

These two thoughts are related, since beavers do spend long hours cutting down trees and then weaving the branches into a functional dam. Their impoundments require constant upkeep and additions of new branches. Along with the woody components, beavers scoop up mud from the bottom of the impoundment and pack it in between the stick framework.

Beaver dams vary in size and height but are frequently 2 to 3 feet high. The beaver dam I studied for my master thesis was more than 200 feet wide and created a pond of almost half an acre.

There are a couple important benefits for the beaver that justify the extensive energy output during dam construction. Perhaps the most obvious benefit is to raise the water level upstream of the dam. The deepened, backed-up water provides a quick escape when confronted with potential predators like cougars, wolves or bears. Besides the safety aspect, the water inundates channels that then provide safe access to feeding areas upstream. These upstream areas are where beavers cut down trees that are used for food or construction materials. While beavers will often take down larger diameter trees, they seem to prefer the young trees that are only a couple inches in diameter. The smaller trees are completely covered with tender and edible bark. It’s like a beaver’s version of a corn dog on a stick.

The beaver pond can provide a series of shipping lanes for moving tree limbs to the lodge or to the dam. Another major role the impoundment plays is as a food locker. Beavers will store hundreds of freshly trimmed limbs and branches underwater. During winter, they can swim from their lodge (or from tunnels into the bank) to the underwater pantry to retrieve a submerged limb. After feeding on the bark, the now-bare sticks can be used for springtime dam repair.

Ecologists often describe beavers as a keystone species in streams. This connotation refers to the major impact beavers have on a stream and the surrounding habitats. The presence of beavers can change many important aspects of the stream, as well as conditions in the surrounding riparian areas.

Beaver impoundments inundate large areas of terrestrial vegetation and will literally drown out most of the original vegetation. Virtually all the inundated trees and shrubs will die. This usually leads to an increase in solar radiation, which provides opportunities for new species of plants and algae to grow. Sometimes sedges and other wetland plants will appear along the edges or right on the breast of the dam.

Construction of a beaver dam immediately slows the stream water and that causes deposition of many materials being washed downstream. Organic materials like leaves, twigs, grasses and fish carcasses, as well as mineral sediments, will collect on the bottom of the dam. This accumulated material will eventually become very rich soil.

Because of the deepened water in the beaver pond, many fish will use these areas as an overwintering refuge. Many resident salmonids in Alaska move out of streams in the winter months and seek out areas like beaver dams where they can be assured of unfrozen waters. Given the opportunity, young silver salmon fry will use a beaver pond for a wintering area or may use it for a year-round place to feed and hide.

Because of the excavations by beavers and scooped-up mud for stabilization of the stick-built dam, there tends to be a fair amount of fine silt downstream of beaver dams. Those silty stream conditions cause changes in the stream’s invertebrate community downstream of the impoundment. These differences in turn can cause alterations in the downstream fish populations, too.

Beaver dams are ephemeral structures. After beavers utilize most of the available trees, they begin to prospect for greener pastures, or areas with more young trees. With no beavers to perform repairs and maintenance on the dam, it will eventually give way and drain out. When a dam washout occurs, those previously underwater areas become terrestrial habitats again. With all the deposited materials creating rich soil, the newly exposed pond bottom quickly becomes revegetated with herbs and woody vegetation.

The released stream cuts down through the deposited silt material and returns to its original physical flow patterns. Soon, the original stream and riparian biota return too. Several years later, when the trees have regrown, the stream section will once again be an attractive site for another beaver dam.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the biology of the Kenai River watershed.

Low impact sparks high debate — Cooper Landing residents voice concern over hydro projects

By Jenny Neyman
Redoubt Reporter

Impact. That one word spurred on four hours of contention in a meeting Jan. 21 between Cooper Landing residents and representatives from Homer Electric Association and its associates that want to build four hydroelectric projects in the Cooper Landing region.

HEA representatives say the projects will be designed to be low-impact, meaning care will be taken to prevent substantive harm to the environment, fish and recreation. And they would be beneficial to HEA consumers, who are struggling with electric bills that rise along with natural gas prices.

Cooper Landing residents, however, classify building roads, tunnels and dams, changing lake levels, disturbing vegetation, altering natural water flows and drying up sections of salmon-spawning creeks as high impacts, especially when residents don’t stand to directly gain anything from the projects.

Brad Zubeck, project engineer with HEA, gave an overview of the projects in the Jan. 21 meeting at Cooper Landing’s Community Hall and explained why the energy co-op is pursuing them. Kenai Hydro has preliminary, three-year permits from the Federal Energy Regulatory Agency and a $50,000 grant for each project from the Alaska Energy Authority to study the feasibility of four hydro projects in the Trail Lakes area near Moose Pass — on Crescent Lake, Ptarmigan Lake, Falls Creek and Grant Lake.

Kenai Hydro was formed as a partnership between HEA and Wind Energy Alaska, which in turn is a partnership between Cook Inlet Region Inc. and enXco, a renewable energy firm. Kenai Hydro has contracted with HDR Alaska to do engineering and environmental study work for the projects, as well as Long View Associates to assist with the regulatory process.

Zubeck told the packed room of more than 50 attendees that HEA needs to find new sources of energy. Its current contract with Chugach Electric Association expires 2013, and HEA hopes to add 70 megawatts of new power generation at that point. As it stands now, about 90 percent of HEA’s power comes from natural gas-fired turbines. Rising gas prices have led HEA members’ rates to nearly double in the last year alone. Wind and hydro power plants, once built, would provide low-cost energy to stabilize rates and lessen dependency on natural gas, Zubeck said. The proposed hydro projects could supply 10 percent of HEA’s future needs, he said.

“The renewables will be one piece of that puzzle,” he said. “… The projects are not going to answer our challenge, but we think it’s a step in the right direction.”

Cooper Landing residents wanted to know why HEA is stepping in their direction at all, since power for Cooper Landing, Moose Pass and beyond is supplied by Chugach, so any rate decreases HEA members may see wouldn’t affect those living near the hydro projects.

Because that’s where the resource is, Zubeck said. The projects are promising, prior research has already been done on them and they’re close to transition lines, which helps make them affordable. The waterways are a state resource, which HEA is entitled to try and use, Zubeck said.

“We need to provide for ourselves. These are on the scale we can accomplish and meet the needs we have in the time frame we’re faced with,” Zubeck said.

“This is also a high-impact area for all the people who live here,” said Ken Green, of Cooper Landing.

Todd Bethard, an engineer with HDR Alaska, explained the project concepts as they stand so far (see related story). They entail a laundry list of elements that residents were skeptical of, if not adamantly opposed to, such as building roads, tunnels and dams, changing lake levels, altering natural creek flows and altogether drying up sections of streams that support spawning salmon.

“How do you have the audacity to tell me it’s low-impact when you’re talking about roads and tunnels? That’s major rape, pillage, plunder, slash and burn. Don’t try to tell me that’s low impact. You’ve got a lot of convincing to convince me of low impact,” said Phil Webber, of Cooper Landing.

Some projects drew more fire than others. A 1.5-mile long tunnel proposed for Ptarmigan Lake and creek, which supports productive fish habitat, generated several questions and comments about whether the 3 MW capacity the project is expected to generate is worth the construction costs and environmental upheaval the project would entail.

Zubeck conceded that he was skeptical the tunnel plan would proceed once HDR comes back with cost estimates.

“We’re looking at it. That’s all were doing now. That’s the stage we’re at,” he said. “…Honestly, I don’t think that Homer’s going to pursue this. We’re not trying to force this project, we’re just working with these concepts here.”

Crescent Lake was the other main sore spot with residents.

“You’re going to ruin some of the best fishing there is. I guarantee it. The best fishing is right under the outlet of Crescent Lake,” Webber said, about a plan to replace the footbridge across Crescent Creek at the outlet of the lake, in prime arctic grayling territory, with a concrete structure that would control water release into the creek and allow fish passage.

Zubeck assured the audience that they would protect grayling habitat and that HDR will conduct environmental studies on fish usage in Crescent and all the streams involved in the projects to determine what it needs to do to protect fish and wildlife in the areas.

“What they need, they’ll get. What they don’t need would go to power generation,” he said.

Audience members voiced skepticism that environmental studies would generate enough data to ensure the hydro projects wouldn’t inflict harm. Especially concerning were complex issues like whether water temperatures would increase after water is diverted through turbines, and what effect that may have on the ecosystem; and how disturbing natural water flows by drying up sections of creeks and eliminating natural flood events might impact everything from microorganisms and vegetation on up to fish.

“I have serious doubts that you’re going to be able to do that, and I don’t know. You’re going to have to convince me and everyone here that you can do that,” said John Thorne, of Cooper Landing.

“It’s not an easy job, I won’t kid you,” said Paul McLarnon, a biologist with HDR who is planning on conducting environmental research on the projects this summer.

Thorne wanted to know if there’s a predetermined amount of losses to fish and habitat that HEA and regulators would find acceptable.

“We don’t have a number,” McLarnon said. “We would provide that information to the regulatory agencies and work with them on that” — meaning FERC and the slate of state agencies that have a hand in approving permits will look at HDR’s research and engineering plans and determine if the likely effects and risks from the projects are acceptable, too great, or plausible with some plan modifications.

That being said, “It’s low-impact, it’s not no-impact. I’ve never worked on a project anywhere where there’s no impact,” McLarnon said.

Several audience members made it clear they opposed any impacts to the area, especially Crescent Lake.

“Right off the bat you’re going to get 10 percent (of HEA’s power needs) off these things, but the cost to the environment alone seems astronomical,” said John Belcik, of Cooper Landing. “For what you’re going to get off it, you’re looking at the most beautiful lake in the whole dag bern Alaska. We don’t need more people having access to it.”

Residents also voiced concerns about whether the regulatory and permit approval process was rigorous enough to adequately protect against environmental and recreational harms, especially since the Alaska Department of Environmental Conservation doesn’t review hydro projects to make sure they comply with the Clean Water Act, essentially leaving the decisions up to people in Washington, D.C.

But representatives from various state agencies in the audience pointed out that FERC and Alaska DEC aren’t the only organizations from which Kenai Hydro needs approval. The Forest Service, Fish and Game and various other agencies also have a hand in process.

Jim Ferguson, statewide hydro-power coordinator for the Alaska Department of Fish and Game, issued a bleak outlook for one element of HDR’s current plans.

“We’ve never authorized the dewatering of a creek, and I seriously doubt we would do that now,” he said. “We’ll certainly look at it, but I think that’s highly unlikely.”

Toward the end of the meeting, residents speculated on where the process would go. Thorne said he thought HEA was serious about two projects — Grant Lake and Falls Creek — and only included Crescent and Ptarmigan lakes because the effects from those seem so much more controversial that people would be relieved to just have Grant and Ptarmigan, by comparison.

Bob Baldwin, chair of the Friends of Cooper Landing, which filed formal opposition with FERC to Kenai Hydro’s preliminary permits, said everyone has a legal voice in the process.

“We are assuming this will not happen. The consultants here are working to see it happen. We will be working on the other side of this. … We are very strongly committed that Crescent Lake will not happen,” he said, to a round of applause.

Webber was less optimistic that the regulatory process would safeguard environmental concerns.

“I may look stupid, but I’m not dumb. You guys have made up your mind. You’re going to gather enough data and press on,” he said, accusing that the environmental study results would be used to make the projects look favorable. “Give me two pages and I can convince God that the sun rises in the east.”

Another public meeting will be held at 7 p.m. today, Jan. 28, at the Moose Pass Community Hall.

HEA details early plans for hydro sites

By Jenny Neyman
Redoubt Reporter

Kenai Hydro is in the preliminary stages of investigating the feasibility of four hydro projects near Moose Pass.

Todd Bethard, an engineer with HDR Alaska, explained the project concepts as they stand so far to a group of Cooper Landing residents Jan. 21. He said the projects are designed to limit visual impacts and harm to recreational and mining uses, fish and the environment.

Grant — Dam would make reservoir

Kenai Hydro is considering building a 9-foot-high concrete dam across the natural outlet of Grant Lake to use the lake for water storage, which would increase the project’s potential power output. The lake could hold 38,200 acre-feet of water, with the lake level rising 9 feet above and 25 feet below its natural elevation as water is stored and released. An aboveground steel pipe, called a penstock, would follow the topography of Grant Creek down to a powerhouse built at 530 feet elevation. An existing dirt mining road north of Falls Creek would be extended to allow access to the dam and powerhouse, and would avoid existing trails. Overhead transmission lines would connect the powerhouse to existing lines along the Seward Highway.

Estimated power capacity would be 4.7 megawatts. With the dam and water diverted through the penstock, the section of creek just below the lake outlet would be “dewatered,” Bethard said, and water would be returned to the creek after it ran through the turbines. Bethard said the lake supports some fish — stickleback and sculpin — but previous studies don’t show fish migration in the upper reaches of the creek. HDR plans to return water to the creek above where migratory salmon use it for spawning.

“So we’re looking at taking water from areas of the creek that don’t have fish in them,” Bethard said.

The project would be similar in concept to Chugach’s dam at Cooper Lake, which is blamed for destroying fish runs in Cooper Creek. Paul McLarnon, a biologist with HDR, said the difference is that water in Cooper Creek today actually comes from Stetson Creek, which is colder than Cooper Lake.

“The water out of Grant Lake is put it back into Grant Creek,” he said. “It’s the same water. There wouldn’t be a temperature difference there.”

Community members were concerned about the possible effects of removing and returning water to the creek, whether running the water through turbines would increase water temperature, and what effect that may have on fish.

“That’s something we definitely want to study. I don’t know that right now,” McLarnon said.

Falls — Water may go to Grant Lake

To the south of Grant Lake is Falls Creek, so named for a 100-foot waterfall and smaller falls. Previous studies in the 1980s concluded the large waterfall impedes fish passage in the upper reaches of the creek, although salmon use the lower reaches of Falls Creek.

The creek isn’t suitable for a dam and water storage, Bethard said, so HDR is considering two other options. A run-of-river intake structure would be built, probably at 800 feet of elevation, to divert water into a 40-inch diameter steel penstock. Run of river means water is diverted out of the creek with a structure built to the creek’s water level, rather than a dam higher than the water level storing up larger volumes of water behind it. The intake would include a sluiceway to release incremental water flows.

The penstock could divert water to a powerhouse built at 500 feet elevation with a rated capacity of 3.9 million kWh. Water would be returned to the creek below the powerhouse, with the section of the creek between the intake and water release being dewatered. Existing mining roads with additional short stubs could be upgraded to provide access. If this method is used, the powerhouse would be shut down November to April, Bethard said.

But the preferred idea is to take the water from Falls Creek over to Grant Lake and add to the water capacity there to increase the potential power output of that dam.

“If we can take water to Grant we do see a little more of a benefit. Diverting is the preferred alternative,” Bethard said.

That would could mean Falls Creek goes without water year-round, unless biological studies show some level of instream flow must occur to maintain fish habitat.

Ptarmigan – Tunnel would carry water

South of Falls Creek, the proposed Ptarmigan Lake project would include an intake structure at the outlet of the lake, a gatehouse and an outlet control structure that would control the amount of water released into the creek.

“Ptarmigan is a very productive system,” McLarnon said of the waterway’s fish usage.

Bethard said the project would maintain a certain amount of water release for fish.

It would also involve a 9-foot-diameter, tunnel just shy of 1.5 miles long to bring water to the powerhouse, which would be built at 550 feet elevation. A new, half-mile road near Kenai Lake would provide access to the powerhouse, which would be built across from Ptarmigan Campground. Another new, single-lane access road, this one two miles long, would be built from the powerhouse to the gatehouse. Bethard said tailings from the tunnel could be used for road construction, as aggregate for concrete, for the foundation of the powerhouse or possibly sold to the Alaska Department of Transportation.

The Ptarmigan project has a capacity of 3 MW, but power output would depend on how much water is left in the creek and how much is diverted through the powerhouse. HDR estimates 3.2 million annual kWh production if 34 percent of the water is used for power, 6.4 million kWh if 67 percent is used for power, and 9.7 million kWh if all the water goes to power, although that number is for modeling purposes and wouldn’t likely happen, Bethard said.

Crescent — Trench would follow trail

On Crescent Lake, the original plan was to bring a penstock down Crescent Creek Valley, but that was abandoned when a suitable intake site wasn’t found. The upper reaches of the creek are productive grayling habitat, and farther down is a steep canyon that presented engineering hurdles, Bethard said.

Now the plan is to replace the bridge over Crescent Creek at the lake outlet with a concrete bridge that would control water release into the creek and allow for fish passage, Bethard said. On the other end of the lake, a 7,750-foot tunnel or deep trench would be dug to install a 13,000-foot steel penstock that would take water from the east end of the lake past Carter Lake and down the mountainside to a powerhouse at 550 feet elevation. The trench would traverse the valley between Carter and Crescent Lakes along roughly the same route as a popular hiking trail.

Bethard said the tunnel or trench would be dug and penstock installed in the winter to minimize harm to the vegetation. Vegetation that’s dug up would be replaced and is expected to regrow, he said. The pipe would re-emerge near the outlet of Carter Lake and travel above ground down the mountainside to the powerhouse.

The existing Crescent Lake trail could be used to access the outlet flow structure on the west side of the lake. On the Carter Lake side, HDR would put in a new, single-lane, 2.5-mile road up past Carter Lake to access the intake structure on Crescent. Bethard said HDR considered just widening and using the existing trail, but the first part is probably too steep for that.

The Crescent Lake project has a rated capacity of 5.8 MW, but energy output would again depend on how much water is used. In its modeling, HDR figures 23.4 million kWh if no water is released through the creek, 16.1 million kWh if 33 percent of the water goes down the creek, and 8.8 million kWh if 66 percent of the water is released.

Cool effects — River ice forms wherever it can amid flowing water

Even when smaller streams have a covering of ice, larger rivers have open sections throughout the coldest months of winter.

Stream and river water slowly lose enough heat to the colder air so ice forms in various ways. In small, slow-moving streams, ice often forms a layer on top of the stream just like it forms on top of lakes. The ice covering the stream tends to be thinner than ice found on lakes because of the moving water underneath. And during winter months, stream levels usually drop and the ice may end up covering an air space with the flowing stream below. Because of the air space between ice and flowing water, the ice doesn’t get any thicker.

In larger, faster streams, the first ice to form is along the slow-moving edges. When the river water gets more uniformly colder, frazil ice forms, and it looks like slush in the water. Winter steelhead fishermen sometimes see what looks like blobs of snow floating downstream. This is frazil ice being formed in the moving, super cooled water, probably right before their eyes. This slushlike ice gets thicker and packs together until it collects on the sides, bottom and top surface of the channel. If you are seeing frazil ice forming in your favorite trout stream, it’s time to put the fly rod away for the season.

Newly formed stream ice tends to block off parts of the channel, but water remains free-flowing in some sections all winter long. Since many streams receive their water from lake outflow, like the Kenai River below Kenai Lake or Skilak Lake, much of the water is too warm to immediately form ice. This is why we frequently see open water under the bridge between Kenai Lake and the start of the Kenai River.

Another major source of water for winter streams is groundwater. Groundwater, by definition, has not been exposed to colder air and is considerably warmer than the rest of the water in the stream. So, we often end up with warmer water flowing between and underneath layers of ice. These flowing channel areas and deeper areas of liquid water are the critical wintertime refuge for resident populations of grayling, trout and whitefish.

When exposed sections of stream water gets very close to freezing, such as later in the winter months, another kind of ice may form. Usually at night or early morning when air temperatures are at their coldest, anchor ice can form. This type of ice looks like a clear layer of ice covering the bottom of the stream. The anchor ice layer may temporarily restrict or block off some of the under-the-ice channels that were flowing previously.

The flowing water can’t descend through the sediment and can’t move laterally so it breaks through the ice somewhere and flows on top of the ice cover. This is called river overflow.

Because the water has considerable inertia and gravity moving it along, huge amounts of water can suddenly begin flowing on top of the ice. River overflow can sometimes be measured in depths of feet and can be quite problematic for travelers. One might expect the overflow to immediately freeze, since it is in contact with cold air. However, if there is snow cover on the ice, overflow water can remain liquid for many days, even when the air temperatures are extremely cold.

Some of the most spooky, and also some of the funniest, stories I have ever heard were told by a well-known Iditarod musher when talking about his experiences with river overflow. In some situations he had his entire sled floating and his dogs swimming in overflow when the air temperatures were minus 10.

In many areas of Alaska, wintertime travel routes are on top of frozen rivers. Most of the time the river ice cover is more than thick enough to support the person, dog sled, snowmachine or even a pickup truck. However, because of constantly changing under-ice channels and the dangers of river overflow, traveling on frozen rivers can be very dangerous, too.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River watershed.

Science of the seasons: Many factors affect lake ice formation, thickness

As air temperatures descended this fall, most lakes became covered with a layer of ice.

Shallow lakes, with lots of surface area compared to the volume, froze first, and some very shallow lakes or ponds freeze all the way to the bottom. At the other end of the size spectrum, those lakes with large volumes and great depths, like Kenai, Skilak, Hidden and Tustumena lakes, are the last to freeze.

The reason for slower ice formation is due to the huge amount of heat loss that must occur before ice is formed. A basic property of water is that it takes a lot of heat loss — one calorie per gram of water — to cause a reduction of 1 degree Celsius. Then it takes even more heat loss — 80 calories per gram of water — to get ice to form after the water has already reached zero degrees Celsius.

In order for a lake to freeze, the entire water body, top to bottom, needs to drop down to 40 C. Another pivotal property of water that comes into play here is that water is most dense at 40 C, and thus it sinks to the bottom when it reaches that temperature. Water that is colder (or warmer) will be less dense and will remain above the deeper, 40 C water. Eventually, the entire lake will be at 40 C.

As the cold winter air on the surface causes the top layer of lake water to get colder yet, it becomes less dense and stays on top. Once it has gotten cold enough to freeze, it is 10 percent less dense than liquid water and, as we all know, ice floats. At that point, all the water underneath the ice is going to be 4 C or colder.

Initially, the formation of ice insulates the underlying lake water from further heat loss. However, heat is continually being lost from the ice. As ice loses heat, the underlying water freezes and ice forms on the bottom of the ice layer. It is not uncommon for ice to grow to 30 inches or more in lakes on the peninsula.

Lakes that have continued inflow of water after an ice cover has formed may have thinner ice cover in areas where groundwater seeps in or where stream water enters. Inflowing water will probably not be as cold as the lake water, so it will rise and possibly melt some of the overlaying ice. Even if the incoming water is colder than 40 C, it will stay on the top of the lake and may still cause some thinning of the overlaying ice. As careful ice skaters have known for a very long time, it is good to avoid those areas where water is still entering a lake.

As water enters and leaves a lake through normal input or drainage patterns, it can have an impact on the ice surface. Imagine a situation where water continues to enter the lake but the shallow outflow is blocked off with ice. The water level will rise imperceptibly and will push up on the ice. Since all lake ice covers have cracks, the rising pressure of extra water underneath can push liquid water through the cracks.

Water leaking through the fissures in the ice is referred to as overflow. When overflow occurs, unfrozen water sits on top of the ice. At times, overflow can be many inches deep. If there is no snow cover, the air will rapidly cool and freeze the newly exposed water. However, a thick snow cover acts as an efficient insulator and keeps the water from contact with the much colder air. Because of this insulating ability of snow cover, lake overflow may remain liquid for weeks at a time.

Ice cover on a lake can decrease the exchange of oxygen from the air into the water. Snow cover can reduce the amount of light reaching the lake bottom to virtually nothing, and very little oxygen-producing photosynthesis can occur.

Bacterial breakdown of dead plant materials on the lake bottom uses up much of the limited oxygen. By the end of winter, there can be very little oxygen left in the water. In some cases, there is so much oxygen depletion that the fish die. Shallower lakes are most often the ones with winter fish kills. Generally, lakes that are more than 15 feet deep can retain enough oxygen in the water to prevent overwinter fish kills.

Because there are so many variables — such as lake size, snow cover, incoming waters and variable air temperatures — that impact how fast ice forms, always check ice thickness before venturing onto the surface. This fall when prospecting for a lake to do some early ice fishing, I found one lake with a mere 4 inches of ice, and a lake less than half a mile away had more than 9 inches.

Have fun on the ice, but be careful the ice is thick enough for your intended use.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River watershed.

Guest column: In Cook Inlet, change stays the same

A number of years ago I spent an evening perched 25 feet up on the cold, windy Cook Inlet bluff south of Deep Creek, watching the tide come in.

A brisk wind was coming out of the southwest and every four seconds a muddy, gray wave crashed onto the beach and dissipated into spray, bubbles and foam. As the water slithered back out, it rattled the beach cobbles menacingly like a shaman working mysterious magic with a puffin-beak rattle. The shaman-waves broke again and again, rhythmically chanting their ancient geological feast‑mantra, “Closer...closer...closer.”

The 20‑foot tide was rising fast, and the sediment‑crazed surf groped for the base of the bluff until finally it nibbled at the talus below my perch. During the 40 minutes of slack, high water, the hungry waves grazed on Tertiary sediments in a 100-mile long feeding frenzy. Eventually the ebbing tide pulled the ravenous water away from the bluff, but not until 600 breakers had been fed.

From Point Possession to Homer, Cook Inlet had taken another long bite out of the bluff. Tikahtnu was satiated — but only until the next big tide.

Most of Cook Inlet’s waves break harmlessly onto the beach, expending their energy on mundane tasks like rearranging sand, polishing stones and erasing footprints. But when the highest tides lift the waves to the base of the bluff, a set of events begin that result in a slowly changing coastline.

When tides reach the base of the bluff, the breaking waves wash out a notch and carry the sediments out to sea. Gravity likes her angles, and this disruption of the bluff’s angle of repose is not to her liking. In time, sand and gravel from above the notch fall down and fill it in. Eventually, the former angle is re-established, gravity is once again content, and the coastline has moved inland a little bit.

The usual process is for individual particles to fall in a slow trickle of downslope movement. However, if the area is saturated with water, a large part of the bluff may surge down in an earth flow and, like the Dow on a bad day, the property owner finds himself a few thousand dollars poorer. Unlike the stock market, however, there will be no recovery.

Usually only a few inches of bluff are removed at a time, but a big tide accompanied by strong onshore winds can take out as much as 5 feet. Over the years, landowners have tried everything imaginable to shore up their investment. Breakwaters have been constructed of pilings sunk into the beach fortified with everything from cement-filled barrels, to old car bodies, to the kitchen sink. Sometimes the erosion has been retarded for a few years, but in the end, the inlet always wins.

Nothing will stop the erosion of the bluff, with the possible exception of encasing the Cook Inlet basin in fiberglass.

Contrary to what one might expect, erosion of the west coast of the peninsula from Point Possession to Kachemak Bay is not due to a rise in sea level. It is due to the exact opposite — the land is rising, like Neptune coming out of the sea, causing a relative lowering of sea level.

Why should the western half of the Kenai Peninsula be rising? According to geologist Richard Reger, the reason is crustal rebound. During the Pleistocene, millions of tons of glacial ice covered the peninsula, depressing the thin crust into the less viscous mantle below. As the ice receded, the weight has been removed and the crust is slowly rising to its former state. The process has almost run its course, but over the past 10,000 years, waves have constantly cut into this rising coastline, making a new bluff.

Today the bluff has stabilized in several places but, in the long run, this, too, is only momentary. The next big earthquake or global climate change will revise the land-sea boundary and again our coastline will be changed.

When the tide lowered, I moved from my perch down to the now-exposed beach. As I picked my way down, a bit of siltstone broke away from the cliff high above me and the particles rained down around me, destined for the notch below recently washed out by the high tide. The siltstone had been layered there for 5 million years, and now, thanks to rebound, tides, waves and the pull of gravity, those particles were starting another trip on their journey through the geologic cycle.

Nothing, it seems, is forever.

Alan Boraas is a professor of anthropology at Kenai Peninsula College’s Kenai River Campus.

Guest editorial: Many hands made light work of Crooked Creek project

With over 61 miles of direct stream and riparian habitat, Crooked Creek, in Kasilof, is one of the longest anadromous streams on the Kenai Peninsula.

It is a major tributary of the Kasilof River, and supports spawning and rearing for substantial runs of chinook and coho salmon and one of the northernmost steelhead runs, as well as migratory bird habitat.

During a flood in 2002, a road crossing the creek near the Crooked Creek facility washed out. For several years following the flood, the area was left with very steep, unstable and unvegetated loose gravel stream banks. This is a very popular community use area because it is one of the few public access areas for viewing spawning chinook salmon on the Kenai Peninsula. This site is also listed in several publications encouraging visitors to view fish in the creek. Community members and travelers are seen in significant numbers. After Aug. 1, it’s heavily used for fishing.

As the need for a restoration project grew, so did the interest of community members, various agencies and local elementary students. The Tustumena Elementary School sixth-grade Adopt-a-Stream program had been active in research work at Crooked Creek for 10 years. Students visited the creek monthly and were interested in partnering with the community and other groups to take on this project.

The Kenai Watershed Forum was granted funds from several agencies to attend to the needs of Crooked Creek. The National Fish and Wildlife Foundation, U.S. Fish and Wildlife Service and ConocoPhilips all contributed money to accomplish the project goals of stabilizing the stream bank, creating a study/monitoring area for students, protecting habitat and improving fishermen and visitor access.

The KWF was to serve as the facilitator to bring all the parties together to work for these common goals. A coalition was organized, including KWF, Tustumena students and parents, Crooked Creek landowners, Kasilof area residents and business owners, local government leaders and staff, U.S. Fish and Wildlife Service, Alaska Department of Fish and Game, Alaska Department of Natural Resources and the Alaska Department of Transportation.

The first matter of business was to bring the community and agencies with a stake in the restoration together. A community planning meeting was held at the Tustumena school in fall 2007, and a site visit was organized with all parties and agencies.

An older student from the area was looking for an Eagle Scout project and approached the watershed forum about adopting the Crooked Creek viewing platform portion of the project. Keith Clancy applied for and received all the appropriate permits. He was instrumental in securing the final design, and put a work crew together for the installation of a new, elevated study platform.

Throughout the planning and restoration stage of work, the students at Tustumena helped support the program. Classroom education continued with testing the waters of Crooked Creek through the Adopt-a-Stream program. Students organized and executed a creek cleanup day, and researched platforms, walkways and habitat restoration techniques. They designed and installed signs to educate the community and visitors about Crooked Creek, explaining how to help protect the area, respect wildlife and “leave no trace.”

Other agencies stepped in with time and materials to help make this project a success. Adjacent trails were improved by Fish and Game, improving visitor fishing and view access. DOT peeled back the original road and a visitor parking area with guardrails was established.

From the beginning, one of the focuses of the project was to bring the community together with various agencies to provide a successful restoration project that would enhance the Tustumena area and Crooked Creek. With the driving force of the Adopt-a-Stream students — known as Tustumena Streamkeepers — and their parents, the project moved forward and involved all the necessary parties.

Although huge steps have been made in making this former flood washout a desirable place to view spawning salmon and other wildlife, there is still more work to come.
KWF looks to complete the project during summer 2009 with installation of permanent viewing signs, further improvements to trails and another viewing platform. And Marathon Oil has come on board with a financial donation to the project. Our streambeds, creeks and watersheds are valuable assets to our communities. We are fortunate to have an abundance of support from the schools, residents, merchants, government agencies and private corporations to protect these critical habitat areas.

Rhonda Orth is the accounting and office manager at the Kenai Watershed Forum.

Die and let live — Cycle of salmon spawning serves valuable purpose on Kenai River

One of the mysteries that has vexed stream ecologists for years involves large Pacific salmon that return from the oceans to spawn in headwater streams and promptly die. Very few fish grow this large and only reproduce once during their lifetime. As an example, halibut can reproduce for decades in the ocean, and many freshwater trout species will reproduce each year for dozens of years.

Evolutionary theories predict that for such an unusual behavior to exist, there must be a benefit to the species when the adults die. Wouldn’t it be better for the adults to survive and reproduce multiple times? The mystery is becoming clearer these days, thanks to stream and fisheries researchers from all over the country and throughout the world.

First, it must be understood that most streams along the Pacific Coast are nutrient-poor. This means that there are not high concentrations of minerals and essential elements in the waters that would support plant and algal growth. In turn, there is only marginal plant growth along and within the stream. The in-stream and riparian (located along the stream banks) plant growth can normally support only small populations of invertebrates that then become food for stream fish. Because of this nutrient-poor stream water situation, salmon have evolved an anadromous life cycle.

Anadromous fish lay their eggs in a stream that cannot actually provide adequate sustenance for their offspring, so the young soon migrate into the oceans to complete their growth. The surrounding oceans are nutrient-rich and provide great opportunities for young fish to find food. As an example, many Alaska silver salmon stay in headwater streams for three years and grow to only 6 inches in length.

They then head to the ocean and return to spawn one year later weighing 10 to 16 pounds. They obviously found a lot of food out in the ocean that they could not have found in the stream where they were hatched.

Since the streams are so nutrient-poor, it now appears that the dying adult salmon carcasses release substantial amounts of elements into the stream. Those nutrients, like the fertilizer we use on our gardens, enable in-stream vegetation and riparian plants to thrive. Those plants then deposit their leaves, twigs, bud scales, pollen, etc., back into the stream. In turn the leaves are used as food sources by various aquatic invertebrates — mostly aquatic insects. The insect populations are then able to grow large enough to support the resident fish and the newly hatched salmon fry.

There has been considerable research on these nutrients using what are called stable isotopes. We know the oceans provide higher concentrations of Nitrogen-15 while atmospheric-captured nitrogen is mostly Nitrogen-14. By looking at the nitrogen isotopes found in riparian vegetation and plants near Alaska salmon streams, we now know that a considerable amount of nutrients in these plants came from the ocean and arrived there as part of salmon tissues.

So, the dead salmon along a stream are providing nutrients for plants that will in turn provide nutrition for the food of the young salmon — a complicated but effective circle of nutrients from adult salmon back to juvenile salmon.

The next time you see a grotesque fish carcass along a stream, remember that it is providing food for its young just as any good parent would do.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. E-mail your science questions to redoubtreporter @alaska.net.