Spring has come to the Chehalis Basin. Leaves are uncurling on the trees along the river bank. Winter rains have soaked the ground, filling the streams and keeping them cool and high.

The days are getting longer. In between drizzly spells, the sun shines high and bright, warming the air, the soil, and the water's surface. As the leaves on the trees grow and the ground drains, the streams and rivers slowly drop. The dramatic changes we watch above the ground are matched by changes beneath the water's surface.

From its headwaters, the Chehalis tumbles through the eastern edge of the Willapa Hills, to be joined by the waters of Elk Creek. After the South Fork flows in, the river begins to change, flowing through more pools and slow stretches.

Once the Newaukum River joins it, it drops into the flat valley where the cities of Centralia and Chehalis sit. The ice-age glacier that covered Puget Sound filled this basin between the hills with the rock and silt, carried from its melting face by the ancient outwash river. The river as it enters this valley becomes slow, meandering, and wide - almost a long, thin lake rather than a river.

Through the spring months, this stretch of the Chehalis (which we'll call the Centralia Reach) is slowly transforming from a more typical river to something quite unusual. As flows drop and the speed of the water slows, the river becomes less turbulent. Oxygen in the air enters the river more slowly, and mixes into deeper waters poorly. The water's surface begins to warm, which also allows less oxygen to enter the water.

Like any organism, the river breathes. It needs oxygen for the life within it. Some creatures, like the young salmon, do not like it stuffy and will leave or die if the oxygen drops too low. Others, like the bacteria and other microorganisms, will use as much oxygen as they need as fast as it can be replenished from the air, even until virtually no oxygen can be found. Some of these organisms live in the sediments on the bottom, feeding off the rich muck deposited there. Others feed on the materials that flow into the river, including the treated wastewater from a city or factory, or the animal waste washed off a field by the rain.

As the days pass through May, the river in the Centralia Reach finds it harder and harder to replenish the oxygen in the water, and the oxygen levels drop lower and lower. Wastewater from Chehalis entering the river just below the Newaukum uses oxygen as it flows downstream, resulting in lower levels as it reaches the Mellen Street bridge in Centralia. By the end of May, oxygen levels in the Centralia Reach are too low for many of the most sensitive creatures.

With the inflow of the Skookumchuck River, the Chehalis is refreshed. The river drops out of the valley and resumes its journey down towards the sea. Cold water from the Skookumchuck and the vigorous churning of riffles and rapids restore the oxygen levels of the river. Scatter Creek and the Black River join the Chehalis as it flows past, and finally the River enters the wide valley of the lower river.

The Black River is a branch of the Chehalis system that deserves a tale of its own. Beginning in the broad wetlands south of Black Lake, it flows slowly down a flat valley that skirts the eastern edge of the Black Hills. As the rains of winter soak into the marshes and drain into the river, the water carries a dark color from the rich organic materials of the marsh. These materials also pull some of the oxygen out of the water, a natural process found in most wetlands.

After meandering through the marshes, two creeks add to the flow of the Black River as it passes the town of Littlerock. Waddell Creek brings clear, pure water from the Black Hills. Beaver Creek, on the other hand, carries to the Black River the telltale pollutants - bacteria, silt, and nutrients - that result when mud from eroded stream banks and manure from livestock are washed off the land by the rains. These problems were observed in the TMDL work of 1991 and 1992, but since that time, local citizens have been working hard to fence the creek and its tributaries and to better manage the livestock. With time and more hard work, Beaver Creek should run as clear and unpolluted as Waddell.

The Black River below Littlerock enters a long, slow stretch. Some have compared this part of the river to a Louisiana bayou or an English country stream. Like the Centralia Reach, as the flows drop in the spring, oxygen is less easily replenished. But flows in the Black are lower than the Chehalis. Even in spring, the deepest waters of the middle Black are cold and depleted of oxygen.

Even more than the Centralia Reach, the middle Black River behaves like a lake. The wide water surface, lack of shade trees, and slow currents allow microscopic floating plants called algae (or "phytoplankton") to flourish. In lakes, the kind of algae present changes from spring to fall, as temperatures, sunlight, and the amount of nutrients that fertilize the algae change.

Like a lake, the Black River has changing cycles of algae over the dry season. The long sunny days of late spring allow green algae to bloom. But as the days begin to shorten and conditions in the river change, the greens die back and other species take over. Small phytoplankton with beautiful, intricate silica shells called diatoms are often most common. At other times, the dominant algae are cryptophytes - tiny phytoplankton that propel themselves by whipping their little tails.

Given the right set of conditions, these phytoplankton could multiply until the Black River looked like pea soup. It's even possible that blue-green algae could appear - an algae that is sometimes toxic to dogs, cats, and humans. Fortunately, the Black River is still relatively low in one of the key nutrients that the phytoplankton require - phosphorus. If population growth in the Black River basin caused more phosphorus to enter the river from septic systems, stormwater, or wastewater, then the situation could deteriorate.

Meanwhile, on a spring day, the Black is dark and murky, but not green and turbid. As the river moves downstream from the lake-like middle stretch, it begins to meander and grow shallower. As it passes the railroad trestle near Rochester the river drops and enters an area of small riffles and pools thick with water plants. Like plants on land, these plants are just beginning to grow in the spring, only hinting at the lush growths that will crowd the river in the summer.

It's summer, and the sun beats down on the Chehalis Basin. Leaves fill the trees and grass covers the ground. The air is warm, and long clear days are only occasionally broken by a rainy spell. In the Chehalis River and its tributaries, flows drop, the water heats up, and in some places streams go dry.

For people, the summer weather is pleasant and easy - kids run barefoot in T-shirts, families camp in the forest and splash in the water. But for the Chehalis River, summer is a harsh and difficult time.

Pumps pull water from the channel for irrigation and stock watering. The water table drops as wells and roots draw on the waters stored in the ground. Very little is left to run through the tributaries into the River and out to the sea.

Where trees grow thick along the stream and river banks, the shade helps the water to stay cool. But where the banks are bare, the sun heats the air, the water, and the channel bottom, and the water gets warmer. In these areas, the fish and other creatures that love cool water are driven to whatever shelter is available, or perish in the heat.

With the warming of the water and decreased flow of the streams and rivers in the Chehalis Basin other problems appear. As the water warms, it carries less oxygen. Unless a riffle or rapids churns the water, oxygen moves from the air to the water poorly. Thus, slow, warm stream and river stretches are easily robbed of oxygen and regain the oxygen only very slowly. As the summer progresses through July into August, oxygen in the waters of the Chehalis River and its tributaries reaches its lowest levels as flows drop and temperatures peak.

The long days and warm temperatures also stimulate the growth of plants and algae in the water. In the slow, open, lake-like stretches of the Centralia Reach and middle portion of the Black River, microscopic floating plants called phytoplankton flourish. Where the channels are sunny and shallow, aquatic plants and attached algae grow. On clear days these plants produce excess oxygen, but at night they continue to breathe oxygen, as all living creatures do. This can make poor oxygen levels worse, driving them down to a minimum in the early morning. If pollutants that enter the river are high in nutrients, the phytoplankton, aquatic plants, and attached algae may bloom, resulting in large growths that may create a nuisance and drive early morning oxygen levels even lower.

The Black River and certain stretches of the Chehalis River have probably always had relatively poor water quality in the summer due to slow flows, summer heat, wetlands, and other natural conditions. Anywhere that human activities add oxygen-demanding or nutrient- rich waste materials to these stretches of the Chehalis or its tributaries, oxygen levels in the water that were naturally low are driven down even more.

These waste materials can come from many different sources. "Point sources" are concentrated sources such as a municipal sewage treatment plant, an industrial wastewater discharge, or a concentrated animal rearing operation. "Nonpoint sources" come from diffuse sources such as storm water, ground water, livestock range operations, or onsite septic systems.

Cattle may be raised in operations of all different sizes, from a few animals raised by a family to a large commercial dairy. The largest dairy farms may have hundreds of animals, and with those animals comes tons of manure. If poorly handled, this waste could reach the streams and rivers, where the fish would be suffocated, stream life poisoned by toxic ammonia, and the bottom smothered in muck. Manure on the bottom could continue to rob oxygen and release ammonia and other nutrients for years.

Where cattle can reach the water, the banks are beaten bare and the water muddied. The cattle leave their manure in the stream, where it remains to decay and rob the stream of oxygen. When fisheries staff from the U.S. Fish and Wildlife Service walked the basin in 1992, they found signs of this problem in almost every creek and river they examined.

Food processing companies use fields along the Chehalis to grow crops with their wastewater, and most dairies use their manure on fields as a fertilizer. The waste must be put on the fields at the right amount for the plants, or the excess will flow down to the ground water or over the surface to the nearest stream. If the field is right next to a stream or river, the excess waste in the ground water may quickly reach the stream.

Wastewater from city sewers or from industrial operations continues to flow to treatment plants day and night, where pollutants are reduced before discharge to the river. Although treated to levels set by national standards, pollutants still remain in the wastewater that the river must assimilate.

Every so often a summer downpour hits the Chehalis Basin. Where the ground is hard and bare, or on paved areas, the water runs quickly off into drains and channels, and on to the streams and rivers. This stormwater can carry with it pollutants from whatever wastes are laying on the ground - livestock and pet manure, fertilizer, trash, or yard waste. A slug of this polluted stormwater may hit the river during the storm, and a day later when the good weather returns, it is still in the river moving downstream, full of bacteria and using up oxygen.

In the Centralia Reach, the Chehalis River feels the problems of summer the worst. Here, the river becomes very wide and meandering, almost like a long, narrow lake. The City of Chehalis and Darigold release their treated wastewater here, which mixes slowly into the river as it moves downstream. At bends in the river deep pools have formed. Here cold water lies trapped at the bottom, while the warmer water flows over the top. Salzer Creek enters, itself depleted of oxygen and full of pollutants. Ground water seeps into the river which may carry pollutants from a number of sources such as a dairy, a landfill, or a field where wastewater is being spread.

In the deep pools, oxygen from the surface barely penetrates the upper layer of warmer water, and the sediments use up what little oxygen is present. In these pools, oxygen disappears, and the chemistry of the water is transformed. Hydrogen sulfide is formed, with its characteristic "rotten-egg" smell; although unpleasant to the nose, it is toxic to fish. The lack of oxygen also allows ammonia and phosphorus to enter the water at high levels. The bottom of these pools are areas completely hostile to fish and most other aquatic life.

In the surface waters of the Centralia Reach, oxygen drops to its lowest levels. Temperatures at the surface soar in the wide unshaded stretches, reaching levels near the surface that are almost too high for a salmon to survive. Any salmon trying to move upstream, as they begin to do in late August, will be forced to move through a narrow layer between the hot surface waters and oxygen-starved bottom waters. Salmon juveniles that might otherwise enjoy the quiet waters of the Centralia Reach are absent due to the harsh conditions, and the only resident fish are squawfish or other warm-water fishes.

In the long, hot days of summer, the Chehalis River is the most sensitive. Burdened with low flows, high temperatures, and oxygen-demanding pollutants the river teeters on the edge of disaster. An accidental spill or unlucky combination of problems can send it over the edge, knocking oxygen down to zero, releasing toxic ammonia, and leaving behind dead salmon and other aquatic creatures. The fish kill of August 1989 showed this to be true.

Autumn comes to the Chehalis Basin slowly and quietly. The leaves start to brown and wither, rainy periods come just a little more often, and flows in the rivers and streams gradually increase.

With shorter days comes cooler temperatures. The warm surface waters of the Centralia Reach cool off, and slowly mix deeper, until the deep pools with their stagnant, anoxic water finally mix back into the whole river. Oxygen levels in the surface waters are gradually rising.

Despite the changes, fall is still a risky time for the Chehalis River. Although the problems of summer are easing, flows are still low and the season adds new complications. As the deep pools in the Centralia Reach slowly mix into surface waters, ammonia and other pollutants are released back into the river. Leaves are falling and plants in the water dying, adding to the overall load of oxygen-demanding pollutants. Bursts of rain flushing pollutants into the rivers and streams may be followed by stretches of warm weather and low flows.

The Chehalis River is still close to the edge, vulnerable to any spill or combination of problems. In October 1991, a treatment plant upset, combined with other pollutant discharges higher in the river, resulted in a complete loss of oxygen in the Centralia Reach. A week passed as the zone of no oxygen travelled downstream to the Skookumchuck River, where it was diluted and reaerated. Mysteriously, no fish died, perhaps because they moved downstream ahead of the low oxygen waters.

Typically in November, the rains begin in earnest. The leaves are gone, false summers past, and the rivers and streams move into their wet season. Cold, swift waters have raised oxygen levels so they are now at high levels. However, heavy rains and high flows bring a different set of problems.

As the rains come more frequently, the ground saturates with water and the stormwater begins to flow overland. If a septic system drainfield is old or poorly built, the sewage will surface and be carried away by the runoff. Barnyards fill with puddles and manure piles get drenched. If a dairy hasn't built a storage lagoon, manure guns may be spreading waste on soaked fields, where it will inevitably run off to the nearest stream or river. When the rain washes off the waste, it carries with it bacteria and other disease organism that will contaminate the rivers and streams.

When the rain hits the ground, trees, bushes and grass break the fall of the drops and slow the runoff of the stormwater. But where the ground is bare, the rain will break loose soil and carry it along. As the rain gathers into channels, it cuts into the ground, increasing its load of sediment. Eventually the turbid runoff reaches a stream where the sediment settles onto the stream bed, smothering aquatic life and clogging salmon spawning gravel.

Nature, left to itself, will cover the ground with vegetation as best it can. But when people develop land for their own uses, they often leave the soil bare. Poorly constructed roads, cleared building sites, plowed fields, livestock paths, and ruts from off-road vehicles can all be areas where the stormwater collects sediment that can pollute the streams and rivers.

Many of the winter problems in the Chehalis Basin become summer problems, and vice versa. The manure carried to the river which releases bacteria in the winter can fall to the bottom to rob oxygen in the summer. Areas cleared of trees that allow the sun to heat the river in the summer will be more likely to erode in the high flows of winter. Often a simple fix can solve a variety of problems.

As the Chehalis Basin enters the 21st century, the citizens and communities of the basin face a daunting task. Years of neglect and a lack of knowledge has hammered the river, until it has become a real possibility that streams will run dry in the summer and salmon runs will be lost forever. A long road lies ahead, but it is a path that residents of the Chehalis Basin share with citizens in watersheds all over the nation, and the challenge is being accepted. The solutions come not from pointing fingers and fixing blame, but from communities working together and each citizen doing his or her part.

For the rural home-owner, onsite septic systems can be repaired and properly maintained. People rearing livestock can fence pastures and limit access to streams. Dairies can work with their Conservation District and the Natural Resource Conservation Service (formerly known as the Soil Conservation Service) to develop a farm plan that manages their cattle waste and uses it as a resource.

Residents of the Centralia and Chehalis urban areas face some difficult decisions. >From late spring to early fall, the Centralia Reach simply does not have the capacity to assimilate oxygen-demanding wastes. To protect this sensitive area, municipal and industrial wastewater must be removed from the river during this period, and storm water controls need to be improved. Other communities have found solutions to similar problems, by reuse of the waste water, creation a regional sewer system, or the construction of retention ponds and wetlands. The solutions come with a price tag, but state and federal funds are available that may provide some relief.

On top of all this is the question of water supplies for the Chehalis Basin and the protection of flows in the Chehalis River and its tributaries. Water rights exceed the available water, and future supplies are uncertain. Water quality and the life that depends on the water cannot be protected without adequate minimum flows in the river system. The solution to this problem will come from everyone in the basin being involved and working together.

The list is long of the agencies and organizations that can help to protect the water quality of the Chehalis: federal agencies like EPA and the US Fish and Wildlife Service; the Department of Ecology and its fellow agencies such as Health, Fish and Wildlife, the Conservation Commission and DNR; the Chehalis and Quinault Tribes; county and city governments; the Conservation Districts and the NRCS; local businesses and industry; and citizens groups such as the Chehalis River Council, the Chehalis Watershed Council, the Chehalis Basin Fisheries Task Force, adopt-a-stream groups, and other community groups. With the passage of each year, the problems become clearer and the search for solutions more important. The whole Chehalis Basin will find the answers together - we all live downstream.