Our seasonal rains have returned in force these past couple of weeks, filling streams and gullies, recharging the water table, and resaturating the wetlands. And in some places, puddling and flooding.
Most of the sites that flood in our normally wet winters are — or used to be — wetlands.
Fed by rain, river, or sea, "wetlands" are places where the water table is at or near the surface of the land. A wetland is land saturated with water or covered by shallow water for prolonged or recurring periods. Such water may be fresh, salty, or a mix. Though many people confuse the terms, a "swamp" is technically a wetland with trees or shrubs.
Although wetlands are typically lush, the heavily soaked wetland soils limit the plant life to species specially adapted to constant or periodic drowning. The extensive water even affects the chemistry of the soils.
The biggest challenge for wetlands in many places, including the Pacific Northwest, is that they’re sometimes the only flat land around — and they’re often land right next to a waterway suitable for transportation or agriculture.
Improved science has brought us a long way from thinking of natural wetlands being suitable only for alterations to become either water deep enough for boats or land solid enough to build on. Long thought to be "wastelands" that are "too thick to drink and too thin to plow," we now know wetlands perform many functions vital to people.
Wetlands produce and recycle huge numbers of plants and animals and vast amounts of organic material — some of which is passed on to adjacent land and water habitats. In wetlands that are seasonally or periodically flooded (like most of ours), the organic material produced there is regularly carried downstream to other parts of the watershed, perhaps traveling great distances.
Further, wetland ecosystems are critical life-long or nursery habitat for myriad species of plants and animals. Two-thirds of marine fish species eaten by people — including salmon, clams, oysters, and crab — depend on coastal wetlands at some stage of their lives. The diet staple for over 3 billion people, rice, is a wetland plant.
Throughout the watershed, wetland soils and plants catch and hold heavy rains and floodwaters, then slowly disperses them. It is estimated that an acre of wetland can store as much as 6,000 cubic meters (about 7,800 cubic yards) of floodwater. Gradually released from the wetland, the water steadily replenishes the stream or river system or recharges the underground aquifer.
The water slows as it enters the wetland, causing water-borne materials to settle out onto the wetland soils. This settling takes sediment out of the water that may smother animals; such settling also cleans excess nitrogen and phosphorous that might otherwise over-fertilize the plants and throw the system's balance out of whack. Further, certain levels of organic nutrients that are troublesome in open water can be enriching in the wetland soil environment. Wetland plants take up the "overabundant" nutrients, drawing them into the food web.
Wetland plants can remove germs, certain heavy metals, and even some other toxic materials from the water. This cleaning ability has led particular human communities, from Arcata, California, to Calcutta, India, to develop natural-system wetlands as part of their sewage treatment systems.
Wetlands along the edges of open waters, such as Coos Bay, buffer the shoreline from erosion. And, world-wide, these ecologic powerhouses help mitigate the effects of climate change.
Wetlands even play a big part in recreation for hunters, fishers, birders, boaters, and more. Wind rippling verdant grasslands; raucous calls of migrating waterfowl; meandering sloughs teeming with life: wetlands serve our spiritual needs as well as our physical ones.
You can celebrate wetlands this Saturday — or any day — with an appreciative visit to a local public access wetland. South Slough National Estuarine Reserve just south of Charleston has several trails that lead down to both freshwater and estuarine wetlands, the Millicoma Marsh Trail in the Eastside district of Coos Bay offers great views of upper Coos Bay’s brackish marshes and freshwater cattail marshes, the Bluebill Trail in the southern end of the Oregon Dunes National Recreation Area features a pond with fringing marshes, and the old settling ponds on Coos Bay’s North Spit showcase different freshwater pond and marsh habitats.