best management practices
Watershed management is holistic and involves everyone.
Watershed management must take into consideration all aspects of the watershed. The Water Environment Federation (“Everyone Shares a Watershed”) compares watershed management to listening to an orchestra. You don’t listen to the music from just one instrument—you hear the entire symphony. It is a holistic or complete experience. The same is true with watersheds. Instead of focusing attention and resources on one or a select few problems, a holistic approach must be taken. Policy-makers and individuals need to make decisions based on all water resources, all water uses, and all threats to water quality and the ecosystem throughout a common geographical area. The watershed approach considers all pollution sources, ranging from industrial discharge to agricultural runoff. It evaluates the combined effect on the total watershed environment.
• The public must become involved in water quality issues that may extend beyond their own immediate neighborhood.
• Political boundaries need to be exchanged for watershed boundaries, and new coalitions need to be formed.
• People must learn to cooperate, stakeholders become involved, and all share a commitment to protect water resources.
urban water quality problems
Impervious surfaces—10 percent (of total surface area) imperviousness causes stream degradation. Impacts are hydrological, physical, water quality, and biological. After 5 percent imperviousness a rapid decline in both fish and macroinvertebrates begins and maximizes at 10 percent imperviousness. Pollutants assume larger impact roles at moderate and high urban imperviousness. Stormwater runoff concentrates in the last 75 feet before entering the stream.
When impervious surfaces exceed 10 percent, the following can happen:
• Increased flooding
• More frequent bank-full flooding
• Lower dry weather flow
• Increased channel and bank erosion
• Loss of pool and riffles
• Stream widening
• Reduced fish passage
• Degradation of stream habitat structure
• Degradation of substrate quality
• Decline in aquatic insect diversity
• Rise in total suspended solids, etc.
• Decline in fish diversity and abundance
• Decline in wetland plants and animals
Build-out in the floodplain—National studies have found that 40 percent of flood damage is actually outside the 100-year flood plain.
Compacted ground—Hard ground, even though not paved, actually contributes significantly to runoff. Fifteen times more rainwater soaks into a wooded area compared to an equivalent managed lawn area. 70% of “pervious” (lawns) surfaces contributed to 60% of the runoff in compacted ground studies. (Thomas Schueler, Executive Director, Center for Watershed Protection, Ellicott City, Maryland)
Storm drain dumping—Dumping of chemicals (oil, paints, leftover pesticides, chemicals) in the storm drain impacts receiving stream.
Oil and gasoline leaks.
Salt and sand from municipal streets are easily washed into storm drains.
Manicured lawns with excessive applications of fertilizers and herbicides. Utilization of lawn services without close oversight of the amount of chemicals being applied to your lawn. Continual application of fertilizer year after year on lawns, school yards, business parks and other green areas is often done without testing the soil to determine its level of fertility.
High levels of bacteria during storm events in urban streams.
Excessive amounts of other chemicals, including oily grit, scum, etc. carried to urban streams.
Dumping of old appliances, tires, building materials, garbage, lawn waste, etc.
urban best management practices
Pass ordinances that prevent further development in the entire 100 year flood plain. This in itself would help in reduction of flood problems—a much better alternative than building dams and extensive stormwater storage facilities.
Low Impact Development (LID) practices can be utilized by private citizens and municipalities alike. Low Impact Development is a different approach for stormwater control that retains and infiltrates rainfall on-site, rather than the traditional management method of rapid conveyance of water via storm sewers to surface waters with a focus on flood control rather than water quality protection. LID infiltration-based storm water management practices include:
• Bioretention cells—These are shallow, landscaped depressions that can handle large volumes of water from extensive impervious surfaces found in commercial, institutional, industrial or residential settings. These may require engineered substratum because of altered and compacted soil conditions from earlier grading and compaction. Usually the subgrade will have a tile drain bedded in gravel and a soil matrix of soil/sand/compost. Native trees, shrubs, grasses can be planted to provide water absorption and shading for parking lots nearby. Bioretention cells should be strategically located to capture roof and other impervious surface runoff.
• Bioswales—Bioswales are vegetated shallow, linear depressions that provide drainage between slopes or adjoining land that is higher. They have many of the same design features as rain gardens and bioretention cells. Bioswales convey water from large runoff events to storm sewer inlets or directly to surface waters after providing infiltration of first flush runoff. During low intensity rains, bioswales allow rainwater to cleanse, infiltrate and recharge groundwater. Existing natural drainage swales can be used. Low maintenance native vegetation that is hardy in moist areas is very suitable for bioswales and rain gardens.
• Rain Gardens—Rain gardens are perennial gardens featuring native vegetation strategically located to capture runoff from home roofs, driveways, and patios. They simultaneously serve as attractive landscaping features in addition to their ability to absorb water, filter pollutants, and reduce runoff on each homeowner’s lot. Natural depressions can be used if located appropriately. Some substrate engineering may be necessary if soil quality is poor. When widely used, in private and commercial/business settings, rain gardens would contribute significantly to reducing stormwater runoff, protecting water quality, and preventing flooding. They perform much like bioretention cells.
• Native Landscaping—Because native plants have extensive root structure that builds soil quality and holds soil in place, and require less water and maintenance, they are more functional as well as more valuable in stormwater control than other traditional plantings. It is recommended to devote at least 30 percent of green space (yards, parks, campuses) to native landscaping and direct runoff toward native landscaped areas. Although people have traditionally had a bias for manicured, well-groomed lawns, it is hoped that with education there will be greater understanding and acceptance of the benefits of native plantings.
• Infiltration Trenches/Systems—These allow temporary storage of runoff in parking lots, perimeters of business parks or other large green areas, or in the center of a swale. They are excavated trenches or cells that are filled with gravel and a biologically active organic matter. They provide temporary storage of runoff and infiltration into surrounding soil.
• Permeable Paving Alternatives—Paving blocks, geoweb reinforced gravel, and grassed surfaces are permeable paving surfaces. Permeable-topped “blacktop-like” surfaces suitable for paths and sidewalks have been used by the Metro Waste Authority at Bondurant (near Des Moines), Iowa. Permeable paver blocks allow water to infiltrate and are suitable for parking lots, fire lanes, driveways, bike paths, private roads, and off-street parking. This new technology should be widely utilized by municipalities and private property owners to provide significant reduction in stormwater runoff.
Urban stream buffer/riparian strips—Riparian areas of modest size can restore streams receiving run-off from 15 to 18 percent imperviousness. Customize the buffers—make them specific for each unique local watershed situation. Integrate the buffers throughout all the watershed sub-basins for urban stream-green corridors. Vegetation plays key role in water quality and the health of streams:
• Retains and stores sediment, filters out bacteria, chemicals, and fertilizers
• Cooling of stream water
• Roots give structure and holds stream banks
• Provides foundation of stream’s foodweb (detritus)
Plant trees around parking lots to reduce nutrients and hydrocarbons by absorbing air-born phosphates and exhaust on their leaves. Trees help stormwater control by water uptake through their extensive root systems; tree litter slows runoff and soaks up rainwater.
When re-grading existing lawns or constructing lawns in new developments, they should have compost blankets for effective temporary site stabilization while vegetation is established. Also, mulching (with wood chip or fiber mulches) can be done to reduce soil erosion, and can be sprayed on as a slurry along with seed. The mulch retains moisture and protects seedlings from temperature extremes.
Developers need to consider designing developments to fit the existing landscape to minimize the amount of grading that will need to be done. This reduces the amount of land exposed to erosion and is more cost effective. Phased grading, grading of each phase is started and completed in sequence, maintains strategic vegetative cover and minimizes the amount of disturbed land at any given time.
Rolled erosion control products—Mats or blankets of organic or synthetic biodegradable netting materials can be applied to the soil surface to protect disturbed areas from erosion until vegetative cover is established. These are especially suitable for severe slopes or areas of concentrated runoff flows.
Sediment control basins—These are basins commonly used on construction sites to retain sediment by impounding and slowly releasing runoff. Sediment settles out of the standing water. Basins are to be placed strategically throughout the construction site and can be temporary as part of a phased grading plan.
Silt fences—Silt fences are temporary sediment barriers of geotextile fabric anchored in the ground and supported by posts on the downstream side of the fabric. They temporarily impound runoff and retain sediment on site if placed and installed correctly. They must be placed on the contour, not too far apart, and routinely cleaned out after each storm event. Silt fences are too often neglected on construction sites.
Compost socks/berms—Mesh tubes filled with biological degradable composted material are used to slow and filter water on construction sites on slopes. The compost-filled socks or berms are placed at the top of the hill on the contour at intervals to intercept and treat sheet flows.
Seeding with a fast-growing annual grass species is an economical way to stabilize a construction site or a new lawn, yard, or municipal green area until permanent vegetation is established. Using winter rye, when reseeding one’s home lawn, serves as a good cool weather cover.
Apply landscape chemicals (fertilizers and pesticides) properly to reduce chemical runoff. Take over lawn maintenance yourself, or if you must have a lawn service, request that only modest amounts of fertilizers and chemicals be applied to your lawn. Follow directions and use sparingly.
Aerate home lawns for greater rainwater infiltration.
Contact the local university extension office for soil testing kits and information. Collect soil samples from your lawn and yard for nitrogen and overall fertility analysis. This will provide guidance for future fertilizer applications and avoid over-fertilizing.
Use organic pesticides and organic methods to reduce the amount of chemical pesticides residuals in runoff.
Apply fertilizers and herbicides/pesticides according to manufacturer’s directions—increasing the strength doesn’t guarantee increased effectiveness. Apply at the right time of year.
Avoid applying fertilizers or pesticides when a rain storm is forecast.
Use water-efficient and conservation-wise lawn watering methods to avoid loss of water through runoff and evaporation.
Mulch barren spots and plant a tolerant ground cover on large barren slopes.
Properly dispose of hazardous materials at Omaha’s Household Hazardous Waste Collection Facility located at 4001 South 120th Street; call 402-444-7465 for an appointment. Do not pour left-over liquids into the storm drain. Recycle used oil. Prevent spills and leaks from being carried into the storm sewer.
Practice timely servicing of your family’s vehicles to avoid leaking oil and gasoline on streets and parking lots. When changing your car’s oil, make sure used oil is collected and not disposed on the ground.
Properly dispose of your pet’s wastes, preferably in the toilet. Even in your own fenced backyard, rainwater runoff will wash bacteria into the storm drain and raise bacterial levels in the receiving stream significantly.
If you live on an acreage and have your own septic system, check for inadequate processing or leakage.
Wash your car, truck or SUV on grass or gravel instead of the street or driveway, or better yet, take it to a car wash where the water gets treated and recycled. Use biodegradable soaps.
Don’t dump anything into the Papillion Creek streams! Take old appliances to the recyling center yourself or make sure that when you purchase a new appliance, the old one is taken and properly disposed. Bag and/or bundle yard waste/leaves/limbs for the city’s pick-up. Take tires to an automotive/tire dealer, place garbage in the trash cans for the city’s garbage pick-up, and take building materials to a recycling center. All items seen dumped on stream banks of the Papillion Creek streams should have been disposed of elsewhere.
Municipalities must conduct thorough street cleaning to remove the salt compounds and sand that are used during winter for the treatment of icy roads. This best management practice is one of the practices that is contained within the MS4 Stormwater Permit.
NOTE: Special thanks to the Natural Resources Conservation Service, “Conservation Strategies for Growing Communities” and other NRCS information for some of the information used above. We recommend a visit to your local NRCS office for assistance in implementing many of the stormwater practices.
agricultural water quality problems
Channelization and stream straightening—Human impact on the Plains changed the hydrology of the area from a ground water system to a surface water system. This change moves pollutants to streams much faster. Channelization of streams is the major hydrologic change in the Cornbelt. By the early 1900s, much of the ditching and channelizing was already done, but it has continued to the present time. Seventy million acres were drained in the Mississippi River Basin.
Nitrate runoff from fertilizer application—This is a substantial problem in the Cornbelt because of the large modification to the hydrology (tiling, direct drainage out of terraces, straightened and channelized streams). Runoff from fields planted to corn is directly responsible for the nitrate runoff that is so prevalent in the Midwest.
Nitrate levels that have been measured during a rain event:
• Baseflow 0.15 ppm
• Rising limb of hydrograph 0.22 ppm
• Peak limb of hydrograph 0.22 ppm
• Falling limb of hydrograph 0.19 ppm
(10 ppm is the maximum standard for drinking water.)
Sheet erosion—This is the uniform movement of a thin layer of soil across an expanse of land devoid of vegetative cover. Raindrops detach soil particles, transporting them downstream to a point of deposition. Farming up and down the slopes with row crops contributes to this.
Sheet and rill erosion—Rill erosion occurs when the duration or intensity of rain increases and the runoff volumes accelerate leaving visible scouring/ditches on the landscape. Large quantities of soil are carried away in this type of erosion. Farming up and down the slopes with row crops contributes to this.
Gully erosion—Gullies form when there is a complete lack of attention by the property owner and rushing water continues to scour out a ditch that grows deeper and wider. Lighter soil types are more inclined to develop into gullies quickly. As gully erosion continues, the area will eventually become so deep that it is no longer crossable with tillage or grading equipment.
Plowing, disking—Plowing and heavy disking of fields covers the crop residue that helps to protect soil surfaces from wind and rain erosion. It leaves the soil bare and loosens the soil, making it more prone for wind to pick it up and for water to make rills and ditches.
Over-application of fertilizer—As “insurance”, excess fertilizer is often applied as a “back-up” to ensure that the corn crop will produce large yields.
Over-usage of chemicals—Herbicides are sometimes used excessively. All chemicals should be used as sparingly as possible, if at all.
Domestic animals in streams—Livestock that access streams on a regular basis break-down stream banks, devoid the banks of vegetation, increase sediment and bacteria in the streams.
Open livestock lots—Can be harmful to water quality because of the drainage to streams or ditches carry significant quantities of bacteria.
Grid-tile whole fields—Removes water from hilly and level areas of a field alike; moves moisture out of the sub-soil and reduces groundwater flow. Eliminates small wet spots or wetlands and destroys natural habitat for a variety of wildlife and plants.
agricultural best management practices
Spring application of nitrogen—Apply nitrogen as close as possible to when your crop needs it most. Fall application of nitrogen increases the loss of nitrogen through denitrification. It also gives nitrogen time to leach through the root zone and into groundwater or subsurface drainage tile. It is estimated that 20% of fall applied fertilizer can be lost to runoff.
No-till or minimum-till farming is a conservation practice highly regarded by agronomists and soil scientists. This method does not plow or disk, therefore the soil surface is not disturbed and soil structure is greatly enhanced. The next year’s seeds are bladed into the previous year’s crop stubble. Thus, the remaining organic material (old stalks and leaves) from the previous year’s crop remains on the ground throughout the winter and into the spring, protecting the soil from wind and rain.
On hilly terrain, contour farming (farming around the hills rather than up and down the length of the slopes) creates little ridges horizontally across the slope which helps to slow down any moving water and gives it a chance to soak into the ground.
Contour strip-cropping is a system of alternating strips of meadow, alfalfa, or small grains (buffer strips) with strips of row crops on the contour. This practice can reduce soil erosion by up to 75 percent when compared to planting row crops up and down the slope.
Cover Crops—Plant cover crops. They do an excellent job of controlling soil erosion during the winter and through the critical high-rainfall months of spring. Convert highly erosive land to forage crops instead of row crops.
Buffer/filter strips next to streams or ditches are invaluable to water quality. Use of buffers is a key element in a watershed approach to improving water quality and stream quality. Buffer strips reduce the velocity of the runoff from adjoining row-crop fields, allows the water to infiltrate, filters sediment, excess fertilizers and chemicals, and holds the streambank and adjoining land in place. In studies, grass buffer strips removed 60 percent of Atrazine and Alachlor—thus, grass buffers aid in herbicide removal (Richard Lowrance, Ecologist, USDA Agricultural Research Service, Tifton, Georgia).
Buffer areas along streams:
1. Shade & temperature—only a few degrees change will cause aquatic organisms to die; 6-15 degrees cooler in the summer when trees are growing along streambanks.
2. Elevated temperature reduces oxygen and increases the impact of other pollutants. Even sediment control structures need to be shaded.
3. Chemical processing—buffers are filters and sinks, trap sediment, filter out phosphorus.
Sloughing-off of stream banks occurs far less when a good buffer or riparian strip is in place. Buffering urban stream with buffer strip corridors is equally as important, and protects water quality, stabilizes stream banks, provides wildlife habitat and linear green space for recreational activities.
Streambank stabilization—One of the most economical and effective ways to control streambank erosion on small streams is the willow-post method. This method controls streambank erosion through the installation of native willow cuttings to stabilize the bank. The dormant posts spout roots, and this root network binds the soil together, reducing erosion. Cedars and other woody material can be woven among the posts to provide greater strength until well established.
The installation of terraces across the hillside slows down the rush of water down the hill and channels it to a receiving stream. Terraces are especially suited for moderate to severe slopes. They are earthen embankments around a hillside that stops the water flow and stores it or guides it off the field. These require maintenance and rebuilding if washed out during especially large rain storms.
Water courses in fields need to be converted to grassed waterways instead of tilling straight across these natural water flow pathways down a slope or hillside. Grassed waterways require some shaping and soil preparation to ensure that the water will flow down the center rather than on both sides. Seeding with brome grass or other grasses and routine mowing and maintenance is important to keep these effective controllers of runoff.
Grade control structures—These structures drop water safely from one level to another, preventing it from gouging out gullies. They can also help to control flooding and trap the sediment moving with runoff water. Grade control structures are typically built across an existing gully, a grassed waterway, or the outlet of a waterway.
Water and sediment control basins—Similar to the previous structures, these trap sediment and runoff, reducing flooding and gully erosion and improving the farmability of a field. Use should be confined to rugged areas and should not take the place of terraces. It is recommended, however, that such ground should not be farmed but, rather, seeded to permanent grasses.
Precision fertility management pinpoints the levels of fertilizers needed in a field and avoids the across-the-board heavy application. The number of bushels of corn and soybeans harvested is tracked by GPS and compared with fertilizer application records. Soil testing by grid is also done to get a full understanding of the soil’s fertility. The producer then can pinpoint fertilizer application in a field. This helps to reduce overall wasted fertilizer and improves water quality.
Soil testing—Soil testing helps you find the balance—applying enough fertilizer to maintain productivity without applying so much that it becomes uneconomical or environmentally hazardous.
Livestock that is allowed to access streams impacts water quality. Sediment-loading increases because livestock break down stream banks and stir up the streambed. Bacterial levels significantly increase. Fish and macroinvertebrate communities are reduced in diversity and abundance in the areas where livestock stand or cross the stream on a regular basis. Cattle can be fenced out of streams but still have a water source with nose-pumps that pump the water from the stream to enclosed pasture areas. Restricting cattle access to streams is a positive move towards improved water quality. If pasture is located on both sides of a stream, stream crossings constructed from gravel encapsulated in a indestructible polyethylene mesh can be installed, which stabilizes the banks and streambed, and reduces erosion and water quality problems.
A rotating paddocks grazing plan (rotating cattle between fenced small plots to prevent over-grazing) ensures the protection of the pasture by avoidance of over-grazing. It allows for grazed areas to rest and re-grow before cattle are allowed onto it again. A rotational grazed pasture provides better cover to reduce erosion.
Livestock operations need to have sound containment structures for careful management of wastes. Lagoons must follow state and federal requirements for approved placement with considerations in regard to geology, soil type, topography, distance to nearest stream, containment capacity, excess/overflow, and other conditions. Use curbs, terraces, channels, dikes, pipes, and culverts to direct the contaminated runoff to an outlet that leads to either a settling tank or a settling basin. Settling tanks and basins capture runoff and allow liquids to slowly drain to a holding pond, lagoon, or infiltration area.
Nutrient and manure management plans for livestock confinement operations need to be filed and followed accurately to ensure avoidance of spreading of manure prior to a storm or repeatedly on the same field over and over. Liquid manure should be knifed-in. Calibrate the manure application equipment to avoid over-application of manure.
Native plants and natural landscapes lend themselves for buffer/filter strips and control of gully formation. Native plant root formation is greater than some domestic grass species, and provides better diversity on the landscape for insects, birds, and wildlife.
Do not channelize and straighten streams and ditches. Leave streams in their existing natural state and enhance them with wetlands and other adjoining conservation practices.
Limit tiling in fields to the replacement of old tile lines. While removal of long-standing water in crop fields may be desired for crop production, these prairie potholes or wetlands provide valuable habitat for waterfowl, prairie birds, amphibians, and marsh plants.
Restore wetlands. Wetlands, ponds, streams, riparian areas serve as sinks for nitrogen; sinks retain one-third of the nitrogen that enters. Wetlands filter pollutants from upland runoff, help control flooding, and maintain populations of wildlife. They are transition zones between flowing water, plants, and recycling of nutrients. Phosphorus, however, is retained only slightly. Phosphorus attaches to clay/soil particles and goes wherever the eroded soil goes.
Septic systems for farmsteads often are in need of replacement or repair. Check systems for leaking and inadequate processing. Also ensure an adequate leach field is in place and that there is no direct connection to a stream or nearby ditch.
