This Section was revised in April of 2011

Critical Areas

Critical areas identified below are considered by the UWRBC Steering Committee to be potential sources of pollution within the watershed. In order to minimize the water quality impacts associated with these areas, it will be important to target the implementation of management measures toward these critical areas.

Failing Septic Systems

A source of the elevated pathogen bacteria in the watershed may be associated with improperly functioning, failed, or non-existent residential septic systems. Many factors can lead to the failure of a residential septic system; the age of the system, lack of regular maintenance to the system, and heavy clay soils. Within the Upper Wabash River watershed, the unincorporated areas lack a centralized sewage disposal system, limiting homeowners to on-site septic systems. It is crucial that these homeowners are equipped with the necessary information and knowledge as to the proper maintenance of the system to prevent failure. As the more populated areas of the City of Berne, the City of Bluffton, the Town of Bryant, the Town of Geneva, and the City of Portland continue to grow in size, it will become more feasible to provide sanitary sewer services to those residences in close proximity to these areas. The importance to provide a centralized sanitary sewer system is underlined by information prepared by Purdue University Extension onsite regarding wastewater disposal in Indiana. Adams County, according to 1990 US Census data had an approximate 4,300 households utilizing onsite wastewater disposal systems. Soils in Adams County considered to be severely limited for proper septic system function based on NRCS criteria was estimated to be 100%. Similarly, within Jay and Wells Counties there are an estimated 3,700 and 4,700 households respectively utilizing onsite wastewater treatment systems. Further, in each of Jay and Wells Counties more than 96% of the soils are classified by NRCS as severely limited for septic systems.

Residential on-site sewage systems located within the floodway or 100-year floodplain are at a higher risk of discharging improperly treated effluent, bacteria, and pathogens into receiving waterbodies. As the soils become saturated due to rainfall, and the receiving streams are inundated, there is little to no treatment occurring within the soil absorption field. Routine flooding of those systems located in the floodplain may also have detrimental effects on the individual components of the system.

The most critical are those areas within the watershed where a cluster of 20 or more rural homes with residential septic systems installed more than 10 years ago in soils with NRCS defined severe limitation for onsite wastewater disposal or treatment. Utilizing digital aerial photography, 8 clusters of septic systems as well as the Town of Linn Grove and the Town of New Corydon were identified and are shown on Exhibit 5. These clusters are all located near to the Wabash River or associated tributary streams and may provide concentrated loadings of nutrients and/or bacteria if several of these systems are failing to adequately treat the household wastes. Water quality monitoring should be initiated immediately upstream as well as immediately downstream of these areas to further assess the impact on water quality and macro-invertebrate communities.

Areas Prone to Flooding

Areas prone to flooding can also be sensitive to other issues related to water or habitat quality degradation, as well as cumulative effects of increased water quantity within the stream system. Poorly managed floodplains where increased construction or other land use changes have occurred result in increased vulnerabilities to the new structures and to downstream areas as well. If water is not allowed to infiltrate the soil layers due to increased impervious surfaces, runoff volumes and downstream loadings will be increased. These increased volumes of water may mobilize trees and other near stream debris creating the potential for in-stream obstructions or log jams.

The term “log-jam” is defined by the Indiana Administrative Code as the accumulation of lodged trees, root wads, or other debris that impedes the ordinary flow of water through a waterway.  As these log jams are created, areas of significant erosion and streambank destabilization are created further degrading water quality through sedimentation. Log jams may range in severity from leaning trees that need to be removed and utilized to stabilize the nearby streambank, to areas requiring large excavation equipment from both the land and within the stream for proper removal. With each degree of severity and corresponding workload, restrictions and guidelines provided by IDNR and the US Army Corps of Engineers (USACE) must be adhered to rigorously. Plans of work and permits are also required for more intensive situations. Some areas in the Wabash River watershed are sensitive to log jams and associated debris deposition and/or increased streambank erosion. These areas, shown on Exhibit 5, were selected by the Adams, Jay, and Wells County Surveyors and are considered critical requiring constant observation and maintenance.

The risks to structural damages and watercourse damages can be decreased through preventative measures including detailed stream studies to establish floodways, floodplains, and base flood elevations. Utilizing the associated information will provide better knowledge regarding the stream and allow for proper floodplain management. Furthermore, the installation of United States Geological Survey (USGS) stream gages designed to monitor water quality, elevation, and flow will provide the necessary baseline information as well as information regarding low and high water events. Longevity of record for each gage is also important to monitor trends over several years. The combination of information obtained through detailed stream studies and long term monitoring can be valuable when proposing methods to prevent repeated flood events as well as reducing the impacts of flooding to water quality and personal property. Areas sensitive to repeated flooding, property damages and the locations of existing are identified on Exhibit 4.

 

Excessive Nutrients

Excessive nutrient inputs to the land often lead to phosphorus and nitrogen entering the waterways through surface and subsurface runoff.  Phosphorus in excess of crop needs becomes soluble in subsurface runoff, whereas phosphorus bound to soil particles is lost to surface runoff.  Managing the quantity and transport of phosphorus fertilizer reduces the loss to waterways.  Nitrogen is often lost to surface and subsurface runoff due to its solubility in runoff.  Locally, nitrate nitrogen is commonly lost due to leaching and denitrification.  Managing quantity and timing of nitrogen fertilizer application reduces the probability of nitrate loss to these processes. 

Livestock manure may also contribute to excess nutrients in the watershed.  Manure placement and timing is important for crop production, yet excess manure is lost to waterways.  Nutrients that exceed crop use and soil holding capacity increase the likelihood of polluting waterways.  Manure generated at approximately 39 facilities in the watershed is managed by IDEM regulations.  However, there are approximately 384 hog operations, 904 cattle, and 224 poultry operations in Adams, Jay, and Wells Counties in addition to the regulated facilities.  These facilities may not utilize manure management practices and are a priority for nutrient management programs.

The critical areas are those where applications have not been managed by amount, source, placement, form, timing or cover and lead to non-point source pollution.  Reducing, trapping and/or avoiding excess nutrients entering waterways from agricultural lands can be accomplished by best management practices, including but not limited to, nutrient management, comprehensive nutrient management, conservation tillage, cover crops, buffer strips, or riparian buffers.  Avoiding excess nutrients and controlling nutrient transport on agricultural fields is preferred for surface and subsurface runoff, while best management practices adjacent to waterways are preferred for surface runoff. 

 

Gully, Sheet and Rill Erosion

Erosion occurs when wind or water runoff carries soil particles from one area to another. Sedimentation occurs when these soil particles are deposited into a receiving waterbody, such as a stream or a lake. These mobilized soil particles may become suspended within the water column, clouding the water which reduces the amount of sunlight reaching aquatic vegetation and obstructs the gills of aquatic organisms.  Particles of silt and sand may eventually precipitate out of the water column settling on the streambed, effectively covering fish spawning areas, and smothering food supplies.  Activities involving land disturbance such as conventional tillage methods, intensive livestock grazing with stream accessibility and removal of wooded areas are likely to increase sediment loadings to the watershed.

Gully formations on agricultural lands contribute to sedimentation problems in waterways.  There are two classes of gully formation, ephemeral and classical.  Gullies are considered classical when channels are too deep or wide to be tilled or filled; ephemeral erosion is defined as sheet and rill formation.  The critical gully formations in the watershed are those that form on a positive gradient to a waterway equal to or greater than one percent and significantly contribute sediment to the waterway.  The determination of this critical area will be made by evaluating soil, slope, gully dimensions, and proximity to the waterway.  A diverse group of conservation practices, including but not limited to grassed waterways, conservation tillage, cover crops and critical area plantings are available to address these formations.