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Degradation of Stream Ecosystems
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Degradation of American riverine-riparian ecosystems has reached alarming proportions (Doppelt, et al. 1993). Agriculture, hydrologic modification, and habitat modification are the three leading sources of river and stream impairment in the USA (USEPA, 2002). While the Clean Water Act (P.L. 92-500) calls for restoring and maintaining the chemical, physical, and biological integrity of our nation's waters, the leading sources of impairment identified above indicate that the physical integrity of riverine systems must be restored as a fundamental component of any management approach to measurably improve water quality (Graf, 2001).
Ohio EPA has established a goal of 80% designated aquatic life use attainment by the year 2010. As of the year 2000, Ohio's had only reached a score of 47% and as 2004, only 64% of Ohio's waters were in Full-Use Attainment status.
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Discussion
(abstracted in part from: Year 2000 Ohio Water Resource Inventory; OPEA)
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Trautman (1981) examined the various reasons why the fish populations throughout Ohio had declined or become threatened during the period 1750 through 1980. Since then, much of the biological monitoring conducted by Ohio EPA has, in part, extended the base of information presented by Trautman (1981). What has evolved is an increasingly quantitative assessment of water resource integrity in Ohio and an understanding of what has changed since Trautman's observations.
Ohio's streams and rivers are impaired by different causes and sources of pollution and other activities. The pattern observed during the past decade has been one of: (1) a general lessening of point source related impairment; and, (2) an increase in nonpoint source related impairments. The latter is the result of the emergence of causes and sources which were "masked" as a major effect by the greater prevalence and severity of past point source impairments rather than a net increase in severity of nonpoint impairment. Thus, as point source problems are abated, other problems are becoming increasingly evident.
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Comparison of 303(d) listing results for Ohio's inland waters
2002 vs. 2004 Integrated Report
Data from OPEA; 2004 Ohio Integrated Report
WQS = Water Quality Standards
TMDL = Total Maximum Daily Load |
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Category
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Number of
Watersheds
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Number of
Large Rivers
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2002
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2004
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2002
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2004
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1 Attaining all WQS
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1
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1
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0
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1
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2 Attaining some WQS
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11
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7
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5
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1
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3 Insufficient data
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105
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75
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1
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0
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4 Impaired, no TMDL needed
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9
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6
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2
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0
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5 Impaired, TMDL needed
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205
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242
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15
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21
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The top seven major causes of impairment, based on current, monitored- level data are: habitat modifications, siltation, organic enrichment/low dissolved oxygen (D.O.), flow alteration, nutrients, metals, and ammonia. Notable in the 2000 cycle is the continued, but slower rate of decline of point source related causes (dissolved oxygen, ammonia) and the predominance of nonpoint related causes such as habitat destruction, sedimentation, nutrients and flow alteration (4 of 5 top causes).
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Sources of impairment are shown below. Many of the nonpoint related causes that now predominate existed in the stream segments 20 years ago, but their effects were of lesser magnitude or were totally masked by more severe point sources causes such as organic enrichment or toxicity (metals/ ammonia). This also reflects the relative effectiveness of the regulatory programs to control point sources.
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As a means to more effectively measure the success of various approaches in managing freshwater resources, including water quality, the total maximum daily load (TMDL) program was initiated by USEPA in 2004. A feature of the 1972 Clean Water Act (CWA), a TMDL quantifies the maximum amount of a pollutant that a water body is able to receive while still meeting water quality standards, and an allocation of that amount to the pollutant's contributing sources. Ultimately an implementation plan must be developed that reduces pollutant loadings by the degree necessary such that a water body may fully attain its designated use. While contentious and subject to ongoing refinement, using TMDLs to achieve water quality goals holds great promise for guiding local and regional efforts to fulfill the intent of the CWA.
We are in an era where thousands of scientists have studied stream systems their entire careers and have provided us with detailed and defensible pieces of the restoration puzzle. There are millions of dollars allocated for the sole purpose of reducing non-point source pollutants, improving water quality and restoring function to stream systems. But in spite of these efforts, the goals of the 1972 Clean Water Act have yet to be met and Ohio's waters continue to be subjected to the effects of hydromodification, urbanization pressures and in many locations other ecosystem alterations resulting in degraded habitats and decreased water quality. |
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Ecosystem Response to Stressors
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| Resources |
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Ohio EPA 305(b) 2000 Resource Inventory Report
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Summary:
The 2000 Ohio Water Resource Inventory focuses on the status of Ohio's surface and ground water resources through the 1998 data year, a description of Ohio's monitoring program including the addition of a stratified sampling component, and a forecast of the status of Ohio's rivers and streams through the year 2010 in an attempt to assess the likelihood of meeting the Ohio 2010 goal of 80% full attainment.
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| Downloads |
| » 2000_OhioWater Resource Inventory; 124 pgs; PDF file 8.1 Mb |
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