How long is long enough to make a Water Quality improvement? Steve Phillips, CPESC
Oxbow River & Stream Restoration, Inc.
Defining the minimum length of stream restoration necessary to make a water quality improvement: Based on Ohio case studies.
Protecting the downstream use of our water resources is an integral part of the Clean Water Act. The top five causes of impairment throughout the Midwest are hydromodification (or ditching), siltation, organic enrichment, nutrients and flow alteration. Bio-assessment methodology can illustrate and track the effect of upstream water quality impairments on downstream channel or lake aquatic life uses. Stream restoration is a tool that should be considered in the spatial context of the watershed and implemented in a matter that mitigates those major upstream impairments to restore ecosystem function and meet federal minimum water quality standards. This paper will start to analyze ecological results of four Ohio restoration projects within impaired watersheds to determine the effect on the downstream aquatic life use. Are receiving streams affected positively, negatively or not at all by upstream restoration projects?
There are many questions as to the “success” of stream restoration projects in the Midwest. While restoration is implemented at a very small scale when compared with the impairments, there is an abundance of academic and agency institutions assessing “success” using very different criteria. Questions such as project costs, different design approaches and the need for more monitoring are continually raised. However, there seems to be little interest or understanding whether a project achieved a measurable improvement in water quality or if the stream was brought up to a defined or designated use, i.e. the “measurable outcome”. More importantly, when considering if these
measurable “outcomes” were obtained in terms of success, are they correlated with a minimum length of project restoration in the context of a watershed scale. Is there any evidence that project length accumulates reductions of stressors that result in little response (biological, nutrient reductions) until some threshold is reached at which time those positive ecological responses accelerate? In the spatial scale of a sub-watershed, how can public money best achieve measurable water quality improvements and mitigate or eliminate downstream impairments?
There have been hundreds of thousands of dollars spent to assess the performance of “restoration” projects. The current trend for studies is to be very academic and assess individual structural elements that make up a project rather than the outcome or success of the project. Agencies and academia that assess the individual structural inputs of restoration projects create a false belief that they have the answers to these questions regardless of the real outcome of those projects. Each project requires many very different ecological and engineering inputs to meet specific project goals, objectives, and site constraints. Many studies tend to develop their own success criteria that may serve to internally validate pre-conceived ideas rather than first, show the outcome of restoration projects and second, understand the scale, context and complexity of “restoration”. Therefore, only a professional
assessment of the outcome of a restoration project as a whole seems appropriate to determine success. We suggest that studies and assessments meant to illustrate the outcome of “restoration” be subjected to vigorous peer review by professional practitioners to prevent erroneous and arbitrary conclusions.
As a result of this arbitrary approach, assessment studies of restoration have numerous claims such as “the need for more monitoring” or that “no standard assessment tools exist to determine success”. In Ohio, the latter is simply not true with bio-assessment and bio-criteria being the foundation of Ohio’s water quality standards and aquatic life use designations. More importantly, it seems that for any non-professional assessing restoration projects, there is no “standard outcome goal” recognized from which one could measure success. Without first recognizing a standard outcome goal, any criteria used to assess project success is simply a moving target, which may show success or failure depending upon the author’s agenda or pre-conceived beliefs. The goal of stream restoration is not to return the river to its original pristine state, but instead to secure the physical stability and biological function of the stream (Rosgen, 2006). The goal in Ohio is to restore impaired waters and meet minimum federal standards as described in Ohio’s tiered and regional Water Quality Standards (WQS).
Recent claims by studies and assessments such as “ the majority of restoration projects were not sustainable”, “less than half were described as ecologically successful”, ‘that restoration is driven principally by mitigation”, or ‘restoration work to date has achieved only modest success in terms of restoring ecological integrity” are all contentious at best and at worst, based upon poorly assembled data sets, a poor understanding of restoration practices in general, and specifically little understanding of the inputs that drive performance based outcomes. For example, are the critical inputs to achieving measurable water quality improvements the planting pallet, invasive management or floodplain soils pH or could it be a minimum length needed to actually achieve treatment of the water column and increase biomass?
Some studies do not acknowledge actual ecological outcomes of restoration projects while scrutinizing specific design elements of those projects at nauseam. Examples of this issue include not only
erroneous conclusions when citing other papers and authors, but development of very poor data sets. One study’s purpose was to show how public money is being spent, yet developed criteria that the authors then used to describe sustainability and ecological success (Alexander and Alan, 2006). Another report (ODNR Division of Soil and Water, 2006) cited the cost of “restoration” to be $600 per linear foot but had no actual data to support that claim and failed to recognize an existing Ohio EPA 319 project database of actual project costs. Another recent study by Mechlenburg and Fay, 2010 looked at 51 mitigation sites and mingled the data from very small site-specific mitigation projects with actual restoration projects. These authors also developed their own set of criteria to determine “ecological success”, yet failed to define success or use existing criteria of “ecological success” used by Ohio EPA when determining aquatic life use attainability. Finally, this study titled “Functional Assessment of Stream Restoration In Ohio” (Mecklenburg and Fay, 2011) claims the “restored streams assimilative capacity had not been increased, but the report has no data to support this and did not examine in any way the assimilative rate for any pollutant pre or post restoration. This report, which leads readers to believe it assessed ecological function, either naively or conveniently ignores a USEPA study (Zika, 2008) of two streams in their data base that clearly compares pre and post conditions and shows the restored segments can assimilate and remove nitrates at rates 10 times greater than that of the un-restored or impaired conditions. More importantly, the authors completely ignored a State of Ohio developed spreadsheet specifically designed to calculate the change in assimilative capacity as a result of restoration, largely based upon channel length. This spreadsheet calculates a reduction (pounds or kilograms) of phosphorus and nitrogen loads over time (days and years) for restored channel versus impaired channels.
Even more problematic, are assessment reports that develop rapid assessment data in lieu of using actual project engineering data. Most often, this is done by non-licensed engineers to evaluate the
engineering design of a project. This typically starts with calculating watershed size, from which flows and channel dimensions are then compared. In one instance, we looked at 5 projects within an assessment study where the watershed size and subsequent channel dimensions were calculated and then used to assess the success of channel form and floodplain connectivity. The assessment report was incorrect for all 5 projects and by as much as 50%, no small mistake with regard to watershed sizes less than 5 square miles. This compounds itself as the watershed size is utilized to establish empirical relationships that are then used to determine “success”. The result can be very poor data sets from which authors then draw “success” conclusions and make recommendations. In yet another biological assessment report, the watershed size was again incorrectly calculated by non-engineers, resulting in using assessment criteria calibrated for large streams rather than headwater intermittent streams (<1 square mile). This resulted in poor conclusions and a recommendation that for “habitat restoration to be successful, base flow augmentation would be necessary”.
While some authors are seemingly desperate to assess the success and function of restoration projects, they completely ignore the multitude of variables and constraints that must be considered in the final engineering design of restoration projects. Examples such as utility crossings that may determine channel inverts, site constraints, budgets, FEMA regulations and flood flows all must be determined and considered by project engineers. Many reports assume that no project has any site constraint, which may have driven a design compromise. Most reports develop their own set of success criteria, which can be arbitrary and conflicting with actual project or state water quality goals.
Assessment of restoration projects
repeatedly measure very small scale design elements rather than the outcome or influence of the restoration in the context of the watershed. Most approaches to assessment assume the benefits to be linear and in most cases do not understand the concept of accumulating stressors or in the case of restoration, the elimination of those stressors.
Figure 1 to the right illustrates the
relationship between accumulating stressor reductions on the x-axis and the responses (biological, nutrient reductions) on the y-axis. As can be seen in this illustration the form of these responses can have a great influence on the long-term success of large
scale restoration strategies. The top curve predicts substantial, early response to restoration while the bottom curve indicates little response until some threshold is reached at which time the responses accelerate.
The challenge then becomes how much restoration needs to occur with any sub-watershed to achieve biological improvement and nutrient reductions and move past the threshold. By comparing some of these different assessment methods for project success that concentrate on structural inputs, the answer to this question does not seem to be considered. By examining the specific outcomes of restoration projects, the answer to that question becomes more apparent. Specific examples of restoration projects include Bokes Creek, Pond Brook, Mac-a-chee Creek, and Woodiebrook. The first
Length of Stream Restored
Percent of Catchment Restored
two projects illustrate the relationship between impaired tributaries and downstream water quality. The second is an example of an impaired tributary with no goal or need to improve downstream water quality and the last illustrates biological results after restoration of a severely impaired tributary. Bokes Creek
In 2000, Ohio EPA developed a “Technical Support Document” a type of watershed action plan for the Bokes Creek watershed. Bio-assessment data collection started in 1992 and bracketed the tributaries to Bokes Creek. This enabled Ohio to identify which tributaries were responsible for impairments to aquatic life use-designation as shown in Figure 2 below. As a result, of this type of bio-assessment, any plan to improve Bokes Creek must recognize and implement a restoration plan that includes the impaired tributaries. Powderlick Run was recognized as having a significant negative impact on Bokes Creek. The segment of Bokes Creek above the Powderlick Run confluence was in good condition and meeting the designated use, however the segment at and below the confluence was rated as poor and in attainment of the designated use. It is important to understand that both the attaining and non-attaining segments of Bokes Creek had similar functional physical characteristics such as sinuosity, floodplain, wooded riparian corridor and sand and gravel substrates. Powderlick Run was in non-attainment of Modified WWH status (pre-restoration) with extremely low biological scores. The major impairment to Powderlick Run was hydromodification. Powderlick Run is an extensively ditched
agricultural watershed with areas of open livestock access. Powderlick Run is approximately seven miles long and has a watershed size of 3.6 miles at the confluence. The project is located between river mile 3.2 and 2.8, isolated about half way up the sub-watershed. The stream segment upstream of the project which is over 3 miles in length, have been historically ditched for agricultural drainage and are
maintained in a straight, trapezoidal shape with no trees. Downstream of the project, cattle still have access to the channel.
The restoration goal of this project was to meet Ohio’s WQS and to improve aquatic life use
designations for both Powderlick Run and Bokes Creek, thereby removing them from the 303d list of impaired waters of the State. This would involve restoring the physical attributes of Powderlick Run adequately enough to reverse the adverse impacts to water quality at the confluence and downstream segment of Bokes Creek. In addition, the restoration goals included minimizing floodplain width to contain the construction footprint within existing ditch filter strips. The question then became, what was the minimum length and width that could be restored and still achieve an ecological bump large enough to bring Powderlick up to the default minimum use designation (WWH) and bring Bokes Creek into attainment of the its designated aquatic life use as well. Approximately 3,200 linear feet of ditch was restored with a meandering channel and accessible floodplain. The results of this approach are illustrated in Figure 3. The cost of this project including design and construction was $54 per foot and was funded through an Ohio EPA Division of Surface Water Section 319 grant.
Figure 3. Ohio EPA 2010 QHEI and IBI wading and headwater scores.
Again, the goals of the project were to improve water quality downstream of the project. It would make sense then to measure success based upon that goal. Figure 3 shows the biological results1 downstream of the actual project location at river mile 1 (RM 1) and the results of Bokes Creek at the confluence, where no restoration work occurred.
This data, using both IBI and QHEI, assesses the outcome of the project. The results indicate the project has eliminated the impairment to the receiving stream and the biology downstream of the project has recovered upward to the point it now meets the designated use (WWH). This is important from two aspects. First, the protection of the downstream use is a very important part of the Clean Water Act and second, it refutes many contentions from other reports that attempt to assess project success which create artificial success criteria by looking at design elements. Interestingly, this ecological data collected by Ohio EPA for this project, while easily available, was completely absent from ODNR “Functional Assessment of Stream Restoration In Ohio” report (Mecklenburg and Fay, 2011). This project would also fail Mecklenburg and Fay’s success criteria when examining specific design elements for floodplain width, soil composition, substrate size developed outside of the project goals. The fact is this restoration project is now assimilating pollutants much differently than the pre-restoration condition resulting in a recovery of the downstream biology.
1 Ohio EPA 2010 QHEI and IBI wading and headwater scores Metric GOAL (ECB
ecoregion), WWH use designation Powderlick Run Pre Condition 1999 (Rm3.2) Powderlick Run Post Condition 2010 (Rm3.2) Boke Creek Pre Condition 1992 (Rm22) Bokes Creek Post Condition 2010 (Rm22) QHEI 60 27 58 62 60 IBI 40 18 12 Rm1 (Relative abundance 763) 32 40 Rm1 (relative abundance 2690) 28 50
Pond Brook
Pond Brook prior to restoration was a petition ditch that had been straightened for drainage purposes. Pond Brook is a very low gradient wetland stream . Pond Brook was a limiting impairment to its
receiving stream, Tinkers Creek. Using Ohio bio-assessment criteria, Pond Brook was recognized as one of the largest suspended sediment load sources and impairments to Tinkers Creek (Figure 4). This stream pre-restoration was in non-attainment of MWH status, well below minimum goals and standards and was on Ohio’s 303d impaired waters list. The dominant fish specie found in Pond Brook at the restoration location was channel carp.
Figure 4.
The project goals were to improve Pond Brook’s aquatic life use attainment to WWH within the limiting factors of wetland stream characteristics. For the Pond Brook project, a local wetland stream (Tare Creek) was used as reference for design (Figure 5). The reference reach had a defined single-thread meander pattern, vertical pools and riffles and a very specific biotic community. This is in contrast to recommendations from the ODNR “Functional Assessment of Stream Restoration In Ohio” report
(Mecklenburg and Fay, 2011), citing a 2010 paper by Nanson of low width/ratio single thread channels in Peat bogs in Australia, contend that for low gradient or “Swamp streams, the common gravel bed riffle pool single thread meandering channel should not be the design objective”.
Pond Brook
Figure 5.
Once constructed, the outcome of this restored single-thread meandering wetland stream has been to achieve ecological recovery up to the point of meeting WWH status within three years (IBI scores of 12 pre and 36 post). The change in fish specie has included the recovery of some headwater darter species, sensitive to sediment, and the virtual elimination of invasive carp. The change in fish species alone indicates this project is processing sediment loads differently.
This project was 6,200 feet long and was funded with mitigation funds. Design and construction cost were $110 per foot. This is again a simple illustration of how information from various assessments may or may not depict success of restoration projects.
Figure 7.
Ditch before restoration
Pond Brook after
Mac-O-Chee Creek
Mac-o-chee Creek should be a cold water fishery. The creek was ditched and straightened for
agricultural drainage and relocated in places for highway construction as early as 1900. The project is located at RM 1.5 prior to its confluence with the Mad River and involved 2,600 linear feet of restoration (Figure 8). Important to consider is the channel segments directly below and above the restoration project are under ditch type maintenance which includes dredging, straightening and tree removal. The goals of this project were to enhance brown trout sport fishing at the site, more along the lines of a habitat island within a more degraded stream segment. The project length was only 2,600 linear feet and restored a previously ditched channel to a sinuous channel capable of supporting riffles and pools within a more active floodplain. The result has been a dramatic increase in fish abundance and species, which was the goal of the project. The project now meets Exceptional and Cold water status (EWH and CWH).
Figure 8
The biological data post restoration from this project directly refutes the contention within the ODNR “Functional Assessment of Stream Restoration In Ohio” report (Mecklenburg and Fay, 2011) that site specific habitat elements are “artificial deviations from natural conditions. Again, by scrutinized very small project components in isolation, assessment can ignore or skew the results of the project as a whole.
Woodiebrook
Woodiebrook is a very small tributary to the Chagrin River with a watershed size of 120 acres. It was historically a CWH stream that supported state endangered brook trout. A substantial segment of Woodiebrook was impounded and channelized for development reasons. The restoration project involved removing the dam, regrading a floodplain and reconstructing two channels. A reference reach several miles away was used in the design process. This project was assessed within the Mecklenburg and Fay, 2011 report as well. Various measurements were recorded and reported in their database such as width, depth, watershed size, floodplain soil characteristics, substrate size, and vegetation.
However, this project was not assessed to determine if after restoration, the designated aquatic life use was met as defined within Ohio’s WQS. While measuring very specific project inputs or structural elements, this report would lead a reader to believe that the project fails based upon their floodplain soil success criteria and their criteria for appropriate substrate size. Interestingly, this project used the existing floodplain soils recovered at the site and the projects geology is conglomerate sandstone, which was used as substrate that included a range of sizes from small sands to large boulders as shown in Figure 9. The larger sized sandstone chunks naturally dissolve over time to rejuvenate the sand and small gravel substrate. The geology is not considered when using a simple computer based energy calculation for D-50 or D-84 particle sizes.
Figure 9.
Most importantly, missing from the author’s assessment of ecological success is the fact that the restored project supports re-introduced native brook trout (the ecological target), which are
assessment” is that the project now has reproducing brook trout and did within three years after construction (Figure 10). So while Mecklenburg and Fay would suggest this project to be ecologically unsuccessful when using their success criteria for various individual structural elements, the outcome of this project as a whole meets the highest aquatic life use designation category in Ohio (EWH) and would refute their claim “Stream restoration efforts around the country have generally been discouraging”. The ecological data that was collected by Ohio EPA and ODNR Division of Wildlife was completely absent from the report. The length of the project was 3,200 linear feet. The cost of this project was $67 per foot for both design and construction.
Figure 10.
Conclusion
The ultimate test of success for stream ecosystem restoration is attaining the aquatic life goals set forth in Ohio’s WQS and the measurable sub-components of that process. As with any activity-based planning approach, there is a natural tendency to measure success in terms of the activity and structural inputs of that process, which stops short of measuring the ultimate outcome (i.e., the biology) of the same process.
The success of restoration projects to improve water quality is represented by that outcome rather than any evaluation of specific individual structural or design inputs. Inputs such as native plants pallets or invasive management plans of the site are all aspects that have little influence on an outcome that measurably improves water quality, especially downstream. Specific design elements such as substrate
size or width/depth ratio are all structural inputs that cannot be seriously assessed by general empirical relationships and again, rarely indicate the outcome of restoration in the context of improving
watershed scale function. The true potential of natural channel design restoration can only be
measured in the context of the watershed and how the individual project moves biological indicators up the ecological ladder. In Figure 11, compares discussed project with two additional smaller projects which would be generally referred to as restoration. These smaller projects, like the larger examples also had unique site constraints but used similar natural channel design elements and construction. Neither changed the aquatic assemblages nor met the aquatic life use designation goals at the project site or downstream. PROJECT DRAINAGE AREA (sq mile) PROJECT LENGTH (feet) PRE RESTORATION CONDITION POST RESTORATION CONDITION SUCCESSFUL
Powderlick Run 1.6 3,600 Non-
attainment of MWH
Attainment of WWH
yes
Pond Brook 4.1 6,200 Non-
attainment of MWH Attainment of WWH Yes Mac-O-Chee Creek 16.1 2,600 In attainment of WWH Attainment of EWH and CWH Yes Woodiebrook 0.17 3,200 Non- attainment of EWH and CWH Attainment of EWH and CWH Yes
Gantz Park 2 245
Non-attainment of WWH Non-attainment of WWH No
Cosgray Ditch 1.3 838
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