Urban Stream Discussion Part 1

I focused on the first set of questions that were directly related to the reading from the discussion led by Ben and myself on urban streams.

As indicated in the reading, why may have previous studies demonstrated that effective impervious area (EIA) is a “better” predictor of stream biological and chemical response than total impervious area (TIA)?

-Effective impervious cover area is impervious cover which is directly connected to a stream. For example, a parking lot that is directly adjacent to a stream. Where as total impervious area includeds all the impervious surfaces such as sidewalks. Therefore, EIA is a stronger indicator for the effects of impervious cover on a stream

2. What is the importance of understanding the historic land cover of an area for predicting current fish assemblages of a stream?

- Understanding the historic land cover of an area is important for predicting the current fish assemblages of a stream because the historic land use could have already degraded the habitat and affect the fish assemblages, such as impoundments could have lead to the populations not being able to be restored to historic population numbers and the introduction of new fish species.

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3. Why might historic land use predict abundance of one fish species but be a poor predictor of another?

-Because the fish that was used in the study, E. scotti, did not show a change in abundance with urban areas as compared to the forested areas.

4. Why might hydrogeomorphic models be a poorer predictor compared to the impervious cover area models for the species used in this study?

- Its not that they are necessarily poor indicators. Often the effective impervious cover influences these indicators as well.

5. Why do you think the species chosen for this study were used as indicator species?

-They are limited in range and are not found abundantly over all. Also, they are fairly sensitive to changes in the geomorphologic processes,

6. What are some indicators of historic land use and how can these be applied to understanding the historic land use?

- Impoundments and reservoirs are fairly good indicators of historic land use.

Developing Sediment Criteria for Water Quality Discussion

During the discussion, I wasn't sure everyone was quite up to speed with the whole SABS framework...so I'm putting up these figures and tables from the paper to try and walk you through the most important points.

We definitely talked about the first figure above. It is the basic framework and main points to follow in the process of developing water quality criteria for suspended and bedded sediments.  The framework is not necessarily limited to sediment criteria...it could be used for any non traditional pollutant that researchers have not been able to test in a laboratory toxicity test setting.

In tables 1 and 2, Cormier et al. go through a hypothetical example to show you how the process might work.  You can see in Table 1 which statistical tests they used and what they intended to learn from the tests. The response indicator they chose was EPT richness.

In table 2, you can see the results of the statistical analysis.  The bottom line (which I circled) is the criteria they chose as their benchmarks for management.  They decided on these numbers for a hypothetical manager trying to protect EPT richness in a mid-Atlantic stream.

Here are some of the questions we went over and how everyone answered:

               What are some ways the authors suggest sediment can affect the biological integrity of waterways?

Low water clarity impairs visibility affecting many animal behaviors such as prey capture, predator avoidance, recognition of reproductive cues, and other behaviors that alter survival.

At very high levels, suspended sediments can cause physical abrasion and clogging of filtration and respiratory organs.

Suspended particles decrease light penetration required for photosynthesis

What are the sources of deposited and bedded sediments? How do human activities increase the rate at which the sediment gets into streams?

Topsoil erosion from land in the watershed

-          Deforestation

-          Agricultural runoff

-          Construction without proper silt fences

Suspended sediment removed from stream banks and from the bed of an upstream channel

-          Channelization

-          Removal of riparian zones

Direct discharge from municipal, industrial and agricultural sources

  

What is the U.S. EPA’s SABS Framework? How does it assist in the development of water quality criteria and restoration targets?

The SABS framework uses a risk assessment approach to estimate effect thresholds for unacceptable levels of SABS in water bodies.

It uses several statistical procedures to compare the estimated effects levels derived from field and laboratory data.

Protective water quality criteria levels are created with scientific evidence to back them up.

  

What were the two levels of protection the team developed for criterion values? Why did they need both? What values did they choose? Were they justified?

ALU: Aquatic Life Uses and MALU: Minimally acceptable aquatic life uses

ALU beneficial in intact ecosystems

MALU beneficial in developed areas which need to set achievable restoration targets.

No more than 7% fines for ALU and no more than 14% fines for MALU

Yes, 7% is justified in that it was deemed protective of the resource and held under the Species Sensitivity Distribution method (most protective precedent). 14% is justified in that it was the mean effect threshold of all methods for MALU.

Urban Stream Discussion Synopsis

My synopsis is the 2nd half of the Urban Streams discussion from Wed, Dec 8th. We broadened our discussion to talk about urban stream restoration in general.

-Someone pointed out that urban stream restoration is a big business and is a good way of employing people. good job security! (assuming, of course, funding sources are reliable)

- We discussed the neccesity of accepting the fact that urban streams are and most likely will always be far from natural, and we can't return to reference conditions

- We talked about the great need to engage urban citizens in the restoration process, and using education of the public to obtain support for restoration activities

- We decided restoration activities should focus on addressing the "urban stream syndrome" before concentrating on in-stream issues: we are not at a place as a society where we can focus on small-scale processes before addressing large issues like flow regime and impervious surface

- We also decided that local ordinances (and possibly fed/state regs) are needed to kick-start folks into using Low Impact Development. The technology is there, we know pervious pavement, rain gardens, green roofs, and rain barrels reduce runoff and increase infiltration, but it is more expensive and there is little incentive for widespread use.

We concluded that for more effective urban restoration, we need an appropriate and reasonable guiding image, and increased knowledge of appropriate techniques and better monitoring.

Ben's Principle

Within stream restorations are only appropriate when the major causes of poor stream quality are identified as in-stream factors. If the flow regime is drastically altered by urbanization, agriculture, or some other changing land use, the driving force behind reduced habitat complexity is likely the change in flow characteristics. Attempting in-stream habitat manipulation will not be a successful strategy in such situations, because it does not fix the problem, and the restoration activities will fail as a result. Most structural changes to in-stream habitat can only be maintained successfully through proper stormwater management (Walsh et al. 2005a), because the degradation to these habitats is a direct result of changing flow regimes. Therefore, in-stream habitat manipulation is a poor use of resources if there are overarching issues with flow regime.

Corey Dunn's Principle

This is an example of ignoring principle 3, which states flow is the primary driver of stream channel physical habitat. While researching interbasin transfers, I came across an example of the drastic economic and potential ecological (if it had been studied) consequences of an interbasin transfer of 88 percent of the flow of the Santee River to the Cooper River for hydropower. The increase in flow in the Cooper River increased the river’s capacity to carry sediment downstream, which was ultimately deposited in the Charleston Harbor. The increased sediment in the harbor had to be constantly dredged to protect shipping lanes inflicting an unforeseen economic cost. To fix this, engineers went full circle and rediverted flow back into the Santee River from downstream sections of the Cooper River (Meador 1994).

Principle and Consequences

Stream habitat is a dynamic system therefore your planning process should be a dynamic process as well (Best Practice)

-Consequences: I chose this as one of my key principles because as a manager it should be your responsibility to view the stream ecosystem as a dynamic system, and if this is not followed using a dynamic planning process then all the efforts that are put into a project could potentially be rendered useless. For example. if a manager were to look at a stream at a certain point in time and were to base all his plans off of this static point in time this could have dramatic outcomes. This point in time could be a low flow or a peak flow, or the use or growing urban area around a stream could be ever changing. If a manager were to place in-stream structures that would be allowable for the low flow, but could not handle the peak flows, they could fail and leave the whole project useless and time wasted.

Stream Restoration: What works? What doesn't?

This is a discussion of the article Roni et al. (2008) "Global review of physical and biological effectiveness of stream habitat rehabilitation techniques".

Note: you can click on any images to enlarge them.

Above are the categories of restoration practices that were documented, the specific techniques involved, the goals of the restoration, and the relative success or factors limiting success. Overall there is the overwhelming need for better monitoring strategy and long term monitoring. It would be very advantegeous to develop monitoring standards so that results from one restoration can be compared to another easily.

SCENARIOS: WHAT WOULD YOU DO IF………
1) Excessive peak flows, as well as normal flows continually undercut steep channel banks, causing large volumes of bank material to enter the stream and lake system.
a. Local Fixes: Reconstruct channel geometry
i. Re-establish floodplain connection
b. Watershed fixes?
i. LID retrofitting
2) Most perennial and intermittent channels have poor streambank integrity and you notice the unusual absence of vegetation.
a. Riparian Vegetation
b. Hydraulic structures
c. Increased floodplain connection
3) Local erosion from concentrated runoff by a large number of paved roads, which are frequently traveled by vehicles.
a. This is a real problem, not sure if you can do anything at all if the roads are commonly used.
4) In a highly urbanized watershed, a stream running through a subdivision frequently floods, risks damage to housing, and has a high sediment load to the lake which it feeds. The stream is severely eroded and houses are situated close to the stream.
a. Instream structures to dissipate energy (reduce sediment load)
b. Watershed fixes
5) Trails caused by livestock, particularly cattle, concentrate runoff into small streams and erodible areas;
a. Fence off livestock
b. Riparian enhancement (slow water velocities)
6) Several watersheds suffer from livestock overuse and improper grazing management systems;
a. Fence off livestock
b. Riparian enhancement
c. Re-structure management systems
7) A stream in an agricultural watershed has exceedingly high nutrient loads. Eutrophication is occuring and is severely impacting biodiversity and aquatic life. You do not know the source of the nutrient pollution.
a. Change farming management strategy?
i. Less use of fertilizer, more controlled management. Offer incentives to farmers to abide by rules.
8) Consider an active meander bend, where the outside of the borders important infrastructure. The river provides habitat to a numerous species of salmon(e.g. Chinook) and trout (e.g. rainbow).

Note: click to enlarge