Project Completion Report
For OWEB grant #204-277
Tide Gate Effectiveness Monitoring
Background
The purpose of this project was to demonstrate the effectiveness of newer (often referred to as “fish-friendly”) tidegates to allow passage between mainstem rivers and adjacent sloughs for rearing juvenile salmonids. In Columbia River tributaries, several stocks of threatened and endangered salmonid species exist which could benefit from a monitoring program such as this, including: Lower Columbia River Coho, Lower Columbia River Chinook, and Chum.
In the Columbia River Estuary, filling and diking of wetlands and subsequent installation of tidegates has reduced the amount of available tidal wetlands for salmonid rearing by nearly half over the last 150 years. Over the past several years, local watershed councils, state and federal agencies have implemented tidegate replacements with the assumption that it will improve access to lost rearing habitat. However, limited data exists to describe fish use of the areas behind tidegates, emigration of juveniles out of tidegated areas, and residency times behind tide gates. Our Lower Columbia watershed councils (Nicolai-Wickiup, Skipanon and Youngs Bay) are implementing estuarine restoration actions that include tidegate replacements. However, some community members and landowners are skeptical of tidegate replacements and question whether juvenile salmonids benefit from using tidegated sloughs and are able to exit once they enter into the rearing habitat.
Likewise, a limited amount of water quality data is available from these same tidal restoration activities. This project has provided an opportunity to collect data on changes in water quality resulting from retrofitting tidegates beyond the traditional informal observation and spotty data collection. A further intent of this monitoring effort was to establish a template to train volunteers to collect a majority of the data from future restoration projects.
Volunteer participation
Astoria High School – fish seining
Clatsop Community College – water quality monitoring
Other participation
Pacific Northwest National Laboratory funded and provided technical assistance towards monitoring a tide-gate retrofit at Vera Slough on Young’s Bay. Although OWEB did not contribute to the monitoring of that project through this grant, we feel that the data collected at Vera Slough is the best that we have available and have therefore included some results of that monitoring effort below.
Materials and Methods
Fish Use
All sample gear and fishing techniques were consistent with the methods described in "Monitoring Protocols for Salmon habitat Restoration Projects in Lower Columbia River and Estuary” (Roegner et al. 2006). Fish were captured at each river site using a fyke trap net with mesh sizes appropriate for catching sub-yearling juvenile salmon. The fyke trap net (3/16” mesh) with two wings measuring 50 feet was set at high water and fished during the outgoing (ebb) tide to catch fish moving out of the gated channel and toward the river with the current. The trap was operated for 4 to 5 hours with catches removed, processed, recorded and released approximately every 40 minutes.
Juvenile salmonids were sorted from the catch first and anesthetized in a buffered MS-222 (tricaine methanesulfonate) solution. They were identified to species, closely examined for any external marks indicating hatchery production, enumerated, and measured to nearest millimeter (fork length). Non-salmonid species were counted and a sub-sample of 30 of each species was measured to the nearest millimeter. Immediately after processing, salmonids were transferred into 19L buckets with cold, aerated water. Salmonids were held until they regained their equilibrium and then released at the site. All other fish were returned to the site immediately after processing. Data recorded on site included: sample crew, time of sample, species identification, number of fish, fish size, and hatchery markings. Any situations that arose that diminished the quality of the sample were noted for each effort.
Water Quality
Monitoring was conducted on a weekly basis for dissolved oxygen, salinity, turbidity and conductivity. Collection of these samples took place at the same locations (both on the river side and slough side of tidegates) of every site following the protocols outlined in the QAPP. Continuous temperature monitoring took place using Vemco temperature loggers. All samples were analyzed on site and recorded on separate data sheets for each location. At the end of each monitoring day, data was double checked before entering it into the database.
Results
Fish Use
Barrett Slough (“old” tide gate) trap netting occurred only once (3/21/2006) on the downstream side of the tidegate. Eighty threespine sticklebacks and one smelt were caught during this event. Fish sampling at Barrett Slough was discontinued due to the large amounts of vegetation exiting the tidegate disabling the nets.
Trapping occurred at Larson Slough (“new” tide gate), just downstream of the tidegate, from March to August 2006. Table 1 shows the species composition for Lewis & Clark tidegate trap netting at Larson Slough. Species caught during the study included: Chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), banded killifish (Fundulus diaphanus), largemouth bass (Micropterus salmoides), peamouth (Mylocheilus caurinus), pumpkinseed (Lepomis gibbosus), shiner perch (Cymatogaster aggregata), smelt (Osmerus sp.), starry flounder (Platichthys stellatus), threespine stickleback (Gasterosteus aculeatus), sucker sp. (Catostomus sp.), and yellow perch (Perca flavescens). Stickleback dominated all the catches throughout the year, and peaked in July. Pumpkinseeds were the next common and peaked in August. One juvenile Chinook was caught on 5/18 and one on 6/16, measuring 71mm and 61mm respectively. Two juvenile hatchery coho were caught on 4/18, measuring 106 and 107mm respectively. One juvenile coho was caught on 5/18, measuring 70mm.
Species / Date3/21/06 / 4/18/06 / 5/18/06 / 6/16/06 / 7/18/06 / 8/14/06 / Grand Total
Chinook / 1 / 1 / 2
coho / 2 / 1 / 3
killifish / 1 / 1
largemouth bass / 1 / 1
peamouth / 2 / 1 / 4 / 4 / 11
pumkinseed / 5 / 2 / 1 / 44 / 52
shiner perch / 3 / 3
smelt / 1 / 1
starry flounder / 1 / 1
stickleback / 102 / 761 / 187 / 703 / 5286 / 1736 / 8775
sucker sp. / 2 / 2
yellow perch / 3 / 1 / 4
Table 1. Species composition for tidegate trap netting – Larson Slough, 2006.
The presence of fish like bass and perch, and the dominance of stickleback, indicate a fish community that is tolerant of shallow, warm waters that are often low in dissolved oxygen during the warmer months. Salmon do not, generally, thrive in such conditions and although salmonids were caught during the 2006 trap netting at Larson Slough, it was very difficult to determine whether or not they originated from behind the tidegate. The trap was located in a wide embayment at the exit of the tidegate, close to where the channel joins the Lewis & Clark River. As these fish were all caught at the very beginning of the ebb tide, it is possible they were originating from the mainstem and simply utilizing this alcove.
The following year’s sample design was adjusted to account for this uncertainty and on March 14, 2007, the trap net was set up inside (or upstream) of the tidegate. This yielded very few fish (two stickleback and one bullfrog), so to verify low fish presence one beach seine was performed upstream of the trap net. The seine yielded only one stickleback. Sampling inside the Larson Slough tidegate was problematic because of dangerously deep mud on the channel bottom, and the gear pulled up large amounts of liquefied cow manure – a potential health hazard to field crew. In addition, it was noted that the “pet door”, the tidegate device allowing fish passage, was closed, eliminating the need for fish monitoring.
Despite the environmental factors confounding our efforts to gather more comprehensive fish community information, our investigation demonstrated that channels behind tidegates are often inadequate habitat for salmon. There is potential for these channels to be flushed of sediments, contaminants, and vegetation when tidegates are operated for both flood control and healthy aquatic ecology, thus creating conditions more suitable for salmon utilization, but with a lack of education or contractual obligation, tidegate improvements are often underutilized. Landowners can be reluctant, even after cooperating on tidegate improvements, to actively manage the tidegate to permit fish passage and tidal inundation during all parts of the year except flood events. Comparison of “old vs. new” tidegates may still be useful in the future, but landowner cooperation and a more comprehensive reconnaissance of sites will be necessary to meet the study objectives.
Water Quality
At Vera Slough (Young’s Bay watershed), preliminary data indicates that the average water level inside Vera Slough increased by ~25 cm after replacement and that tidal amplitude increased from ~10 to ~50 cm (Graph 1). Increased circulation by tidal mixing is a likely consequence of the increased tidal amplitude. Preliminary data also indicate that temperatures inside the gate are decreasing and that salinity is increasing, suggesting that project goals are being achieved at this site. Likewise, salinity levels exhibited tidal fluctuations after tide-gate replacement (Graph 2).
Graph 1. Vera Slough Water Level Comparison.
Graph 2. Vera Slough, post-project salinity level.
Temperature measurements at Blind Slough (Nicolai-Wickiup watershed) indicate an insignificant change in water quality pre- and post-project (Graphs 3-4. This is likely related to management of the gates. While residents of the Brownsmead area have shown reluctance in opening their tide gates, they have also remarked extensively on qualitative water quality improvement since the Brownsmead tide-gate retrofits.
Graph 3. Blind Slough plug, inside tide gate, pre-project.
Graph 4. Blind Slough plug, inside tide gate, post-project.
Temperatures inside and outside tide gates averaged slightly higher inside the tide gate. Likewise, daily fluctuations were more pronounced inside the tide gate (Graphs 5-8). Increased daily fluctuations inside the gate may be a result of the constrained flow associated with only a partially opened door.
Graph 5. Blind Slough plug, outside tide gate.
Graph 4. Blind Slough plug, inside tide gate.
Graph 5. Blind Slough plug, outside tide gate, 7-day averages.
Graph 6. Blind Slough plug, inside tide gate, 7-day averages.
At Warren Slough (Nicolai-Wickiup watershed), measurements of dissolved oxygen correlated well inside and outside of the tide gate (Graph 7).
Graph 7. Warren Slough, dissolved oxygen levels, inside and outside tide gate.
Similarly, water quality measurements at Johnson Creek (Young’s Bay watershed; samples taken at submerged points) also correlate quite well (Graphs 8-9).
Graph 8. Johnson Creek, water quality levels, inside tide gate.
Graph 9. Johnson Creek, water quality levels, outside tide gate.
Our water quality data suggests that water quality can increase with the replacement of outdated tide gates with new self-regulating or automatic tide-gates (Vera Slough) and that water quality levels do not change significantly inside vs. outside these new tide-gates once an equilibrium is established (Warren Slough, Johnson Creek). However, if tide-gates are not managed properly for tidal fluctuations, then water quality improvements, such as decreased temperatures, will not be seen (Blind Slough).
Other information (strengths, weaknesses, assumptions)
Due to staff turnover within the watershed council and at CREST, this project passed through the hands of several project managers. While monitoring at some project sites occurred regularly and with adequate quality assurance, monitoring at other sites did not. Goals and objectives of the initial project were not clearly translated to subsequent project managers, which has resulted in a deterioration of data quality, in some cases to “B” quality data and in other cases to “E” quality data. Partial data from Vera Slough, which was not funded from this grant, was therefore deemed important to include in this project report as it was one of our best data sources available.
As a direct result of this problem within the project (staff turnover and subsequent loss of project intent, scope and quality), the watershed councils and CREST used a portion of the allotted OWEB funds to hire a contractor to organize, standardize and evaluate the data collected through this project and evaluate its quality according to DEQ standards. More importantly, the contractor trained our staff on DEQ QA/QC procedures, as well as provided us with database templates, analysis tools, and advice on field collection to use for our future water quality monitoring efforts. Our staff now feels much more comfortable with procedures to collect “A” quality data and is developing a system for data collection and analysis that will be much easier to transfer to future project managers.
Accounting of expenditures
Oregon Watershed Enhancement Board (OWEB) / File: F:/user/oweb/forms/match spreadsheetMatch / In-Kind Documentation for Final Report
OWEB Grant # 204-277
Organization Name / Actual / Donated / In-Kind / Volunteers / General
Cash Contribution / Services / Hours Worked / Hourly Rate / Volunteer Value / Description
OWEB Final Expenditures--> / $23,079.02 / N/A / N/A / N/A / N/A / OWEB Cash
Other Organizations
Clatsop Community College (Debra Sheldon) / $ / $ / 240 / 18 / $1,080 / Monitoring of Blind Slough
Astoria High School / $ / $ / 16 / 18 / $288.00 / Monitoring
CREST / $ / $8,995 / $ / Monitoring and equipment
$ / $ / $
$ / $ / $
$ / $ / $
$ / $ / $
$ / $ / $
$ / $ / $
$ / $ / $
$ / $ / $
$ / $ / $
Total Dollar Amount / $ / $8,995 / $1,368.00
Total Overall Project Costs / $33,442.02 / (Total dollar value of OWEB & Other Organization's Actual Cash Contributions,
In-Kind Services and Volunteer value ALL added together)
Total Non-OWEB Funds / $10,363.00 / (Total dollar value of Other Organization's Actual Cash Contributions,
In-Kind Services and Volunteer value ALL added together)
OWEB Match / $10,363.00 / (What dollar value of the Total Non-OWEB Funds are you claiming
as OWEB Match. You are required to show a minimum of 25% of
the total actual OWEB cash contributions. You may show more
than 25%.)
(General Description column can be used to describe categories such as Tree Planting, Rent, Cash, etc.)
Note: Volunteer Hours X Volunteer Rate = Volunteer Value (Combine Volunteer Hours by Type of Work. Example:
Total project tree planting hours (500) x rate. Do not shown individual amounts - retain those records in your files)