Weston Mountain Ponds

PROJECT COMPLETION REPORT - OWEB GRANT #201-516

Grant Period: 3/3/02 to 6/30/04

Background:
The ability of the Walla Walla River Basin to minimize sediment runoff and store water has been reduced throughout recent history due to two major factors: land use practices have increased the rate of topsoil lost through wind and water erosion, and beaver, that had (through their natural tendencies) created small ponds promoting water storage and sediment controls, were eradicated.

This project installed four small-scale infiltration ponds for the primary purpose of collecting and retaining water from surface flow, snow melt, and precipitation. This retained water should then saturate the ground and slowly seep into nearby Heifer, Rayborn, and Dry Creek Canyons, ultimately resulting in increased instream flow in Pine Creek during low-flow periods. Any additional water should benefit the downstream habitat for bull trout and steelhead (ESA-listed as threatened/endangered), as well as address issues delineated under the Clean Water Act. This is a demonstration project for utilizing small-scale infiltration ponds as a method of upland water storage and in-stream flow restoration. It is the intention of the Walla Walla Basin Watershed Council (WWBWC) to use these first ponds to encourage other landowners throughout the Walla Walla River watershed to install ponds to enhance stream flow during low flow periods. (Map of Project Area)

The overall watershed benefits of this project should include:

• a net increase instream flows during the critical low-flow period,

• wildlife and wetland habitat,

• improved water quality conditions through sediment and non-point source pollution retention, and
• riparian vegetation enhancement.
   

Project Siting, Permitting and Design:
The siting, permitting, and design of this project resulted in a very lengthy process. Eight ponds were proposed and submitted for site review to the Natural Resource Conservation Service (NRCS) - Pendleton. Watershed drainage and pond design software developed by the NRCS - Redmond office (Buck Hollow Project) was used for placement and dam sizing on the Weston Mountain ponds project. Guided by criteria developed for the Buck Hollow Project (also funded by OWEB), four sites were found to be suitable for construction. Final pond placement was based on the best hydrologic and topographical conditions to maximize pond benefits for restoring stream flows while still considering all permitting issues and taking into consideration landowners' site preferences. The four sites were also preferred because they are all located in the same sub-watershed, and it was hoped that downstream benefits could therefore be demonstrated more easily. The development process included the following tasks to ensure the project complied with Oregon Aquatic Habitat Restoration and Enhancement guidelines:

1. Greg Card (NRCS Engineer) had developed a checklist approach to pond design and permitting (NRCS Permitting Codes # 378, 410 and 638), as well as an operation and maintenance checklist and landowner agreement forms. These checklists were utilized in concert with site-specific designs developed and supervised by Bob Martin (NRCS Engineer-Retired) and our local NRCS staff (Cliff Harris - Pendleton Office).

2. Oregon Water Resources Department was consulted and a legal water right attained for each pond for water storage, wildlife, and watershed benefit (excluding stock watering).

3. Oregon Department of Fish and Wildlife, Oregon Department of State Lands were each consulted regarding wetland issues and permitting.

4. Oregon Department of Fish and Wildlife, United States Fish and Wildlife Service, United States Forest Service - Umatilla along with local NRCS staff were consulted regarding endangered species issues and permitting.

5. Umatilla County Planning was consulted for zone and other site permitting issues and permitting.

6. NRCS - Portland was consulted on Cultural Resource sites and issues.

7. Anderson Perry & Associates, Inc. was contracted to conduct soil proctor and nuclear densitometer testing to address dam construction concerns (NRCS/OWRD requirements).

8. Local and regional contractors were given site tours and bids were accepted for pond construction.

9. Umatilla Soil and Water Conservation Service and NRCS were consulted on site fencing costs and native planting issues.

10. Landowners were consulted throughout this entire process regarding pond locations, access issues, cost share, precipitation quantities, plantings, and all project elements. Tom Buell and Sally Wilson have been very helpful and enthusiastic about the project. Jim Burns also helped with site visits and promoted the project to other landowners.

Project Survey and Construction:
The pond locations were surveyed by Bob Martin (Retired NRCS) with support and review by staff from the NRCS - Pendleton office. Spillway siting was the most problematic of the issues taken into account for construction due to basalt bedrock outcrops and steep elevation changes. In the end, suitable spillways were able to be sited and built. Construction began in early summer of 2003, once the ground was firm enough for the earth-moving equipment to make it onto the mountain sites. Construction of all four ponds was completed quite rapidly, taking only eight days from the earth movement phase all the way to compaction for all sites and final NRCS site inspection. Anderson Perry & Associates, Inc. conducted tests on each of the dams using a nuclear densitometer to ensure that compaction was to NRCS-OWRD standards. Figure 4, Figure 5, Figure 6, Figure 7, and Figure 8 depict the construction of each pond in various stages along with the physical characteristics of each.

Fencing and seeding was done by landowners during the fall of 2003, and finished during the early summer of 2004. Fencing materials, labor, NRCS-approved seed, and some wetland plants were furnished by the landowners as cost share for the project. The landowners will continue to manage their sites for weeds, fence repairs and additional native grass seeding.

Preliminary Results:
After one fall-to-spring wet season, the ponds all filled to capacity with continuous flow of water over the spillways. During a spring freshet (huge flush of rain and runoff), overflow water on two of the four ponds caused some head cutting on the spillway. A site inspection by NRCS-Pendleton engineer Cliff Harris resulted in the conclusion that the head cuts should be observed closely during the coming wet season. It was estimated that bedrock should inhibit any further degradation and that the pond dams should remain stable. WWBWC and the landowners will continue to monitor the erosion and take action if the erosion persists.

The primary goal of the Weston Mountain Ponds project is to slow runoff and thereby increase low season flow. However, quantifying water seepage from the ponds moving down gradient to increase flow volumes in ephemeral streams is a difficult task. WWBWC staff attempted to quantify a before and after change in the down-gradient water table using a mini-piezometer at one pond location.  Unfortunately, both the before and after-construction results showed "dry" or "no static level recorded" conditions at the site. More promising results were found at one pond location where an abandoned cistern was located about ten feet from the dam of the new pond. Cisterns historically were used to develop low-flow springs or streams for domestic and livestock uses. During the construction of this particular pond (summer 2003), the cistern was noted to be dry. Late during the following summer (2004), with the pond still full of water, standing water was noted in the cistern.

Additional evidence of slower water seepage can be seen in some of the photo monitoring conducted by WWBWC. Photos were then taken at set points throughout the project to capture comparisons at each pond site for the different stages and seasons of the project. While it is difficult to see in some pictures, the zone below the ponds has shown a marked improvement in greener riparian vegetation and increased wetness, evidence that water is seeping slowly from the pond into the streambed. Photo monitoring will continue in order to track long-term changes in riparian condition and vegetation.

Other indicators of habitat restoration success are the ample presence of waterfowl, frogs and toads noted on monthly monitoring visits. Terrestrial animal tracks have also been seen, demonstrating the ponds are being used by wild turkeys, deer, elk, coyote, bear, and other mammals as high altitude water refuge. Monitoring will continue and five follow-up annual reports will be sent to OWEB.

From a pure water budget perspective, the benefits of the project are quite clear: 5.2 acre-feet of water that normally would have drained out of the Walla Walla basin during the spring freshet was still contained in the upper headwaters during the hottest, driest months of the water year. When comparing the benefits to wildlife, sediment control, esthetics and perceived down-gradient riparian improvement, this project can be considered a success. The Feasibility Study being conducted by the Army Corps of Engineers (USACE) and the Confederated Tribes of the Umatilla Indian Reservation (CTUIR) has shown that large-scale water storage options will be very costly for the Walla Walla basin's small community with issues from seismic-dam failure concerns to multi-million dollar price tags. When considering water storage options, small scale infiltration ponds should be considered a viable alternative.

The ponds have enhanced the properties of the landowners and increased their knowledge of WWBWC's other projects and efforts. It has introduced WWBWC staff to many types of permitting and helped us develop relationships with other agencies and contractors, as various new services were required. We look forward now to working with other landowners to complete similar projects that will increase low-season flows to an easily measurable amount.

Changes to the Original Proposal:
The original grant application for the project proposed to build eight ponds. After the siting process was completed, only four ponds were built due to concerns over existing wetlands, stream proximity, dam safety, and watershed benefits. This resulted in less than the total amount of the grant being used for the project ($34,894.30 was spent out of an award of $52,877). The grant was also extended twice in order to accommodate all the various challenges and delays from the complexity of the permitting, to late snow on the ground, to schedules of all the site visitors, etc. OWEB's flexibility in allowing for needed changes has helped greatly in bringing this project to completion.

Lessons learned from the Project and Recommendations for Similar Projects:
This project turned out to be one of the most challenging projects WWBWC staff have taken part in. From the complexity of multiple types of permitting, legal requirements, and construction bids, to the difficulty of demonstrating watershed hydrologic benefits when working with small-scale volumes of water, this project has been a real challenge. We benefited greatly from the Buck Hollow project (also funded by OWEB) and highly recommend new pond projects connect with others who have completed a similar project. We also recommend allowing extra time for permitting.