Washington

Irrigation Best Management Practices in the Moxee Drain -
The Yakima River Basin Water Quality Plan

Nonpoint source pollution stemming from surface irrigation, inadequate tailwater management, sedimentation, and irrigation spills have been depositing approximately 40 tons of sediment per irrigation day to the Yakima River via the Moxee Drain. This figure -- and the sediment carries all manner of associated agricultural chemicals -- is based on monitoring performed by the Bureau of Reclamation from 1974 to 1981.

In January 1994, the Washington State Department of Ecology approved the Yakima River Basin Water Quality Plan that had been developed by the Yakima County Conference of Governments (COG Plan). The COG Plan identified 31 major tributaries within the Yakima River Basin and summarized information on the natural conditions, land and water uses, and quality for each basin. Based on that information, the COG Plan recommended 529 specific actions to address water quality issues in the basin.

In relation to the Moxee Drain, the COG Plan identified five problems and recommended an action for each one. For example, irrigation delivery systems contribute to water quality problems; COG called for financial incentives and technical assistance as the action needed to help landowners improve the delivery system.

LIT Reduction in TSS goal

Starting in late 1993, the North Yakima Conservation District received a section 319 grant to work on this action item. The goal of the project was to initiate a common effort among many agencies and other stakeholders to reduce on- and off-farm soil erosion, improve the water quality of irrigation return flows to the Yakima River, conserve irrigation water, and improve the irrigation district's operational capabilities.

In addition, the project was expected to

• protect groundwater quality;
• improve in-stream flows of the Yakima River for fisheries and downstream users;
• enhance and expand wetland and wildlife habitat areas;
• enhance Yakima County, Terrace Heights, and Moxee's surface water management;
• develop and implement adequate voluntary incentive programs; and
• enhance the agricultural economies of the diversified crops of the Moxee Hydrologic Unit.

The specific measurement goal was a 75 percent reduction of total suspended solids (TSS) in the agricultural tailwater draining to the Yakima River.

Watershed delineation

The Moxee Hydrologic Unit is in the Yakima River Basin in the center of Washington State. The Yakima River Basin consists of nearly 4 million acres; however, this Unit covers 97,680 acres near the middle of the river basin. The Moxee Drain carries the primary return flow of surface water to the Yakima River from the entire Moxee Hydrologic Unit. Annual precipitation in the Unit is under 10 inches and mean annual runoff is less than 0.2 inches.

Land uses in the Unit are furrow-irrigated land, 7,000 acres (all in hops production); other irrigated land, 12,880 acres; tailwater areas, 1,000 acres; dry cropland, 2,700 acres; and dry rangeland, 74,110 acres.

Priority was directed first to furrow-irrigated lands, second to irrigation tailwater management, third to all other irrigated lands, fourth to cultivated dryland, and fifth to nonirrigated rangeland.

Project interventions by year

The 7,000 acres of furrow-irrigated land were producing up to 100 tons of sediment per acre per year, and the sediment carried additional pollutants, such as DDT and its derivatives, at levels in excess of water quality standards. The first year of this five-year project was spent developing farm plans, doing project outreach to hops farmers, and developing contacts and partners.

During the second and third years, the major emphasis has been the development of contracts with over 80 individual hops farmers to convert to drip irrigation.

Evaluation data and criteria

The evaluation of best management practices (BMPs) in large-scale watershed projects is always a difficult task. Current recommendations from EPA and others generally state that many years (10 or more) are needed to monitor, observe, and analyze conditions and to relate changes in water quality to nonpoint source control efforts. However, several measures of success can be used to rate this project, despite the uncertainty of the scientific data.

On individual farms, for example, the conversion from furrow to drip irrigation has reduced sediment loads to zero tons per acre. The Moxee drain sediment load now averages 28 tons per irrigation day, a 30 percent reduction over the numbers recorded 20 years ago. The 1997 growing season will see the implementation of drip irrigation BMPs on a total of 2,148 acres. This event will double the impact of previous seasons' conversions.

With the cooperation of Education Service District 105 and using this area for a field training, 50 Washington teachers have been trained in watershed management. This effort has also encouraged several thousand individuals to volunteer their time for water quality improvement work throughout the Yakima River Basin.

The absolute need for active partnerships to develop planning, create multiple funding sources for project administration and implementation, and organize a solid education and outreach program was the major lesson in this project. These programs require tremendous time and effort to set up. They cannot be properly done as an adjunct to other duties. Major partners in this effort included the Washington Hop Growers Association and the USDA. USDA helped with a Small Watershed Project Grant and direct support from its Natural Resources Conservation Service.

Sediment Control in the Skagit and Stillaguamish River Basins -
A Pilot Project

The Skagit and Stillaguamish Rivers flow easterly from the Cascade mountains into Puget Sound. The Skagit River, a national Wild and Scenic River, drains 3,093 square miles while the Stillaguamish River basin, directly to the south, drains 557 square miles. Annual precipitation in the eastern, mountainous areas of these watersheds is over 100 inches but decreases as it moves west to less than 30 inches annually in some areas. Land-use activities, principally logging, have added greatly to the flow of sediment from these basins. Numerous stream reaches and various tributaries to the rivers are listed on the state's section 303(d) report for nonattain- ment of sediment and temperature standards.

Forest roads used to access logging areas are significant contributors of sediment to streams. They increase surface erosion and the problem is compounded for roads on steep and unstable slopes and in areas with high water flows. Such roads are also vulnerable to dam breaks and landslides that contribute even larger amounts of sediment to downstream waters. These events widen streams, reducing their depth and further increasing their temperature.

Forest roads and riparian enhancement

Two watersheds, one each in the Skagit and Stillaguamish River Basins, were selected for a forest roads and riparian enhancement and restoration pilot project. The first, Deer Creek, flows into the North Fork of the Stillaguamish River; the second, Finney Creek, flows into the Skagit River immediately to the north.

The Deer Creek basin contains 43,000 acres located north of the town of Oso, Washington. Elevation ranges from 340 feet at its confluence with the North Fork of the Stillaguamish, to 5,142 feet at the top of Mount Higgins. The basin bedrock can be generally described as metamorphosed sedimentary rock with igneous intrusions that have been glaciated over the past 2 million years.

The lower basin is dominantly glacial outwash in terraces cut by subsequent erosions. Stream valleys are typically quite narrow, with only a few intermittent broad sections. Very narrow, ravine and canyon conditions predominate in the lower five miles of Deer Creek. Stream gradient throughout the remainder of the basin is moderately steep.

Floodplain characteristics exist in areas of the drainage where the valley floor broadens. The federal government owns approximately half the land, especially along the upper reaches of the Creek. The remaining land is controlled by the state and private owners. Private forest landowners include John Hancock Mutual Life Insurance Company, the Port Blakely Tree Farms, and Merrill, Ring, Green, and Crow (MRGC). Land near the town of Oso is controlled by small nonforest landowners.

The Finney basin, directly to the north, contains 38,000 acres and approximately 75 linear miles of stream with elevations between 300 and 5,000 feet.

Initial efforts involve a diverse partnership

Partners in the project include landowners, tribes, state and federal resource agencies, and user groups. Among these many partners one finds expertise in forestry, engineering, biology, hydrology, and geology. In addition, U.S. Forest Service lands are included in the Adaptive Management Area and the Mount Baker Snoqulamie National Forest is included in the President's Northwest Forest Plan. These initiatives provide additional incentives to bolster section 319 program management.

The Department of Natural Resources performs watershed analysis (i.e., collects data) on state and private forest lands for the entire Watershed Analysis Unit. The analysis generally covers hydrology, mass wasting, soil erosion (especially relating to roads and timber harvest), fisheries, channel morphology, and riparian condition.

Project plans were developed based on related scientific studies and watershed protection and improvement projects already done or underway in these watersheds. The major techniques used for limiting sediment production are road abandonment/improvement, in- stream deflectors, landslide stabilization, in-stream projects, and riparian manipulations.

A network of experienced field managers using historic data move the project forward without jeopardizing the watersheds' health, even while detailed watershed analysis is occurring. Thus, a proactive pollution prevention plan has begun using priorities established by this group.

Respecting nature's timelines

Project managers and generally proactive citizens can learn patience if they will from their involvement in this project. Results may not be measurable in less than 30 years. Consider only the riparian plantings, for example. Conifers planted to shade the stream require that many years to grow tall enough to produce shade.

Still, a few results are evident even now. Perhaps the most striking early result is that despite two extremely wet years with reports of extensive landslides in many areas similar to the treated areas, no landslides have occurred in the project area in several years.

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