BONITO WATERSHED PROJECT HYDROLOGY AND SOILS SPECIALIST REPORT Smokey Bear Ranger District, Lincoln National Forest Lincoln County, New Mexico Mike McConnell, Forest Hydrologist Bob Dancker, Soils Scientist May 2009 INTRODUCTION This report is an analysis of existing conditions and effects related to hydrology and soils in the major portion of the Upper Rio Bonito watershed and parts of Middle Rio Bonito and Magado watersheds. This report will summarize information about soils and hydrologic conditions along with with effects analysis on alternatives as they relate to the planned upcoming Bonito Watershed Project on the Lincoln National. The Bonito Watershed Project is a planned hazardous fuels reduction project covering 28,488 acres across three 6th level Hydrologic Unit Code (HUC) watersheds, the Upper Rio Bonito (HUC #130600080201), Middle Rio Bonito (#130600080207) and Magado Canyon (#130600080202). These smaller watersheds are part of the larger 5th level HUC Rio Bonito watershed (189,455 acres). The 28,488 acre (44.5 mi2) Bonito project area lies in the upper portion of the Rio Bonito watershed with the majority of the project above Lake Bonito or the Upper Rio Bonito watershed which includes the 16,029 acres of the White Mountain Wilderness. Mechanized travel is not allowed in the White Mountain Wilderness and there are no roads there. Roads in the non-wilderness area are primarily the Class 1, 2 and 3 roads. The majority of the Bonito project lies within the Upper Rio Bonito watershed (25,847 acres or 40.39 mi2) where 82 percent of it (21,254 acres or 33.2 mi2) feeds into Bonito Lake. The Upper Rio Bonito watershed serves as the municipal supply watershed for Holloman Air Force Base, the City of Alamogordo and the towns of Nogal, Carrizozo, and Fort Stanton where Lake Bonito is located. Purpose and Need The project goal is to improve forest health and reduce the threat of catastrophic wildfire through strategies that utilize ecosystem restoration principles, best available science, and technical expertise of interdisciplinary team. 1 1. Existing Condition Climate Climate data was derived from NOAA’s “Precipitation-Frequency Atlas of the United States” and Western Regional Climate Center. The nearest climate data center near the project area would be Ruidoso (elevation approximately at 6920 feet) located 7 miles to the south with similar elevation level as the lower end of the Bonito project area which starts at 7000 feet. The upper end of the Rio Bonito watershed rises to an elevation of 11,300 feet, an elevation gain of over 4,000 feet. Ruidoso’s average annual rainfall for Ruidoso is 21.5 inches. Annual rainfall runoff is approximately 2.5 inches. A 2-year rainfall return interval (50% chance of occurring in a given year) produces a 1.1 inch/hour rainfall intensity storm for the Ruidoso area. Precipitation occurs primarily as high intensity short duration summer thunderstorms and winter snowfall. Summer season is regarded as the wet season (monsoon) with most of its precipitation occurring from June to August with moisture coming off from the Gulf of Mexico from the southeast direction. Average annual precipitation varies from about 32 inches at the highest elevations and near 20 inches near Angus. Spring and fall are the driest season is typically when most wildfires occur on the forest. Winter precipitation falls as mostly in the frozen form and Ruidoso gets about 39 inches of snowfall a year. Snow accumulation is most significant in the upper headwater portions and ridges with annual snowfall anywhere between 70 to 90 inches. Temperatures vary from 70s - 90s degree Fahrenheit in the summer to sub-zero levels in the winter. Strong southwesterly winds prevail during the spring and early summer Perennial streams There are approximately 26.5 miles of perennial streams throughout the Bonito planning area on Forest Service lands only. For the entire Upper Rio Bonito watershed, which includes the planning area, White Mountain Wilderness and non-Forest Service lands, there are approximately 31 miles of perennial streams. Kraut Canyon, Philadelphia Canyon, and the South Fork Rio Bonito all flow into the Rio Bonito creek. Philadelphia Canyon is located below the Bonito Lake reservoir and is tributary to the Rio Bonito. Most major streams are mostly perennial with some having perennial-interrupted stream characteristics either due to geology or limited moisture (or both). Kraut canyon is mostly an intermittent channel. The main stem of Rio Bonito Creek within the Bonito watershed above the reservoir is approximately 9.1 miles. Below the reservoir the creek becomes the Rio Bonito and flows some 2.5 miles where it meets the tributary channel Philadelphia creek outside of the Bonito watershed. Flood plains Identified areas of flood plain areas are mostly located along stream reaches of the main stem of the Rio Bonito above the reservoir due to its lower gradient and depositional alluvial and colluvial soils consisting of gravel, sand, silt, and clay. These “active” flood 2 plains may flood approximately at least once every 20 years (i.e. 5 year storm) along some stretches of the stream channels where flood plain terraces can be seen. Along these areas have the most recreational use due to convenient nearby access to streams (e.g. road crossings and camp grounds) and nearby popular hiking trails. As a result, some of these areas are currently eroded although light and continue to contribute sediment into the Rio Bonito which ends up in the Bonito Reservoir Stream Type (Rosgen) Rosgen Classification stream type varies from A1 in the upper reaches of the headwaters to B4 the project area. In the upper elevation stream channels are fairly straight containing bedrock and large boulders. In the lower elevation channels become more sinuous and progress to a B4 or B5 Rosgen channel type containing more gravel and sand with less cobble. Stream channels containing boulder or bedrock components contribute greatly to channel structure and stability. Riparian areas Data on riparian vegetation comes from on-the-ground observations, survey team photo monitoring efforts, infra-red aerial photo interpretation, corporate GIS database layers, and the Land Resource Management Plan for the Lincoln National Forest (Forest Plan). Direction for managing riparian areas on the Forest is found in the Forest Service Manual 2526 (USDA 2000), and the Forest Plan (USDA 1986). Much of the entire stream channels within the project boundary are identified as having riparian features or the potential to contain riparian features based on 1982 infrared aerial photos. Photos showed riparian and potential riparian areas that are dependent on moisture availability to maintain their ecosystem. These riparian features are seen mostly along perennial water sources. Most of the riparian areas along stream channels exist anywhere from a few feet to small, open valley-like areas where the water table is near the surface conducive for riparian plant species growth. Riparian areas are delineable areas as distinct riparian ecosystems separate from the upper terrestrial ecosystem. Riparian features are identified by certain soil characteristics and distinctive vegetative communities that have access to free and unbound water. Healthy riparian zones along stream banks help stabilize stream channels against unnecessary erosion, provide sediment storage, source of nutrient sinks, shades water to help control water temperature, reduce “flashy” flows, and improve water quality. In a July 2007 field survey three team members collected riparian data at numerous locations on tributary streams that enter the main stem of the Rio Bonito creek. A total of 10 separate stream drainages were surveyed over a total of 24 miles to document existing riparian conditions along 292 transects or 12.2 transects per mile. Several hundred photos were taken along with riparian and morphological data, and amount of large woody debris with logs 20 inches or greater in diameter to help determine general riparian health 3 in 10 major drainages (Tanbark, Big Bear, Little Bear, Anan, Turkey, George Washington, Iron, Littleton, Philadelphia, and Argentina Canyon). The current overall health of existing riparian corridors is satisfactory with some areas experiencing minor impact from sedimentation from gravel or dirt roads or at crossing locations. Lakes or Open Body of Water Bonito Lake is the only open body of water within the project boundary of the Upper Rio Bonito watershed. It is a 44 acre lake (surface area at average storage) and serves as a municipal water supply for the City of Alamogordo, Holloman Air Force Base, Fort Stanton, Eagle Creek, Nogal Canyon, and Carrizozo. This reservoir is located on private land within the Lincoln National Forest boundary and was first built in 1931. It’s drainage area is 21,254 acres. Water from Bonito Lake is superior in chemical quality at 300 mg/L TDS where water is mixed with the spring and ground water at the La Luz’ Water Treatment Plant to increase the overall water supply and improve water quality. There is a relatively unknown volume of sediment settled at the bottom of the reservoir over the past 78 years and that no dredging of sediment ever took place. Although in 1992 the City of Alamogordo Engineering Department explored a dredging possibility and estimated that 400,000 cubic yards of sediment material have been deposited since 1961 from several major storm events resulting in a 25% decrease in volume capacity (80 million gallons) of water for the reservoir. The figure was obtained after taking partial measurements of the lake bottom and compared to the original lake topography map. These measurements were based on preliminary soundings of the lake bottom in various places. This would mean on average of about 13,000 cubic yards of sediment material (about 1,300 truckloads) is deposited annually on the lake bottom. This number may be large and it is only expressed by taking into consideration large storm events that may take place once every 5 or 10 years pushing large amount of sediment materials downstream.