Lake Hopatcong Water Level

5/21/12 NOTICE - The Division of Parks & Forestry will once again temporarily reduce the outflow to 8.3 cfs for approximately 24 hours during the precipitation.

5/18/12 NOTICE - Due to deteriorating downstream conditions and warm temperature forecast, the Division of Parks and Forestry will adjust the outflow to 12 cfs.

5/15/12 NOTICE - The Division of Fish and Wildlife, in coordination with the Division of Parks and Forestry, will reduce the outflow from Lake Hopatcong into the Musconetcong River, from 8.2 to 6.8 cfs, to capture rainfall into the Lake.  This reduction is being done for only a 24 hour period beginning May 15, 2012 around noon.

4/23/12 NOTICE - As a result of Morris County receiving over 2 inches on April 21-22, 2012, the Division of Fish and Wildlife, in coordination with the Division of Parks and Forestry, will once again reduce the outflow from Lake Hopatcong into the Musconetcong River, from 8.3 to 6.8 cfs, to further capture the rainfall into the Lake. This reduction is being done for only a 24 hour period, as river flows, currently at 692 are starting to drop, but to be the most beneficial the reduction will be done immediately.

4/12/12 NOTICE - Per the provisions in the Lake Hopatcong Water Level Management Plan and the required assessment and recommendation from Division of Fish and Wildlife (DFW) staff, NJ DEP Assistant Commissioner of Natural and Historic Resources in consultation with the Assistant Commissioner of Water Resources, has approved a temporary reduction of outflow from the Lake Hopatcong Dam to the Musconetcong River. The NJDEP will continue to carefully monitor the situation and return the outflow back to 12cfs as soon as conditions in the river indicate stress.  Again this is a temporary reduction.

The following facts reflect recent and current circumstances in Lake Hopatcong and in the Musconetcong River immediately downstream of the Lake Hopatcong dam: 

1.  The lake was lowered over the winter approximately 26" per the Lake Hopatcong Water Level Management Plan. Refilling of the lake was initiated earlier than usual this year due to the lack of ice cover on the lake and in recognition of minimal rainfall.  On Feb. 18 the passing flow was reduced from  approx. 23 CFS to 12 CFS (data from USGS website) to accelerate the rate of refill.  Unfortunately the lake has not refilled appreciably due to minimal rainfall.  The lake level as of April 12 is at 7.10 ft (gage height), which is 1.9 ft below normal pool elevation (gage height of the crest of the dam at Lake Hopatcong is 9.0 feet). 

2.  Provisional data  obtained from the Office of the NJ State Climatologist website (http://climate.rutgers.edu/stateclim_v1/data/north_njhistprecip.html)  indicates that the monthly precipitation for northern NJ for the past 3 months (Jan - Mar) was 5.82".    The Plan states (p. 32) that "In the event that spring precipitation for any preceding three months is less than seven (7) inches in aggregate, (eight inches following a 60 inch drawdown) the Assistant Commissioner for Natural and Historic Resources, after consultation with, and upon the advice and consent from, the Commissioner for Water Resources may reduce the passing flow out of Lake Hopatcong below the normal 12 CFS passing flow." 

 3.  Water temperatures were taken at several locations in the Musconetcong River on Monday, April 9 (mid-morning) by DFW.  Water temperatures ranged from 9.4 - 10.8C, which are well below the temperature criterion for trout maintenance waters (not to exceed an absolute maximum of 25C (77F) and not to exceed a rolling seven day average of maximum temperatures of 23C (73.4F); N.J.A.C. 7:9B-1.14(d)11.).  Existing flow conditions in the river between Lake Hopatcong and Lake Musconetcong were considered adequate to support the fisheries and water was flowing over the Lake Musconetcong dam. Note that the opening day of recreational trout fishing was on Saturday, April 7 and trout stocking occurs weekly, for the next 7 Fridays, through May 25.

4.  In light of abnormal circumstances (lack of precipitation) and current river conditions, NJ DFW supports a temporary reduction in the passing flow, from 12 CFS to 8.2 CFS.  In our best professional judgment, a temporary reduction is not expected to jeopardize the downstream aquatic resources.  DFW will continue to monitor stream and weather conditions to determine when a minimum passing flow of 12 CFS must be reinstated to protect downstream resources.  

4/9/12 NOTICE - The provision in the Lake Hopatcong Water Level Management Plan to reduce the 12 CFS passing flow out of Lake Hopatcong is contingent on NJ DEP making an evaluation of stream health and various other ecological conditions. This evaluation has been done and at this time no reduction in the outflow is possible.  NJ DEP can not adjust the outflow at this time because of the great detriment to the Musconetcong River that a reduced outflow would produce.  An outflow reduction from 12 cfs to 8 cfs would likely yield about 1 inch of water in Lake Hopatcong over a one month period.  The damage to aquatic life and the Musconetcong River over that period of time would be significant.  Water temperatures are higher than normal and the water level in the River is lower than normal.  NJ DEP scientists are monitoring conditions carefully and will continue to evaluate the situation.
 

2/18/12 NOTICE - NJ DEP Assistant Commissioner of  Natural and Historic Resources approved the refilling of Lake Hopatcong to the 9' level to commence on Saturday, February 18 since there is no ice the lake and a mild weather forecast. The Citizens Advisory Committee (CAC) for the Lake Hopatcong Water Level Management Plan and Hopatcong State Park maintenance staff made the recommendation for the early refill of the Lake.

IMPORTANT REMINDER:  SLOW-SPEED - NO WAKE restriction for all vessels operating on Lake Hopatcong is in effect until the water levels recede below a measurement of 9.50 as gauged from the dam at Hopatcong State Park

The approved Lake Hopatcong Water Level Management Plan 2011 has been issued by NJ DEP.  NJ DEP also provided responses to public comment on the draft plan

2012 Lake Hopatcong Water Level Management Report

The Lake Hopatcong Commission is not responsible for managing the water level of Lake Hopatcong nor is it responsible for updating the Lake Hopatcong Water Level Management Plan. 

The U.S. Geological Survey (USGS) sites below are available to monitor the lake level, outflow into the Musconetcong River and precipitation at the Hopatcong State Park.

Citizen Advisory Committee

Meeting Minutes 9-13-12 & 10-10-2012


Q&As About Lake Hopatcong Water Level

  1. How can I monitor the water level in Lake Hopatcong?
  2. Who controls the water level for Lake Hopatcong?
  3. When is the lake lowered in the fall and raised in the spring?
  4. What determines if there is a "SLOW SPEED - NO WAKE" restriction on Lake Hopatcong?

How can I monitor the water level in Lake Hopatcong?

The New Jersey Department of Environmental Protection  funds the operation and maintenance of gages on Lake Hopatcong and at the outflow into the Musconetcong River through an agreement with the U.S. Geological Survey (USGS).  The lake level gage is located near the dam at the Hopatcong State Park in Landing, New Jersey. 

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Who controls the water level for Lake Hopatcong?

Mother Nature and Hopatcong State Park personnel control the water level in Lake Hopatcong.  Hopatcong State Park personnel manage the lake level as outlined in the Lake Hopatcong Water Level Management Plan 2011 The goal of the plan is to protect the environmental health and the natural and scenic resources of Lake Hopatcong/Musconetcong River System, maximize recreational opportunities, minimize the potential for damage to property and waterfront structures, while maintaining the minimum flow requirements necessary to protect downstream uses, including but not necessarily limited to: aquatic biota, historic resources and water quality.  Each year the NJ DEP Division of Parks and Forestry - State Park Service follows procedures to to manage the level of Lake Hopatcong.  However, the annual precipitation does effect the raising or lowering of the lake.  A gage to monitor the precipitation is also funded by the NJ DEP through a USGS agreement.

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When is the lake lowered in the fall and raised in the spring?

Both the 26 inch annual drawdown and the 60 inch (five foot) drawdown dates will vary depending on the water level.  See the Lake Hopatcong Water Level Management Plan 2011 for dates. 

The 26 inch annual drawdown begins on or after November 12 except when the 60 inch drawdown occurs every fifth year.  Starting in late winter or early spring, depending on when the ice breaks away from the docks, rainfall is allowed to raise the lake level.

The 60 inch (five foot) drawdown is scheduled every five years and begins on or after September 22.    During the 60 inch drawdown from December through February, when ice conditions permit, the lake is allowed to rise but not higher than the 26 inches below the spillway elevation.  The next 60 inch drawdown is scheduled for September 2013.

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What determines if there is a "SLOW SPEED - NO WAKE" restriction on Lake Hopatcong?

The water level determines when there is a "SLOW SPEED - NO WAKE" restriction on the Lake.   This "SLOW SPEED - NO WAKE" restriction shall exist until the water level recedes below a measurement of 9.50 as gauged from the dam at the Hopatcong State Park.  "SLOW SPEED- NO WAKE" is defined as minimal speed to make headway in a the prevailing conditions.  The New Jersey State Police enforce all Lake Hopatcong boating regulations

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Crest of Dam/Spillway at Hopatcong State Park flowing into Musconetcong River - Fall, 2003 (60 inch drawdown)

Lake level reading of 9.00 feet on the Lake Hopatcong gage is 923.70 feet above mean sea level or the top of the spillway.

Crest of Dam/Spillway at Hopatcong State Park from Lake Hopatcong - Fall, 2003 (60 inch drawdown)

 
Revised: 03/01/13.